Transformation nanostructured nickel hydroxide to nickel oxide film by aqueous chemical growth

Abstract

Nickel hydroxide, [Ni(OH)2] has been used extensively as the positive electrode material in rechargeable nickel-based batteries. Several approaches are known to be able for Ni(OH)2 growth including dc reactive magnetron sputtering, chemical spray pyrolysis, thermal evaporation, etc. This study discusses about nanostructured Ni(OH)2 film growth by aqueous chemical growth based technique. Ni(OH)2 film grown at 150 °C has a coral-like morphology whereas converted to NiO film by oxidation of Ni(OH)2 at 400 °C, confirmed by X-ray diffraction (XRD). Field Emission Scanning Electron Microscopy (FESEM) revealed a coral-like structure of Ni(OH)2 were grown on the glass substrates. Flake-like morphology was obtained for NiO film. The XRD pattern reveals that the intensity of observed peaks increased with the longer reaction time and film thickness which indicated an improvement in crystallinity. The optical band gap for Ni(OH)2 film calculated from transmission spectra increased from 3.72 eV to 3.91 eV with the increasing of reaction time. Higher optical band gap of 4.00 eV was obtained for NiO film. This result indicates that the Ni(OH)2/NiO films grown by aqueous chemical growth could to produce similar quality properties to other conventional methods either nanoparticle or bulk size.