(600cb) Kinetics of Platinum Dissolution in Acidic Electrolyte: Investigation By Rotating Ring-Disk Electrode

Despite the high nobility of platinum metal, the trace dissolution of platinum is a limiting factor for supported nanoparticle catalysts in proton exchange membrane fuel cells. The kinetics of platinum dissolution in acid solutions are not well known due to the very low solubility of dissolved platinum and the simultaneous formation of a surface oxide layer, which prevents measurements at steady state. The rotating ring-disk electrode (RRDE) technique is ideally suited for the transient detection of dissolution under arbitrary potential cycling conditions. In this work, the RRDE technique was applied to the study of the anodic and cathodic dissolution of platinum. Experimental challenges were addressed, including measuring nanoamp ring currents while drawing milliamp disk currents and eliminating impurity effects. The RRDE results were fit to a combined kinetic model of platinum dissolution and surface oxidation, building on the authors’ previous work.