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Zinc oxide (ZnO) nanoparticles of varying sizes (20, 44 and 73 nm) have been successfully synthesized by a hybrid electrochemical-thermal method using aqueous sodium bicarbonate electrolyte and sacrificial Zn anode and cathode in an undivided cell under galvanostatic mode at room temperature. The as-synthesized product was characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Scanning electron microscopy along with Energy dispersive analysis of X-ray (SEM/EDAX), Transmission electron microscopy (TEM), Ultra Violet -Diffuse reflectance spectroscopic methods (UV-DRS). and UV-DRS spectral methods. The as-synthesized compound were single-crystalline and Rietveld refinement of calcined samples exhibited hexagonal (Wurtzite) structure with space group of P63mc (No.186). The band gaps for synthesized ZnO nanoparticles were 3.07, 3.12 and 3.13 eV, respectively, based on the results of diffuse reflectance spectra (DRS). The electrochemically synthesized ZnO powder was used as photocatalysts for UV-induced degradation of Methylene blue (MB). Photodegradation was also found to be function of exposure time and dye solution pH. It has been found that as-synthesized powder has excellent photocatalytic activity with 92% degradation of MB, indicating ZnO nanoparticles can play an important role as a semiconductor photocatalyst.

The nanocrystalline nickel oxide (NiO) particles have been successfully prepared by a simple, fast, economical, and eco‐friendly solution‐combustion method using Ni(NO3)2 · 6H2O (oxidizer) and sugar (dextrose as fuel). The as‐prepared compound was calcined for an hour at different temperatures. The synthesized NiO was characterized by XRD, TGA, SEM/EDX, TEM, XPS, FT‐IR, and UV–Vis spectral methods. The crystallite sizes of the NiO particles were measured. Rietveld refinement of X‐ray data matches the cubic structure with space group of Fm3m (No. 225). The thermal behavior of as‐prepared compound was examined. Scanning electron micrographs show uniform cubic like morphology of NiO and its chemical composition was measured. The TEM results reveal that the particle sizes were in the order of 70–80 nm. The red shift was noticed in UV–Vis absorption spectra. As an application part the ZnNiO composite coating was prepared by electrodeposition method and its corrosion behavior was analyzed by Tafel, impedance and anodic polarization in aggressive medium.