Iridium-Based Electrocatalysts for Oxygen Evolution Reaction in Proton Exchange Membrane Water Electrolyzers

Proton exchange membrane water electrolyzers (PEMWEs) show the fast response to a wide electrical load range, making them compatible to couple with intermittent renewable energy systems such as wind and solar power. However, the low efficiency, instability, and high cost of anodic electrocatalysts for the oxygen evolution reaction (OER) severely hinder the widespread deployment of PEMWEs. Hitherto, iridium-based catalysts still play an irreplaceable role for their trade-off catalytic activity and stability. To meet the scarcity of iridium, reducing the iridium loading and designing low iridium-based electrocatalysts have become the mainstream. Particularly, perovskite-type oxides possess flexible compositions, enabling them ideal material platform for the optimization of catalytic performance. In this work, several materials of iridium-based perovskite-type oxides were acquired by coupling iridium with various transition elements in B-site and regulating A-site cations, which both diluted the usage of iridium and utilized the multi-metallic synergistic effect to achieve high activity and stability. Evolution of the surface structure was monitored by in-situ Raman spectroscopy to identify the active site and to uncover the catalytic mechanism. Besides, density functional theory (DFT) calculation was used as an auxiliary tool to analyze the local structure and electrochemical behavior of the electrode surface for its cost-effectiveness. Furthermore, membrane electrode assembly (MEA) based on the optimum composition was assembled to evaluate the performance of novel electrocatalysts for PEMWEs. Results of this work provide a new perspective of designing low iridium content electrocatalysts for OER in PEMWEs. Acknowledgement This work is funded by the National Natural Science Foundation of China (No. 22002089, 52072239).