Iridium Doped Pyrochlore Ruthenates for Efficient and Durable Electrocatalytic Oxygen Evolution in Acidic Media
Hai Liu, Zhuang Zhang, Mengxuan Li, Zhaolei Wang, Xingheng Zhang, Tianshui Li, Yaping Li, Shubo Tian, Yun Kuang, Xiaoming Sun
Abstract
Abstract 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 RuO 2 , IrO 2 , and most of the reported Ru or Ir‐based OER electrocatalysts. Typically, the representative Y 2 Ru 1.2 Ir 0.8 O 7 OER catalyst demands a low overpotential of 220 mV to achieve 10 mA cm −2 , which is much lower than that of RuO 2 (300 mV) and IrO 2 (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.