Degradation Mechanism of an IrO2 Anode Co-Catalyst for Cell Voltage Reversal Mitigation under Transient Operation Conditions of a PEM Fuel Cell

IrO 2 is the most stable oxygen evolution reaction (OER) catalyst in acidic media and it has been widely used as co-catalyst to mitigate cell reversal damages anode of PEM fuel cells (PEMFCs). In this study, a mechanistic understanding degradation an under transient operation PEMFC provided. Thermogravimetric analysis (TGA) reductive atmosphere (3.3 vol.% H /Ar) shows that not containing at operational temperatures PEMFCs. By conducting series physical-chemical electrochemical analyses, proven operating conditions can chemically reduce few outer monolayers surface nanoparticles metallic Ir. The Ir formed on then dissolve during start-up/shut-down (SUSD) cycles. At least part dissolved species electrode are shown diffuse through membrane cathode electrode, where they lead deterioration reduction (ORR) activity Pt catalyst. consequences dissolution tolerance also discussed.