Nanomaterials

13 pages, 3513 KiB

Open AccessEditor’s ChoiceArticle

Amorphous Fe₂O₃ Anchored on N-Doped Graphene with Internal Micro-Channels as an Active and Durable Anode for Sodium-Ion Batteries

by Lin Li, Hui Li, Linxin Liu, Xunchang Yan, Yunze Long and Wenpeng Han

Nanomaterials 2024, 14(11), 937; https://doi.org/10.3390/nano14110937 - 27 May 2024

Viewed by 525

Abstract

The reduced graphene oxide (rGO) exhibits outstanding electrical conductivity and a high specific surface area, making it a promising material for various applications. Fe₂O₃ is highly desirable due to its significant theoretical capacity and cost-effectiveness, high abundance, and environmental friendliness. [...] Read more.

The reduced graphene oxide (rGO) exhibits outstanding electrical conductivity and a high specific surface area, making it a promising material for various applications. Fe₂O₃ is highly desirable due to its significant theoretical capacity and cost-effectiveness, high abundance, and environmental friendliness. However, the performance of these r-GO/Fe₂O₃ composite electrodes still needs to be further improved, especially in terms of cycle stability. The composite of Fe₂O₃ anchored on N-doped graphene with inside micro-channels (Fe₂O₃@N-GIMC) was used to be efficiently prepared. Because the inside channels can furnish extra transmission pathways and absorption websites and the interconnected structure can efficaciously forestall pulverization and aggregation of electrode materials. In addition, N do** is also beneficial to improve its electrochemical performance. Thus, it demonstrates exceptional sodium storage characteristics, including notable electrochemical activity, impressive initial Coulombic efficiency, and favorable rate performance. The optimized Fe₂O₃@N-GIMC indicates outstanding discharge capacity (573.5 mAh g⁻¹ at 1 A g⁻¹), significant rate performance (333.6 mAh g⁻¹ at 8 A g⁻¹), and stable long-term cycle durability (308.9 mAh g⁻¹ after 1000 cycles at 1 A g⁻¹, 200.8 mAh g⁻¹ after 4000 cycles at 1 A g⁻¹) as a sodium-ion battery anode. This presents a new approach for preparing graphene-based high-functional composites and lays a stable basis for further expanding its application field. Full article

(This article belongs to the Special Issue Synthesis & Devices of Graphene-Based 2D Nanomaterials for Energy Storage and Conversion)

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25 pages, 6668 KiB

Open AccessEditor’s ChoiceArticle

Two-Dimensional MoS₂ Nanosheets Derived from Cathodic Exfoliation for Lithium Storage Applications

by Alberto Martínez-Jódar, Silvia Villar-Rodil, José M. Munuera, Alberto Castro-Muñiz, Jonathan N. Coleman, Encarnación Raymundo-Piñero and Juan I. Paredes

Nanomaterials 2024, 14(11), 932; https://doi.org/10.3390/nano14110932 - 25 May 2024

Viewed by 483

Abstract

The preparation of 2H-phase MoS₂ thin nanosheets by electrochemical delamination remains a challenge, despite numerous efforts in this direction. In this work, by choosing appropriate intercalating cations for cathodic delamination, the insertion process was facilitated, leading to a higher degree of exfoliation [...] Read more.

The preparation of 2H-phase MoS₂ thin nanosheets by electrochemical delamination remains a challenge, despite numerous efforts in this direction. In this work, by choosing appropriate intercalating cations for cathodic delamination, the insertion process was facilitated, leading to a higher degree of exfoliation while maintaining the original 2H-phase of the starting bulk MoS₂ material. Specifically, trimethylalkylammonium cations were tested as electrolytes, outperforming their bulkier tetraalkylammonium counterparts, which have been the focus of past studies. The performance of novel electrochemically derived 2H-phase MoS₂ nanosheets as electrode material for electrochemical energy storage in lithium-ion batteries was investigated. The lower thickness and thus higher flexibility of cathodically exfoliated MoS₂ promoted better electrochemical performance compared to liquid-phase and ultrasonically assisted exfoliated MoS₂, both in terms of capacity (447 vs. 371 mA·h·g⁻¹ at 0.2 A·g⁻¹) and rate capability (30% vs. 8% capacity retained when the current density was increased from 0.2 A·g⁻¹ to 5 A·g⁻¹), as well as cycle life (44% vs. 17% capacity retention at 0.2 A·g⁻¹ after 580 cycles). Overall, the present work provides a convenient route for obtaining MoS₂ thin nanosheets for their advantageous use as anode material for lithium storage. Full article

(This article belongs to the Section 2D and Carbon Nanomaterials)

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20 pages, 18539 KiB

Open AccessEditor’s ChoiceReview

Nanostructured Flame-Retardant Layer-by-Layer Architectures for Cotton Fabrics: The Current State of the Art and Perspectives

by Giulio Malucelli

Nanomaterials 2024, 14(10), 858; https://doi.org/10.3390/nano14100858 - 15 May 2024

Viewed by 810

Abstract

Nowadays, nanotechnology represents a well-established approach, suitable for designing, producing, and applying materials to a broad range of advanced sectors. In this context, the use of well-suited “nano” approaches accounted for a big step forward in conferring optimized flame-retardant features to such a [...] Read more.

Nowadays, nanotechnology represents a well-established approach, suitable for designing, producing, and applying materials to a broad range of advanced sectors. In this context, the use of well-suited “nano” approaches accounted for a big step forward in conferring optimized flame-retardant features to such a cellulosic textile material as cotton, considering its high ease of flammability, yearly production, and extended use. Being a surface-localized phenomenon, the flammability of cotton can be quite simply and effectively controlled by tailoring its surface through the deposition of nano-objects, capable of slowing down the heat and mass transfer from and to the textile surroundings, which accounts for flame fueling and possibly interacting with the propagating radicals in the gas phase. In this context, the layer-by-layer (LbL) approach has definitively demonstrated its reliability and effectiveness in providing cotton with enhanced flame-retardant features, through the formation of fully inorganic or hybrid organic/inorganic nanostructured assemblies on the fabric surface. Therefore, the present work aims to summarize the current state of the art related to the use of nanostructured LbL architectures for cotton flame retardancy, offering an overview of the latest research outcomes that often highlight the multifunctional character of the deposited assemblies and discussing the current limitations and some perspectives. Full article

(This article belongs to the Special Issue Nanomaterials and Textiles)

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18 pages, 5879 KiB

Open AccessEditor’s ChoiceArticle

Study on Microstructure and Tribological Mechanism of Mo Incorporated (AlCrTiZr)N High-Entropy Ceramics Coatings Prepared by Magnetron Sputtering

by Jia Zheng, Yiman Zhao, **gchuan Li, Sam Zhang, Jian Zhang and Deen Sun

Nanomaterials 2024, 14(10), 814; https://doi.org/10.3390/nano14100814 - 7 May 2024

Viewed by 645

Abstract

(AlCrTiZrMo_x)N coatings with varying Mo content were successfully prepared using a multi-target co-deposition magnetron sputtering system. The results reveal that the Mo content significantly affects the microstructure, hardness, fracture toughness, and tribological behavior of the coatings. As the Mo content in [...] Read more.

(AlCrTiZrMo_x)N coatings with varying Mo content were successfully prepared using a multi-target co-deposition magnetron sputtering system. The results reveal that the Mo content significantly affects the microstructure, hardness, fracture toughness, and tribological behavior of the coatings. As the Mo content in the coatings increases gradually, the preferred orientation changes from (200) to (111). The coatings consistently exhibit a distinct columnar structure. Additionally, the hardness of the coatings increases from 24.39 to 30.24 GPa, along with an increase in fracture toughness. The friction coefficient is reduced from 0.72 to 0.26, and the wear rate is reduced by 10 times. During the friction process, the inter-column regions of the coatings are initially damaged, causing the wear track to exhibit a wavy pattern. Greater frictional heat is generated at the crest of the wave, resulting in the formation of a MoO₂ lubricating layer. The friction reaction helps to reduce the shear force during friction, demonstrating the lower friction coefficient of the (AlCrTiZrMo_x)N coatings. Both the hardness and fracture toughness work together to reduce the wear rate, and the (AlCrTiZrMo_x)N coatings show excellent wear resistance. Most notably, although the columnar structure plays a negative role in the hardness, it contributes greatly to the wear resistance. Full article

(This article belongs to the Special Issue Thin-Film Processing and Deposition Techniques)

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15 pages, 8158 KiB

Open AccessEditor’s ChoiceArticle

Repeated Injection of Very Small Superparamagnetic Iron Oxide Particles (VSOPs) in Murine Atherosclerosis: A Safety Study

by Tobias Haase, Antje Ludwig, Anke Stach, Azadeh Mohtashamdolatshahi, Ralf Hauptmann, Lars Mundhenk, Harald Kratz, Susanne Metzkow, Avan Kader, Christian Freise, Susanne Mueller, Nicola Stolzenburg, Patricia Radon, Maik Liebl, Frank Wiekhorst, Bernd Hamm, Matthias Taupitz and Jörg Schnorr

Nanomaterials 2024, 14(9), 773; https://doi.org/10.3390/nano14090773 - 28 Apr 2024

Viewed by 954

Abstract

Citrate-coated electrostatically stabilized very small superparamagnetic iron oxide particles (VSOPs) have been successfully tested as magnetic resonance angiography (MRA) contrast agents and are promising tools for molecular imaging of atherosclerosis. Their repeated use in the background of pre-existing hyperlipidemia and atherosclerosis has not [...] Read more.

Citrate-coated electrostatically stabilized very small superparamagnetic iron oxide particles (VSOPs) have been successfully tested as magnetic resonance angiography (MRA) contrast agents and are promising tools for molecular imaging of atherosclerosis. Their repeated use in the background of pre-existing hyperlipidemia and atherosclerosis has not yet been studied. This study aimed to investigate the effect of multiple intravenous injections of VSOPs in atherosclerotic mice. Taurine-formulated VSOPs (VSOP-T) were repeatedly intravenously injected at 100 µmol Fe/kg in apolipoprotein E-deficient (ApoE KO) mice with diet-induced atherosclerosis. Angiographic imaging was carried out by in vivo MRI. Magnetic particle spectrometry was used to detect tissue VSOP content, and tissue iron content was quantified photometrically. Pathological changes in organs, atherosclerotic plaque development, and expression of hepatic iron-related proteins were evaluated. VSOP-T enabled the angiographic imaging of heart and blood vessels with a blood half-life of one hour. Repeated intravenous injection led to VSOP deposition and iron accumulation in the liver and spleen without affecting liver and spleen pathology, expression of hepatic iron metabolism proteins, serum lipids, or atherosclerotic lesion formation. Repeated injections of VSOP-T doses sufficient for MRA analyses had no significant effects on plaque burden, steatohepatitis, and iron homeostasis in atherosclerotic mice. These findings underscore the safety of VSOP-T and support its further development as a contrast agent and molecular imaging tool. Full article

(This article belongs to the Special Issue Advances in Nanotoxicology: Health and Safety)

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18 pages, 3872 KiB

Open AccessEditor’s ChoiceArticle

Biopolymer Meets Nanoclay: Rational Fabrication of Superb Adsorption Beads from Green Precursors for Efficient Capture of Pb(II) and Dyes

by Jie Qi, Xue Wang, Huan Zhang, **angyu Liu, Wenbo Wang, Qingdong He and Fang Guo

Nanomaterials 2024, 14(9), 766; https://doi.org/10.3390/nano14090766 - 26 Apr 2024

Viewed by 812

Abstract

Renewable, green, and safe natural biopolymer-derived materials are highly desired for the purification of pollutants, but significantly improving their performance without the introduction of additional harmful chemicals remains a huge challenge. Based on the concept of “structure optimization design”, environment-friendly composite beads (named [...] Read more.

Renewable, green, and safe natural biopolymer-derived materials are highly desired for the purification of pollutants, but significantly improving their performance without the introduction of additional harmful chemicals remains a huge challenge. Based on the concept of “structure optimization design”, environment-friendly composite beads (named SA/PASP/RE) with excellent adsorption performance and recyclability were rationally constructed through a green ionic crosslinking route, using the completely green biopolymer sodium alginate (SA), sodium salt of polyaspartic acid (PASP), and the natural nanoclay rectorite (RE) as starting materials. The nano-layered RE was embedded in the polymer matrix to prevent the polymer chain from becoming over-entangled so that more adsorption sites inside the polymer network were exposed, which effectively improved the mass transfer efficiency of the adsorbent and the removal rate of contaminants. The composite beads embedded with 0.6% RE showed high adsorption capacities of 211.78, 197.13, and 195.69 mg/g for Pb(II) and 643.00, 577.80, and 567.10 mg/g for methylene blue (MB) in Yellow River water, Yangtze River water, and tap water, respectively. And the beads embedded with 43% RE could efficiently adsorb Pb(II) and MB with high capacities of 187.78 mg/g and 586.46 mg/g, respectively. This study provides a new route to design and develop a green, cost-effective, and efficient adsorbent for the decontamination of wastewater. Full article

(This article belongs to the Special Issue Novel Nanostructured Materials and Their Applications in Wastewater Treatment)

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12 pages, 6290 KiB

Open AccessEditor’s ChoiceArticle

Development of Au Nanoparticle Two-Dimensional Assemblies Dispersed with Au Nanoparticle-Nanostar Complexes and Surface-Enhanced Raman Scattering Activity

by Kosuke Sugawa, Kaichi Ono, Ritsurai Tomii, Yuka Hori, Yu Aoki, Koki Honma, Kaoru Tamada and Joe Otsuki

Nanomaterials 2024, 14(9), 764; https://doi.org/10.3390/nano14090764 - 26 Apr 2024

Viewed by 947

Abstract

We recently found that polyvinylpyrrolidone (PVP)-protected metal nanoparticles dispersed in water/butanol mixture spontaneously float to the air/water interface and form two-dimensional assemblies due to classical surface excess theory and Rayleigh–Bénard–Marangoni convection induced by butanol evaporation. In this study, we found that by leveraging [...] Read more.

We recently found that polyvinylpyrrolidone (PVP)-protected metal nanoparticles dispersed in water/butanol mixture spontaneously float to the air/water interface and form two-dimensional assemblies due to classical surface excess theory and Rayleigh–Bénard–Marangoni convection induced by butanol evaporation. In this study, we found that by leveraging this principle, a unique structure is formed where hetero gold nanospheres (AuNPs)/gold nanostars (AuNSs) complexes are dispersed within AuNP two-dimensional assemblies, obtained from a mixture of polyvinylpyrrolidone-protected AuNPs and AuNSs that interact electrostatically with the AuNPs. These structures were believed to form as a result of AuNPs/AuNSs complexes formed in the water/butanol mixture floating to the air/water interface and being incorporated into the growth of AuNP two-dimensional assemblies. These structures were obtained by optimizing the amount of mixed AuNSs, with excessive addition resulting in the formation of random three-dimensional network structures. The AuNP assemblies dispersed with AuNPs/AuNSs complexes exhibited significantly higher Raman (surface-enhanced resonance Raman scattering: SERRS) activity compared to simple AuNP assemblies, while the three-dimensional network structure did not show significant SERRS activity enhancement. These results demonstrate the excellent SERRS activity of AuNP two-dimensional assemblies dispersed with hetero AuNPs/AuNSs complexes. Full article

(This article belongs to the Section Nanofabrication and Nanomanufacturing)

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13 pages, 3436 KiB

Open AccessEditor’s ChoiceArticle

Additive Manufacturing of Electrically Conductive Multi-Layered Nanocopper in an Air Environment

by David Pervan, Anil Bastola, Robyn Worsley, Ricky Wildman, Richard Hague, Edward Lester and Christopher Tuck

Nanomaterials 2024, 14(9), 753; https://doi.org/10.3390/nano14090753 - 25 Apr 2024

Viewed by 731

Abstract

The additive manufacturing (AM) of functional copper (Cu) parts is a major goal for many industries, from aerospace to automotive to electronics, because Cu has a high thermal and electrical conductivity as well as being ~10× cheaper than silver. Previous studies on AM [...] Read more.

The additive manufacturing (AM) of functional copper (Cu) parts is a major goal for many industries, from aerospace to automotive to electronics, because Cu has a high thermal and electrical conductivity as well as being ~10× cheaper than silver. Previous studies on AM of Cu have concentrated mainly on high-energy manufacturing processes such as Laser Powder Bed Fusion, Electron Beam Melting, and Binder Jetting. These processes all require high-temperature heat treatment in an oxygen-free environment. This paper shows an AM route to multi-layered microparts from novel nanoparticle (NP) Cu feedstocks, performed in an air environment, employing a low-power (<10 W) laser sintering process. Cu NP ink was deposited using two mechanisms, inkjet printing, and bar coating, followed by low-power laser exposure to induce particle consolidation. Initial parts were manufactured to a height of approximately 100 µm, which was achieved by multi-layer printing of 15 (bar-coated) to 300 (inkjetted) layers. There was no evidence of oxidised copper in the sintered material, but they were found to be low-density, porous structures. Nonetheless, electrical resistivity of ~28 × 10⁻⁸ Ω m was achieved. Overall, the aim of this study is to offer foundational knowledge for upscaling the process to additively manufacture Cu 3D parts of significant size via sequential nanometal ink deposition and low-power laser processing. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: New Trends in Inorganic Nanoparticles and Composites from Preparation to Applications)

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18 pages, 6275 KiB

Open AccessEditor’s ChoiceArticle

The Influence of the Mechanical Compliance of a Substrate on the Morphology of Nanoporous Gold Thin Films

by Sadi Shahriar, Kavya Somayajula, Conner Winkeljohn, Jeremy K. Mason and Erkin Seker

Nanomaterials 2024, 14(9), 758; https://doi.org/10.3390/nano14090758 - 25 Apr 2024

Viewed by 942

Abstract

Nanoporous gold (np-Au) has found its use in applications ranging from catalysis to biosensing, where pore morphology plays a critical role in performance. While the morphology evolution of bulk np-Au has been widely studied, knowledge about its thin-film form is limited. This work [...] Read more.

Nanoporous gold (np-Au) has found its use in applications ranging from catalysis to biosensing, where pore morphology plays a critical role in performance. While the morphology evolution of bulk np-Au has been widely studied, knowledge about its thin-film form is limited. This work hypothesizes that the mechanical compliance of the thin film substrate can play a critical role in the morphology evolution. Via experimental and finite-element-analysis approaches, we investigate the morphological variation in np-Au thin films deposited on compliant silicone (PDMS) substrates of a range of thicknesses anchored on rigid glass supports and compare those to the morphology of np-Au deposited on glass. More macroscopic (10 s to 100 s of microns) cracks and discrete islands form in the np-Au films on PDMS compared to on glass. Conversely, uniformly distributed microscopic (100 s of nanometers) cracks form in greater numbers in the np-Au films on glass than those on PDMS, with the cracks located within the discrete islands. The np-Au films on glass also show larger ligament and pore sizes, possibly due to higher residual stresses compared to the np-Au/PDMS films. The effective elastic modulus of the substrate layers decreases with increasing PDMS thickness, resulting in secondary np-Au morphology effects, including a reduction in macroscopic crack-to-crack distance, an increase in microscopic crack coverage, and a widening of the microscopic cracks. However, changes in the ligament/pore widths with PDMS thickness are negligible, allowing for independent optimization for cracking. We expect these results to inform the integration of functional np-Au films on compliant substrates into emerging applications, including flexible electronics. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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34 pages, 15745 KiB

Open AccessEditor’s ChoiceArticle

A Systematic Genotoxicity Assessment of a Suite of Metal Oxide Nanoparticles Reveals Their DNA Damaging and Clastogenic Potential

by Silvia Aidee Solorio-Rodriguez, Dongmei Wu, Andrey Boyadzhiev, Callum Christ, Andrew Williams and Sabina Halappanavar

Nanomaterials 2024, 14(9), 743; https://doi.org/10.3390/nano14090743 - 24 Apr 2024

Viewed by 891

Abstract

Metal oxide nanoparticles (MONP/s) induce DNA damage, which is influenced by their physicochemical properties. In this study, the high-throughput CometChip and micronucleus (MicroFlow) assays were used to investigate DNA and chromosomal damage in mouse lung epithelial cells induced by nano and bulk sizes [...] Read more.

Metal oxide nanoparticles (MONP/s) induce DNA damage, which is influenced by their physicochemical properties. In this study, the high-throughput CometChip and micronucleus (MicroFlow) assays were used to investigate DNA and chromosomal damage in mouse lung epithelial cells induced by nano and bulk sizes of zinc oxide, copper oxide, manganese oxide, nickel oxide, aluminum oxide, cerium oxide, titanium dioxide, and iron oxide. Ionic forms of MONPs were also included. The study evaluated the impact of solubility, surface coating, and particle size on response. Correlation analysis showed that solubility in the cell culture medium was positively associated with response in both assays, with the nano form showing the same or higher response than larger particles. A subtle reduction in DNA damage response was observed post-exposure to some surface-coated MONPs. The observed difference in genotoxicity highlighted the mechanistic differences in the MONP-induced response, possibly influenced by both particle stability and chemical composition. The results highlight that combinations of properties influence response to MONPs and that solubility alone, while playing an important role, is not enough to explain the observed toxicity. The results have implications on the potential application of read-across strategies in support of human health risk assessment of MONPs. Full article

(This article belongs to the Special Issue New Approach Methodologies for the Toxicity Assessment of Nanomaterials)

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21 pages, 2238 KiB

Open AccessEditor’s ChoiceSystematic Review

In Vitro Toxicological Insights from the Biomedical Applications of Iron Carbide Nanoparticles in Tumor Theranostics: A Systematic Review and Meta-Analysis

by Maria Antoniou, Georgia Melagraki, Iseult Lynch and Antreas Afantitis

Nanomaterials 2024, 14(9), 734; https://doi.org/10.3390/nano14090734 - 23 Apr 2024

Viewed by 869

Abstract

(1) Background: Despite the encouraging indications regarding the suitability (biocompatibility) of iron carbide nanoparticles (ICNPs) in various biomedical applications, the published evidence of their biosafety is dispersed and relatively sparse. The present review synthesizes the existing nanotoxicological data from in vitro studies relevant [...] Read more.

(1) Background: Despite the encouraging indications regarding the suitability (biocompatibility) of iron carbide nanoparticles (ICNPs) in various biomedical applications, the published evidence of their biosafety is dispersed and relatively sparse. The present review synthesizes the existing nanotoxicological data from in vitro studies relevant to the diagnosis and treatment of cancer. (2) Methods: A systematic review was performed in electronic databases (PubMed, Scopus, and Wiley Online Library) on December 2023, searching for toxicity assessments of ICNPs of different sizes, coatings, and surface modifications investigated in immortalized human and murine cell lines. The risk of bias in the studies was assessed using the ToxRTool for in vitro studies. (3) Results: Among the selected studies (n = 22), cell viability emerged as the most frequently assessed cellular-level toxicity endpoint. The results of the meta-analysis showed that cell models treated with ICNPs had a reduced cell viability (SMD = −2.531; 95% CI: −2.959 to −2.109) compared to untreated samples. A subgroup analysis was performed due to the high magnitude of heterogeneity (I² = 77.1%), revealing that ICNP concentration and conjugated ligands are the factors that largely influence toxicity (p < 0.001). (4) Conclusions: A dose-dependent cytotoxicity of ICNP exposure was observed, regardless of the health status of the cell, tested organism, and NP size. Inconsistent reporting of ICNP physicochemical properties was noted, which hinders comparability among the studies. A comprehensive exploration of the available in vivo studies is required in future research to assess the safety of ICNPs’ use in bioimaging and cancer treatment. Full article

(This article belongs to the Special Issue New Approach Methodologies for the Toxicity Assessment of Nanomaterials)

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12 pages, 1508 KiB

Open AccessEditor’s ChoiceArticle

Heteropolyacids@Silica Heterogeneous Catalysts to Produce Solketal from Glycerol Acetalization

by Catarina N. Dias, Isabel C. M. S. Santos-Vieira, Carlos R. Gomes, Fátima Mirante and Salete S. Balula

Nanomaterials 2024, 14(9), 733; https://doi.org/10.3390/nano14090733 - 23 Apr 2024

Viewed by 772

Abstract

The composites of heteropolyacids (H₃PW₁₂, H₃PMo₁₂) incorporated into amine-functionalized silica materials were used for the first time as heterogeneous catalysts in the valorization of glycerol (a major waste from the biodiesel industry) through acetalization reaction [...] Read more.

The composites of heteropolyacids (H₃PW₁₂, H₃PMo₁₂) incorporated into amine-functionalized silica materials were used for the first time as heterogeneous catalysts in the valorization of glycerol (a major waste from the biodiesel industry) through acetalization reaction with acetone. The polyoxotungstate catalyst H₃PW₁₂@AptesSBA-15 exhibited higher catalytic efficiency than the phosphomolybdate, achieving 97% conversion and 97% of solketal selectivity, after 60 min at 25 °C, or 91% glycerol conversion and the same selectivity, after 5 min, performing the reaction at 60 °C. A correlation between catalytic performance and catalyst acidity is presented here. Furthermore, the stability of the solid catalyst was investigated and discussed. Full article

(This article belongs to the Special Issue Recent Developments in Nanochemistry for Heterogeneous Catalysis Advancements (2nd Edition))

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15 pages, 11880 KiB

Open AccessEditor’s ChoiceArticle

Epitaxial Growth of GaN Films on Chemical-Vapor-Deposited 2D MoS₂ Layers by Plasma-Assisted Molecular Beam Epitaxy

by Iwan Susanto, Hong-Shan Liu, Yen-Ten Ho and Ing-Song Yu

Nanomaterials 2024, 14(8), 732; https://doi.org/10.3390/nano14080732 - 22 Apr 2024

Viewed by 1020

Abstract

The van der Waals epitaxy of wafer-scale GaN on 2D MoS₂ and the integration of GaN/MoS₂ heterostructures were investigated in this report. GaN films have been successfully grown on 2D MoS₂ layers using three different Ga fluxes via a plasma-assisted [...] Read more.

The van der Waals epitaxy of wafer-scale GaN on 2D MoS₂ and the integration of GaN/MoS₂ heterostructures were investigated in this report. GaN films have been successfully grown on 2D MoS₂ layers using three different Ga fluxes via a plasma-assisted molecular beam epitaxy (PA-MBE) system. The substrate for the growth was a few-layer 2D MoS₂ deposited on sapphire using chemical vapor deposition (CVD). Three different Ga fluxes were provided by the gallium source of the K-cell at temperatures of 825, 875, and 925 °C, respectively. After the growth, RHEED, HR-XRD, and TEM were conducted to study the crystal structure of GaN films. The surface morphology was obtained using FE-SEM and AFM. Chemical composition was confirmed by XPS and EDS. Raman and PL spectra were carried out to investigate the optical properties of GaN films. According to the characterizations of GaN films, the van der Waals epitaxial growth mechanism of GaN films changed from 3D to 2D with the increase in Ga flux, provided by higher temperatures of the K-cell. GaN films grown at 750 °C for 3 h with a K-cell temperature of 925 °C demonstrated the greatest crystal quality, chemical composition, and optical properties. The heterostructure of 3D GaN on 2D MoS₂ was integrated successfully using the low-temperature PA-MBE technique, which could be applied to novel electronics and optoelectronics. Full article

(This article belongs to the Special Issue III-Nitride Semiconductors: Design, Characterization, Applications, and Devices)

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10 pages, 3353 KiB

Open AccessEditor’s ChoiceCommunication

Photoelectric Properties of GaS_1−xSe_x (0 ≤ x ≤ 1) Layered Crystals

by Yu-Tai Shih, Der-Yuh Lin, Bo-Chang Tseng, Ting-Chen Huang, Yee-Mou Kao, Ming-Cheng Kao and Sheng-Beng Hwang

Nanomaterials 2024, 14(8), 701; https://doi.org/10.3390/nano14080701 - 18 Apr 2024

Viewed by 848

Abstract

In this study, the photoelectric properties of a complete series of GaS_1−xSe_x (0 ≤ x ≤ 1) layered crystals are investigated. The photoconductivity spectra indicate a decreasing bandgap of GaS_1−xSe_x as the Se composition x [...] Read more.

In this study, the photoelectric properties of a complete series of GaS_1−xSe_x (0 ≤ x ≤ 1) layered crystals are investigated. The photoconductivity spectra indicate a decreasing bandgap of GaS_1−xSe_x as the Se composition x increases. Time-resolved photocurrent measurements reveal a significant improvement in the response of GaS_1−xSe_x to light with increasing x. Frequency-dependent photocurrent measurements demonstrate that both pure GaS crystals and GaS_1−xSe_x ternary alloy crystals exhibit a rapid decrease in photocurrents with increasing illumination frequency. Crystals with lower x exhibit a faster decrease in photocurrent. However, pure GaSe crystal maintains its photocurrent significantly even at high frequencies. Measurements for laser-power-dependent photoresponsivity and bias-voltage-dependent photoresponsivity also indicate an increase in the photoresponsivity of GaS_1−xSe_x as x increases. Overall, the photoresponsive performance of GaS_1−xSe_x is enhanced with increasing x, and pure GaSe exhibits the best performance. This result contradicts the findings of previous reports. Additionally, the inverse trends between bandgap and photoresponsivity with increasing x suggest that GaS_1−xSe_x-based photodetectors could potentially offer a high response and wavelength-selectivity for UV and visible light detection. Thus, this work provides novel insights into the photoelectric characteristics of GaS_1−xSe_x layered crystals and highlights their potential for optoelectronic applications. Full article

(This article belongs to the Special Issue 2D Materials and van der Waals Heterostructures for Optoelectronic Devices)

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25 pages, 6943 KiB

Open AccessEditor’s ChoiceArticle

Dependence of the Structural and Magnetic Properties on the Growth Sequence in Heterostructures Designed by YbFeO₃ and BaFe₁₂O₁₉

by Sondes Bauer, Berkin Nergis, **aowei **, Reinhard Schneider, Di Wang, Christian Kübel, Petr Machovec, Lukas Horak, Vaclav Holy, Klaus Seemann, Tilo Baumbach and Sven Ulrich

Nanomaterials 2024, 14(8), 711; https://doi.org/10.3390/nano14080711 - 18 Apr 2024

Cited by 1 | Viewed by 708

Abstract

The structure and the chemical composition of individual layers as well as of interfaces belonging to the two heterostructures M1 (BaFe₁₂O₁₉/YbFeO₃/YSZ) and M2 (YbFeO₃/BaFe₁₂O₁₉/YSZ) grown by pulsed laser deposition on yttria-stabilized [...] Read more.

The structure and the chemical composition of individual layers as well as of interfaces belonging to the two heterostructures M1 (BaFe₁₂O₁₉/YbFeO₃/YSZ) and M2 (YbFeO₃/BaFe₁₂O₁₉/YSZ) grown by pulsed laser deposition on yttria-stabilized zirconia (YSZ) substrates are deeply characterized by using a combination of methods such as high-resolution X-ray diffraction, transmission electron microscopy (TEM), and atomic-resolution scanning TEM with energy-dispersive X-ray spectroscopy. The temperature-dependent magnetic properties demonstrate two distinct heterostructures with different coercivity, anisotropy fields, and first anisotropy constants, which are related to the defect concentrations within the individual layers and to the degree of intermixing at the interface. The heterostructure with the stacking order BaFe₁₂O₁₉/YbFeO₃, i.e., M1, exhibits a distinctive interface without any chemical intermixture, while an Fe-rich crystalline phase is observed in M2 both in atomic-resolution EDX maps and in mass density profiles. Additionally, M1 shows high c-axis orientation, which induces a higher anisotropy constant K1 as well as a larger coercivity due to a high number of phase boundaries. Despite the existence of a canted antiferromagnetic/ferromagnetic combination (T < 140 K), both heterostructures M1 and M2 do not reveal any detectable exchange bias at T = 50 K. Additionally, compressive residual strain on the BaM layer is found to be suppressing the ferromagnetism, thus reducing the Curie temperature (Tc) in the case of M1. These findings suggest that M1 (BaFe₁₂O₁₉/YbFeO₃/YSZ) is suitable for magnetic storage applications. Full article

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24 pages, 4642 KiB

Open AccessEditor’s ChoiceArticle

Electrochemical Detection of Cd²⁺, Pb²⁺, Cu²⁺ and Hg²⁺ with Sensors Based on Carbonaceous Nanomaterials and Fe₃O₄ Nanoparticles

by Ancuța Dinu (Iacob), Alexandra Virginia Bounegru, Catalina Iticescu, Lucian P. Georgescu and Constantin Apetrei

Nanomaterials 2024, 14(8), 702; https://doi.org/10.3390/nano14080702 - 18 Apr 2024

Viewed by 931

Abstract

Two electrochemical sensors were developed in this study, with their preparations using two nanomaterials with remarkable properties, namely, carbon nanofibers (CNF) modified with Fe₃O₄ nanoparticles and multilayer carbon nanotubes (MWCNT) modified with Fe₃O₄ nanoparticles. The modified screen-printed [...] Read more.

Two electrochemical sensors were developed in this study, with their preparations using two nanomaterials with remarkable properties, namely, carbon nanofibers (CNF) modified with Fe₃O₄ nanoparticles and multilayer carbon nanotubes (MWCNT) modified with Fe₃O₄ nanoparticles. The modified screen-printed electrodes (SPE) were thus named SPE/Fe₃O₄-CNF and SPE/Fe₃O₄-MWCNT and were used for the simultaneous detection of heavy metals (Cd²⁺, Pb²⁺, Cu²⁺ and Hg²⁺). The sensors have been spectrometrically and electrochemically characterized. The limits of detection of the SPE/Fe₃O₄-CNF sensor were 0.0615 μM, 0.0154 μM, 0.0320 μM and 0.0148 μM for Cd²⁺, Pb²⁺, Cu²⁺ and Hg²⁺, respectively, and 0.2719 μM, 0.3187 μM, 1.0436 μM and 0.9076 μM in the case of the SPE/ Fe₃O₄-MWCNT sensor (following optimization of the working parameters). Due to the modifying material, the results showed superior performance for the SPE/Fe₃O₄-CNF sensor, with extended linearity ranges and detection limits in the nanomolar range, compared to those of the SPE/Fe₃O₄-MWCNT sensor. For the quantification of heavy metal ions Cd²⁺, Pb²⁺, Cu²⁺ and Hg²⁺ with the SPE/Fe₃O₄-CNF sensor from real samples, the standard addition method was used because the values obtained for the recovery tests were good. The analysis of surface water samples from the Danube River has shown that the obtained values are significantly lower than the maximum limits allowed according to the quality standards specified by the United States Environmental Protection Agency (USEPA) and those of the World Health Organization (WHO). This research provides a complementary method based on electrochemical sensors for in situ monitoring of surface water quality, representing a useful tool in environmental studies. Full article

(This article belongs to the Special Issue Nanostructured Materials for the Assay of Organic/Inorganic Water Pollutants)

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20 pages, 1087 KiB

Open AccessEditor’s ChoiceArticle

Pump-Driven Opto-Magnetic Properties in Semiconducting Transition-Metal Dichalcogenides: An Analytical Model

by Habib Rostami, Federico Cilento and Emmanuele Cappelluti

Nanomaterials 2024, 14(8), 707; https://doi.org/10.3390/nano14080707 - 18 Apr 2024

Viewed by 668

Abstract

Single-layer transition-metal dichalcogenides provide an unique intrinsic entanglement between the spin/valley/orbital degrees of freedom and the polarization of scattered photons. This scenario gives rise to the well-assessed optical dichroism observed by using both steady and time-resolved probes. In this paper, we provide compact [...] Read more.

Single-layer transition-metal dichalcogenides provide an unique intrinsic entanglement between the spin/valley/orbital degrees of freedom and the polarization of scattered photons. This scenario gives rise to the well-assessed optical dichroism observed by using both steady and time-resolved probes. In this paper, we provide compact analytical modeling of the onset of a finite Faraday/Kerr optical rotation upon shining with circularly polarized light. We identify different optical features displaying optical rotation at different characteristic energies, and we describe in an analytical framework the time-dependence of their intensities as a consequence of the main spin-conserving and spin-flip processes. Full article

(This article belongs to the Special Issue Superconductivity and Magnetism in Two-Dimensional and Layered Materials)

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19 pages, 10539 KiB

Open AccessEditor’s ChoiceArticle

Elastic Liposomes Containing Calcium/Magnesium Ferrite Nanoparticles Coupled with Gold Nanorods for Application in Photothermal Therapy

by Ana Rita F. Pacheco, Ana Margarida Barros, Carlos O. Amorim, Vítor S. Amaral, Paulo J. G. Coutinho, Ana Rita O. Rodrigues and Elisabete M. S. Castanheira

Nanomaterials 2024, 14(8), 679; https://doi.org/10.3390/nano14080679 - 15 Apr 2024

Viewed by 870

Abstract

This work reports on the design, development, and characterization of novel magneto-plasmonic elastic liposomes (MPELs) of DPPC:SP80 (85:15) containing Mg_0.75Ca_0.25Fe₂O₄ nanoparticles coupled with gold nanorods, for topical application of photothermal therapy (PTT). Both magnetic and plasmonic [...] Read more.

This work reports on the design, development, and characterization of novel magneto-plasmonic elastic liposomes (MPELs) of DPPC:SP80 (85:15) containing Mg_0.75Ca_0.25Fe₂O₄ nanoparticles coupled with gold nanorods, for topical application of photothermal therapy (PTT). Both magnetic and plasmonic components were characterized regarding their structural, morphological, magnetic and photothermal properties. The magnetic nanoparticles display a cubic shape and a size (major axis) of 37 ± 3 nm, while the longitudinal and transverse sizes of the nanorods are 46 ± 7 nm and 12 ± 1.6 nm, respectively. A new methodology was employed to couple the magnetic and plasmonic nanostructures, using cysteine as bridge. The potential for photothermia was evaluated for the magnetic nanoparticles, gold nanorods and the coupled magnetic/plasmonic nanoparticles, which demonstrated a maximum temperature variation of 28.9 °C, 33.6 °C and 37.2 °C, respectively, during a 30 min NIR-laser irradiation of 1 mg/mL dispersions. Using fluorescence anisotropy studies, a phase transition temperature (T_m) of 35 °C was estimated for MPELs, which ensures an enhanced fluidity crucial for effective crossing of the skin layers. The photothermal potential of this novel nanostructure corresponds to a specific absorption rate (SAR) of 616.9 W/g and a maximum temperature increase of 33.5 °C. These findings point to the development of thermoelastic nanocarriers with suitable features to act as photothermal hyperthermia agents. Full article

(This article belongs to the Special Issue Preparation, Characterization, Properties, Simulation, and Applications of Nanostructured Materials)

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11 pages, 4030 KiB

Open AccessEditor’s ChoiceArticle

Non-Volatile Memory Based on ZnO Thin-Film Transistor with Self-Assembled Au Nanocrystals

by Hui **e, Hao Wu and Chang Liu

Nanomaterials 2024, 14(8), 678; https://doi.org/10.3390/nano14080678 - 14 Apr 2024

Viewed by 966

Abstract

Non-volatile memory based on thin-film transistor is crucial for system-on-panel and flexible electronic systems. Achieving high-performance and reliable thin-film transistor (TFT) memory still remains challenging. Here, for the first time, we present a ZnO TFT memory utilizing self-assembled Au nanocrystals with a low [...] Read more.

Non-volatile memory based on thin-film transistor is crucial for system-on-panel and flexible electronic systems. Achieving high-performance and reliable thin-film transistor (TFT) memory still remains challenging. Here, for the first time, we present a ZnO TFT memory utilizing self-assembled Au nanocrystals with a low thermal budget, exhibiting excellent memory performance, including a program/erase window of 9.8 V, 29% charge loss extrapolated to 10 years, and remarkable endurance characteristics. Moreover, the memory exhibits favorable on-state characteristics with mobility, subthreshold swing, and current on–off ratio of 17.6 cm²V⁻¹s⁻¹, 0.71 V/dec, and 10⁷, respectively. Our study shows that the fabricated TFT memory has great potential for practical applications. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications)

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17 pages, 4906 KiB

Open AccessEditor’s ChoiceArticle

Sensing at the Nanoscale Using Nitrogen-Vacancy Centers in Diamond: A Model for a Quantum Pressure Sensor

by Hari P. Paudel, Gary R. Lander, Scott E. Crawford and Yuhua Duan

Nanomaterials 2024, 14(8), 675; https://doi.org/10.3390/nano14080675 - 12 Apr 2024

Viewed by 1136

Abstract

The sensing of stress under harsh environmental conditions with high resolution has critical importance for a range of applications including earth’s subsurface scanning, geological CO₂ storage monitoring, and mineral and resource recovery. Using a first-principles density functional theory (DFT) approach combined with [...] Read more.

The sensing of stress under harsh environmental conditions with high resolution has critical importance for a range of applications including earth’s subsurface scanning, geological CO₂ storage monitoring, and mineral and resource recovery. Using a first-principles density functional theory (DFT) approach combined with the theoretical modelling of the low-energy Hamiltonian, here, we investigate a novel approach to detect unprecedented levels of pressure by taking advantage of the solid-state electronic spin of nitrogen-vacancy (NV) centers in diamond. We computationally explore the effect of strain on the defect band edges and band gaps by varying the lattice parameters of a diamond supercell hosting a single NV center. A low-energy Hamiltonian is developed that includes the effect of stress on the energy level of a ±1 spin manifold at the ground state. By quantifying the energy level shift and split, we predict pressure sensing of up to 0.3 MPa/

\sqrt{Hz}

using the experimentally measured spin dephasing time. We show the superiority of the quantum sensing approach over traditional optical sensing techniques by discussing our results from DFT and theoretical modelling for the frequency shift per unit pressure. Importantly, we propose a quantum manometer that could be useful to measure earth’s subsurface vibrations as well as for pressure detection and monitoring in high-temperature superconductivity studies and in material sciences. Our results open avenues for the development of a sensing technology with high sensitivity and resolution under extreme pressure limits that potentially has a wider applicability than the existing pressure sensing technologies. Full article

(This article belongs to the Special Issue First-Principle Calculation Study of Nanomaterials)

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13 pages, 4189 KiB

Open AccessEditor’s ChoiceArticle

Multifunctional Vanadium Nitride-Modified Separator for High-Performance Lithium–Sulfur Batteries

by Sen Liu, Yang Liu, Xu Zhang, Maoqiang Shen, Xuesen Liu, **nyue Gao, Linrui Hou and Changzhou Yuan

Nanomaterials 2024, 14(8), 656; https://doi.org/10.3390/nano14080656 - 10 Apr 2024

Cited by 1 | Viewed by 1150

Abstract

Lithium–sulfur batteries (LSBs) are recognized as among the best potential alternative battery systems to lithium-ion batteries and have been widely investigated. However, the shuttle effect has severely restricted the advancement in their practical applications. Here, we prepare vanadium nitride (VN) nanoparticles grown in [...] Read more.

Lithium–sulfur batteries (LSBs) are recognized as among the best potential alternative battery systems to lithium-ion batteries and have been widely investigated. However, the shuttle effect has severely restricted the advancement in their practical applications. Here, we prepare vanadium nitride (VN) nanoparticles grown in situ on a nitrogen-doped carbon skeleton (denoted as VN@NC) derived from the MAX phase and use it as separator modification materials for LSBs to suppress the shuttle effect and optimize electrochemical performance. Thanks to the outstanding catalytic performance of VN and the superior electrical conductivity of carbon skeleton derived from MAX, the synergistic effect between the two accelerates the kinetics of both lithium polysulfides (LiPSs) to Li₂S and the reverse reaction, effectively suppresses the shuttle effect, and increases cathode sulfur availability, significantly enhancing the electrochemical performance of LSBs. LSBs constructed with VN@NC-modified separators achieve outstanding rate performance and cycle stability. With a capacity of 560 mAh g⁻¹ at 4 C, it exhibits enhanced structural and chemical stability. At 1 C, the device has an incipient capacity of 1052.4 mAh g⁻¹, and the degradation rate averaged only 0.085% over 400cycles. Meanwhile, the LSBs also show larger capacities and good cycling stability at a low electrolyte/sulfur ratio and high surface-loaded sulfur conditions. Thus, a facile and efficient way of preparing modified materials for separators is provided to realize high-performance LSBs. Full article

(This article belongs to the Special Issue Nanomaterials for Lithium-Sulfur Batteries)

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25 pages, 5809 KiB

Open AccessEditor’s ChoiceArticle

The Dominance of Pretransitional Effects in Liquid Crystal-Based Nanocolloids: Nematogenic 4-methoxybenzylidene-4′–butylaniline with Transverse Permanent Dipole Moment and BaTiO₃ Nanoparticles

by Aleksandra Drozd-Rzoska, Joanna Łoś and Sylwester J. Rzoska

Nanomaterials 2024, 14(8), 655; https://doi.org/10.3390/nano14080655 - 9 Apr 2024

Viewed by 796

Abstract

The report presents static, low-frequency, and dynamic dielectric properties in the isotropic liquid, nematic, and solid phases of MBBA and related nanocolloids with paraelectric BaTiO₃ nanoparticles (spherical, d = 50 nm). MBBA (4-methoxybenzylidene-4′–butylaniline) is a liquid crystalline compound with a permanent dipole [...] Read more.

The report presents static, low-frequency, and dynamic dielectric properties in the isotropic liquid, nematic, and solid phases of MBBA and related nanocolloids with paraelectric BaTiO₃ nanoparticles (spherical, d = 50 nm). MBBA (4-methoxybenzylidene-4′–butylaniline) is a liquid crystalline compound with a permanent dipole moment transverse to the long molecular axis. The distortions-sensitive analysis of the dielectric constant revealed its hidden pretransitional anomaly, strongly influenced by the addition of nanoparticles. The evolution of the dielectric constant in the nematic phase shows the split into two regions, with the crossover coinciding with the standard melting temperature. The ‘universal’ exponential-type behavior of the low-frequency contribution to the real part of the dielectric permittivity is found. The critical-like pretransitional behavior in the solid phase is also evidenced. This is explained by linking the Lipovsky model to the Mossotti catastrophe concept under quasi-negative pressure conditions. The explicit preference for the ‘critical-like’ evolution of the apparent activation enthalpy is worth stressing for dynamics. Finally, the long-range, ‘critical-like’ behavior of the dissipation factor (D = tgδ), covering the isotropic liquid and nematic phases, is shown. Full article

(This article belongs to the Special Issue Current Research in Nematic Liquid Crystal Nanocomposites)

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34 pages, 25645 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Biocompatible PANI-Encapsulated Chemically Modified Nano-TiO₂ Particles for Visible-Light Photocatalytic Applications

by Nefeli Papadopoulou-Fermeli, Nefeli Lagopati, Maria-Anna Gatou and Evangelia A. Pavlatou

Nanomaterials 2024, 14(7), 642; https://doi.org/10.3390/nano14070642 - 7 Apr 2024

Viewed by 1113

Abstract

Polyaniline (PANI) constitutes a very propitious conductive polymer utilized in several biomedical, as well as environmental applications, including tissue engineering, catalysis, and photocatalysis, due to its unique properties. In this study, nano-PANI/N-TiO₂ and nano-PANI/Ag-TiO₂ photocatalytic composites were fabricated via aniline’s oxidative [...] Read more.

Polyaniline (PANI) constitutes a very propitious conductive polymer utilized in several biomedical, as well as environmental applications, including tissue engineering, catalysis, and photocatalysis, due to its unique properties. In this study, nano-PANI/N-TiO₂ and nano-PANI/Ag-TiO₂ photocatalytic composites were fabricated via aniline’s oxidative polymerization, while the Ag-and N-chemically modified TiO₂ nanopowders were synthesized through the sol–gel approach. All produced materials were fully characterized. Through micro-Raman and FT-IR analysis, the co-existence of PANI and chemically modified TiO₂ particles was confirmed, while via XRD analysis the composites’ average crystallite size was determined as ≈20 nm. The semi-crystal structure of polyaniline exhibits higher photocatalytic efficiency compared to that of other less crystalline forms. The spherical-shaped developed materials are innovative, stable (zeta potential in the range from −26 to −37 mV), and cost-effective, characterized by enhanced photocatalytic efficiency under visible light (energy band gaps ≈ 2 eV), and synthesized with relatively simple methods, with the possibility of recycling and reusing them in potential future applications in industry, in wastewater treatment as well as in biomedicine. Thus, the PANI-encapsulated Ag and N chemically modified TiO₂ nanocomposites exhibit high degradation efficiency towards Rhodamine B dye upon visible-light irradiation, presenting simultaneously high biocompatibility in different normal cell lines. Full article

(This article belongs to the Special Issue Application of Metal (Oxide) Nanomaterials in Photocatalysis)

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35 pages, 1386 KiB

Open AccessEditor’s ChoiceReview

Engineered and Mimicked Extracellular Nanovesicles for Therapeutic Delivery

by Verena Poinsot, Nathalie Pizzinat and Varravaddheay Ong-Meang

Nanomaterials 2024, 14(7), 639; https://doi.org/10.3390/nano14070639 - 6 Apr 2024

Viewed by 1095

Abstract

Exosomes are spherical extracellular nanovesicles with an endosomal origin and unilamellar lipid-bilayer structure with sizes ranging from 30 to 100 nm. They contain a large range of proteins, lipids, and nucleic acid species, depending on the state and origin of the extracellular vesicle [...] Read more.

Exosomes are spherical extracellular nanovesicles with an endosomal origin and unilamellar lipid-bilayer structure with sizes ranging from 30 to 100 nm. They contain a large range of proteins, lipids, and nucleic acid species, depending on the state and origin of the extracellular vesicle (EV)-secreting cell. EVs’ function is to encapsulate part of the EV-producing cell content, to transport it through biological fluids to a targeted recipient, and to deliver their cargos specifically within the aimed recipient cells. Therefore, exosomes are considered to be potential biological drug-delivery systems that can stably deliver their cargo into targeted cells. Various cell-derived exosomes are produced for medical issues, but their use for therapeutic purposes still faces several problems. Some of these difficulties can be avoided by resorting to hemisynthetic approaches. We highlight here the uses of alternative exosome-mimes involving cell-membrane coatings on artificial nanocarriers or the hybridization between exosomes and liposomes. We also detail the drug-loading strategies deployed to make them drug-carrier systems and summarize the ongoing clinical trials involving exosomes or exosome-like structures. Finally, we summarize the open questions before considering exosome-like disposals for confident therapeutic delivery. Full article

(This article belongs to the Special Issue Advances in Pharmaceutical Applications of Lipid-Based Nanoparticles)

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15 pages, 9753 KiB

Open AccessEditor’s ChoiceArticle

Structure and Mechanical Properties of iPP-Based Nanocomposites Crystallized under High Pressure

by Sivan**eyulu Veluri, Przemyslaw Sowinski, Mariia Svyntkivska, Zbigniew Bartczak, Tomasz Makowski and Ewa Piorkowska

Nanomaterials 2024, 14(7), 629; https://doi.org/10.3390/nano14070629 - 4 Apr 2024

Viewed by 756

Abstract

The unique nonparallel chain arrangement in the orthorhombic γ-form lamellae of isotactic polypropylene (iPP) results in the enhancement of the mechanical properties of γ-iPP. Our study aimed at the investigation of the mechanical properties of γ-iPP nanocomposites with 1–5 wt.% multiwall carbon nanotubes [...] Read more.

The unique nonparallel chain arrangement in the orthorhombic γ-form lamellae of isotactic polypropylene (iPP) results in the enhancement of the mechanical properties of γ-iPP. Our study aimed at the investigation of the mechanical properties of γ-iPP nanocomposites with 1–5 wt.% multiwall carbon nanotubes (MWCNT) and 5 wt.% organo-modified montmorillonite prepared by melt-mixing and high-pressure crystallization. Neat iPP and the nanocomposites were crystallized under high pressures of 200 MPa and 300 MPa, and for comparison under 1.4 MPa, in a custom-built high-pressure cell. The structure of the materials was studied using WAXS, SAXS, DSC, and SEM, whereas their mechanical properties were tested in plane-strain compression. Under a small pressure of 1.4 MPa, polymer matrix in all materials crystallized predominantly in the α-form, the most common monoclinic form of iPP, whereas under high pressure it crystallized in the γ-form. This caused a significant increase in the elastic modulus, yield stress, and stress at break. Moreover, due to the presence of MWCNT, these parameters of the nanocomposites exceeded those of the neat polymer. As a result, a 60–70% increase in the elastic modulus, yield stress, and stress at break was achieved by filling of iPP with MWCNT and high-pressure crystallization. Full article

(This article belongs to the Topic Advanced Polymeric Composites: Processing, Characterization and Mechanical Behavior)

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12 pages, 3526 KiB

Open AccessEditor’s ChoiceArticle

Effect of Oxidizing Agent on the Synthesis of ZnO Nanoparticles for Inverted Phosphorescent Organic Light-Emitting Devices without Multiple Interlayers

by Se-** Lim, Hyeon Kim, Hyun-A Hwang, Hee-** Park and Dae-Gyu Moon

Nanomaterials 2024, 14(7), 622; https://doi.org/10.3390/nano14070622 - 2 Apr 2024

Viewed by 882

Abstract

Inverted organic light-emitting devices (OLEDs) have been aggressively developed because of their superiorities such as their high stability, low driving voltage, and low drop of brightness in display applications. The injection of electrons is a critical issue in inverted OLEDs because the ITO [...] Read more.

Inverted organic light-emitting devices (OLEDs) have been aggressively developed because of their superiorities such as their high stability, low driving voltage, and low drop of brightness in display applications. The injection of electrons is a critical issue in inverted OLEDs because the ITO cathode has an overly high work function in injecting electrons into the emission layer from the cathode. We synthesized hexagonal wurtzite ZnO nanoparticles using different oxidizing agents for an efficient injection of electrons in the inverted OLEDs. Potassium hydroxide (KOH) and tetramethylammonium hydroxide pentahydrate (TMAH) were used as oxidizing agents for synthesizing ZnO nanoparticles. The band gap, surface defects, surface morphology, surface roughness, and electrical resistivity of the nanoparticles were investigated. The inverted devices with phosphorescent molecules were prepared using the synthesized nanoparticles. The inverted devices with ZnO nanoparticles using TMAH exhibited a lower driving voltage, lower leakage current, and higher maximum external quantum efficiency. The devices with TMAH-based ZnO nanoparticles exhibited the maximum external quantum efficiency of 19.1%. Full article

(This article belongs to the Special Issue Applications of Advanced Nanomaterials in Display)

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12 pages, 3169 KiB

Open AccessEditor’s ChoiceArticle

Phonon Pseudoangular Momentum in α-MoO₃

by Meiqi Li, Zhibing Li, Huanjun Chen and Weiliang Wang

Nanomaterials 2024, 14(7), 607; https://doi.org/10.3390/nano14070607 - 29 Mar 2024

Viewed by 1004

Abstract

In recent studies, it has been discovered that phonons can carry angular momentum, leading to a series of investigations into systems with three-fold rotation symmetry. However, for systems with two-fold screw rotational symmetry, such as α-MoO₃, there has been no relevant [...] Read more.

In recent studies, it has been discovered that phonons can carry angular momentum, leading to a series of investigations into systems with three-fold rotation symmetry. However, for systems with two-fold screw rotational symmetry, such as α-MoO₃, there has been no relevant discussion. In this paper, we investigated the pseudoangular momentum of phonons in crystals with two-fold screw rotational symmetry. Taking α-MoO₃ as an example, we explain the selection rules in circularly polarized Raman experiments resulting from pseudoangular momentum conservation, providing important guidance for experiments. This study of pseudoangular momentum in α-MoO₃ opens up a new degree of freedom for its potential applications, expanding into new application domains. Full article

(This article belongs to the Section Nanophotonics Materials and Devices)

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24 pages, 8974 KiB

Open AccessEditor’s ChoiceReview

Autonomous Nanorobots as Miniaturized Surgeons for Intracellular Applications

by Daitian Tang, **qi Peng, Song Wu and Songsong Tang

Nanomaterials 2024, 14(7), 595; https://doi.org/10.3390/nano14070595 - 28 Mar 2024

Viewed by 1521

Abstract

Artificial nanorobots have emerged as promising tools for a wide range of biomedical applications, including biosensing, detoxification, and drug delivery. Their unique ability to navigate confined spaces with precise control extends their operational scope to the cellular or subcellular level. By combining tailored [...] Read more.

Artificial nanorobots have emerged as promising tools for a wide range of biomedical applications, including biosensing, detoxification, and drug delivery. Their unique ability to navigate confined spaces with precise control extends their operational scope to the cellular or subcellular level. By combining tailored surface functionality and propulsion mechanisms, nanorobots demonstrate rapid penetration of cell membranes and efficient internalization, enhancing intracellular delivery capabilities. Moreover, their robust motion within cells enables targeted interactions with intracellular components, such as proteins, molecules, and organelles, leading to superior performance in intracellular biosensing and organelle-targeted cargo delivery. Consequently, nanorobots hold significant potential as miniaturized surgeons capable of directly modulating cellular dynamics and combating metastasis, thereby maximizing therapeutic outcomes for precision therapy. In this review, we provide an overview of the propulsion modes of nanorobots and discuss essential factors to harness propulsive energy from the local environment or external power sources, including structure, material, and engine selection. We then discuss key advancements in nanorobot technology for various intracellular applications. Finally, we address important considerations for future nanorobot design to facilitate their translation into clinical practice and unlock their full potential in biomedical research and healthcare. Full article

(This article belongs to the Special Issue Innovation in Nanoparticles for Biomedical Applications)

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15 pages, 4387 KiB

Open AccessEditor’s ChoiceArticle

Reduced Graphene Oxide Modified Nitrogen-Doped Chitosan Carbon Fiber with Excellent Electromagnetic Wave Absorbing Performance

by Mengyao Guo, Ming Lin, **gwei Xu, Yongjiao Pan, Chen Ma and Guohua Chen

Nanomaterials 2024, 14(7), 587; https://doi.org/10.3390/nano14070587 - 27 Mar 2024

Viewed by 894

Abstract

Lightweight and low-cost one-dimensional carbon materials, especially biomass carbon fibers with multiple porous structures, have received wide attention in the field of electromagnetic wave absorption. In this paper, graphene-coated N-doped porous carbon nanofibers (PCNF) with excellent wave absorption properties were successfully synthesized via [...] Read more.

Lightweight and low-cost one-dimensional carbon materials, especially biomass carbon fibers with multiple porous structures, have received wide attention in the field of electromagnetic wave absorption. In this paper, graphene-coated N-doped porous carbon nanofibers (PCNF) with excellent wave absorption properties were successfully synthesized via electrostatic spinning, electrostatic self-assembly, and high-temperature carbonization. The obtained results showed that the minimum reflection loss of the absorbing carbon fiber obtained under the carbonization condition of 800 °C is −51.047 dB, and the absorption bandwidth of reflection loss below −20 dB is 10.16 GHz. This work shows that carbonization temperature and filler content have a certain effect on the wave-absorbing properties of fiber, graphene with nanofiber, and the design and preparation of high-performance absorbing materials by combining the characteristics of graphene and nanofibers and multi-component coupling to provide new ideas for the research of absorbing materials. Full article

(This article belongs to the Special Issue Graphene and Graphene-Based Polymer Composites: From Preparation to Applications)

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13 pages, 2970 KiB

Open AccessEditor’s ChoiceArticle

Nanoscale Structure of Lipid–Gemini Surfactant Mixed Monolayers Resolved with AFM and KPFM Microscopy

by Robert D. E. Henderson, Nanqin Mei, Yue Xu, Ravi Gaikwad, Shawn Wettig and Zoya Leonenko

Nanomaterials 2024, 14(7), 572; https://doi.org/10.3390/nano14070572 - 26 Mar 2024

Viewed by 978

Abstract

Drug delivery vehicles composed of lipids and gemini surfactants (GS) are promising in gene therapy. Tuning the composition and properties of the delivery vehicle is important for the efficient load and delivery of DNA fragments (genes). In this paper, we studied novel gene [...] Read more.

Drug delivery vehicles composed of lipids and gemini surfactants (GS) are promising in gene therapy. Tuning the composition and properties of the delivery vehicle is important for the efficient load and delivery of DNA fragments (genes). In this paper, we studied novel gene delivery systems composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-dipalmitoyl-sn-3-phosphocholine (DPPC), and GS of the type N,N-bis(dimethylalkyl)-

α, ω

-alkanediammonium dibromide at different ratios. The nanoscale properties of the mixed DOPC–DPPC–GS monolayers on the surface of the gene delivery system were studied using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We demonstrate that lipid–GS mixed monolayers result in the formation of nanoscale domains that vary in size, height, and electrical surface potential. We show that the presence of GS can impart significant changes to the domain topography and electrical surface potential compared to monolayers composed of lipids alone. Full article

(This article belongs to the Special Issue Nanotransporters for Drug Delivery and Precise Medicine)

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13 pages, 6727 KiB

Open AccessEditor’s ChoiceArticle

Effect of Anisotropy of Reduced Graphene Oxide on Thermal and Electrical Properties in Silicon Carbide Matrix Composites

by Kamil Broniszewski, Jarosław Woźniak, Tomasz Cygan, Marek Kostecki, Dorota Moszczyńska, Marcin Chmielewski, Kamil Dydek and Andrzej Olszyna

Nanomaterials 2024, 14(6), 555; https://doi.org/10.3390/nano14060555 - 21 Mar 2024

Cited by 1 | Viewed by 1008

Abstract

Reduced graphene oxide, due to its structure, exhibits anisotropic properties, which are particularly evident in electrical and thermal conductivity. This study focuses on examining the influence of reduced graphene oxide in silicon carbide on these properties in directions perpendicular and parallel to the [...] Read more.

Reduced graphene oxide, due to its structure, exhibits anisotropic properties, which are particularly evident in electrical and thermal conductivity. This study focuses on examining the influence of reduced graphene oxide in silicon carbide on these properties in directions perpendicular and parallel to the direction of the aligned rGO flakes in produced composites. Reduced graphene oxide is characterized by very high in-plane thermal and electrical conductivity. It was observed that the addition of rGO increases thermal conductivity from 64 W/mK (reference sample) up to 98 W/mK for a SiC–3 wt.% rGO composite in the direction parallel to the rGO flakes. In the perpendicular direction, the values were slightly lower, reaching up to 84 W/mK. The difference observed in electrical conductivity values is more significant and is 1–2 orders of magnitude higher for the flakes’ alignment direction. The measured electrical conductivity increased from 1.2710⁻⁸ S/m for the reference SiC sinter up to 1.55 × 10⁻⁵ S/m and 1.2410⁻⁴ S/m for the composites with 3 wt.% rGO for the perpendicular and parallel directions, respectively. This represents an enhancement of four orders of magnitude, with a clearly visible influence of the anisotropy of the rGO. The composite’s enhanced electrical and thermal conductivity make it particularly attractive for electronic devices and high-power applications. Full article

(This article belongs to the Section 2D and Carbon Nanomaterials)

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33 pages, 9959 KiB

Open AccessEditor’s ChoiceReview

Resistive Switching Devices for Neuromorphic Computing: From Foundations to Chip Level Innovations

by Kannan Udaya Mohanan

Nanomaterials 2024, 14(6), 527; https://doi.org/10.3390/nano14060527 - 15 Mar 2024

Viewed by 1847

Abstract

Neuromorphic computing has emerged as an alternative computing paradigm to address the increasing computing needs for data-intensive applications. In this context, resistive random access memory (RRAM) devices have garnered immense interest among the neuromorphic research community due to their capability to emulate intricate [...] Read more.

Neuromorphic computing has emerged as an alternative computing paradigm to address the increasing computing needs for data-intensive applications. In this context, resistive random access memory (RRAM) devices have garnered immense interest among the neuromorphic research community due to their capability to emulate intricate neuronal behaviors. RRAM devices excel in terms of their compact size, fast switching capabilities, high ON/OFF ratio, and low energy consumption, among other advantages. This review focuses on the multifaceted aspects of RRAM devices and their application to brain-inspired computing. The review begins with a brief overview of the essential biological concepts that inspire the development of bio-mimetic computing architectures. It then discusses the various types of resistive switching behaviors observed in RRAM devices and the detailed physical mechanisms underlying their operation. Next, a comprehensive discussion on the diverse material choices adapted in recent literature has been carried out, with special emphasis on the benchmark results from recent research literature. Further, the review provides a holistic analysis of the emerging trends in neuromorphic applications, highlighting the state-of-the-art results utilizing RRAM devices. Commercial chip-level applications are given special emphasis in identifying some of the salient research results. Finally, the current challenges and future outlook of RRAM-based devices for neuromorphic research have been summarized. Thus, this review provides valuable understanding along with critical insights and up-to-date information on the latest findings from the field of resistive switching devices towards brain-inspired computing. Full article

(This article belongs to the Special Issue Neuromorphic Devices: Materials, Structures and Bionic Applications)

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10 pages, 561 KiB

Open AccessEditor’s ChoiceArticle

Optical Analysis of Perovskite III-V Nanowires Interpenetrated Tandem Solar Cells

by Matteo Tirrito, Phillip Manley, Christiane Becker, Eva Unger and Magnus T. Borgström

Nanomaterials 2024, 14(6), 518; https://doi.org/10.3390/nano14060518 - 14 Mar 2024

Viewed by 812

Abstract

Multi-junction photovoltaics approaches are being explored to mitigate thermalization losses that occur in the absorption of high-energy photons. However, the design of tandem cells faces challenges such as light reflection and parasitic absorption. Nanostructures have emerged as promising solutions due to their anti-reflection [...] Read more.

Multi-junction photovoltaics approaches are being explored to mitigate thermalization losses that occur in the absorption of high-energy photons. However, the design of tandem cells faces challenges such as light reflection and parasitic absorption. Nanostructures have emerged as promising solutions due to their anti-reflection properties, which enhances light absorption. III-V nanowires (NWs) solar cells can achieve strong power conversion efficiencies, offering the advantage of potentially integrating tunnel diodes within the same fabrication process. Metal halide perovskites (MHPs) have gained attention for their optoelectronic attributes and cost-effectiveness. Notably, both material classes allow for tunable bandgaps. This study explores the integration of MHPs with III-V NWs solar cells in both two-terminal and three-terminal configurations. Our primary focus lies in the optical analysis of a tandem design using III-V semiconductor nanowire arrays in combination with perovskites, highlighting their potential for tandem applications. The space offered by the compact footprint of NW arrays is used in an interpenetrated tandem structure. We systematically optimize the bottom cell, addressing reflectivity and parasitic absorption, and extend to a full tandem structure, considering experimentally feasible thicknesses. Simulation of a three-terminal structure highlights a potential increase in efficiency, decoupling the operating points of the subcells. The two-terminal analysis underscores the benefits of nanowires in reducing reflection and achieving a higher matched current between the top and the bottom cells. This research provides significant insights into NW tandem solar cell optics, enhancing our understanding of their potential to improve photovoltaic performance. Full article

(This article belongs to the Section Solar Energy and Solar Cells)

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13 pages, 1322 KiB

Open AccessEditor’s ChoiceArticle

Enhanced Stability of Oral Vitamin C Delivery: A Novel Large-Scale Method for Liposomes Production and Encapsulation through Dynamic High-Pressure Microfluidization

by Eugenia Romano, Roberta Palladino, Mariagabriella Cannavale, Erwin Pavel Lamparelli and Barbara Maglione

Nanomaterials 2024, 14(6), 516; https://doi.org/10.3390/nano14060516 - 14 Mar 2024

Cited by 1 | Viewed by 1445

Abstract

In recent years, nanocarriers have been widely used as an effective solution for oral administration of pharmaceuticals. However, there is still an urgent need to speed up their translation to clinical practice. Cost-effective and industrially scalable methodologies are still needed. Herein, the production [...] Read more.

In recent years, nanocarriers have been widely used as an effective solution for oral administration of pharmaceuticals. However, there is still an urgent need to speed up their translation to clinical practice. Cost-effective and industrially scalable methodologies are still needed. Herein, the production of vitamin C-loaded liposomes for nutraceutical purposes has been investigated and optimized by adopting a High-Pressure Homogenizer. Initially, the impact of process parameters on particles size, distributions, and morphology was explored. The findings document that the pressure and cycle manipulation allow for control over liposome size and polydispersity, reaching a maximum encapsulation efficiency exceeding 80%. This significantly improves the storage stability of vitamin C, as demonstrated by monitoring its antioxidant activity. Furthermore, the in vitro simulation of gastrointestinal digestion shows that liposomes could protect the active substance from damage and control its release in the gastrointestinal fluid. Thus, the whole nanodelivery system can contribute to enhancing vitamin C bioavailability. In conclusion, the results indicate that this innovative approach to producing vitamin C liposomes holds promise for clinical translation and industrial scale-up. Indeed, by utilizing food-grade materials and straightforward equipment, it is possible to produce stable and functional liposomes suitable for health products. Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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22 pages, 6977 KiB

Open AccessEditor’s ChoiceArticle

Enhanced Adsorption of Methylene Blue Dye on Functionalized Multi-Walled Carbon Nanotubes

by Ludovica Ceroni, Stefania Benazzato, Samuel Pressi, Laura Calvillo, Ester Marotta and Enzo Menna

Nanomaterials 2024, 14(6), 522; https://doi.org/10.3390/nano14060522 - 14 Mar 2024

Cited by 3 | Viewed by 1236

Abstract

Carbon nanomaterials are promising adsorbents for dye removal from wastewater also due to their possible surface functionalization that, in principle, can increase the adsorption rate and provide regeneration. To investigate the real advantages of functionalization, we synthesized and characterized through IR, TGA, TEM, [...] Read more.

Carbon nanomaterials are promising adsorbents for dye removal from wastewater also due to their possible surface functionalization that, in principle, can increase the adsorption rate and provide regeneration. To investigate the real advantages of functionalization, we synthesized and characterized through IR, TGA, TEM, XPS and DLS measurements a multi-walled carbon nanotube (MWCNT) derivative bearing benzenesulfonate groups (MWCNT-S). The obtained material demonstrated to have good dispersibility in water and better capability to adsorb methylene blue (MB) compared to the pristine MWCNT adsorbent. Adsorption kinetic studies showed a very fast process, with a constant significantly higher with respect not only to that of the unfunctionalized MWCNT adsorbent but also to those of widely used activated carbons. Moreover, the adsorption capacity of MWCNT-S is more than doubled with respect to that of the insoluble pristine MWCNT adsorbent, thanks to the dispersibility of the derivatives, providing a larger available surface, and to the possible electrostatic interactions between the cationic MB and the anionic sulfonate groups. Additionally, the reversibility of ionic interactions disclosed the possibility to release the adsorbed cationic pollutant through competition with salts, not only regenerating the adsorbent, but also recovering the dye. Indeed, by treating the adsorbed material for 1 h with 1 M NaCl, a regeneration capacity of 75% was obtained, demonstrating the validity of this strategy. Full article

(This article belongs to the Special Issue Nanomaterial Application in Environmental Monitoring and Water Treatment)

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14 pages, 6090 KiB

Open AccessEditor’s ChoiceArticle

Cellulose Sulfate Nanofibers for Enhanced Ammonium Removal

by Ken I. Johnson, William Borges, Priyanka R. Sharma, Sunil K. Sharma, Hao-Yen Chang, Mortaga M. Abou-Krisha, Abdulrahman G. Alhamzani and Benjamin S. Hsiao

Nanomaterials 2024, 14(6), 507; https://doi.org/10.3390/nano14060507 - 12 Mar 2024

Cited by 1 | Viewed by 918

Abstract

In this study, a sulfonation approach using chlorosulfonic acid (CSA) to prepare cellulose sulfate nanofibers (CSNFs) from raw jute fibers is demonstrated. Both elemental sulfur content and zeta potential in the CSNFs are found to increase with increasing CSA content used. However, the [...] Read more.

In this study, a sulfonation approach using chlorosulfonic acid (CSA) to prepare cellulose sulfate nanofibers (CSNFs) from raw jute fibers is demonstrated. Both elemental sulfur content and zeta potential in the CSNFs are found to increase with increasing CSA content used. However, the corresponding crystallinity in the CSNFs decreases with the increasing amount of CSA used due to degradation of cellulose chains under harsh acidic conditions. The ammonium adsorption results from the CSNFs with varying degrees of sulfonation were analyzed using the Langmuir isotherm model, and the analysis showed a very high maximum ammonium adsorption capacity (41.1 mg/g) under neutral pH, comparable to the best value from a synthetic hydrogel in the literature. The high ammonium adsorption capacity of the CSNFs was found to be maintained in a broad acidic range (pH = 2.5 to 6.5). Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Water Remediation (2nd Edition))

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31 pages, 43899 KiB

Open AccessEditor’s ChoiceArticle

“Polymerization” of Bimerons in Quasi-Two-Dimensional Chiral Magnets with Easy-Plane Anisotropy

by Natsuki Mukai and Andrey O. Leonov

Nanomaterials 2024, 14(6), 504; https://doi.org/10.3390/nano14060504 - 11 Mar 2024

Viewed by 1094

Abstract

We re-examine the internal structure of bimerons, which are stabilized in easy-plane chiral magnets and represent coupled states of two merons with the same topological charge

| 1 / 2 |

but with opposite vorticity and the polarity. We find that, in addition [...] Read more.

We re-examine the internal structure of bimerons, which are stabilized in easy-plane chiral magnets and represent coupled states of two merons with the same topological charge

| 1 / 2 |

but with opposite vorticity and the polarity. We find that, in addition to the vortices and antivortices, bimerons feature circular regions which are located behind the anti-vortices and bear the rotational sense opposite to the rotational sense chosen by the Dzyaloshinskii–Moriya interaction. In an attempt to eliminate these wrong-twist regions with an excess of positive energy density, bimerons assemble into chains, and as such exhibit an attracting interaction potential. As an alternative to chains, we demonstrate the existence of ring-shaped bimeron clusters of several varieties. In some rings, bimeron dipoles are oriented along the circle and swirl clockwise and/or counterclockwise (dubbed “roundabouts”). Moreover, a central meron encircled by the outer bimerons may possess either positive or negative polarity. In other rings, the bimeron dipoles point towards the center of a ring and consequently couple to the central meron (dubbed “crossings”). We point out that the ringlike solutions for baryons obtained within the Skyrme model of pions, although driven by the same tendency of the energy reduction, yield only one type of bimeron rings. The conditions of stability applied to the described bimeron rings are additionally extended to bimeron networks when bimerons fill the whole space of two-dimensional samples and exhibit combinations of rings and chains dispersed with different spatial density (dubbed bimeron “polymers”). In particular, bimeron crystals with hexagonal and the square bimeron orderings are possible when the sides of the unit cells represent chains of bimerons joined in intersections with three or four bimerons, respectively; otherwise, bimeron networks represent disordered bimeron structures. Moreover, we scrutinize the inter-transformations between hexagonal Skyrmion lattices and disordered bimeron polymers occuring via nucleation and mutual annihilation of merons within the cell boundaries. Our theory provides clear directions for experimental studies of bimeron orderings in different condensed-matter systems with quasi-two-dimensional geometries. Full article

(This article belongs to the Section Theory and Simulation of Nanostructures)

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14 pages, 3643 KiB

Open AccessEditor’s ChoiceArticle

A Long-Term Study on the Bactericidal Effect of ZrN-Cu Nanostructured Coatings Deposited by an Industrial Physical Vapor Deposition System

by Sahand Behrangi, Eva Staňková, Ivo Sedláček, Lucie Šimoníková, Pavel Souček, Vilma Buršíková, Vjačeslav Sochora, Karel Novotný and Petr Vašina

Nanomaterials 2024, 14(6), 496; https://doi.org/10.3390/nano14060496 - 10 Mar 2024

Viewed by 1018

Abstract

ZrN-Cu coatings containing two different amounts of Cu (~11 at.% and ~25 at.%) were deposited using an industrial physical vapor deposition (PVD) system. The as-deposited coatings exhibited 100% bactericidal efficiency against Escherichia coli CCM 3988 for an exposure time of 40 min. Subsequently, [...] Read more.

ZrN-Cu coatings containing two different amounts of Cu (~11 at.% and ~25 at.%) were deposited using an industrial physical vapor deposition (PVD) system. The as-deposited coatings exhibited 100% bactericidal efficiency against Escherichia coli CCM 3988 for an exposure time of 40 min. Subsequently, the samples were attached onto our faculty’s door handles for six months to study the coatings’ long-term effectiveness and durability under actual operational conditions. The samples were periodically evaluated and it was observed that the coatings with 25 at.% Cu performed better than the ones with 11 at.% Cu. For example, following 15 days of being touched, the bactericidal effectiveness of the sample containing 25 at.% Cu dropped to 65% while it fell to 42% for the sample containing 11 at.%. After 6 months, however, both samples showed bactericidal efficiency of ~16–20%. The bactericidal efficiency of the samples touched for 6 months was successfully restored by polishing them. Furthermore, a group of samples was kept untouched and was also evaluated. The untouched samples with Cu content of ~25 at.% did not show any drop in their bactericidal properties after 6 months. ZrN-Cu coatings were concluded to be promising materials for self-sanitizing application on high-touch surfaces. Full article

(This article belongs to the Special Issue Nanocoating for Antibacterial Applications)

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14 pages, 3820 KiB

Open AccessEditor’s ChoiceArticle

Regioselectively Carboxylated Cellulose Nanofibril Models from Dissolving Pulp: C6 via TEMPO Oxidation and C2,C3 via Periodate–Chlorite Oxidation

by Mengzhe Guo, James D. Ede, Christie M. Sayes, Jo Anne Shatkin, Nicole Stark and You-Lo Hsieh

Nanomaterials 2024, 14(5), 479; https://doi.org/10.3390/nano14050479 - 6 Mar 2024

Cited by 1 | Viewed by 1015

Abstract

Regioselective C6 and C2,C3 carboxylated cellulose nanofibrils (CNFs) have been robustly generated from dissolving pulp, a readily available source of unmodified cellulose, via stoichiometrically optimized 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO)-mediated and sequential sodium periodate-sodium chlorite (PC) oxidation coupled with high-speed blending. Both regioselectively optimized carboxylated CNF [...] Read more.

Regioselective C6 and C2,C3 carboxylated cellulose nanofibrils (CNFs) have been robustly generated from dissolving pulp, a readily available source of unmodified cellulose, via stoichiometrically optimized 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO)-mediated and sequential sodium periodate-sodium chlorite (PC) oxidation coupled with high-speed blending. Both regioselectively optimized carboxylated CNF series possess the widest ranges of comparable charges (0.72–1.48 mmol/g for T-CNFs vs. 0.72–1.10 mmol/g for PC-CNFs), but similar ranges of thickness (1.3–2.4 nm for T-CNF, 1.8–2.7 nm PC-CNF), widths (4.6–6.6 nm T-CNF, 5.5–5.9 nm PC-CNF), and lengths (254–481 nm T-CNF, 247–442 nm PC-CNF). TEMPO-mediated oxidation is milder and one-pot, thus more time and process efficient, whereas the sequential periodate–chlorite oxidation produces C2,C3 dialdehyde intermediates that are amenable to further chemical functionalization or post-reactions. These two well-characterized regioselectively carboxylated CNF series represent coherent cellulose nanomaterial models from a single woody source and have served as references for their safety study toward the development of a safer-by-design substance evaluation tool. Full article

(This article belongs to the Special Issue From Biomass to Nanomaterials)

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24 pages, 2443 KiB

Open AccessEditor’s ChoiceReview

An Updated Overview of Silica Aerogel-Based Nanomaterials

by Adelina-Gabriela Niculescu, Dana-Ionela Tudorache, Maria Bocioagă, Dan Eduard Mihaiescu, Tony Hadibarata and Alexandru Mihai Grumezescu

Nanomaterials 2024, 14(5), 469; https://doi.org/10.3390/nano14050469 - 4 Mar 2024

Cited by 5 | Viewed by 3693

Abstract

Silica aerogels have gained much interest due to their unique properties, such as being the lightest solid material, having small pore sizes, high porosity, and ultralow thermal conductivity. Also, the advancements in synthesis methods have enabled the creation of silica aerogel-based composites in [...] Read more.

Silica aerogels have gained much interest due to their unique properties, such as being the lightest solid material, having small pore sizes, high porosity, and ultralow thermal conductivity. Also, the advancements in synthesis methods have enabled the creation of silica aerogel-based composites in combination with different materials, for example, polymers, metals, and carbon-based structures. These new silica-based materials combine the properties of silica with the other materials to create a new and reinforced architecture with significantly valuable uses in different fields. Therefore, the importance of silica aerogels has been emphasized by presenting their properties, synthesis process, composites, and numerous applications, offering an updated background for further research in this interdisciplinary domain. Full article

(This article belongs to the Collection Metallic and Metal Oxide Nanohybrids and Their Applications)

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30 pages, 4620 KiB

Open AccessEditor’s ChoiceReview

Recent Advances in Tactile Sensory Systems: Mechanisms, Fabrication, and Applications

by Jianguo ** Zhang, Lin Dong, Zhenjun Yang, Zuqing Yuan, Junlu Sun and Qilin Hua

Nanomaterials 2024, 14(5), 465; https://doi.org/10.3390/nano14050465 - 4 Mar 2024

Viewed by 2876

Abstract

Flexible electronics is a cutting-edge field that has paved the way for artificial tactile systems that mimic biological functions of sensing mechanical stimuli. These systems have an immense potential to enhance human–machine interactions (HMIs). However, tactile sensing still faces formidable challenges in delivering [...] Read more.

Flexible electronics is a cutting-edge field that has paved the way for artificial tactile systems that mimic biological functions of sensing mechanical stimuli. These systems have an immense potential to enhance human–machine interactions (HMIs). However, tactile sensing still faces formidable challenges in delivering precise and nuanced feedback, such as achieving a high sensitivity to emulate human touch, co** with environmental variability, and devising algorithms that can effectively interpret tactile data for meaningful interactions in diverse contexts. In this review, we summarize the recent advances of tactile sensory systems, such as piezoresistive, capacitive, piezoelectric, and triboelectric tactile sensors. We also review the state-of-the-art fabrication techniques for artificial tactile sensors. Next, we focus on the potential applications of HMIs, such as intelligent robotics, wearable devices, prosthetics, and medical healthcare. Finally, we conclude with the challenges and future development trends of tactile sensors. Full article

(This article belongs to the Special Issue Advances in Flexible Nanoelectronics)

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11 pages, 2842 KiB

Open AccessEditor’s ChoiceArticle

Fish Scale for Wearable, Self-Powered TENG

by Liwei Zhao, ** Han, **ng Zhang and Chunchang Wang

Nanomaterials 2024, 14(5), 463; https://doi.org/10.3390/nano14050463 - 3 Mar 2024

Viewed by 3228

Abstract

Flexible and wearable devices are attracting more and more attention. Herein, we propose a self-powered triboelectric nanogenerator based on the triboelectric effect of fish scales. As the pressure on the nanogenerator increases, the output voltage of the triboelectric nanogenerator increases. The nanogenerator can [...] Read more.

Flexible and wearable devices are attracting more and more attention. Herein, we propose a self-powered triboelectric nanogenerator based on the triboelectric effect of fish scales. As the pressure on the nanogenerator increases, the output voltage of the triboelectric nanogenerator increases. The nanogenerator can output a voltage of 7.4 V and a short-circuit current of 0.18 μA under a pressure of 50 N. The triboelectric effect of fish scales was argued to be related to the lamellar structure composed of collagen fiber bundles. The nanogenerator prepared by fish scales can sensitively perceive human activities such as walking, finger tap**, and elbow bending. Moreover, fish scales are a biomass material with good biocompatibility with the body. The fish-scale nanogenerator is a kind of flexible, wearable, and self-powered triboelectric nanogenerator showing great prospects in healthcare and body information monitoring. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications)

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15 pages, 1819 KiB

Open AccessEditor’s ChoiceArticle

Comparative Study of the Orientation and Order Effects on the Thermoelectric Performance of 2D and 3D Perovskites

by Yi-Hsiang Wang, Cheng-Hsien Yeh, I-Ta Hsieh, Po-Yu Yang, Yuan-Wen Hsiao, Hsuan-Ta Wu, Chun-Wei Pao and Chuan-Feng Shih

Nanomaterials 2024, 14(5), 446; https://doi.org/10.3390/nano14050446 - 28 Feb 2024

Viewed by 1086

Abstract

Calcium titanium oxide has emerged as a highly promising material for optoelectronic devices, with recent studies suggesting its potential for favorable thermoelectric properties. However, current experimental observations indicate a low thermoelectric performance, with a significant gap between these observations and theoretical predictions. Therefore, [...] Read more.

Calcium titanium oxide has emerged as a highly promising material for optoelectronic devices, with recent studies suggesting its potential for favorable thermoelectric properties. However, current experimental observations indicate a low thermoelectric performance, with a significant gap between these observations and theoretical predictions. Therefore, this study employs a combined approach of experiments and simulations to thoroughly investigate the impact of structural and directional differences on the thermoelectric properties of two-dimensional (2D) and three-dimensional (3D) metal halide perovskites. Two-dimensional (2D) and three-dimensional (3D) metal halide perovskites constitute the focus of examination in this study, where an in-depth exploration of their thermoelectric properties is conducted via a comprehensive methodology incorporating simulations and experimental analyses. The non-equilibrium molecular dynamics simulation (NEMD) was utilized to calculate the thermal conductivity of the perovskite material. Thermal conductivities along both in-plane and out-plane directions of 2D perovskite were computed. The NEMD simulation results show that the thermal conductivity of the 3D perovskite is approximately 0.443 W/mK, while the thermal conductivities of the parallel and vertical oriented 2D perovskites increase with n and range from 0.158 W/mK to 0.215 W/mK and 0.289 W/mK to 0.309 W/mK, respectively. Hence, the thermal conductivity of the 2D perovskites is noticeably lower than the 3D ones. Furthermore, the parallel oriented 2D perovskites exhibit more effective blocking of heat transfer behavior than the perpendicular oriented ones. The experimental results reveal that the Seebeck coefficient of the 2D perovskites reaches 3.79 × 10² µV/K. However, the electrical conductivity of the 2D perovskites is only 4.55 × 10⁻⁵ S/cm, which is one order of magnitude lower than that of the 3D perovskites. Consequently, the calculated thermoelectric figure of merit for the 2D perovskites is approximately 1.41 × 10⁻⁷, slightly lower than that of the 3D perovskites. Full article

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23 pages, 4263 KiB

Open AccessEditor’s ChoiceReview

Zein-Based Nanoparticles as Active Platforms for Sustainable Applications: Recent Advances and Perspectives

by Emilia Oleandro, Mariamelia Stanzione, Giovanna Giuliana Buonocore and Marino Lavorgna

Nanomaterials 2024, 14(5), 414; https://doi.org/10.3390/nano14050414 - 23 Feb 2024

Cited by 2 | Viewed by 1647

Abstract

Nanomaterials, due to their unique structural and functional features, are widely investigated for potential applications in a wide range of industrial sectors. In this context, protein-based nanoparticles, given proteins’ abundance, non-toxicity, and stability, offer a promising and sustainable methodology for encapsulation and protection, [...] Read more.

Nanomaterials, due to their unique structural and functional features, are widely investigated for potential applications in a wide range of industrial sectors. In this context, protein-based nanoparticles, given proteins’ abundance, non-toxicity, and stability, offer a promising and sustainable methodology for encapsulation and protection, and can be used in engineered nanocarriers that are capable of releasing active compounds on demand. Zein is a plant-based protein extracted from corn, and it is biocompatible, biodegradable, and amphiphilic. Several approaches and technologies are currently involved in zein-based nanoparticle preparation, such as antisolvent precipitation, spray drying, supercritical processes, coacervation, and emulsion procedures. Thanks to their peculiar characteristics, zein-based nanoparticles are widely used as nanocarriers of active compounds in targeted application fields such as drug delivery, bioimaging, or soft tissue engineering, as reported by others. The main goal of this review is to investigate the use of zein-based nanocarriers for different advanced applications including food/food packaging, cosmetics, and agriculture, which are attracting researchers’ efforts, and to exploit the future potential development of zein NPs in the field of cultural heritage, which is still relatively unexplored. Moreover, the presented overview focuses on several preparation methods (i.e., antisolvent processes, spry drying), correlating the different analyzed methodologies to NPs’ structural and functional properties and their capability to act as carriers of bioactive compounds, both to preserve their activity and to tune their release in specific working conditions. Full article

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21 pages, 3743 KiB

Open AccessEditor’s ChoiceArticle

Origin of Multiferroism in VOX₂ (X = Cl, Br, I) Monolayers

by Angel Todorov Apostolov, Iliana Naumova Apostolova and Julia Mihailova Wesselinowa

Nanomaterials 2024, 14(5), 408; https://doi.org/10.3390/nano14050408 - 23 Feb 2024

Viewed by 785

Abstract

Based on the proposed microscopic model, we investigate the multiferroic characteristics of VOX₂ (X = Cl, Br, I) monolayers using a Green’s function method. The dependence of the microscopic parameters of the ferroelectric system (pseudo-spin arrangement and flip** rate) on the magnitude [...] Read more.

Based on the proposed microscopic model, we investigate the multiferroic characteristics of VOX₂ (X = Cl, Br, I) monolayers using a Green’s function method. The dependence of the microscopic parameters of the ferroelectric system (pseudo-spin arrangement and flip** rate) on the magnitude and sign of the exchange magnetic interaction along the b-axis and the value of the Dzyaloshinskii–Moria vector have been investigated and qualitatively explained. The possibility of observing a spin-reorientation transition with a change in the character of spin ordering from antiferromagnetic to ferromagnetic is investigated. It is found that the antisymmetric magnetoelectric interaction may be responsible for the spin-reorientation transition without a change in the ordering of magnetic moments. Changing the sign of the exchange magnetic interaction along the b-axis leads to ferromagnetic ordering without observing a spin-reorientation transition. The dependence of isotropic and antisymmetric magnetic interactions on the microscopic parameters of the ferroelectric system is qualitatively explained. A mechanism for the occurrence of the spin-reorientation transition is presented based on the proposed microscopic model. The obtained results qualitatively coincide with Density Functional Theory calculations. Full article

(This article belongs to the Special Issue Multifunctional Nanomaterials Based on Oxide Nanocrystals: Synthesis, Properties and Applications)

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12 pages, 2879 KiB

Open AccessEditor’s ChoiceArticle

Superprotonic Conductivity in a Metalloporphyrin-Based SMOF (Supramolecular Metal–Organic Framework)

by Arkaitz Fidalgo-Marijuan, Idoia Ruiz de Larramendi and Gotzone Barandika

Nanomaterials 2024, 14(5), 398; https://doi.org/10.3390/nano14050398 - 21 Feb 2024

Viewed by 867

Abstract

Metal–organic frameworks and supramolecular metal–organic frameworks (SMOFs) exhibit great potential for a broad range of applications taking advantage of the high surface area and pore sizes and tunable chemistry. In particular, metalloporphyrin-based MOFs and SMOFs are becoming of great importance in many fields [...] Read more.

Metal–organic frameworks and supramolecular metal–organic frameworks (SMOFs) exhibit great potential for a broad range of applications taking advantage of the high surface area and pore sizes and tunable chemistry. In particular, metalloporphyrin-based MOFs and SMOFs are becoming of great importance in many fields due to the bioessential functions of these macrocycles that are being mimicked. On the other hand, during the last years, proton-conducting materials have aroused much interest, and those presenting high conductivity values are potential candidates to play a key role in some solid-state electrochemical devices such as batteries and fuel cells. In this way, using metalloporphyrins as building units we have obtained a new crystalline material with formula [H(bipy)]₂[(MnTPPS)(H₂O)₂]·2bipy·14H₂O, where bipy is 4,4′-bipyidine and TPPS⁴⁻ is the meso-tetra(4-sulfonatephenyl) porphyrin. The crystal structure shows a zig-zag water chain along the [100] direction located between the sulfonate groups of the porphyrin. Taking into account those structural features, the compound was tested for proton conduction by complex electrochemical impedance spectroscopy (EIS). The as-obtained conductivity is 1 × 10⁻² S·cm⁻¹ at 40 °C and 98% relative humidity, which is a remarkably high value. Full article

(This article belongs to the Special Issue Nanoscale Coordination Polymers for Advanced Applications)

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12 pages, 3715 KiB

Open AccessEditor’s ChoiceArticle

Terahertz Detection by Asymmetric Dual Grating Gate Bilayer Graphene FETs with Integrated Bowtie Antenna

by E. Abidi, A. Khan, J. A. Delgado-Notario, V. Clericó, J. Calvo-Gallego, T. Taniguchi, K. Watanabe, T. Otsuji, J. E. Velázquez and Y. M. Meziani

Nanomaterials 2024, 14(4), 383; https://doi.org/10.3390/nano14040383 - 19 Feb 2024

Cited by 1 | Viewed by 1347

Abstract

An asymmetric dual-grating gate bilayer graphene-based field effect transistor (ADGG-GFET) with an integrated bowtie antenna was fabricated and its response as a Terahertz (THz) detector was experimentally investigated. The device was cooled down to 4.5 K, and excited at different frequencies (0.15, 0.3 [...] Read more.

An asymmetric dual-grating gate bilayer graphene-based field effect transistor (ADGG-GFET) with an integrated bowtie antenna was fabricated and its response as a Terahertz (THz) detector was experimentally investigated. The device was cooled down to 4.5 K, and excited at different frequencies (0.15, 0.3 and 0.6 THz) using a THz solid-state source. The integration of the bowtie antenna allowed to obtain a substantial increase in the photocurrent response (up to 8 nA) of the device at the three studied frequencies as compared to similar transistors lacking the integrated antenna (1 nA). The photocurrent increase was observed for all the studied values of the bias voltage applied to both the top and back gates. Besides the action of the antenna that helps the coupling of THz radiation to the transistor channel, the observed enhancement by nearly one order of magnitude of the photoresponse is also related to the modulation of the hole and electron concentration profiles inside the transistor channel by the bias voltages imposed to the top and back gates. The creation of local n and p regions leads to the formation of homojuctions (

n p

,

p n

or

p p^{+}

) along the channel that strongly affects the overall photoresponse of the detector. Additionally, the bias of both back and top gates could induce an opening of the gap of the bilayer graphene channel that would also contribute to the photocurrent. Full article

(This article belongs to the Special Issue Abridging the CMOS Technology II)

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17 pages, 6532 KiB

Open AccessEditor’s ChoiceArticle

Silver-Sulfamethazine-Conjugated β-Cyclodextrin/Dextran-Coated Magnetic Nanoparticles for Pathogen Inhibition

by Anastasiia B. Shatan, Vitalii Patsula, Hana Macková, Andrii Mahun, Renáta Lehotská, Elena Piecková and Daniel Horák

Nanomaterials 2024, 14(4), 371; https://doi.org/10.3390/nano14040371 - 17 Feb 2024

Viewed by 1214

Abstract

In the fight against antibiotic resistance, which is rising to dangerously high levels worldwide, new strategies based on antibiotic-conjugated biocompatible polymers bound to magnetic nanoparticles that allow the drug to be manipulated and delivered to a specific target are being proposed. Here, we [...] Read more.

In the fight against antibiotic resistance, which is rising to dangerously high levels worldwide, new strategies based on antibiotic-conjugated biocompatible polymers bound to magnetic nanoparticles that allow the drug to be manipulated and delivered to a specific target are being proposed. Here, we report the direct surface engineering of nontoxic iron oxide nanoparticles (IONs) using biocompatible dextran (Dex) covalently linked to β-cyclodextrin (β-CD) with the ability to form non-covalent complexes with silver-sulfamethazine (SMT-Ag). To achieve a good interaction of β-CD-modified dextran with the surface of the nanoparticles, it was functionalized with diphosphonic acid (DPA) that provides strong binding to Fe atoms. The synthesized polymers and nanoparticles were characterized by various methods, such as nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) and ultraviolet–visible (UV–Vis) spectroscopies, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), atomic absorption spectroscopy (AAS), dynamic light scattering (DLS), etc. The resulting magnetic ION@DPA-Dex-β-CD-SMT-Ag nanoparticles were colloidally stable in water and contained 24 μg of antibiotic per mg of the particles. When tested for in vitro antimicrobial activity on Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and fungi (yeast Candida albicans and mold Aspergillus niger), the particles showed promising potential. Full article

(This article belongs to the Special Issue Antimicrobial and Antioxidant Activity of Nanoparticles)

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14 pages, 7941 KiB

Open AccessEditor’s ChoiceArticle

In Situ Lubrication in Forging of Pure Titanium Using Carbon Supersaturated Die Materials

by Tatsuhiko Aizawa, Tatsuya Funazuka and Tomomi Shiratori

Nanomaterials 2024, 14(4), 363; https://doi.org/10.3390/nano14040363 - 15 Feb 2024

Viewed by 863

Abstract

A new solid lubrication method was proposed for dry forging of pure titanium with high reduction in thickness. A free-carbon tribofilm was formed in situ at the hot spots on the contact interface to protect the die surfaces from severe adhesion of work [...] Read more.

A new solid lubrication method was proposed for dry forging of pure titanium with high reduction in thickness. A free-carbon tribofilm was formed in situ at the hot spots on the contact interface to protect the die surfaces from severe adhesion of work materials. This film consisted of the free carbon, which isolated from the carbon supersaturated die substrate materials, diffused to the contact interface and agglomerated to a thin film. Two different routes of carbon supersaturation process were developed to prepare carbon supersaturated ceramic and metal dies for the dry forging of pure titanium wires. A pure titanium bar was utilized as an easy-to-adherent work material for upsetting in dry and cold. The round bar was upset up to 70% in reduction in thickness with a low friction coefficient from 0.05 to 0.1 in a single stroke. Work hardening was suppressed by this low friction. SEM-EDX, EBSD and Raman spectroscopy were utilized to analyze the contact interface and to understand the role of in situ formed free-carbon films on the low friction and low work hardening during forging. Precise nanostructure analyses were utilized to describe low friction forging behavior commonly observed in these two processes. The in situ solid lubrication mechanism is discussed based on the equivalence between the nitrogen and carbon supersaturation processes. Full article

(This article belongs to the Section Nanofabrication and Nanomanufacturing)

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10 pages, 3169 KiB

Open AccessEditor’s ChoiceArticle

Fully Printed Cellulose Nanofiber–Ag Nanoparticle Composite for High-Performance Humidity Sensor

by Mi** Won, Minhun Jung, Jaehwan Kim and Dong-Soo Kim

Nanomaterials 2024, 14(4), 343; https://doi.org/10.3390/nano14040343 - 10 Feb 2024

Viewed by 1060

Abstract

This paper reports a high-performance humidity sensor made using a novel cellulose nanofiber (CNF)–silver nanoparticle (AgNP) sensing material. The interdigital electrode pattern was printed via reverse-offset printing using Ag nano-ink, and the sensing layer on the printed interdigitated electrode (IDE) was formed by [...] Read more.

This paper reports a high-performance humidity sensor made using a novel cellulose nanofiber (CNF)–silver nanoparticle (AgNP) sensing material. The interdigital electrode pattern was printed via reverse-offset printing using Ag nano-ink, and the sensing layer on the printed interdigitated electrode (IDE) was formed by depositing the CNF-AgNP composite via inkjet printing. The structure and morphology of the CNF-AgNP layer are characterized using ultraviolet–visible spectroscopy, an X-ray diffractometer, field emission scanning electron microscopy, energy-dispersive X-ray analysis, and transmission electron microscopy. The humidity-sensing performance of the prepared sensors is evaluated by measuring the impedance changes under the relative humidity variation between 10 and 90% relative humidity. The CNF-AgNP sensor exhibited very sensitive and fast humidity-sensing responses compared to the CNF sensor. The electrode distance effect and the response and recovery times are investigated. The enhanced humidity-sensing performance is reflected in the increased conductivity of the Ag nanoparticles and the adsorption of free water molecules associated with the porous characteristics of the CNF layer. The CNF-AgNP composite enables the development of highly sensitive, fast-responding, reproducible, flexible, and inexpensive humidity sensors. Full article

(This article belongs to the Special Issue Nanomaterials for Flexible and Printed Electronics)

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