Synthesis and Characterization of NiO Nanoparticles by Sol-Gel Method

Due to the outstanding electrical, magnetic and catalytic properties, nickel oxide (NiO) has been received considerable attention during the past decades. In this study, NiO nanoparticles were prepared by sol­gel method, which is one of the simplest and lowest-cost techniques. The synthesis was accomplished by using Poly(alkylene oxide) block copolymer as the surfactant, and Ni(NO3)2·6H2O as the inorganic precursor. The effect of experimental parameters, such as calcination temperatures and H2O concentration on the NiO nanoparticles formation were investigated. TGA, XRD, SEM, TEM and N2 adsorption­desorption isotherms were used to characterize the microstructure and specific surface area of the samples. TGA and FTIR analyses demonstrated that copolymers were expelled at 573K. The formation of NiO nanoparticles and their structural features were greatly dependent on the calcination temperature. The sample calcined at 923K was composed of pure NiO nanoparticles as shown by XRD. As H2O concentration was increased, the reoxidation process of metallic Ni to form NiO would reduce, but it would not affect the structural type of NiO nanoparticles. In general, the addition of water would weaken and inhibit oxidation effects. The temperature of stable metallic Ni was increased up to 823K. The specific surface area evaluated from the N2 adsorption­desorption indicated that the samples consisting of non-porous NiO nanoparticles. Increasing H2O addition resulted in an increase of specific surface area of nanocrystalline NiO powder. [doi:10.2320/matertrans.M2012244]