NiO morphology dependent optical and electrochemical properties

In this paper, NiO nanoparticles were prepared by hydrothermal synthesis of Ni(OH)2 precursors using different alkalis (NH3 and NaOH) followed by a calcination at different temperatures (400°C and 600°C) and characterized by XRD and SEM. Their electrochemical and optical properties were probed by cyclic voltammetry and reflectance spectroscopy and related to the structural and morphological properties. It was found that the smallest peak-to-peak separations and band gaps attain to the NiO nanoparticles prepared at 400°C, which are smaller and more porous. The preparations at 600°C correspond to larger nanoparticles, with a larger size distribution and in one case (preparation with NaOH) a compact structure. The associated band gaps are larger and the electrochemical performances worse.