Affiliation:
1. State Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Electrochemical Process and Technology for Materials Beijing University of Chemical Technology Beijing 100029 P. R. China
2. National Engineering Research Center for Fuel Cell and Hydrogen Source Technology Beijing University of Chemical Technology Beijing 100029 P. R. China
3. Research Initiative for Supra-Materials Shinshu University Nagano 380-8553 Japan
Abstract
AbstractRu‐based pyrochlores (e.g., Y2Ru2O7−δ) are promised to replace IrO2 in polymer electrolyte membrane (PEM) electrolyzers. It is significant to reveal the cliff attenuation on the oxygen evolution reaction (OER) performance of these pyrochlores. In this work, we monitor the structure changes and electrochemical behavior of Y2Ru2O7−δ over the OER process, and it is found that the reason of decisive OER inactivation is derived from an insulator transition occurred within Y2Ru2O7−δ due to its inner “perfecting” lattice induced by continuous atom rearrangement. Therefore, a stabilization strategy of the Ir‐substituted Y2Ru2O7−δ is proposed to alleviate this undesirable behavior. The double‐exchange interaction between Ru and Ir in [RuO6] and [IrO6] octahedra leads the charge redistribution with simultaneous spin configuration adjustment. The electronic state in newly formed octahedrons centered with Ru 4d3 (with the state of eg′↑↑a1g↑ eg0) and Ir 5d6 (eg′↑↓↑↓a1g↑↓ eg0) relieves the uneven electron distributions in [RuO6] orbital. The attenuated Jahn–Teller effect alleviates atom rearrangement, represented as the mitigation of insulator transition, surface reconstruction, and metal dissolution. As results, the Ir‐substituted Y2Ru2O7−δ presents the greatly improved OER stability and PEM durability. This study unveils the OER degradation mechanism and stabilization strategy for material design of Ru‐based OER catalysts for electrochemical applications.