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Nanomaterials, Volume 14, Issue 1 (January-1 2024) – 128 articles

Cover Story (view full-size image): In tungsten-based semiconducting transition metal dichalcogenides, the recombination of lower energy electron–hole optical excitations does not lead to photon emissions, because they correspond to transitions that are forbidden either by spin or momentum selection rules. However, these dark transitions can be brightened via scattering with defects or phonons. We find that strong exciton–phonon coupling yields the brightening of dark transitions up to sixth-order phonon replicas. Although defects play a critical role in the brightening pathways of dark excitons and their phonon replicas, these emissions are intrinsic to the material and independent of substrate, encapsulation, growth method, and transfer approach. View this paper
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2 pages, 138 KiB  
Editorial
Functional Nanomaterials for Sensing and Detection
by Weiping Cai
Nanomaterials 2024, 14(1), 128; https://doi.org/10.3390/nano14010128 - 04 Jan 2024
Viewed by 812
Abstract
Functional nanomaterials involve various nanostructured objects, such as zero-dimensional (0D), 1D, and 2D nano-objects (nanoparticles, nanowires, nanotubes, nanosheets, etc [...] Full article
(This article belongs to the Special Issue Functional Nanomaterials for Sensing and Detection)
16 pages, 11422 KiB  
Article
Mechanism Exploration of the Effect of Polyamines on the Polishing Rate of Silicon Chemical Mechanical Polishing: A Study Combining Simulations and Experiments
by Ziwei Lin, Junli Zhu, Qi Huang, Lei Zhu, Weimin Li and Wenjie Yu
Nanomaterials 2024, 14(1), 127; https://doi.org/10.3390/nano14010127 - 04 Jan 2024
Viewed by 1017
Abstract
Polyamines have become important chemical components used in several integrated circuit manufacturing processes, such as etching, chemical mechanical polishing (CMP), and cleaning. Recently, researchers pointed out that polyamines can be excellent enhancers in promoting the material removal rate (MRR) of Si CMP, but [...] Read more.
Polyamines have become important chemical components used in several integrated circuit manufacturing processes, such as etching, chemical mechanical polishing (CMP), and cleaning. Recently, researchers pointed out that polyamines can be excellent enhancers in promoting the material removal rate (MRR) of Si CMP, but the interaction mechanism between the polyamines and the silicon surface has not been clarified. Here, the micro-interaction mechanisms of polyamines, including ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), and pentaethylenehexamine (PEHA), with the Si(1, 0, 0) surface were investigated through molecular dynamics (MD) simulations using the ReaxFF reactive force field. Polyamines can adsorb onto the Si(1, 0, 0) surface, and the adsorption rate first accelerates and then tends to stabilize with the increase in the quantity of -CH2CH2NH-. The close connection between the adsorption properties of polyamines and the polishing rate has been confirmed by CMP experiments on silicon wafers. A comprehensive bond analysis indicates that the adsorption of polyamines can stretch surface Si–Si bonds, which facilitates subsequent material removal by abrasive mechanical wear. This work reveals the adsorption mechanism of polyamines onto the silicon substrate and the understanding of the MRR enhancement in silicon CMP, which provides guidance for the design of CMP slurry. Full article
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14 pages, 4108 KiB  
Article
Enhanced Electrostatic Safety and Thermal Compatibility of Special Powders Based on Surface Modification
by Xuchao Pan, Libo Zhang, Jialu Guan, Jing Lv, Yifei Xie, Haifeng Yang and Linghua Tan
Nanomaterials 2024, 14(1), 126; https://doi.org/10.3390/nano14010126 - 04 Jan 2024
Viewed by 818
Abstract
Electrostatic accumulation is associated with almost all powder-conveying processes which could bring about electrostatic discharges. In most cases of industrial accidents, electrostatic discharge is proven to be the primary source of ignition and explosion. Herein, a surface modification process of polyaniline (PANI) is [...] Read more.
Electrostatic accumulation is associated with almost all powder-conveying processes which could bring about electrostatic discharges. In most cases of industrial accidents, electrostatic discharge is proven to be the primary source of ignition and explosion. Herein, a surface modification process of polyaniline (PANI) is proposed to construct highly exothermic special powders, namely, HMX@PANI energetic composites, with low charge accumulation for improving powder electrostatic safety. Pure HMX are encapsulated within the PANI-conductive polymer layer through simple hydrogen bonding. Simulation results demonstrate that the forming process of HMX/aniline structure is a spontaneously thermodynamical process. The resultant inclusion complex exhibits excellent thermal stability, remarkable compatibility and intensive heat release. Importantly, PANI possesses superior electrostatic mobility characteristics because of the π-conjugated ligand, which can significantly reduce the accumulated charges on the surface of energetic powders. Moreover, the modified explosive has a narrower energy gap, which will improve the electron transition by reducing the energy barrier. The electrostatic accumulation test demonstrates that HMX@PANI composites possess a trace electrostatic accumulation of 34 nC/kg, which is two orders of magnitude lower than that of pure HMX (−6600 nC/kg) and might indicate a higher electrostatic safety. In conclusion, this surface modification process shows great promise for potential applications and could be extensively used in the establishment of high electrostatic safety for special powders. Full article
(This article belongs to the Special Issue Thermally Conductive Nanomaterials and Their Applications)
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12 pages, 1751 KiB  
Article
3D Magnetization Textures: Toroidal Magnetic Hopfion Stability in Cylindrical Samples
by Konstantin Guslienko
Nanomaterials 2024, 14(1), 125; https://doi.org/10.3390/nano14010125 - 04 Jan 2024
Viewed by 801
Abstract
Topologically non-trivial magnetization configurations in ferromagnetic materials on the nanoscale, such as hopfions, skyrmions, and vortices, have attracted considerable attention of researchers during the last few years. In this article, by applying the theory of micromagnetism, I demonstrate that the toroidal hopfion magnetization [...] Read more.
Topologically non-trivial magnetization configurations in ferromagnetic materials on the nanoscale, such as hopfions, skyrmions, and vortices, have attracted considerable attention of researchers during the last few years. In this article, by applying the theory of micromagnetism, I demonstrate that the toroidal hopfion magnetization configuration is a metastable state of a thick cylindrical ferromagnetic nanodot or a nanowire of a finite radius. The existence of this state is a result of the competition among exchange, magnetostatic, and magnetic anisotropy energies. The Dzyaloshinskii–Moriya exchange interaction and surface magnetic anisotropy are of second importance for the hopfion stabilization. The toroidal hopfion metastable magnetization configuration may be reached in the process of remagnetizing the sample by applying an external magnetic field along the cylindrical axis. Full article
(This article belongs to the Special Issue Magnetism and Magnetic Properties of Nanomaterials)
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20 pages, 5164 KiB  
Article
Novel Nanostructured Pd/Co-Alumina Materials for the Catalytic Oxidation of Atmospheric Pollutants
by Eleni F. Iliopoulou, Eleni Pachatouridou and Angelos A. Lappas
Nanomaterials 2024, 14(1), 124; https://doi.org/10.3390/nano14010124 - 04 Jan 2024
Viewed by 666
Abstract
Cobalt-doped alumina catalysts were prepared using different methods, either conventional wet impregnation (WI) and/or advanced spray impregnation (SI), and they were evaluated as novel oxidation catalysts for CO and MeOH oxidation. The spray impregnation technique was used with the aim of achieving the [...] Read more.
Cobalt-doped alumina catalysts were prepared using different methods, either conventional wet impregnation (WI) and/or advanced spray impregnation (SI), and they were evaluated as novel oxidation catalysts for CO and MeOH oxidation. The spray impregnation technique was used with the aim of achieving the synthesis of core–shell catalytic nanostructures to secure the chemical/thermal stability of active sites on the catalyst carrier. The catalysts were further promoted with a low Pd content (0.5 wt.%) incorporated via either incipient wetness impregnation (DI) or spray impregnation. The results revealed the superior performance of the spray-impregnated catalysts (Co/γ-Al2O3-SI) for both reactions. The deposition of Co oxide on the outer surface of the alumina particle (SEM images) and the availability of the active Co phase resulted in the enhancement of the Co/γ-Al2O3 catalysts’ oxidation activity. Pd incorporation increased the catalysts’ reducibility (TPR-H2) and improved the catalysts’ performance for both reactions. However, the Pd incorporation method affected the catalytic performance; with the SI method, the active phase of Co3O4 was probably covered with PdO and was not available for the oxidation reactions. On the contrary, the incorporation of Pd with the DI method resulted in a better dispersion of PdO all over the Co/Al catalyst surface, maintaining available Co active sites and a better Pd-Co interaction. MeOH desorption studies revealed the methanol oxidation mechanism: the Co/Al catalysts promoted the partial oxidation of MeOH to formaldehyde (HCHO) and dehydration to dimethyl ether (DME), while the Pd-based Co/Al catalysts enhanced the complete oxidation of methanol to CO2 and H2O. Full article
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20 pages, 5487 KiB  
Article
Nitrogen-Doped Graphene Materials with High Electrical Conductivity Produced by Electrochemical Exfoliation of Graphite Foil
by Hela Kammoun, Benjamin D. Ossonon and Ana C. Tavares
Nanomaterials 2024, 14(1), 123; https://doi.org/10.3390/nano14010123 - 04 Jan 2024
Viewed by 1527
Abstract
Nitrogen-doped graphene-based materials are of utmost importance in sensing and energy conversion devices due to their unique physicochemical properties. However, the presence of defects such as pyrrolic nitrogen and oxygenated functional groups reduces their electrical conductivity. Herein, a two-step approach based on the [...] Read more.
Nitrogen-doped graphene-based materials are of utmost importance in sensing and energy conversion devices due to their unique physicochemical properties. However, the presence of defects such as pyrrolic nitrogen and oxygenated functional groups reduces their electrical conductivity. Herein, a two-step approach based on the electrochemical exfoliation of graphite foils in aqueous mixed electrolytes followed by thermal reduction at 900 °C is used to prepare high-quality few layers of N-doped graphene-based materials. The exfoliations were conducted in 0.1 M (NH4)2SO4 or H2SO4 and HNO3 (5 mM or 0.1 M) electrolytes mixtures and the HNO3 vol% varied. Chemical analysis demonstrated that the as-prepared graphene oxides contain nitro and amine groups. Thermal reduction is needed for substitutional N-doping. Nitrogen and oxygen surface concentrations vary between 0.23–0.96% and 3–8%, respectively. Exfoliation in (NH4)2SO4 and/or 5 mM HNO3 favors the formation of pyridinic-N (10–40% of the total N), whereas 1 M HNO3 favors the formation of graphitic-N (≈60%). The electrical conductivity ranges between 166–2705 Scm−1. Raman spectroscopy revealed a low density of defects (ID/IG ratio between 0.1 and 0.7) and that most samples are composed of mono-to-bilayer graphene-based materials (IG/I2D integrated intensities ratio). Structural and compositional stability of selected samples after storage in air for three months is demonstrated. These results confirm the high quality of the synthesized undoped and N-doped graphene-type materials. Full article
(This article belongs to the Special Issue Electronic Applications of Graphene-Based Composites)
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23 pages, 9881 KiB  
Article
Effect of Co Doping on the Physical Properties and Organic Pollutant Photodegradation Efficiency of ZnO Nanoparticles for Environmental Applications
by Hajer Saadi, Othmen Khaldi, João Pina, Telma Costa, J. Sérgio Seixas de Melo, Paula Vilarinho and Zohra Benzarti
Nanomaterials 2024, 14(1), 122; https://doi.org/10.3390/nano14010122 - 04 Jan 2024
Viewed by 857
Abstract
This paper presents a comprehensive investigation of the synthesis and characterization of Zn1−xCoxO (0 ≤ x ≤ 0.05) nanopowders using a chemical co-precipitation approach. The structural, morphological, and vibrational properties of the resulting ZnO nanostructures were assessed through X-ray [...] Read more.
This paper presents a comprehensive investigation of the synthesis and characterization of Zn1−xCoxO (0 ≤ x ≤ 0.05) nanopowders using a chemical co-precipitation approach. The structural, morphological, and vibrational properties of the resulting ZnO nanostructures were assessed through X-ray diffraction, scanning electronic microscopy, and Raman spectroscopy to examine the influence of cobalt doping. Remarkably, a notable congruence between the experimental results and the density functional theory (DFT) calculations for the Co-doped ZnO system was achieved. Structural analysis revealed well-crystallized hexagonal wurtzite structures across all samples. The SEM images demonstrated the formation of spherical nanoparticles in all the samples. The vibrational properties confirmed the formation of a hexagonal wurtzite structure, with an additional Raman peak corresponding to the F2g vibrational mode characteristic of the secondary phase of ZnCo2O4 observed at a 5% cobalt doping concentration. Furthermore, a theoretical examination of cobalt doping’s impact on the elastic properties of ZnO demonstrated enhanced mechanical behavior, which improves stability, recyclability, and photocatalytic activity. The photocatalytic study of the synthesized compositions for methylene blue (MB) dye degradation over 100 min of UV light irradiation demonstrated that Co doping significantly improves photocatalytic degradation. The material’s prolonged lifetime, reduced rate of photogenerated charge carrier recombination, and increased surface area were identified as pivotal factors accelerating the degradation process. Notably, the photocatalyst with a Zn0.99Co0.01O composition exhibited exceptional efficiency compared to that reported in the literature. It demonstrated high removal activity, achieving an efficiency of about 97% in a shorter degradation time. This study underscores the structural and photocatalytic advancements in the ZnO system, particularly at lower cobalt doping concentrations (1%). The developed photocatalyst exhibits promise for environmental applications owing to its superior photocatalytic performance. Full article
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3 pages, 177 KiB  
Editorial
Advances in Energy Harvesters/Nanogenerators and Self-Powered Sensors II
by Jianxiong Zhu and Qiongfeng Shi
Nanomaterials 2024, 14(1), 121; https://doi.org/10.3390/nano14010121 - 04 Jan 2024
Viewed by 765
Abstract
The Internet of Things (IoT) has become a focal point in the realm of information technology and has facilitated the interconnectedness and communication of various objects, such as devices and sensors in smart cities, intelligent transportation, industrial automation, agriculture, healthcare, etc [...] Full article
14 pages, 2213 KiB  
Article
Raman Spectroscopy Unfolds the Fate and Transformation of SWCNTs after Abrasive Wear of Epoxy Floor Coatings
by Amaia Soto Beobide, Rudolf Bieri, Zoltán Szakács, Kevin Sparwasser, Ioanna G. Kaitsa, Ilias Georgiopoulos, Konstantinos S. Andrikopoulos, Gunther Van Kerckhove and George A. Voyiatzis
Nanomaterials 2024, 14(1), 120; https://doi.org/10.3390/nano14010120 - 03 Jan 2024
Viewed by 1663
Abstract
Nanomaterials are integrated within consumer products to enhance specific properties of interest. Their release throughout the lifecycle of nano-enabled products raises concerns; specifically, mechanical strains can lead to the generation of fragmented materials containing nanomaterials. We investigated the potential release of single-walled carbon [...] Read more.
Nanomaterials are integrated within consumer products to enhance specific properties of interest. Their release throughout the lifecycle of nano-enabled products raises concerns; specifically, mechanical strains can lead to the generation of fragmented materials containing nanomaterials. We investigated the potential release of single-walled carbon nanotubes (SWCNTs—brand TUBALL™) from epoxy composite materials. A pin-on-disk-type tribometer was used for the accelerated mechanical aging of the nanocomposites. A pristine nanocomposite material, abraded material and debris obtained from the abrasion in the tribometer were analyzed by Raman spectroscopy. The airborne-produced particles were captured using particle collectors. Stat Peel’s Identifier C2 system was used to monitor the SWCNT content of respirable particles produced during the abrasion test. The SWCNT amounts found were below the LoQ. The Raman spectra conducted on the Stat Peel filters helped identify the presence of free SWCNTs released from the epoxy matrix, although they were notably scarce. Raman spectroscopy has been proved to be a crucial technique for the identification, characterization and assessment of structural changes and degradation in SWCNTs that occurred during the abrasion experiments. Full article
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11 pages, 4532 KiB  
Article
Cost-Effective Preparation of Hydrophobic and Thermal-Insulating Silica Aerogels
by Jiaqi Shan, Yunpeng Shan, Chang Zou, Ye Hong, Jia Liu and Xingzhong Guo
Nanomaterials 2024, 14(1), 119; https://doi.org/10.3390/nano14010119 - 03 Jan 2024
Cited by 1 | Viewed by 1139
Abstract
The aim of this study is to reduce the manufacturing cost of a hydrophobic and heat-insulating silica aerogel and promote its industrial application in the field of thermal insulation. Silica aerogels with hydrophobicity and thermal-insulation capabilities were synthesized by using water-glass as the [...] Read more.
The aim of this study is to reduce the manufacturing cost of a hydrophobic and heat-insulating silica aerogel and promote its industrial application in the field of thermal insulation. Silica aerogels with hydrophobicity and thermal-insulation capabilities were synthesized by using water-glass as the silicon source and supercritical drying. The effectiveness of acid and alkali catalysis is compared in the formation of the sol. The introduction of sodium methyl silicate for the copolymerization enhances the hydrophobicity of the aerogel. The resultant silica aerogel has high hydrophobicity and a mesoporous structure with a pore volume exceeding 4.0 cm3·g−1 and a specific surface area exceeding 950 m2·g−1. The obtained silica aerogel/fiber-glass-mat composite has high thermal insulation, with a thermal conductivity of less than 0.020 W·m−1·K−1. The cost-effective process is promising for applications in the industrial preparation of silica aerogel thermal-insulating material. Full article
(This article belongs to the Special Issue Nanomaterials in Aerogel Composites)
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12 pages, 4335 KiB  
Article
In-Situ Construction of Anti-Aggregation Tellurium Nanorods/Reduced Graphene Oxide Composite to Enable Fast Sodium Storage
by Haiguo Hu, Jiarui Zhong, Bangquan Jian, Cheng Zheng, Yonghong Zeng, Cuiyun Kou, Quanlan Xiao, Yiyu Luo, Huide Wang, Zhinan Guo and Li Niu
Nanomaterials 2024, 14(1), 118; https://doi.org/10.3390/nano14010118 - 03 Jan 2024
Viewed by 794
Abstract
Sodium-ion batteries (SIBs) as a replaceable energy storage technology have attracted extensive attention in recent years. The design and preparation of advanced anode materials with high capacity and excellent cycling performance for SIBs still face enormous challenges. Herein, a solution method is developed [...] Read more.
Sodium-ion batteries (SIBs) as a replaceable energy storage technology have attracted extensive attention in recent years. The design and preparation of advanced anode materials with high capacity and excellent cycling performance for SIBs still face enormous challenges. Herein, a solution method is developed for in situ synthesis of anti-aggregation tellurium nanorods/reduced graphene oxide (Te NR/rGO) composite. The material working as the sodium-ion battery (SIB) anode achieves a high reversible capacity of 338 mAh g−1 at 5 A g−1 and exhibits up to 93.4% capacity retention after 500 cycles. This work demonstrates an effective preparation method of nano-Te-based composites for SIBs. Full article
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14 pages, 2959 KiB  
Article
Impact of Single-Walled Carbon Nanotube Functionalization on Ion and Water Molecule Transport at the Nanoscale
by Alia Mejri, Nicolas Arroyo, Guillaume Herlem, John Palmeri, Manoel Manghi, François Henn and Fabien Picaud
Nanomaterials 2024, 14(1), 117; https://doi.org/10.3390/nano14010117 - 03 Jan 2024
Cited by 1 | Viewed by 934
Abstract
Nanofluidics has a very promising future owing to its numerous applications in many domains. It remains, however, very difficult to understand the basic physico-chemical principles that control the behavior of solvents confined in nanometric channels. Here, water and ion transport in carbon nanotubes [...] Read more.
Nanofluidics has a very promising future owing to its numerous applications in many domains. It remains, however, very difficult to understand the basic physico-chemical principles that control the behavior of solvents confined in nanometric channels. Here, water and ion transport in carbon nanotubes is investigated using classical force field molecular dynamics simulations. By combining one single walled carbon nanotube (uniformly charged or not) with two perforated graphene sheets, we mimic single nanopore devices similar to experimental ones. The graphitic edges delimit two reservoirs of water and ions in the simulation cell from which a voltage is imposed through the application of an external electric field. By analyzing the evolution of the electrolyte conductivity, the role of the carbon nanotube geometric parameters (radius and chirality) and of the functionalization of the carbon nanotube entrances with OH or COO groups is investigated for different concentrations of group functions. Full article
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9 pages, 7530 KiB  
Article
Simulated Guidance in Interpreting Nano-Patterned Co70Fe30 Film Imaging with Differential Phase Contrast
by Björn Büker, Daniela Ramermann, Pierre-M. Piel, Judith Bünte, Inga Ennen and Andreas Hütten
Nanomaterials 2024, 14(1), 116; https://doi.org/10.3390/nano14010116 - 03 Jan 2024
Viewed by 717
Abstract
Our paper introduces a simulation-based framework designed to interpret differential phase contrast (DPC) magnetic imaging within the transmission electron microscope (TEM). We investigate patterned magnetic membranes, particularly focusing on nano-patterned Co70Fe30 thin-film membranes fabricated via focused ion beam (FIB) milling. [...] Read more.
Our paper introduces a simulation-based framework designed to interpret differential phase contrast (DPC) magnetic imaging within the transmission electron microscope (TEM). We investigate patterned magnetic membranes, particularly focusing on nano-patterned Co70Fe30 thin-film membranes fabricated via focused ion beam (FIB) milling. Our direct magnetic imaging reveals regular magnetic domain patterns in these carefully prepared systems. Notably, the observed magnetic structure aligns precisely with micromagnetic simulations based on the dimensions of the underlying nanostructures. This agreement emphasizes the usefulness of micromagnetic simulations, not only for the interpretation of DPC data, but also for the prediction of possible microstructures in magnetic sensor systems with nano-patterns. Full article
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14 pages, 8292 KiB  
Article
Highly Conducting Surface-Silverized Aromatic Polysulfonamide (PSA) Fibers with Excellent Performance Prepared by Nano-Electroplating
by Ruicheng Bai, Pei Zhang, Xihai Wang, Hengxin Zhang, Hao Wang and Qinsi Shao
Nanomaterials 2024, 14(1), 115; https://doi.org/10.3390/nano14010115 - 02 Jan 2024
Viewed by 874
Abstract
In this work, bilayer nanocoatings were designed and constructed on high-performance aromatic polysulfonamide (PSA) fibers for robust electric conduction and electromagnetic interference (EMI) shielding. More specifically, PSA fibers were first endowed with necessary electric conductivity via electroless nickel (Ni) or nickel alloy (Ni-P-B) [...] Read more.
In this work, bilayer nanocoatings were designed and constructed on high-performance aromatic polysulfonamide (PSA) fibers for robust electric conduction and electromagnetic interference (EMI) shielding. More specifically, PSA fibers were first endowed with necessary electric conductivity via electroless nickel (Ni) or nickel alloy (Ni-P-B) plating. Afterward, silver electroplating was carried out to further improve the performance of the composite. The morphology, microstructure, environmental stability, mechanical properties, and EMI shielding performance of the proposed cladded fibers were thoroughly investigated to examine the effects of electrodeposition on both amorphous Ni-P-B and crystalline Ni substrates. The acquired results demonstrated that both PSA@Ni@Ag and PSA@Ni-P-B@Ag composite fibers had high environment stability, good tensile strength, low electric resistance, and outstanding EMI shielding efficiency. This indicates that they can have wide application prospects in aviation, aerospace, telecommunications, and military industries. Furthermore, the PSA@Ni-P-B@Ag fiber configuration seemed more reasonable because it exhibited smoother and denser silver surfaces as well as stronger interfacial binding, leading to lower resistance (185 mΩ cm−1) and better shielding efficiency (82.48 dB in the X-band). Full article
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18 pages, 12200 KiB  
Article
The Plastic Deformation Mechanism in Nano-Polycrystalline Al/Mg Layered Composites: A Molecular Dynamics Study
by Zhou Li, Tong Shen, Xiao Hu, Lu Zhang, Xianshi Jia, Jiaqing Li and Che Zhang
Nanomaterials 2024, 14(1), 114; https://doi.org/10.3390/nano14010114 - 02 Jan 2024
Viewed by 865
Abstract
Understanding plastic deformation behaviour is key to optimising the mechanical properties of nano-polycrystalline layered composites. This study employs the molecular dynamics (MD) simulation to comprehensively investigate the effects of various factors, such as grain sizes, strain rates, and the interlayer thicknesses of the [...] Read more.
Understanding plastic deformation behaviour is key to optimising the mechanical properties of nano-polycrystalline layered composites. This study employs the molecular dynamics (MD) simulation to comprehensively investigate the effects of various factors, such as grain sizes, strain rates, and the interlayer thicknesses of the intermetallic compounds (IMCs), on the plastic deformation behaviour of nano-polycrystalline Al/Mg layered composites. Our findings reveal that the influence of grain size on deformation behaviour is governed by the strain rate, and an increase in grain size is inversely proportional to yield stress at low strain rates, whereas it is positively proportional to tensile stress at high strain rates. Moreover, an optimal thickness of the intermediate layer contributes to enhanced composite strength, whereas an excessive thickness leads to reduced tensile strength due to the fewer grain boundaries (GBs) available for accommodating dislocations. The reinforcing impact of the intermediate IMCs layer diminishes at excessive strain rates, as the grains struggle to accommodate substantial large strains within a limited timeframe encountered at high strain rates. The insights into grain sizes, strain rates, and interlayer thicknesses obtained from this study enable the tailored development of nanocomposites with optimal mechanical characteristics. Full article
(This article belongs to the Section Nanocomposite Materials)
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13 pages, 3702 KiB  
Article
Hydroxyapatite Nanorods Based Drug Delivery Systems for Bumetanide and Meloxicam, Poorly Water Soluble Active Principles
by Valeria Friuli, Lauretta Maggi, Giovanna Bruni, Francesca Caso and Marcella Bini
Nanomaterials 2024, 14(1), 113; https://doi.org/10.3390/nano14010113 - 02 Jan 2024
Viewed by 915
Abstract
Poorly water-soluble drugs represent a challenge for the pharmaceutical industry because it is necessary to find properly tuned and efficient systems for their release. In this framework, organic–inorganic hybrid systems could represent a promising strategy. A largely diffused inorganic host is hydroxyapatite (HAP, [...] Read more.
Poorly water-soluble drugs represent a challenge for the pharmaceutical industry because it is necessary to find properly tuned and efficient systems for their release. In this framework, organic–inorganic hybrid systems could represent a promising strategy. A largely diffused inorganic host is hydroxyapatite (HAP, Ca10(PO4)6(OH)2), which is easily synthesized with different external forms and can adsorb different kinds of molecules, thereby allowing rapid drug release. Hybrid nanocomposites of HAP nanorods, obtained through hydrothermal synthesis, were prepared with two model pharmaceutical molecules characterized by low and pH-dependent solubility: meloxicam, a non-steroidal anti-inflammatory drug, and bumetanide, a diuretic drug. Both hybrids were physically and chemically characterized through the combined use of X-ray powder diffraction, scanning electron microscopy with energy-dispersive spectroscopy, differential scanning calorimetry, and infrared spectroscopy measurements. Then, their dissolution profiles and hydrophilicity (contact angles) in different media as well as their solubility were determined and compared to the pure drugs. This hybrid system seems particularly suitable as a drug carrier for bumetanide, as it shows higher drug loading and good dissolution profiles, while is less suitable for meloxicam, an acid molecule. Full article
(This article belongs to the Special Issue Nanoparticles in Drug Delivery Applications)
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30 pages, 3709 KiB  
Review
Functionalized Nanomaterials for Inhibiting ATP-Dependent Heat Shock Proteins in Cancer Photothermal/Photodynamic Therapy and Combination Therapy
by Thejas P. Premji, Banendu Sunder Dash, Suprava Das and Jyh-Ping Chen
Nanomaterials 2024, 14(1), 112; https://doi.org/10.3390/nano14010112 - 02 Jan 2024
Cited by 1 | Viewed by 1327
Abstract
Phototherapies induced by photoactive nanomaterials have inspired and accentuated the importance of nanomedicine in cancer therapy in recent years. During these light-activated cancer therapies, a nanoagent can produce heat and cytotoxic reactive oxygen species by absorption of light energy for photothermal therapy (PTT) [...] Read more.
Phototherapies induced by photoactive nanomaterials have inspired and accentuated the importance of nanomedicine in cancer therapy in recent years. During these light-activated cancer therapies, a nanoagent can produce heat and cytotoxic reactive oxygen species by absorption of light energy for photothermal therapy (PTT) and photodynamic therapy (PDT). However, PTT is limited by the self-protective nature of cells, with upregulated production of heat shock proteins (HSP) under mild hyperthermia, which also influences PDT. To reduce HSP production in cancer cells and to enhance PTT/PDT, small HSP inhibitors that can competitively bind at the ATP-binding site of an HSP could be employed. Alternatively, reducing intracellular glucose concentration can also decrease ATP production from the metabolic pathways and downregulate HSP production from glucose deprivation. Other than reversing the thermal resistance of cancer cells for mild-temperature PTT, an HSP inhibitor can also be integrated into functionalized nanomaterials to alleviate tumor hypoxia and enhance the efficacy of PDT. Furthermore, the co-delivery of a small-molecule drug for direct HSP inhibition and a chemotherapeutic drug can integrate enhanced PTT/PDT with chemotherapy (CT). On the other hand, delivering a glucose-deprivation agent like glucose oxidase (GOx) can indirectly inhibit HSP and boost the efficacy of PTT/PDT while combining these therapies with cancer starvation therapy (ST). In this review, we intend to discuss different nanomaterial-based approaches that can inhibit HSP production via ATP regulation and their uses in PTT/PDT and cancer combination therapy such as CT and ST. Full article
(This article belongs to the Special Issue Functional Nanomaterials for Cancer Therapy)
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35 pages, 7305 KiB  
Review
Review of Gold Nanoparticles in Surface Plasmon-Coupled Emission Technology: Effect of Shape, Hollow Nanostructures, Nano-Assembly, Metal–Dielectric and Heterometallic Nanohybrids
by Kalathur Mohan Ganesh, Seemesh Bhaskar, Vijay Sai Krishna Cheerala, Prajwal Battampara, Roopa Reddy, Sundaresan Chittor Neelakantan, Narendra Reddy and Sai Sathish Ramamurthy
Nanomaterials 2024, 14(1), 111; https://doi.org/10.3390/nano14010111 - 02 Jan 2024
Cited by 2 | Viewed by 1367
Abstract
Point-of-care (POC) diagnostic platforms are globally employed in modern smart technologies to detect events or changes in the analyte concentration and provide qualitative and quantitative information in biosensing. Surface plasmon-coupled emission (SPCE) technology has emerged as an effective POC diagnostic tool for developing [...] Read more.
Point-of-care (POC) diagnostic platforms are globally employed in modern smart technologies to detect events or changes in the analyte concentration and provide qualitative and quantitative information in biosensing. Surface plasmon-coupled emission (SPCE) technology has emerged as an effective POC diagnostic tool for developing robust biosensing frameworks. The simplicity, robustness and relevance of the technology has attracted researchers in physical, chemical and biological milieu on account of its unique attributes such as high specificity, sensitivity, low background noise, highly polarized, sharply directional, excellent spectral resolution capabilities. In the past decade, numerous nano-fabrication methods have been developed for augmenting the performance of the conventional SPCE technology. Among them the utility of plasmonic gold nanoparticles (AuNPs) has enabled the demonstration of plethora of reliable biosensing platforms. Here, we review the nano-engineering and biosensing applications of AuNPs based on the shape, hollow morphology, metal–dielectric, nano-assembly and heterometallic nanohybrids under optical as well as biosensing competencies. The current review emphasizes the recent past and evaluates the latest advancements in the field to comprehend the futuristic scope and perspectives of exploiting Au nano-antennas for plasmonic hotspot generation in SPCE technology. Full article
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13 pages, 4722 KiB  
Communication
Stability of Zr-Based UiO-66 Metal–Organic Frameworks in Basic Solutions
by Jun Yeong Kim, Jiwon Kang, Seungheon Cha, Haein Kim, Dopil Kim, Houng Kang, Isaac Choi and Min Kim
Nanomaterials 2024, 14(1), 110; https://doi.org/10.3390/nano14010110 - 02 Jan 2024
Cited by 1 | Viewed by 1235
Abstract
Although Zr-based metal–organic frameworks (MOFs) exhibit robust chemical and physical stability in the presence of moisture and acidic conditions, their susceptibility to nucleophilic attacks from bases poses a critical challenge to their overall stability. Herein, we systematically investigate the stability of Zr-based UiO-66 [...] Read more.
Although Zr-based metal–organic frameworks (MOFs) exhibit robust chemical and physical stability in the presence of moisture and acidic conditions, their susceptibility to nucleophilic attacks from bases poses a critical challenge to their overall stability. Herein, we systematically investigate the stability of Zr-based UiO-66 (UiO = University of Oslo) MOFs in basic solutions. The impact of 11 standard bases, including inorganic salts and organic bases, on the stability of these MOFs is examined. The destruction of the framework is confirmed through powder X-ray diffraction (PXRD) patterns, and the monitored dissolution of ligands from the framework is assessed using nuclear magnetic resonance (NMR) spectroscopy. Our key findings reveal a direct correlation between the strength and concentration of the base and the destruction of the MOFs. The summarized data provide valuable insights that can guide the practical application of Zr-based UiO-66 MOFs under basic conditions, offering essential information for their optimal utilization in various settings. Full article
(This article belongs to the Special Issue Metal Organic Framework (MOF)-Based Micro/Nanoscale Materials)
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13 pages, 7639 KiB  
Article
Plasmon Resonance in a System of Bi Nanoparticles Embedded into (Al,Ga)As Matrix
by Vitalii I. Ushanov, Sergey V. Eremeev, Vyacheslav M. Silkin and Vladimir V. Chaldyshev
Nanomaterials 2024, 14(1), 109; https://doi.org/10.3390/nano14010109 - 02 Jan 2024
Viewed by 672
Abstract
We reveal the feasibility of the localized surface plasmon resonance in a system of Bi nanoparticles embedded into an AlxGa1xAs semiconductor matrix. With an ab initio determined dielectric function for bismuth and well-known dielectric properties of Al [...] Read more.
We reveal the feasibility of the localized surface plasmon resonance in a system of Bi nanoparticles embedded into an AlxGa1xAs semiconductor matrix. With an ab initio determined dielectric function for bismuth and well-known dielectric properties of AlxGa1xAs solid solution, we performed calculations of the optical extinction spectra for such metamaterial using Mie’s theory. The calculations demonstrate a strong band of the optical extinction using the localized surface plasmons near a photon energy of 2.5 eV. For the semiconducting matrices with a high aluminum content x>0.7, the extinction by plasmonic nanoparticles plays the dominant role in the optical properties of the medium near the resonance photon energy. Full article
(This article belongs to the Section Nanophotonics Materials and Devices)
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16 pages, 5150 KiB  
Article
Modified 3D Graphene for Sensing and Electrochemical Capacitor Applications
by Kavitha Mulackampilly Joseph, Gabrielle R. Dangel and Vesselin Shanov
Nanomaterials 2024, 14(1), 108; https://doi.org/10.3390/nano14010108 - 02 Jan 2024
Viewed by 765
Abstract
Less defective, nitrogen-doped 3-dimensional graphene (N3DG) and defect-rich, nitrogen-doped 3-dimensional graphene (N3DG-D) were made by the thermal CVD (Chemical Vapor Deposition) process via varying the carbon precursors and synthesis temperature. These modified 3D graphene materials were compared with pristine 3-dimensional graphene (P3DG), which [...] Read more.
Less defective, nitrogen-doped 3-dimensional graphene (N3DG) and defect-rich, nitrogen-doped 3-dimensional graphene (N3DG-D) were made by the thermal CVD (Chemical Vapor Deposition) process via varying the carbon precursors and synthesis temperature. These modified 3D graphene materials were compared with pristine 3-dimensional graphene (P3DG), which has fewer defects and no nitrogen in its structure. The different types of graphene obtained were characterized for morphological, structural, and compositional assessment through Scanning Electron Microscopy (SEM), Raman Spectroscopy, and X-ray Photoelectron Spectroscopy (XPS) techniques. Electrodes were fabricated, and electrochemical characterizations were conducted to evaluate the suitability of the three types of graphene for heavy metal sensing (lead) and Electric Double-Layer Capacitor (EDLC) applications. Initially, the various electrodes were treated with a mixture of 2.5 mM Ruhex (Ru (NH3)6Cl3 and 25 mM KCl to confirm that all the electrodes underwent a reversible and diffusion-controlled electrochemical process. Defect-rich graphene (N3DG-D) revealed the highest current density, followed by pristine (P3DG) and less-defect graphene (N3DG). Further, the three types of graphene were subjected to a sensing test by square wave anodic stripping voltammetry (SWASV) for lead detection. The obtained preliminary results showed that the N3DG material provided a great lead-sensing capability, detecting as little as 1 µM of lead in a water solution. The suitability of the electrodes to be employed in an Electric Double-Layer Capacitor (EDLC) was also comparatively assessed. Electrochemical characterization using 1 M sodium sulfate electrolyte was conducted through cyclic voltammetry and galvanostatic charge-discharge studies. The voltammogram and the galvanostatic charge-discharge (GCD) curves of the three types of graphene confirmed their suitability to be used as EDLC. The N3DG electrode proved superior with a gravimetric capacitance of 6.1 mF/g, followed by P3DG and N3DG, exhibiting 1.74 mF/g and 0.32 mF/g, respectively, at a current density of 2 A/g. Full article
(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Storage)
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12 pages, 2122 KiB  
Article
Formamidinium Perovskite Deposition in Ambient Air Environment for Inverted p-i-n Solar Cells
by Nadir Vanni, Riccardo Pò, Paolo Biagini, Gianluca Bravetti, Sonia Carallo, Antonella Giuri and Aurora Rizzo
Nanomaterials 2024, 14(1), 107; https://doi.org/10.3390/nano14010107 - 02 Jan 2024
Cited by 1 | Viewed by 1254
Abstract
In order to move towards large-scale fabrication, perovskite solar cells need to detach themselves from strictly controlled environmental conditions and, to this end, fabrication in ambient air is highly desirable. Formamidinium iodide perovskite (FAPI) is one of the most promising perovskites but is [...] Read more.
In order to move towards large-scale fabrication, perovskite solar cells need to detach themselves from strictly controlled environmental conditions and, to this end, fabrication in ambient air is highly desirable. Formamidinium iodide perovskite (FAPI) is one of the most promising perovskites but is also unstable at room temperature, which may make the ambient air deposition more difficult. Herein, we investigated different formulations of pure FAPI for the fabrication of perovskite solar cells (PSCs) in air. We found that formulations using a mixture of N,N-Dimethylformamide (DMF): N-methyl-2-pyrrolidone (NMP) and only dimethyl sulfoxide (DMSO) are suitable for the deposition in air. To fabricate inverted p-i-n solar cells, we tested different hole transporting layers (HTLs) and observed the effects on the wettability of the perovskite solution and on the performance. A self-assembly monolayer of 2PACz (2-(9H-Carbazol-9-yl)ethyl]phosphonic acid) was found to be the best option as a HTL, allowing us to achieve efficiencies >15% on both FTO and ITO. Full article
(This article belongs to the Section Synthesis, Interfaces and Nanostructures)
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20 pages, 6104 KiB  
Article
Monocyte (THP-1) Response to Silver Nanoparticles Synthesized with Rumex hymenosepalus Root Extract
by Francisco Javier Alvarez-Cirerol, José Manuel Galván-Moroyoqui, Ericka Rodríguez-León, Carmen Candía-Plata, César Rodríguez-Beas, Luis Fernando López-Soto, Blanca Esthela Rodríguez-Vázquez, José Bustos-Arriaga, Adriana Soto-Guzmán, Eduardo Larios-Rodríguez, Juan M. Martínez-Soto, Aaron Martinez-Higuera and Ramón A. Iñiguez-Palomares
Nanomaterials 2024, 14(1), 106; https://doi.org/10.3390/nano14010106 - 02 Jan 2024
Viewed by 1256
Abstract
The study, synthesis, and application of nanomaterials in medicine have grown exponentially in recent years. An example of this is the understanding of how nanomaterials activate or regulate the immune system, particularly macrophages. In this work, nanoparticles were synthesized using Rumex hymenosepalus as [...] Read more.
The study, synthesis, and application of nanomaterials in medicine have grown exponentially in recent years. An example of this is the understanding of how nanomaterials activate or regulate the immune system, particularly macrophages. In this work, nanoparticles were synthesized using Rumex hymenosepalus as a reducing agent (AgRhNPs). According to thermogravimetric analysis, the metal content of nanoparticles is 55.5% by weight. The size of the particles ranges from 5–26 nm, with an average of 11 nm, and they possess an fcc crystalline structure. The presence of extract molecules on the nanomaterial was confirmed by UV-Vis and FTIR. It was found by UPLC-qTOF that the most abundant compounds in Rh extract are flavonols, flavones, isoflavones, chalcones, and anthocyanidins. The viability and apoptosis of the THP-1 cell line were evaluated for AgRhNPs, commercial nanoparticles (AgCNPs), and Rh extract. The results indicate a minimal cytotoxic and apoptotic effect at a concentration of 12.5 μg/mL for both nanoparticles and 25 μg/mL for Rh extract. The interaction of the THP-1 cell line and treatments was used to evaluate the polarization of monocyte subsets in conjunction with an evaluation of CCR2, Tie-2, and Arg-1 expression. The AgRhNPs nanoparticles and Rh extract neither exhibited cytotoxicity in the THP-1 monocyte cell line. Additionally, the treatments mentioned above exhibited anti-inflammatory effects by maintaining the classical monocyte phenotype CD14++CD16, reducing pro-inflammatory interleukin IL-6 production, and increasing IL-4 production. Full article
(This article belongs to the Special Issue Advances in Nanoscale Materials in Biomedicine)
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15 pages, 32658 KiB  
Article
Thermoelectric Sensor with CuI Supported on Rough Glass
by Gustavo Panama and Seung S. Lee
Nanomaterials 2024, 14(1), 105; https://doi.org/10.3390/nano14010105 - 01 Jan 2024
Cited by 1 | Viewed by 976
Abstract
Thermoelectric generators convert heat into a potential difference with arrays of p- and n-type materials, a process that allows thermal energy harvesting and temperature detection. Thermoelectric sensors have attracted interest in relation to the creation of temperature and combustible gas sensors due to [...] Read more.
Thermoelectric generators convert heat into a potential difference with arrays of p- and n-type materials, a process that allows thermal energy harvesting and temperature detection. Thermoelectric sensors have attracted interest in relation to the creation of temperature and combustible gas sensors due to their simple operation principle and self-powering ability. CuI is an efficient p-type thermoelectric material that can be readily produced from a Cu layer by an iodination method. However, the vapor iodination of Cu has the disadvantage of weak adhesion on a bare glass substrate due to stress caused by crystal growth, limiting microfabrication applications of this process. This work presents a rough soda-lime glass substrate with nanoscale cavities to support the growth of a CuI layer, showing good adhesion and enhanced thermoelectric sensitivity. A rough glass sample with nanocavities is developed by reactive ion etching of a photoresist-coated glass sample in which aggregates of carbon residuals and the accumulation of NaF catalyze variable etching rates to produce local isotropic etching and roughening. A thermoelectric sensor consists of 41 CuI/In-CoSb3 thermoelectric leg pairs with gold electrodes for electrical interconnection. A thermoelectric leg has a width of 25 μm, a length of 3 mm, and a thickness of 1 μm. The thermoelectric response results in an open-circuit voltage of 13.7 mV/K on rough glass and 0.9 mV/K on bare glass under ambient conditions. Rough glass provides good mechanical interlocking and introduces important variations of the crystallinity and composition in the supported thermoelectric layers, leading to enhanced thermopower. Full article
(This article belongs to the Section Synthesis, Interfaces and Nanostructures)
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24 pages, 4776 KiB  
Article
Efficiency of InN/InGaN/GaN Intermediate-Band Solar Cell under the Effects of Hydrostatic Pressure, In-Compositions, Built-in-Electric Field, Confinement, and Thickness
by Hassan Abboudi, Haddou EL Ghazi, Redouane En-nadir, Mohamed A. Basyooni-M. Kabatas, Anouar Jorio and Izeddine Zorkani
Nanomaterials 2024, 14(1), 104; https://doi.org/10.3390/nano14010104 - 01 Jan 2024
Cited by 1 | Viewed by 1064
Abstract
This paper presents a thorough numerical investigation focused on optimizing the efficiency of quantum-well intermediate-band solar cells (QW-IBSCs) based on III-nitride materials. The optimization strategy encompasses manipulating confinement potential energy, controlling hydrostatic pressure, adjusting compositions, and varying thickness. The built-in electric fields in [...] Read more.
This paper presents a thorough numerical investigation focused on optimizing the efficiency of quantum-well intermediate-band solar cells (QW-IBSCs) based on III-nitride materials. The optimization strategy encompasses manipulating confinement potential energy, controlling hydrostatic pressure, adjusting compositions, and varying thickness. The built-in electric fields in (In, Ga)N alloys and heavy-hole levels are considered to enhance the results’ accuracy. The finite element method (FEM) and Python 3.8 are employed to numerically solve the Schrödinger equation within the effective mass theory framework. This study reveals that meticulous design can achieve a theoretical photovoltaic efficiency of quantum-well intermediate-band solar cells (QW-IBSCs) that surpasses the Shockley–Queisser limit. Moreover, reducing the thickness of the layers enhances the light-absorbing capacity and, therefore, contributes to efficiency improvement. Additionally, the shape of the confinement potential significantly influences the device’s performance. This work is critical for society, as it represents a significant advancement in sustainable energy solutions, holding the promise of enhancing both the efficiency and accessibility of solar power generation. Consequently, this research stands at the forefront of innovation, offering a tangible and impactful contribution toward a greener and more sustainable energy future. Full article
(This article belongs to the Topic Advances in Computational Materials Sciences)
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18 pages, 5619 KiB  
Article
Exploring the Remarkably High Photocatalytic Efficiency of Ultra-Thin Porous Graphitic Carbon Nitride Nanosheets
by Zahra Kalantari Bolaghi, Cristina Rodriguez-Seco, Aycan Yurtsever and Dongling Ma
Nanomaterials 2024, 14(1), 103; https://doi.org/10.3390/nano14010103 - 01 Jan 2024
Viewed by 1129
Abstract
Graphitic carbon nitride (g-C3N4) is a metal-free photocatalyst used for visible-driven hydrogen production, CO2 reduction, and organic pollutant degradation. In addition to the most attractive feature of visible photoactivity, its other benefits include thermal and photochemical stability, cost-effectiveness, [...] Read more.
Graphitic carbon nitride (g-C3N4) is a metal-free photocatalyst used for visible-driven hydrogen production, CO2 reduction, and organic pollutant degradation. In addition to the most attractive feature of visible photoactivity, its other benefits include thermal and photochemical stability, cost-effectiveness, and simple and easy-scale-up synthesis. However, its performance is still limited due to its low absorption at longer wavelengths in the visible range, and high charge recombination. In addition, the exfoliated nanosheets easily aggregate, causing the reduction in specific surface area, and thus its photoactivity. Herein, we propose the use of ultra-thin porous g-C3N4 nanosheets to overcome these limitations and improve its photocatalytic performance. Through the optimization of a novel multi-step synthetic protocol, based on an initial thermal treatment, the use of nitric acid (HNO3), and an ultrasonication step, we were able to obtain very thin and well-tuned material that yielded exceptional photodegradation performance of methyl orange (MO) under visible light irradiation, without the need for any co-catalyst. About 96% of MO was degraded in as short as 30 min, achieving a normalized apparent reaction rate constant (k) of 1.1 × 10−2 min−1mg−1. This represents the highest k value ever reported using C3N4-based photocatalysts for MO degradation, based on our thorough literature search. Ultrasonication in acid not only prevents agglomeration of g-C3N4 nanosheets but also tunes pore size distribution and plays a key role in this achievement. We also studied their performance in a photocatalytic hydrogen evolution reaction (HER), achieving a production of 1842 µmol h−1 g−1. Through a profound analysis of all the samples’ structure, morphology, and optical properties, we provide physical insight into the improved performance of our optimized porous g-C3N4 sample for both photocatalytic reactions. This research may serve as a guide for improving the photocatalytic activity of porous two-dimensional (2D) semiconductors under visible light irradiation. Full article
(This article belongs to the Special Issue Degradation and Photocatalytic Properties of Nanocomposites)
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15 pages, 7286 KiB  
Article
Enhanced Electrocatalytic Nitrate Reduction to Ammonia Using Functionalized Multi-Walled Carbon Nanotube-Supported Cobalt Catalyst
by Minghao Ye, Xiaoli Jiang, Yagang Zhang, Yang Liu, Yanxia Liu and Lin Zhao
Nanomaterials 2024, 14(1), 102; https://doi.org/10.3390/nano14010102 - 01 Jan 2024
Viewed by 1122
Abstract
Ammonia (NH3) is vital in modern agriculture and industry as a potential energy carrier. The electrocatalytic reduction of nitrate (NO3) to ammonia under ambient conditions offers a sustainable alternative to the energy-intensive Haber−Bosch process. However, achieving high selectivity [...] Read more.
Ammonia (NH3) is vital in modern agriculture and industry as a potential energy carrier. The electrocatalytic reduction of nitrate (NO3) to ammonia under ambient conditions offers a sustainable alternative to the energy-intensive Haber−Bosch process. However, achieving high selectivity in this conversion poses significant challenges due to the multi-step electron and proton transfer processes and the low proton adsorption capacity of transition metal electrocatalysts. Herein, we introduce a novel approach by employing functionalized multi-walled carbon nanotubes (MWCNTs) as carriers for active cobalt catalysts. The exceptional conductivity of MWCNTs significantly reduces charge transfer resistance. Their unique hollow structure increases the electrochemical active surface area of the electrocatalyst. Additionally, the one-dimensional hollow tube structure and graphite-like layers within MWCNTs enhance adsorption properties, thus mitigating the diffusion of intermediate and stabilizing active cobalt species during nitrate reduction reaction (NitRR). Using the MWCNT-supported cobalt catalyst, we achieved a notable NH3 yield rate of 4.03 mg h−1 cm−2 and a high Faradaic efficiency of 84.72% in 0.1 M KOH with 0.1 M NO3. This study demonstrates the potential of MWCNTs as advanced carriers in constructing electrocatalysts for efficient nitrate reduction. Full article
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10 pages, 2475 KiB  
Article
Determining the Dependence of Single Nitrogen−Vacancy Center Light Extraction in Diamond Nanostructures on Emitter Positions with Finite−Difference Time−Domain Simulations
by Tianfei Zhu, Jia Zeng, Feng Wen and Hongxing Wang
Nanomaterials 2024, 14(1), 99; https://doi.org/10.3390/nano14010099 - 31 Dec 2023
Viewed by 843
Abstract
In this study, we obtained a diamond nanocone structure using the thermal annealing method, which was proposed in our previous work. Using finite–difference time–domain (FDTD) simulations, we demonstrate that the extraction efficiencies of nitrogen–vacancy (NV) center emitters in nanostructures are dependent on the [...] Read more.
In this study, we obtained a diamond nanocone structure using the thermal annealing method, which was proposed in our previous work. Using finite–difference time–domain (FDTD) simulations, we demonstrate that the extraction efficiencies of nitrogen–vacancy (NV) center emitters in nanostructures are dependent on the geometries of the nanocone/nanopillar, emitter polarizations and axis depths. Our results show that nanocones and nanopillars have advantages in extraction from emitter dipoles with s− and p−polarizations, respectively. In our simulations, the best results of collection efficiency were achieved from the emitter in a nanocone with s−polarization (57.96%) and the emitter in a nanopillar with p−polarization (38.40%). Compared with the nanopillar, the photon extraction efficiency of the emitters in the nanocone is more sensitive to the depth and polarization angle. The coupling differences between emitters and the nanocone/nanopillar are explained by the evolution of photon propagation modes and the internal reflection effects in diamond nanostructures. Our results could have positive impacts on the design and fabrication of NV center−based micro− and nano−optics in the future. Full article
(This article belongs to the Special Issue Nanodiamond Applications: From Biomedicine to Quantum Optics)
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14 pages, 2215 KiB  
Article
Theoretical Study on the Open-Shell Electronic Structure and Electron Conductivity of [18]Annulene as a Molecular Parallel Circuit Model
by Naoka Amamizu, Mitsuhiro Nishida, Keisuke Sasaki, Ryohei Kishi and Yasutaka Kitagawa
Nanomaterials 2024, 14(1), 98; https://doi.org/10.3390/nano14010098 - 31 Dec 2023
Viewed by 1070
Abstract
Herein, the electron conductivities of [18]annulene and its derivatives are theoretically examined as a molecular parallel circuit model consisting of two linear polyenes. Their electron conductivities are estimated by elastic scattering Green’s function (ESGF) theory and density functional theory (DFT) methods. The calculated [...] Read more.
Herein, the electron conductivities of [18]annulene and its derivatives are theoretically examined as a molecular parallel circuit model consisting of two linear polyenes. Their electron conductivities are estimated by elastic scattering Green’s function (ESGF) theory and density functional theory (DFT) methods. The calculated conductivity of the [18]annulene does not follow the classical conductivity, i.e., Ohm’s law, suggesting the importance of a quantum interference effect in single molecules. By introducing electron-withdrawing groups into the annulene framework, on the other hand, a spin-polarized electronic structure appears, and the quantum interference effect is significantly suppressed. In addition, the total current is affected by the spin polarization because of the asymmetry in the coupling constant between the molecule and electrodes. From these results, it is suggested that the electron conductivity as well as the quantum interference effect of π-conjugated molecular systems can be designed using their open-shell nature, which is chemically controlled by the substituents. Full article
(This article belongs to the Special Issue Electrical Conductivity of Nanostructured Materials)
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16 pages, 5434 KiB  
Article
Eco-Friendly Silver Nanoparticles Synthesized from a Soybean By-Product with Nematicidal Efficacy against Pratylenchus brachyurus
by Letícia Santana de Oliveira, Leila Lourenço Furtado, Francisco de Assis dos Santos Diniz, Bruno Leonardo Mendes, Thalisson Rosa de Araújo, Luciano Paulino Silva and Thaís Ribeiro Santiago
Nanomaterials 2024, 14(1), 101; https://doi.org/10.3390/nano14010101 - 31 Dec 2023
Viewed by 890
Abstract
This study explores an eco-friendly approach to synthesizing silver nanoparticles (AgNPs) using soybean leaf extracts, employing a reaction with silver nitrate at 65 °C for 2.5 h. Optimal results were achieved at extract concentrations of 3.12 and 6.25 mg of the leaf mL [...] Read more.
This study explores an eco-friendly approach to synthesizing silver nanoparticles (AgNPs) using soybean leaf extracts, employing a reaction with silver nitrate at 65 °C for 2.5 h. Optimal results were achieved at extract concentrations of 3.12 and 6.25 mg of the leaf mL−1, termed 3.12AgNP and 6.25AgNP, respectively. UV-Vis spectrophotometric analysis between 350 and 550 nm exhibited a peak at 410–430 nm, along with a color transition in the suspensions from pale yellow to brown, indicating successful synthesis. Dynamic light scattering (DLS) further delineated the favorable properties of these AgNPs, including nanometric dimensions (73–104 nm), negative charge, and moderate polydispersity, portraying stable and reproducible synthesis reactions. The bioreduction mechanism, possibly expedited by leaf extract constituents such as amino acids, phenolic acids, and polysaccharides, remains to be fully elucidated. Notably, this study underscored the potent nematicidal effectiveness of biosynthesized AgNPs, especially 6.25AgNP, against Pratylenchus brachyurus, which is a common plant-parasitic nematode in tropical soybean cultivation regions. In vitro tests illustrated significant nematicidal activity at concentrations above 25 µmol L−1, while in vivo experiments displayed a pronounced nematode population diminishment in plant roots, particularly with a 6.25AgNP rhizosphere application at concentrations of 500 µmol L−1 or twice at 250 µmol L−1, attaining a reproduction factor below 1 without any morphological nematode alterations. This research highlights the potential of 6.25AgNPs derived from soybean leaf extracts in forging sustainable nematicidal solutions, marking a significant stride toward eco-friendly phytonematode management in soybean cultivation. This novel methodology signals a promising avenue in harnessing botanical resources for nematode control and propelling a greener agricultural horizon. Full article
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