Exploring the Potential of Carbonized Nano-Si within G@C@Si Anodes for Lithium-Ion Rechargeable Batteries.

This study presents the synthesis, characterization, and electrochemical performance evaluation of carbon@silicon (C@Si) and graphite@carbon@silicon (G@C@Si) nanocomposites as potential anode materials for lithium-ion batteries (LIBs). Employing a combination of mechanical milling and carbonization using citric acid, we developed nanocomposites exhibiting unique core-shell structures, as confirmed by detailed SEM and TEM analysis. The G@C@Si nanocomposite displayed superior electrochemical performance, delivering an initial discharge capacity of 1724 mAh g-1 and a high initial Coulombic efficiency of 87.37%. The nanocomposite demonstrated remarkable cycling durability with a discharge capacity of 1248 mAh g-1 over 200 cycles and an average Coulombic efficiency of 99.1% and high-capacity retention of about 83%. Notably, a high capacity of 1325 mAh g-1 was observed at a high 3C rate, and the electrode showed excellent resilience by rapidly recovering to a discharge capacity of 1637 mAh g-1 when the C rate was reduced back to 0.5C. Electrochemical impedance spectra revealed a reduced charge transfer resistance of approximately 43 Ω in the G@C@Si nanocomposite as compared to that of C@Si (∼56 Ω) and nano-Si (105 Ω), indicating enhanced lithium-ion diffusion due to the integration of graphite. Postcycle electrode analysis revealed excellent structural integrity, with minimized volume changes in both C@Si and G@C@Si. XPS studies revealed a thinner SEI layer formation in the G@C@Si electrode compared to C@Si. The C@Si core-shell formation through the citric acid treatment of nano-Si and integration of graphite by mechanical milling significantly boosts the electrochemical performance of the G@C@Si nanocomposite. These findings suggest that the G@C@Si nanocomposite offers immense potential for utilization in high-capacity and high-efficiency LIBs.

Fabrication of Pressure Conductive Silicone Rubber Socket Device by Shape-Controlled Nickel Powders Produced by High-Energy Ball Milling.

The pressure conductive silicone rubber socket (PCR) is one of the promising test socket devices in high-speed testing environments. In this study, we report highly dense PCR device channels comprised of high aspect-ratio flake-shaped Ni powders. The shape-controlled Ni powders are prepared by the high-energy milling process. The scanning electron microscopy (SEM) and particle size analyzer (PSA) results of the synthesized powder samples showed well-defined flake type Ni powder morphology, and the powder sizes are distributed in the range of ~24-49 µm. The cross-sectional SEM study of the fabricated PCR revealed that the channels consisting of flake Ni powder are uniformly, densely distributed, and connected as face-to-face contact. The resistance of the PCR channels comprised of flake-shaped Ni powders showed ~23% lower resistance values than the spherical-shaped Ni powders-based channels, which could be due to the face-to-face contact of the powders in the channels. The magnetic properties study for the flake-type Ni powder showed a high remanence (~2.2 emu/g) and coercivity (~5.24 mT), owing to the shape anisotropy factor. Finally, the fabricated highly dense and conductive channels of the silicone rubber socket device by shape-controlled Ni powder could be a potential test socket device.

Enhanced Visible-Light-Driven Photocatalysis of Ag/Ag2O/ZnO Nanocomposite Heterostructures.

Visible-light-driven photocatalysis is one promising and efficient approach for decontaminating pollutants. Herein, we report the combination of localized surface plasmon resonance (LSPR) and p-n heterojunction structure Ag-Ag2O-ZnO nanocomposite synthesized by a hydrothermal process for the suppression of photogenerated electron-hole pair recombination rates, the extension of the absorption edge to the visible region, and the enhancement of photocatalytic efficiency. The prepared nanocomposites were investigated by standard analytical techniques and the results revealed that the synthesized powders were comprised of Ag, Ag2O, and ZnO phases. Photocatalytic activity of the photocatalyst tested for methylene blue, methyl orange, and rhodamine B showed the highest photocatalytic degradation efficiency: 97.3%, 91.1%, and 94.8% within 60 min under visible-light irradiation. The average lifetime of the photogenerated charge carriers was increased twofold in the Ag-Ag2O-ZnO photocatalyst (~10 ns) compared to the pure ZnO (~5.2 ns). The enhanced photocatalytic activity resulted from a decrease of the charge carrier recombination rate as inferred from the steady-state and time-resolved photoluminescence investigations, and the increased photoabsorption ability. The Ag-Ag2O-ZnO photocatalyst was stable over five repeated cyclic photodegradation tests without showing any significant changes in performance. Additionally, the structure indicated a potential for application in environmental remediation. The present study showcases the robust design of highly efficient and reusable visible-light-active photocatalysts via the combination of p-n heterojunction and LSPR phenomena.

Dewetted Silver Nanoparticle-Dispersed WO3 Heterojunction Nanostructures on Glass Fibers for Efficient Visible-Light-Active Photocatalysis by Magnetron Sputtering.

Fabrication of hybrid-heterojunction nanostructures comprising the Z-scheme and localized surface plasmon resonance is essential for enhancing the photocatalytic degradation of organic compounds to enable environmental remediation. This study focuses on the dispersion of dewetted Ag nanoparticles over the 3D network-like silica glass fibers (SGFs) coated with a Cu-doped WO3 heterojunction system by a high-throughput and cost-effective method using magnetron sputtering, followed by solid-state dewetting. The influence of Cu doping on the crystal structure, growth direction, and morphology of WO3 and the effect of localized surface diffusion-driven dewetted Ag nanoparticles on the photocatalytic performance were investigated. The Cu doping changed the optical band gap, and the 2Cu-WO3/SGF exhibited excellent photocatalytic activity. The surface dispersion of dewetted Ag nanoparticles over Cu-WO3/SGFs exhibited lowest photoluminescence intensity, indicating the effective separation of photogenerated electrons-holes, which led to highest efficiency (∼98%) in photocatalytic degradation of methylene blue among all the fibers with a degradation rate constant (k = 0.0205 min-1) that was ∼18.6 times higher than that of pure WO3 (k = 0.0011 min-1). The findings of this study can provide insights for designing low-cost and efficient visible-light-active photocatalysts for organic dye degradation, enabling environmental remediation.

Electrochemical Performance of an Ultrathin Surface Oxide-Modulated Nano-Si Anode Confined in a Graphite Matrix for Highly Reversible Lithium-Ion Batteries.

Si-based anode materials have attracted considerable attention for use in high-capacity lithium-ion batteries (LIBs), but their practical application is hindered by huge volume changes and structural instabilities that occur during lithiation/delithiation and low-conductivity. In this regard, we report a novel Si-nanocomposite by modulating the ultrathin surface oxide of nano-Si at a low temperature and highly conductive graphene-graphite matrix. The Si nanoparticles are synthesized by high-energy mechanical milling of micro-Si. The prepared Si/SiOx@C nanocomposite electrode delivers a high-discharge capacity of 1355 mAh g-1@300th cycle with an average Coulombic efficiency of 99.5% and a discharge capacity retention of ∼88% at 1C-rate (500 mA g-1). Remarkably, the nanocomposite exhibits a high initial Coulombic efficiency of ∼87% and excellent charge/discharge rate performance in the range of 0.5-5C. Moreover, a comparative investigation of the three different electrodes nano-Si, Si/SiOx, and Si/SiOx@C are presented. The exceptional electrochemical performance of Si/SiOx@C is owing to the nanosized silicon and ultrathin SiOx followed by a high-conductivity graphene-graphite matrix, since such a nanostructure is beneficial to suppress the volume changes of silicon, maintain the structural integrity, and enhance the charge transfer during cycling. The proposed nanocomposite and the synthesis method are novel, facile, and cost-effective. Consequently, the Si/SiOx@C nanocomposite can be a promising candidate for widespread application in next-generation LIB anodes.

Fabrication of Ag2O/WO3 p-n heterojunction composite thin films by magnetron sputtering for visible light photocatalysis.

Semiconductor-based nanostructures which are photo-catalytically active upon solar light irradiation were extensively used for environmental remediation due to the potential decomposition of various kinds of pollutants. In this work, we report the preparation of a sustainable thin film composite, i.e. Ag2O/WO3 p-n heterojunction, and investigation of its photocatalytic activity. To achieve the composite structure, WO3/Ag-WO3 layers were deposited over a quartz substrate by magnetron sputtering at room temperature and subsequently annealed at 823 to 923 K. The thin film structure, morphology, and chemical states were thoroughly characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron spectroscopy, and X-ray photoelectron spectroscopy. The obtained results revealed that the amorphous Ag-doped WO3 was crystallized into monoclinic WO3 and Ag2O, in which nanocrystalline Ag2O was diffused towards the surface of WO3. Optical transmittance spectra recorded by UV-vis-NIR spectroscopy revealed that the WO3/Ag-WO3 films became transparant in the visible region after annealing at high temperature (873 K and 923 K). The Ag2O/WO3 p-n heterojunction composite thin films showed high photocatalytic activity (0.915 × 10-3 min-1) under visible light irradiation, which is attributed to the efficiency of effective photogenerated charge-carrier formation and the reduced recombination rate of photogenerated electron-hole pairs. Unlike the powder-based photocatalysts, the reported thin film-based heterojunction photocatalyst could be very sustainable, and cost-effective.