Nanotechnology最新文献

Enhancing catalytic activity, durability and reducing costs are major challenges in commercialization of proton exchange membrane fuel cells (PEMFCs). Non-precious metal catalysts face durability challenges when applied to PEMFCs, while platinum (Pt)-based catalysts are hampered by their high costs and weak interactions with carbon supports, limiting their application in PEMFCs. Combining Pt-based catalysts with iron-nitrogen-carbon (FeNC) supports can improve the oxygen reduction reaction performance. However, traditional preparation methods for FeNC supports, such as liquid-phase and hydrothermal synthesis, are cumbersome and have low yield. Here, we introduce a simple ball-milling method to synthesize FeNC with high yield that achieves a high-surface-area and uniform dispersion of Fe atoms. The FeNC support anchors PtFe nanoparticles at FeN_xsites. This enhances support-alloy interactions and suppresses particle aggregation. The obtained catalyst denoted as PtFe/B-FeNC exhibits an exceptional mass activity of 2.57 A mg_Pt^-1at 0.9 V, representing a 12.2-fold increase compared to the commercial Pt/C. There is only 30 mV degradation for the catalyst after 120 k cycles, indicating outstanding stability. This research paves the way for the green synthesis of PtFe/B-FeNC with high yield, facilitating the development of commercial materials for other electrochemical devices.

Radiation detectors have gained significant attention due to their extensive applications in high-energy physics, medical diagnostics, aerospace, and nuclear radiation protection. Advances in relevant technologies have made the drawbacks of traditional semiconductor detectors, including high leakage currents and instability, increasingly apparent. Ga₂O₃, diamond, and BN represent a new generation of semiconductor materials following GaN and SiC, offering wide bandgaps of around 5 eV. These ultra-wide bandgap semiconductors demonstrate excellent properties, including ultra-low dark current, high breakdown fields, and superior radiation tolerance, underscoring their promising potential in radiation detection. In this review, we first discuss the materials and electrical properties of Ga₂O₃, diamond, and BN, along with the general performance metrics relevant to radiation detectors. Subsequently, the review provides a comprehensive overview of the research progress in x-ray detection, charged particle detection (e.g.αparticles and carbon ions), as well as fast neutron and thermal neutron detection, focusing on aspects such as chip fabrication processes, device architectures, and testing results for radiation detectors based on these three materials.

This study presents an eco-friendly mechanochemical (MC) synthesis of cesium lead bromide (CsPbBr3), eliminating the need of organic solvents and high temperatures. The synthesized CsPbBr3 powder is used to fabricate poly(methyl methacrylate) (PMMA)-CsPbBr3 films and CsPbBr3 nanocrystals (NCs). The photoluminescence (PL) peaks of the emission light are centered at 541 nm, 538 nm, and 514 nm for the CsPbBr3 powder, PMMA-CsPbBr3 films, and CsPbBr3 NCs, respectively, correlating with crystal sizes of 0.96, 0.56, and 0.12 μm, respectively. The PL lifetime analysis reveals decay times (τ_1,τ_2) of (4.18, 20.08), (5.7, 46.99), and (5.81, 23.14) in the units (ns, ns) for the CsPbBr3 powder, PMMA-CsPbBr3 films, and CsPbBr3 NCs, respectively. The PLQY of the CsPbBr3 NCs in toluene is 61.3%. Thermal activation energies for thermal quenching are 217.48 meV (films) and 178.15 meV (powder), indicating improved thermal stability with the PMMA encapsulation. The analysis of the PL decay from water diffusion in the PMMA-CsPbBr3 films yields 1.70x10^-12 m2/s for the diffusion coefficient of water, comparable to that for water diffusion in pure PMMA. This work demonstrates a scalable, sustainable strategy for CsPbBr3 synthesis and stability enhancement for optoelectronic applications.

Tuberculosis (TB) remains a pressing global health challenge, necessitating precise and reliable biomarkers for early detection. Lipoarabinomannan (LAM), an FDA-approved biomarker (Monoclonal Antibody-MBS320597), holds significant potential due to its association with theMycobacterium tuberculosiscell wall. This study systematically evaluates LAM concentrations ranging from 1 pg ml^-1to 6 ng ml^-1using square wave voltammetry analysis, achieving an exceptional limit of detection of 0.077 pg ml^-1. A comprehensive review of current diagnostics highlights critical gaps, including limitations in speed and accuracy, underscoring the urgency for advanced methodologies. In this study, LAM's performance is assessed by analyzing spiked urine samples, demonstrating its high sensitivity, specificity, and reliability as an early-stage TB biomarker. By comparing findings with existing diagnostic tools and addressing identified limitations, this study emphasizes LAM's potential to transform TB diagnostic strategies. These results contribute to global efforts to improve early detection, enhance patient outcomes, and pave the way for future advancements in TB diagnostics.

In the realm of sustainable and renewable nanotechnology, supercapacitors have appeared as the dominant solution for energy conversion and storage. Ferrites have been widely explored in magnetic, electronic and microwave devices, and are now being explored for applications in energy storage devices due to the possibility of achieving fast and reversible surface Faradic reactions. From this perspective, a simple and inexpensive chemical co-precipitation method was used to synthesize ultrasmall ZnFe₂O₄nanoparticles (NPs). As an electrode material the ZnFe₂O₄NPs show a gravimetric capacitance of 186.6 F g^-1at a current density of 1 A g^-1in 1 M H₂SO₄. Furthermore, the ZnFe₂O₄NP-based electrode shows exceptional capacitive retention of 98% over 1000 cycles at a current density of 3 A g^-1. An asymmetric ZnFe₂O₄NP//NiO NP device was fabricated, which achieved a power density of 302.3 W kg^-1at a current density of 1.5 A g^-1and an energy density of 14.85 W h kg^-1. After 1500 cycles, the device demonstrated capacity retention of 99.4% at 1.5 A g^-1in long-term stability testing with 100% efficiency. Our study suggests that ZnFe₂O₄NPs are promising as a material for future energy storage applications.

Given the promising applications of large magnetoresistance in the Dirac semimetal cadmium arsenide (Cd3As2), extensive research into Si-compatible Cd3As2 devices is highly desirable. To prevent surface degradation and oxidation, the implementation of a protection layer on Cd3As2 is imperative. In this study, two vastly different protecting layers were prepared by on top of two Cd3As2 samples. A zinc telluride layer was grown on top of one Cd3As2 film, giving rise to an ten-fold increased mobility, compared to that of the pristine Cd3As2 sample. Interestingly, unusual negative magnetoresistance is observed in the hexagonal boron nitride (h-BN)-capped Cd3As2 device when a magnetic field is applied perpendicularly to the Cd3As2 plane. This is in sharp contrast to the chiral anomaly that requires a magnetic field parallel to the Cd3As2 plane. We suggest that a protection layer on MBE-grown Cd3As2 should be useful for realizing its great device applications in magnetic sensing.

Hydrogen is regarded as an ideal substitute for fossil fuels on account of its advantages of high energy density, zero carbon emissions, and abundant reserves. Solid-state hydrogen storage is one of the most promising hydrogen storage methods in terms of high-volume storage density and safety. MgH2 is a promising solid hydrogen storage material because of its high hydrogen storage capacity and favorable cycle reversibility. Nevertheless, its inferior thermodynamic and kinetic properties restrict its extensive application. Catalyst modification is considered to be an efficient way to enhance the thermodynamic and kinetic properties of hydrogenation and dehydrogenation for MgH2. This review summarizes the latest research progress on MXene-based composites, such as MAX, single metal MXene, bimetallic MXene, MXene/elemental metal, and MXene/transition metal compounds for promoting the hydrogen storage performances of MgH2. At the same time, the catalyst of MXene-based composites to optimize the hydrogenation/dehydrogenation kinetics, long cycle performance and catalytic mechanism of Mg/MgH2 are discussed in detail.

X-ray methods can offer unique insights into the structural and electronic properties of nanomaterials. Recent years have seen a dramatic improvement in both x-ray sources and x-ray optics, providing unprecedented resolution and sensitivity. These developments are particularly useful for nanowires, which are inherently small and give weak signals. This review gives an overview of how different x-ray methods have been used to analyze nanowires, showing the different types of insight that can be gained. The methods that are discussed include x-ray diffraction, x-ray fluorescence, x-ray photoelectron spectroscopy and x-ray photoelectron emission microscopy, as well as several others. The review is especially focused on high spatial resolution methods used at the single nanowire level, but it also covers ensemble experiments.

MXenes, specifically Ti₃C₂T_xhaving peculiar structural and electronic characteristics display not only high surface area, and excellent thermal and electrical conductivity but also have the potential for functionalization. The primary focus of this research is to control the decay time of gold nanoparticle (NP) (Au NP) decorated multilayer Ti₃C₂T_xMXene (Au-Ti₃C₂T_x) synthesized by a simple two-step selective etching technique. Incorporation of Au NPs in the multilayer Ti₃C₂T_xMXene leads to lattice expansion, micro-strain reduction, and crystallinity improvement, as confirmed by x-ray diffraction analysis. Observation of a well-developed G band in the Au-Ti₃C₂T_xMXene across different Au concentrations by Raman spectroscopy investigations suggests the accumulation of graphitic carbon on the MXene surface which has greatly improved the charge transfer characteristic of the carbide layer. Furthermore, the Au-Ti₃C₂T_xMXene exhibits promising optical properties for different concentrations of gold. The time-resolved photoluminescence spectroscopy studies displayed a reduction in the average decay time (τ_av) to ∼30% with increasing gold concentration from 100 to 150μl in Au NPs solution which is explained based on Au NPs induced surface plasmon resonance. The decoration of Au NPs facilitates the accumulation of carbon on the surface of MXene, resulting in enhanced crystallinity, reduced micro-strain, and decreased decay time. By engineering decay time through the decoration of noble metal NPs onto MXene, it becomes possible to fabricate highly efficient photodetectors and imaging devices. This is especially advantageous in applications where shorter decay times are desired.

Friction and wear are critical factors that significantly impact the efficiency and durability of mechanical systems. The demand for improved lubricating oils capable of reducing friction and wear has spurred the exploration of advanced additives. Two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides (MXenes), a new class of materials, have emerged as promising additives with exceptional tribological properties. This review paper aims to understand the usability of MXenes, specifically the ones derived from Ti3C2TX as anti-friction and antiwear additives in lubricating oils. A brief discussion is presented about the synthesis and characterization techniques employed in the synthesis of Ti3C2TX MXenes, emphasizing their unique structural and surface properties that could contribute to their tribological performance, followed by their influence on the lubricant's tribological properties is thoroughly discussed. The underlying anti-friction and antiwear mechanisms, their ability to form tribofilms on sliding surfaces, reduce direct metal-to-metal contact, and minimize wear are also highlighted. Additionally, the role of MXenes in modifying the lubricant's chemical and physical interactions with sliding surfaces is analyzed. This review also attempts to identify and address the roadblocks hindering the use of Ti3C2TX MXenes in lubricating oils, such as their aggregation tendencies, stability under extreme conditions, and potential side effects on lubricant properties along with the tentative strategies to overcome these hurdles. Relevant experimental findings in which Ti3C2TX derived 2D nano-sheets have been explored as friction and wear-reducing additives in different lubricating oils are critically assessed. Although these MXenes are claimed to be highly effective as lubricant additives in lubricating oils owing to their unique properties and versatile chemistry, further research is required to address the challenges and optimize the formulation and integration of MXenes into lubricating oils for practical implementation. This article presents a comprehensive discussion about Ti3C2TX MXenes as friction and wear-reducing additives in lubricating oils, will be crucial in understanding what has been done and needs to be done.