Toward highly robust reversal-tolerant anodes in polymer electrolyte membrane fuel cells

A reversal tolerant anode (RTA) mitigates carbon corrosion under hydrogen starvation by promoting a water oxidation reaction with an oxygen-evolution-reaction catalyst. However, achieving long-lasting and repeatable voltage-reversal tolerance remains a challenge. Herein, we propose highly robust bi-layered RTAs consisting of IrOx and Pt black layers (IrOx//Pt) for use in polymer electrolyte membrane fuel cells. Compared to bi-layered IrOx//Pt/C RTAs, the carbon-free IrOx//Pt RTAs have an exceptionally longer voltage-reversal time and unprecedented level of repeatability. Additionally, placing the IrOx layer on the membrane side of the RTA is more effective in maintaining the water oxidation reaction than placing it on the diffusion layer side. Oxidative dissolution of IrOx in the IrOx//Pt RTAs under repeated voltage reversals emphasizes the importance of lowering the water oxidation potential of RTA. The carbon-free, bi-layered RTA design presented in this work provides a new path for achieving long-lasting and repeatable voltage-reversal tolerance.