Nanotechnology最新文献

In this work, TiCrC nanocarbide was consolidated via spark plasma sintering (SPS) from TiCrC nanopowder prepared via mechanical alloying (MA). The microstructure, elemental compositions, and morphology of the prepared samples were investigated using x-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive x-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The mechanical properties of the sintered (Ti,Cr)C nanocarbide were also studied. XRD studies of the bulk samples show the presence of (Ti,Cr)C and a small amount of Cr₃C₂and graphite. SEM study reveals the presence of transgranular cleavage in fracture surfaces and the shape of grains is partially rounded. TEM analysis shows that the SPS process leads to the increase in grain size with retention of nanoscale. The optimized SPS parameters were a pressure of 80 MPa, a sintering temperature of 1800 °C and a holding time of 5 min. Results reveal that TiCrC nanocarbide also has an excellent mechanical properties achieving microhardness, relative density, fracture toughness, and compressive strength of 28 GPa, 98.51%, 6.5 MPa m^1/2, and 2290 MPa, respectively. Finally, our study shows that the prepared TiCrC nanocarbide can be used for cutting tools without loss of mechanical strength.

This work presents a facile, scalable nanocomposite-based resistive memory device incorporating a 2D hybrid of hydrothermally synthesized and exfoliated tungsten disulfide (E-WS₂) nanosheets embedded in a poly (ethylene oxide) (PEO) matrix for energy efficient neuromorphic applications. WS₂was synthesized via a simple, cost-effective hydrothermal method and subsequently exfoliated via liquid phase exfoliation to obtain few-layer nanosheets with improved surface uniformity and reduced defect density. These nanosheets were integrated into the active layer of an ITO/E-WS₂+ PEO/Cu device fabricated via spin coating and thermal evaporation. The device exhibits reliable bipolar resistive switching with low SET voltages, a high ON/OFF current ratio (∼10⁴), excellent retention (>450 s), and endurance over 70 cycles. The transport mechanism is governed by Ohmic conduction at low voltages, followed by space charge limited current (SCLC) and trap-controlled SCLC (TC-SCLC) mechanisms near-threshold voltages. Energy band analysis indicates that charge trapping and de-trapping at the WS₂/PEO interface plays a critical role in the switching process. Compared to bulk WS₂, exfoliated WS₂offers enhanced interfacial contact, lower resistance pathways, and reduced variability in switching, resulting in improved device performance and stability. It also shows more analog like behavior. Sulfur vacancies in E-WS₂ assist in forming conductive filaments, while the PEO matrix enhances ionic mobility and switching behavior. This work offers a scalable, environmentally benign approach to fabricating 2D material-based resistive memory, establishing solution-processed E-WS₂ nanocomposites as strong candidates for next-generation, scalable, energy-efficient non-volatile memory and neuromorphic technologies.

As silicon-based FETs face scaling limits, two-dimensional (2D) material emerge as promising alternatives with potential to suppress short-channel effects and reduce power consumption. We present a comprehensive investigation of the novel 2D bismuth carbide (Bi₂C₃) semiconductor using first-principles density functional theory (DFT) calculations combined with non-equilibrium green's function (NEGF) quantum transport simulations. Electronic band structure calculations indicate that monolayer Bi₂C₃possesses a moderate direct bandgap, a sharp conduction band, and a low electron effective mass (0.48m₀). Device simulations reveal outstanding performance: a Bi₂C₃FET with a 10 nm channel length achieves an ultra-high on-state current (I_on) of 2540μAμm^-1while maintaining a high on/off current ratio (exceeding 10⁴), satisfying the requirements of the international technology roadmap for semiconductors (ITRS) for high-performance (HP) applications. Furthermore, scaling the channel length down to 5 nm still yields device performance compliant with ITRS specifications. Crucially, devices across different channel lengths exhibit fast switching speeds, low power-delay (τ), power-delay product, and excellent energy-delay product, fully meeting the ITRS HP targets. This study, for the first time, systematically evaluates the application potential of Bi₂C₃in MOSFETs via DFT-NEGF. Its excellent comprehensive performance metrics demonstrate that monolayer Bi₂C₃is a highly competitive candidate channel material for future HP integrated circuits.

A ternary stepped heterojunction of PbS/CdS/TiO₂was fabricated using the successive ionic layer adsorption and reaction method, which significantly enhanced the photocathodic protection performance of TiO₂. The experimental results demonstrate the superiority of the dual-loading modification over its single-loading counterparts. The co-loading of CdS and PbS resulted in a TiO₂nanocomposite with a reduced bandgap of 1.0 eV, a further extended light absorption range, and enhanced visible light utilization efficiency. The PbS/CdS/TiO₂electrode exhibited a photogenerated current density of 6.46 mA cm^-2, which is 1.6 times and 22.1 times higher than that of PbS/TiO₂and pure TiO₂, respectively. The dual loading of metal sulfide semiconductors markedly improved the photoelectrochemical properties of TiO₂and its corresponding photocathodic protection effect.

Self-powered ultraviolet (UV) photodetectors are widely applicable in various fields due to their ability to operate autonomously, offering unparalleled portability and flexibility. In this letter, a high-performance self-powered UV photodetector based on MAPbCl₃/GaN nn heterojunction is demonstrated. The n-MAPbCl₃microplates were grownin situon the n-GaN substrate using a simple solution process. Thanks to the differences in the energy band between MAPbCl₃and GaN, a built-in electric field is formed, which facilitates efficient separation of photo-generated charge carriers. This enables the photodetector to operate without the need of an external bias voltage. Furthermore, the wide bandgap of both MAPbCl₃and GaN endows the photodetector with exceptional sensitivity to UV light. The optimized MAPbCl₃/GaN device exhibits high-performance metrics, including low dark current and noise, high photo to dark current ratio, responsivity, and detectivity at zero bias.

Amylases are essential enzymatic macromolecules widely employed in industrial sectors such as starch processing, textiles, detergents, paper manufacturing, pharmaceuticals, and biomedical research. Among α-, β-, and γ-amylases, thermostable α-amylases from thermophilic microbes show high catalytic activity and structural stability under heat, pH variation, and solvent stress. These properties make them valuable for stable, contamination-resistant, and efficient bioprocesses. Thermostable amylases also hold promise in biomedical fields, including diagnostics, enzyme replacement therapy, and nanocarrier-based drug delivery. This review summarizes microbial sources and production approaches for thermostable amylases, highlighting submerged and solid-state fermentation methods. The discussion also outlines optimization of carbon and nitrogen substrates, fermentation duration, and moisture control strategies that directly influence enzyme yield and activity. Factors governing enzyme yield and stability are analyzed, including nutrient balance, pH, temperature, and moisture. Despite their potential, widespread application remains limited by low native production yields, suboptimal heterologous expression, and functional trade-offs between thermostability and enzymatic activity. Recent advances in protein engineering (rational design and directed evolution), omics-driven strain improvement, and nanotechnology integration provide paths to address these limitations. By integrating these strategies, researchers are achieving enzymes with longer operational lifetimes, higher substrate specificity, and improved reusability under industrial and physiological conditions. These advances highlight the growing relevance of thermostable amylases in industrial biotechnology and biomedical research.

Glycerol, one of the important bio-platform molecules, is produced in large quantities as a byproduct in the biodiesel industry. It is imperative to convert glycerol into more value-added products (such as dihydroxyacetone, glyceraldehyde, glyceric acid, tartronic acid (TA), mesoxalic acid, glycolic acid, and formic acid) through various methods. Currently, the glycerol electrocatalytic oxidation reaction (GEOR) is one of the most promising routes owing to the mild operating conditions, efficient conversion, and high energy utilizations via coupling the cathodic reaction. In this review, we systematically introduce the recent advances in GEOR for the application of various products synthesis, focusing on the influence of reaction conditions, types of catalysts, and involved oxidation pathway and mechanisms. Furthermore, novelty coupled systems of GEOR and other cathodic reactions are summarized. Lastly, the subsistent challenges and perspectives are highlighted for GEOR.

The development of efficient heterojunction photocatalysts for environmental remediation remains challenging due to rapid charge recombination and insufficient active sites in conventional single-component systems. This study developed a facile wet impregnation method of In₂O₃-Bi₂O₃heterojunction photocatalysts with tunable compositions for enhanced visible-light-driven photocatalytic degradation. By systematically modulating the In₂O₃to Bi₂O₃ratio, the optical properties, electronic structures, and photocatalytic activities of the materials can be precisely manipulated. The optimized 30% In₂O₃-Bi₂O₃heterojunction exhibited a remarkable methylene blue degradation efficiency of 93% under visible light, outperforming pure In₂O₃and Bi₂O₃. Mechanistic studies revealed that the type-II band alignment facilitated spatial separation of photogenerated electron-hole pairs and enhanced redox capacity. Furthermore, the surface oxygen vacancies of materials introduced by the alkaline etching method were found to significantly enhance the availability of active sites and optimize the band structure, contributing to a notable increase in photocatalytic activity. These heterojunctions also exhibited remarkable stability, retaining over 90% degradation efficiency after five consecutive cycles. This study indicates the significant potential of In₂O₃-Bi₂O₃heterojunctions for enhancing environmental remediation and solar energy conversion initiatives, and also introduces a straightforward and effective synthesis approach to photocatalyst design by composition regulation and defect engineering.

Single-walled carbon nanotubes (SWNTs) are promising materials for next-generation electronics, but their application is limited by the coexistence of semiconducting (s-SWNTs) and metallic (m-SWNTs) species produced during synthesis. Here, we systematically optimized the separation of s-SWNTs using the conjugated polymer poly (9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFDD) by varying polymer concentration and decoupling the effects of sonication time and temperature: we evaluated temperature dependence at fixed sonication times (1, 2, and 3 h) and time dependence at fixed temperatures (25 °C, 35 °C, and 45 °C). Increasing PFDD concentration enhanced yield but reduced purity due to non-selective interactions with m-SWNTs. Excessive sonication (e.g. 45 °C for 3 h) further degraded selectivity, while extending sonication beyond 1 h offered little additional yield and shortened nanotube length. The optimal conditions-PFDD 1 mg ml^-1and sonication at 45 °C for 1 h-balanced yield, purity, and length. Field-effect transistors fabricated with s-SWNTs separated under these conditions showed a low off-current (∼10^-11A), a high ON/OFF ratio of 10⁶, and a mobility of 2.2 cm²V^-1s^-1, confirming the effectiveness of this systematic optimization for high-performance electronic devices.

Oblique light emissions are reflected from the interface owing to the total internal reflection. It is found that a waveguide can be used to effectively collect the oblique light emissions of aligned organic dipoles because of the formation of a local quasi-mode evanescent wave. The numerical results show that the highest coupling efficiency and 3 dB spatial deviation of transverse magnetic (transverse electric) wave are 74.3% (78.9%) and 4.1μm (5.2μm), respectively. The proposed structure can be used in an organic light-emitting device for the applications of silicon photonic integrated circuits.