Nanoscale最新文献

The chemical and physical properties of nanomaterials ultimately rely on their crystal structures, chemical compositions and distributions. In this paper, a series of AuCu bimetallic nanoparticles with well-defined architectures and variable compositions has been addressed to explore their thermal stability and thermally driven behavior by molecular dynamics simulations. By combination of energy and Lindemann criteria, the solid-liquid transition and its critical temperature were accurately identified. Meanwhile, atomic diffusion, bond order, and particle morphology were examined to shed light on thermodynamic evolution of the particles. Our results reveal that composition-dependent melting point of AuCu nanoparticles significantly departs from the Vegard's law prediction. Especially, chemically disordered (ordered) alloy nanoparticles exhibited markedly low (high) melting points in comparison with their unary counterparts, which should be attributed to enhancing (decreasing) atomic diffusivity in alloys. Furthermore, core-shell structures and heterostructures demonstrated a mode transition between the ordinary melting and the two-stage melting with varying Au content. AuCu alloyed nanoparticles presented the evolution tendency of chemical ordering from disorder to order before melting and then to disorder during melting. Additionally, as the temperature increases, the shape transformation was observed in AuCu nanoparticles with heterostructure or L1₀ structure owing to the difference in thermal expansion coefficients of elements and/or of crystalline orientations. Our findings advance the fundamental understanding on thermodynamic behavior and stability of metallic nanoparticles, offering theoretical insights for design and application of nanosized particles with tunable properties.

In the current study, polyaniline (PANI) modified two-dimensional Ti₃C₂T_x MXene composites (PANI-Ti₃C₂T_x) are exploited as photocathodes in dye-sensitized solar cells (DSSCs). The study revealed that incorporating PANI into Ti₃C₂T_x improved the material's electrochemical properties, owing to the presence of amino groups in PANI that enhanced the material's electrical conductivity and thereby facilitated more rapid ion transport. In addition, PANI enhanced the surface wettability of Ti₃C₂T_x, resulting in an increase in the number of electroactive sites. The presence of PANI molecules in the interlayer and on the surface of Ti₃C₂T_x was confirmed through X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), and X-ray photoelectron spectroscopy (XPS). Subsequently, electrochemical analysis of the PANI-Ti₃C₂T_x photocathode or counter electrode (CE) revealed a commendable electrocatalytic activity with the iodide/triiodide electrolyte, a favourable charge transfer kinetics, and a charge transfer resistance as low as platinum. Additionally, at AM 1.5G, the performance of the DSSC constructed using the thermally decomposed Pt-CE was 8.3% when subjected to simulated 1 sun light, whereas the efficiency of the DSSC constructed using the as-prepared composite material was 6.9% under corresponding conditions. PANI-Ti₃C₂T_x as the photocathode (CE) in a DSSC showed a higher power conversion efficiency (PCE) improvement than PANI CE and Ti₃C₂T_x CE DSSCs, emphasizing its potent catalytic activity and quick mass transport of electron capability. By capitalizing on the conductivity and electrocatalytic property of the two components, the as-fabricated PANI-Ti₃C₂T_x photocathode significantly increased the overall PCE of DSSCs. Furthermore, the DSSC utilizing the PANI-Ti₃C₂T_x CE demonstrated exceptional reproducibility and stability. This underscores its consistently high performance and significant resistance to corrosion in the iodide/triiodide redox electrolyte environment. Overall, these findings show that the PANI-Ti₃C₂T_x composite has the potential to be a competitive alternative to platinum-based CE materials for the development of DSSCs with exceptional performance.

The present study employed a solvothermal method utilizing triphenylphosphine and nickel acetylacetonate as precursors for phosphide preparation, followed by analysis and characterization. The Ni-MOF precursor was prepared using benzene diacid, triethylenediamine, and nickel sulfate as raw materials. Ni₂P was introduced into the Ni-MOF precursor during its preparation while maintaining the synthesis conditions, allowing for the adsorption of Ni₂P nanoparticles during Ni-MOF synthesis to produce Ni₂P@MOF composite materials. The materials underwent individual testing for UV, magnetic, and microwave absorption properties. Magnetic testing results demonstrated that the incorporation of Ni₂P led to an increase in the saturation magnetization (M_s) of Ni₂P@MOFs compared to the Ni-MOF, thereby enhancing its electromagnetic loss capability. Microwave absorption property testing indicated that the Ni₂P@MOFs exhibited enhanced dielectric and electromagnetic loss capabilities compared to the Ni-MOF, optimizing impedance matching properties and increasing effective absorption bandwidth compared to pure Ni₂P materials.