The Effect of Dynamic and Steady State Voltage Excursions on the Stability of Carbon Supported Pt and PtCo Catalysts

Abstract

To improve the stability of Pt-based catalysts to meet the targets set for automotive fuel cell operation, a detailed understanding of the mechanisms of corrosion and Pt particle stability is required. The stability of Pt and PtCo on both high-area and low-area carbon supports has been studied using both dynamic and steady state voltage excursion measurements. At 1.2V steady state, the catalysation of carbon did not significantly increase the rate of carbon corrosion. However, corrosion rates of the low area carbon was 1/20th that of the high-area carbon. Under dynamic cycling, the stability of small Pt particles was found to be poor due to dissolution/sintering on the high-area carbon, however the PtCo alloy particles were found to be very stable on both the high-area and low-area carbons. In addition, it has been found that Pt oxide/reduction can catalyse carbon corrosion with both high and low-area carbons.