Dissolution and Stabilization of Platinum in Oxygen Cathodes

Abstract

In this brief review of the dissolution and solubility of platinum under equilibrium conditions and the degradation of platinum nanoparticles at the cathode under various operating conditions, we discuss some mechanisms of degradation, and then offer recent possibilities for overcoming the problem. The data indicate that platinum nanoparticle electrocatalysts at the cathode are unstable under harsh operating conditions, and, as yet, often would be unsatisfactory for usage as the cathode material for fuel cells. Carbon corrosion, particularly under start/stop circumstances in automobiles, also entails electrical isolation and aggregation of platinum nanoparticles. We also discuss new approaches to alleviate the problem of stability of cathode electrocatalysts. One involves a class of platinum monolayer electrocatalysts that, with adequate support and surface segregation, demonstrated enhanced catalytic activity and good stability in a long-term durability test. The other approach rests on the stabilization effects of gold clusters. This effect is likely to be applicable to various platinum- and platinum-alloy-based electrocatalysts, causing their improved stability against platinum dissolution under potential cycling regimes.