Oxide loading effect on the electrochemical performance of LaNiO3 coatings in alkaline media

Abstract

LaNiO3 film electrodes were prepared by brush painting using nickel-foam supports in order to increase its surface area available for electrochemical reactions. Loadings varying between 20 and 140 mg cm-2 were tested. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to evaluate the coatings roughness (Rf) and morphology (f) factors, complemented by optical microscopy observations. The values obtained from the two methods are in excellent agreement. The Rf values, ranging from 848 ± 50 to 4260 ± 60, are within the highest in the open literature. A simulation, of the effect of the oxide loading on the coatings Rf values, was performed using just the experimental values of the roughness factors for oxide free foam and pelleted electrodes. It was found that the increase of oxide loading causes a quasi linear increase of the electrodes active surface area. Simulated values were in excellent agreement with the experimental roughness factors and pore resistances obtained by CV and EIS. The electrodes were tested for oxygen evolution.