Sree Sevugan Annamalai College

This work presents the development of a nickel-based alloy and Ni-W-SnO2 designed to replace chromium plating, which is known for its toxic, corrosive, and carcinogenic properties. This study is focused on improving surface properties, corrosion resistance and wear resistance of the coatings. Nickel-Tungsten alloy was electrodeposited using a nickel sulfate electroplating bath, with various amounts of SnO2 particulates co-deposited uniformly in the nickel-tungsten alloy matrix. Nickel-tungsten and nickel-tungsten-tinoxide composite coatings were characterized by scanning electron microscopy, atomic force microscopy, x-ray diffraction analysis and microhardness. XRD analysis showed that, the (111) plane was dominant in both the Ni-W alloy and the Ni-W-SnO2 composite, confirming an FCC crystal structure. SEM images indicated finer grains and a uniform dispersion of SnO2 particles within the Ni-W matrix. The microhardness of the coating increased with the incorporation of SnO2. Corrosion resistance was assessed using Tafel polarization and electrochemical impedance spectroscopy in a 3.5% sodium chloride medium. These outcomes indicate that, optimized content of SnO2 in the nickel-tungsten alloy matrix improved the surface properties of the nanocomposite coatings, resulting in reasonable microhardness, a smooth surface, lower friction coefficients, remarkable wear resistance, and better corrosion resistance.

Nickel tungsten oxide (NT) thin films were fabricated on fluorine-doped tin oxide (FTO) substrates using RF sputtering at varying substrate temperatures, viz., RT, 150 degrees C, 250 degrees C and 350 degrees C and tested as a counter electrode for electrochromic devices (ECDs). Structural investigations demonstrated that tungsten inclusion impaired the crystallinity of the NiO, leading to amorphization under all deposition conditions. Raman and XPS analysis validated the presence of Ni2+ & Ni3+ ions, with Ni vacancies acting as active defect sites for Li+ ion transport. Electrochemical and optical analysis revealed that the substrate temperature greatly influenced the electrochromic performance of the film. Increasing substrate temperatures resulted in higher film density and decreased nickel vacancies, constraining Li+ intercalation channels and hence, reducing electrochromic efficiency. The NT film fabricated at 150 degrees C demonstrated optimal performance, achieving enhanced optical modulation (70 % @ 550 nm), rapid switching cycles (0.7 s for bleaching and 1.4 s for coloring), and improved diffusion coefficients. The research findings emphasize the significance of defect engineering and substrate temperature optimization in attaining high-performance nickel-tungsten oxide-based counter electrodes for energy-efficient smart windows.

Abstract This study presents the preparation, detailed characterization, and antibacterial evaluation of nanoscale Fe 2 O 3 -incorporated halloysite nanocomposites. Fe 2 O 3 nanoparticles were synthesized via a hydrothermal method and subsequently integrated into halloysite nanotubes (HNTs) through controlled chemical processes. Comprehensive characterization using UV–Vis spectroscopy, x-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy confirmed the successful embedding of Fe 2 O 3 both within and on the surfaces of the nanotubes. Spectroscopic and microscopic analyses demonstrated that the tubular morphology of halloysite was preserved, while Fe 2 O 3 nanoparticles were uniformly dispersed, resulting in enhanced optical and surface properties. Antibacterial assays revealed that Fe 2 O 3 -HNT composites exhibited markedly superior inhibitory activity against both Gram-positive ( S. aureus ) and Gram-negative ( E. coli ) bacteria compared to either Fe 2 O 3 or HNTs alone. The enhanced antibacterial effect is attributed to the generation of reactive oxygen species and the release of Fe 2+ ions, which disrupt microbial membranes and impair cellular functions. These findings underscore the potential of Fe 2 O 3 -incorporated halloysite nanocomposites as multifunctional materials for healthcare, environmental remediation, and protective coatings, offering a potent strategy to combat bacterial pathogens.

This research investigates the effects of nitric acid (HNO3) treatment on the structural, morphological, and electrochemical properties of Bi2WO6 nanosheets. The monoclinic structure of Bi2WO6 was verified by the X-ray diffraction (XRD) analysis. Morphological observations were made using Field emission scanning electron microscopy (FE-SEM). TEM, HRTEM and SAED confirm the formation of highly crystalline Bi2WO6 nanosheets with controlled morphology influenced by HNO3 treatment. The FTIR spectrum showed absorption peaks 450 cm−1 and 1000 cm−1, due to the stretching and bending vibrational frequencies of Bi–W–O bonds. The Raman spectroscopy showed an active W–O stretching mode at 889 cm−1. In a 3 M KOH aqueous electrolyte, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to evaluate the samples' electrochemical performance. Compared to earlier reported Bi2WO6 electrodes (generally 150–350 Fg−1), the HNO3 treated Bi2WO6 nanosheets exhibits relatively enhanced performance, achieving 422–449 F g⁻1, resistance of 0.91 Ω, coulombic efficiency was 99.9

Copper nanoparticles stabilized by bioactive compounds from Acalypha indica leaf extract (AITE-CuNPs) represent an eco-friendly strategy for the development of effective antibacterial agents. In this study, AITE-CuNPs were synthesized using a two-step phase transfer method, employing toluene-soluble A. indica leaf extract as a capping and stabilizing agent, and were systematically characterized by FT-IR, UV–Vis spectroscopy, XRD, SEM, and TEM analyses, which confirmed their crystalline nature, quasi-spherical morphology, and stabilization by plant-derived biomolecules. Antibacterial evaluation revealed that AITE-CuNPs exhibited significantly enhanced activity compared to the plant extract alone, with lower MIC/MBC values against Shigella sonnei (7.33/25.00 mg/L), Staphylococcus aureus (10.00/29.00 mg/L), Escherichia coli (19.00/49.67 mg/L), and Klebsiella pneumoniae (16.33/31.33 mg/L). In addition to antimicrobial efficacy, in vivo zebrafish embryo toxicity studies demonstrated a concentration- and time-dependent embryotoxic and teratogenic effect at 100 and 200 µg (0.1 and 0.2 mg) exposure levels, with hatching reduced to 53.33