SrTi1-xIrxO3 solid solution as a robust electrocatalyst for oxygen evolution reaction in proton exchange membrane water electrolyzers

Reducing iridium loading in oxygen evolution reaction (OER) is a promising solution to promote the widespread deployment of proton exchange membrane water electrolyzers (PEMWEs). In this work, we synthesized SrTi 1- x Ir x O 3 ( x  = 0, 0.25, 0.50, 0.75, 0.80 and 1) perovskites by the conventional sol-gel reaction route and evaluated their OER electrocatalytic activity and durability in 0.5 M H 2 SO 4 to reveal the critical role of B-site cations. The optimum composition, SrTi 0.25 Ir 0.75 O 3 , exhibited excellent activity with an overpotential of 294 mV to drive 10 mA cm −2 and marvelous durability with a negligible increase in the overpotential of 15 mV in 580 h, and even a remarkable durability with a small increase in the overpotential of only 30 mV after 140 h when performed at 100 mA cm −2 . Multiple characterizations combined with DFT calculations indicated that the bimetallic synergistic effect caused by mixture of Ti and Ir on the B-site decreased the band gap to improve electrical conductivity and induced electronic coupling between Ir and Ti to lower the energy barriers for OER. When assembled in the membrane electrode assembly (MEA), the optimum composition also showed a superb performance and excellent durability. Results of this work provide a new perspective for designing electrocatalyst with low iridium content for OER in PEMWEs.