Paracrystalline IrCoOx stabilization by rutile SnO2 towards durable acidic oxygen evolution

Abstract The development of oxygen evolution reaction catalysts featuring high activity with long-term durability in acidic media remains a major challenge for proton exchange membrane water electrolysis. Herein, we report a strategy to stabilize highly active paracrystalline IrCoO x phase by integrating it with rutile SnO 2 , achieving an optimal activity-durability balance. The formation of paracrystalline phase, directly visualized by in-situ heating transmission electron microscopy, enhances lattice oxygen activation and oxygen evolution kinetics. Owing to their shared P4 2 /mnm space group, the resulting IrCoO x −2@SnO 2 catalyst demonstrates a mass activity of 1192 A g Ir −1 (114 times that of IrO 2 ), and a durable operation for 3880 h at 2 A cm −2 in electrolysis cell, representing a very competitive stability under the identical conditions. The SnO 2 was proven to stabilize the paracrystalline phase by mitigating metal dissolution, agglomeration, and Ir over-oxidation, while favorable interfacial water dynamics enables reversible oxygen species cycling and efficient proton transfer, collectively contributing to the satisfactory durability.