Oxygen reduction at platinum modified gold electrodes

The reduction of oxygen has been studied on polycrystalline gold electrodes modified by platinum deposited spontaneously from an aqueous K2PtCl6 solution via the displacement of copper or lead adlayers. The change in the surface composition and morphology has been checked by XPS, AES and AFM data. The kinetic results have shown that such electrodes may present a higher catalytic activity compared to bulk platinum electrodes during a scan where the potential is made more positive and is thus clearly expressed by an hysteresis in the CV curves. The displacement of copper and lead deposits gave similar amplitudes of the hysteresis but the modified electrodes obtained via a lead deposit present a better stability upon cycling in acid solutions. The observed behaviour can be correlated to the modification of the M-OH formation and reduction on noble metals. (C) 2003 Elsevier Ireland Ltd. All rights reserved.