Boosting acidic water oxidation performance by constructing arrays-like nanoporous Ir_xRu_1−xO₂ with abundant atomic steps

The fabrication of electrocatalysts with high activity and acid stability for acidic oxygen evolution reaction (OER) is an urgent need, yet extremely challenging. Here, we report the design and successful fabrication of a high performance self-supported cogwheel arrays-like nanoporous Ir_xRu_1−xO₂ catalyst with abundant atomic steps for acidic OER using a facile alloy-spinning-electrochemical activation method that allows large-scale fabrication. The obtained Ir_xRu_1−xO₂ catalysts merely need overpotentials of 211 and 295 mV to deliver catalytic current densities of 10 and 300 mA·cm⁻² in 0.5 M H₂SO₄, respectively, and can sustain constant OER electrolysis for at least 140 h at a high current density of 300 mA·cm⁻². Further density functional theory (DFT) calculations uncover that such high intrinsic activities mainly originate from the largely exposed high-index atomic step planes, which markedly lower the limiting potential of the rate-determining step (RDS) of OER. These findings provide an insight into the exploration of high performance electrocatalysts, and open up an avenue for further developing the state-of-the-art Ir and/or Ru-based catalysts for large-scale practical applications.