Influence of Nickel Oxide Transformation Reaction on Oxygen Evolution Kinetics as Ascertained

The 02 evolution reaction and nickel oxide transformation reactions were investigated on Ni electrodes in 50 w/o KOH as a function of temperature using steady-state and cyclic voltammetrie techniques, respectively. A change in the valence state of the oxide occurs in the region of oxygen evolution at temperatures above 150 ~ The previously reported change in Tafel slope at elevated temperatures is explained on the basis of the role played by the trans-formation of surface oxides, and its effect on the kinetics of the OER. The oxygen evolution reaction (OER) was inves-tigated recently on nickel electrodes in 50 weight percent (w/o) KOH as a function of temperature (1). A change in the Tafel slope from 3 RT/2F at tem-peratures below 208 ~ to RT/4F at temperatures above this value was reported. The main purpose of the present work was to determine the influence of oxid