COMPARATIVE THERMAL KINETIC ANALYSIS OF NICKEL HYDROXIDE NANOPARTICLES THROUGH CHEMICAL PRECIPITATION AND SOL–GEL ROUTES

In most of the chemical methods, the as-prepared NPs have a metal hydroxide form. The calcination temperature is very important to prepare the metal oxide from metal hydroxide. Thus, in this work, the chemical precipitation and sol–gel routes were employed to produce the Nickel hydroxide nanoparticles and analyze their functional, structural, thermal, and morphological behavior of prepared NPs. The formation of Ni(OH)₂ is confirmed by FTIR analysis including both techniques. Rietveld refinement techniques were used to diffraction patterns by the program FullProf. The well-matched XRD patterns reveal that prepared NPs have $\beta$-Ni(OH)₂ phase and hexagonal structure (HCP) with a space group of P3m1 for both the methods. The kinetic factors were calculated using different models. The Phadnis–Deshpande model is employed to identify the mechanism of solid state kinetic reaction. Solid state kinetic model observes nucleation and nuclei growth (Avrami–Erofeev nuclei growth) and 2D diffusion mechanism for chemical precipitation and sol–gel, respectively. From the FESEM analysis, flower-shaped architectures and nanosheet morphology are presented in the prepared sample by chemical precipitation and sol–gel, respectively. From the kinetic parameters, we conclude that the decomposition of Ni(OH)₂ to NiO is thermally stable, has slow reaction and spontaneous process at 300^∘C. The results show that the chemical precipitation method is more suitable for energy storage application compare to the Sol–gel method.