α-Ni(OH) 2 thin films fabricated by liquid phase deposition method

Abstract

α-Ni(OH)2 thin films have been synthesized on various substrates by liquid phase deposition method. The deposited films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope (SEM). The addition of boric acid (H3BO3) as fluoride scavenger to the treatment solution destabilized the [NiFx(x − 2n)−] metal-fluoro complex bonds and forced the oxide precipitation, resulting in the formation of α-Ni(OH)2. The obtained thin films exhibited transparency and interference color. SEM images showed that the films consisted of interconnected thread-like fibers with a width of ca. 50 nm. The deposition process and morphology of fibrous particles showed strong dependence to the initial concentrations of H3BO3 solution and temperature. Transparency and interference color were related to the film thickness, which can be controlled by the concentration of Ni metal-fluoro complex and the reaction time. Calcination at 500 °C led to the formation of NiO particles. For comparison purpose, β-Ni(OH)2 thin films prepared by “direct deposition” method which consists of simple heterogeneous nucleation in an aqueous solution without adding boric acid is reported.