10.1039/c8nj01223g
The research focuses on the green synthesis of gold (Au), silver (Ag), platinum (Pt), and palladium (Pd) nanoparticles using sodium rhodizonate as a bifunctional reducing and stabilizing agent. The study involves the preparation of these nanoparticles in water through a single-step process and evaluates their catalytic efficiency in reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydride (NaBH4) and in the dual-catalytic oxidation of formic acid followed by the reduction of methyl orange (MO). The synthesized nanoparticles were characterized using UV-Vis spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, and zeta potential measurements to determine their size, morphology, crystallinity, elemental composition, and surface charge. The catalytic activities of the nanoparticles were assessed through UV-Vis spectrophotometer monitoring of the absorbance changes at specific wavelengths, corresponding to the reactants and products in the reduction reactions.
10.1039/c3ce42654h
The study examines the adsorption and photocatalytic performance of bismuth oxyiodide (BiOI) for the degradation of three dyes: methyl orange (MO), Rhodamine B (RhB), and methylene blue (MB). The adsorption performance of BiOI was found to vary depending on the dye, with the order of adsorption efficiency being MO < RhB < MB. This trend was attributed to the electrostatic interactions between the positively charged RhB and MB dyes and the negatively charged BiOI surface, while MO, being negatively charged, interacted less favorably. Under UV and visible light irradiation, the photocatalytic degradation of MO followed the order BiOI < Ag–BiOI < Ti–BiOI, indicating that Ti-doping enhanced the photocatalytic activity. For RhB, BiOI alone was more effective under UV light, but Ag and Ti-doped BiOI showed better performance under visible light, suggesting a dye-sensitized mechanism where the dye absorbs light and transfers energy to the catalyst. Methylene blue (MB), despite being efficiently adsorbed, showed poor photocatalytic degradation under both UV and visible light, indicating that its removal was primarily through adsorption rather than photocatalysis. The study also identified superoxide radicals (?O2 -) and holes (h+) as the active species responsible for dye degradation under visible light, with no significant contribution from hydroxyl radicals (?OH). These findings highlight the complex interplay between adsorption and photocatalytic mechanisms in BiOI and its doped variants for dye degradation.