Enhancing Voltage Reversal Tolerance of Proton Exchange Membrane Fuel Cells by Tuning the Microstructure of IrO_x Catalysts

Voltage reversal of proton exchange membrane fuel cells caused by hydrogen deficiency seriously deteriorates the anodes and lowers their performance and lifetime. A commonly used method is to add oxygen evolution reaction catalysts (e.g., IrO2) to the anode to extend the water electrolysis plateau against harmful carbon corrosion. Herein, strongly connected IrOx nanoparticles (SC-IrOx) are prepared by removing the low surface area carbon carrier of the as-synthesized Ir/C catalyst. The reversal-tolerant anode with SC-IrOx owns an anti-reversal time of 9.32 h, which is 3.2 and 4.4 times that of the reversal-tolerant anode with commercial IrOx and weakly connected IrOx, respectively. Further transmission electron microscope characterizations reveal that SC-IrOx can construct a stable electron and proton transport pathway in the anode catalyst layer, which can delay the isolation of oxygen evolution reaction catalyst from the electron and proton conducting network, thus extending the water electrolysis plateau. Herein, our findings suggest that tuning the microstructures of IrOx catalysts is indeed an effective and promising approach to extend the water electrolysis plateau and alleviate the performance degradation of proton exchange membrane fuel cells during the voltage reversal process.