Physicochemical and electrochemical characterization of active films of LaNiO3 for use as anode in alkaline water electrolysis

Abstract

Thin films of LaNiO3 were prepared on Ni by the sequential coating method, and the effects of film preparation variables, such as concentration of the mixed metal nitrates solution, temperature and oxide loading, were examined for the electrocatalytic activity of the film regarding oxygen evolution in concentrated KOH solution. The oxide film with a loading of ~6 mg cm-2 was found to be the best electocatalyst among the electrodes prepared in situ. The activity of this film electrode was better than those prepared by othermethods, following sequential coatings of solution or mixed oxide coatings. Electrode kinetic parameters, such as Tafel slope, reaction order and activation energy, were found to be ~65 mV decade-1, ~1.2 and 18.4 kcal, respectively. Cyclic voltammetric studies, prior to the onset of oxygen evolution, exhibited two characteristic peaks corresponding to a diffusion-controlled surface redox process: Ni2+ → Ni3+. Based on these results, a probable mechanism for oxygen evolution on the oxide film electrode is suggested. © 1995.