Influence of Ionomer Content in Pt/mesoporous SnO₂ Electrodes on PEM Fuel Cell Performance

The search for more durable supports for oxygen reduction reaction (ORR) catalyst is a topic of increasing importance in the development of polymer electrolyte fuel cells (PEFCs). Recently, tin oxide (SnO 2 ) supports have garnered attention because of their high oxidative stability. However, improving their cell performance, particularly under wet conditions, remains a challenge before their successful deployment. Herein, we expand on our previous work on carbon-free mesoporous SnO 2 -based catalyst supports and investigate the effects of ionomer content on ORR performance and cathode catalyst layer (CCL) structure. Optimization of the ionomer content resulted in a more uniform ionomer distribution and alleviation of CCL flooding and a 2-fold increase in catalytic activity under wet conditions. As a result, the mesoporous SnO 2 -based catalyst supports exhibited comparable performance to solid-core carbon supports under both wet and dry conditions. Finally, we present a summary of our progress on the development of mesoporous SnO 2 -based catalyst support and highlight critical areas of improvements needed towards their future deployment.