Surface modifications with heteropoly and isopoly oxometalates: Part IV . Further details and kinetic aspects of the h.e.r. on the modified electrodes

Abstract

Heteropoly and isopoly oxometalates can be used to modify electrode surfaces persistently, giving very durable and robust electrocatalytic materials for the h.e.r. Cyclic voltammetric characterization of the modified surfaces in pure acidic aqueous supporting electrolyte, reveals the presence of surface waves, which are pH-dependent and can interfere severely with the h.e.r. wave. Therefore, the kinetic analysis of the h.e.r. on the modified electrodes is performed by rotating disk voltammetry. The main Tafel parameters obtained for an electrode modified in the presence of α 2-K 6P 2W 17MoO 62 are log ( i 0/A cm −2) = −1.7 and α = 0.50, with a slope of 0.118 V and a stoichiometric number v = 2. It appears that the mechanism of the h.e.r. on the electrode surfaces modified with heteropoly and isopoly oxometalates is different from that observed on platinum.