A STUDY OF RUO2 AS AN ELECTROCATALYST FOR HYDROGEN EVOLUTION IN ALKALINE-SOLUTION

The hydrogen evolution reaction (HER) on RuO2 coated nickel electrodes was investigated by d.c. polarization studies and a.c. impedance meas urements in alkaline solution. The electroactive RuO2 coatings were pr epared by thermal decomposition of a RuCl3 solution at 450 degrees C i n air. The real surface area of the cathodes was estimated from cyclic voltammetric measurements and from the double layer capacitance (eval uated by impedance measurements). A mechanism for the HER has been pro posed involving two steps (Volmer and Heyrovsky reactions). The rate c onstants of the forward and backward reactions of these two steps have been estimated by a nonlinear fitting procedure.