Degradation analyses of Ru85Se15 catalyst layer in proton exchange membrane fuel cells

Abstract

Accelerated degradation tests (ADTs) for the H2/air single cell are carried out at 65 °C and ambient pressure by cycling the cell between 0 and 200 mA cm−2 up to 6000 cycles. Membrane electrode assemblies (MEAs) are prepared using the Nafion 212 membrane and the carbon supported platinum as an anode catalyst, as well as the carbon supported Ru85Se15 as a cathode catalyst prepared with five selected Nafion contents and Ru loads to represent the optimized (33% Nafion and 0.27 mg Ru cm−2), overloaded (43% Nafion and 0.61 mg Ru cm−2) and underloaded (20% Nafion and 0.14 mg Ru cm−2) conditions. The lowest cell performance loss of 44% in terms of peak power density is achieved with 33% Nafion and 0.27 mg Ru cm−2. Very severe losses of 80% and 82% are found for 20% and 43% Nafion contents, respectively, while relatively moderate losses of 57% and 64% for 0.14 and 0.61 mg Ru cm−2, respectively. Dissolution and migration of Se/Ru and corrosion of carbon support from the catalyst, together with the shrinkage and release of sulfonic acid from the membrane are identified and correlated to decayed cell performances.