Tailoring of pyramid cobalt doped nickel oxide nanostructures by composite-hydroxide-mediated approach

Abstract

Nickel oxide nanostructures have been synthesized successfully by composite hydroxide mediated (CHM) approach at 200 °C for various cobalt concentrations (0%, 5%, 10% and 15%). Incorporation of cobalt was explored by employing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM, and ultraviolet visible spectroscopy. An influence of increase in cobalt doping on average crystallite size was found from 31 to 56 nm. The increase in crystallite size is due to the introduction of point defects and oxygen vacancies caused by the incorporation of Co ions in NiO lattice. The influence of defects is also seen from variation in lattice parameters and X-ray density. The effect of incorporation of increasing cobalt contents was seen from SEM micrographs. The spherical characteristics of pure NiO nanostructures changed to sharp edge pyramids with smooth surfaces. The growth of pyramids is evident with increase in side length 421–691 nm for various cobalt concentrations (5%, 10% and 15%). FT-IR confirms the purity of product while the band gap was estimated by UV–Vis spectroscopy which was found from 5.59 to 1.50 eV.