Regulating Strain and Electronic Structure of Indium Tin Oxide Supported IrO_<i>x</i> Electrocatalysts for Highly Efficient Oxygen Evolution Reaction in Acid

The development of proton exchange membrane water electrolysis is a promising technology for hydrogen production, which has always been restricted by the slow kinetics of the oxygen evolution reaction (OER). Although IrO_<i>x</i> is one of the benchmark acidic OER electrocatalysts, there are still challenges in designing highly active and stable Ir-based electrocatalysts for commercial application. Herein, a Ru-doped IrO_<i>x</i> electrocatalyst with abundant twin boundaries (TB-Ru_0.3Ir_0.7O_<i>x</i>@ITO) is reported, employing indium tin oxide with high conductivity as the support material. Combing the TB-Ru_0.3Ir_0.7O_<i>x</i> nanoparticles with ITO support could expose more active sites and accelerate the electron transfer. The TB-Ru_0.3Ir_0.7O_<i>x</i>@ITO exhibits a low overpotential of 203 mV to achieve 10 mA cm^-2 and a high mass activity of 854.45 A g^-1_{noble metal} at 1.53 V vs RHE toward acidic OER, which exceeds most reported Ir-based OER catalysts. Moreover, improved long-term stability could be obtained, maintaining the reaction for over 110 h at 10 mA cm^-2 with negligible deactivation. DFT calculations further reveal the activity enhancement mechanism, demonstrating the synergistic effects of Ru doping and strains on the optimization of the d-band center (ε_d) position and the adsorption free energy of oxygen intermediates. This work provides ideas to realize the trade-off between high catalytic activity and good stability for acidic OER electrocatalysts.