Iridium Doped Pyrochlore Ruthenates for Efficient and Durable Electrocatalytic Oxygen Evolution in Acidic Media

Developing highly active, durable, and cost-effective electrocatalysts for the oxygen evolution reaction (OER) is of prime importance in proton exchange membrane (PEM) water electrolysis techniques. Ru-based catalysts have high activities but always suffer from severe fading and dissolution issues, which cannot satisfy the stability demand of PEM. Herein, a series of iridium-doped yttrium ruthenates pyrochlore catalysts is developed, which exhibit better activity and much higher durability than commercial RuO2, IrO2, and most of the reported Ru or Ir-based OER electrocatalysts. Typically, the representative Y2Ru1.2Ir0.8O7 OER catalyst demands a low overpotential of 220 mV to achieve 10 mA cm(-2), which is much lower than that of RuO2 (300 mV) and IrO2 (350 mV). In addition, the catalyst does not show obvious performance decay or structural degradation over a 2000 h stability test. EXAFS and XPS co-prove the reduced valence state of ruthenium and iridium in pyrochlore contributes to the improved activity and stability. Density functional theory reveals that the potential-determining steps barrier of OOH* formation is greatly depressed through the synergy effect of Ir and Ru sites by balancing the d band center and oxygen intermediates binding ability.

Automated summary

Developing highly active, durable, and cost-effective electrocatalysts for the oxygen evolution reaction (OER) is crucial for proton exchange membrane (PEM) water electrolysis techniques. The study introduces iridium-doped yttrium ruthenates pyrochlore catalysts with better activity and higher durability than commercial RuO2, IrO2, and most of the reported Ru or Ir-based OER electrocatalysts.