Guo Hengyu, Huang Yanzong, Long Chuan, Shao Chenyi, Fang Feifei, Yu Yinglong, Zhang Zhengping, Wang Feng
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.
National Engineering Research Center for Fuel Cell and Hydrogen Source Technology, Beijing University of Chemical Technology Beijing, Beijing, 100029, P. R. China.
Small. 2025 Aug;21(33):e2505222. doi: 10.1002/smll.202505222. Epub 2025 Jun 19.
Pyrochlores ruthenates, owing to their D symmetric configurations of [RuO] octahedra to efficiently avoid the Ru dissolution during the oxygen evolution reaction (OER) process, have been promising as non-iridium electrocatalysts for proton exchange membrane water electrolysis (PEMWE). In this work, a lattice-distortion strategy is proposed, by using a series of lanthanides (from Gd to Lu) as the dominant A sites and a series of alkalines (from Mg to Ba) as the A-site substitutions, to investigate the geometric effect on the pyrochlores for OER. It is found that the larger radii difference between the A sites and the A-site substitutions, the larger lattice expansion of these alloyed pyrochlore ruthenates, accompanied by the shortened Ru─O bonding, the enlarged Ru─O─Ru bond angle, and the enhanced covalency of [RuO] octahedra. The large lattice expansion also leads a rapid A-site leaching and the formation of protective RuO reconstruction layers, which suppress the progressive metal dissolution, the lattice contraction, and the resulting insulated OER deactivation. On account of the synergistic effect from the lattice distortion, the most distorted LuBa pyrochlores exhibit the highest OER performance and the greatest enhancement in either electrochemical testing or PEMWE operation, demonstrating their considerable potential for practical applications.
烧绿石钌酸盐由于其[RuO]八面体的D对称构型能够在析氧反应（OER）过程中有效避免Ru溶解，作为质子交换膜水电解（PEMWE）的非铱电催化剂具有广阔前景。在这项工作中，提出了一种晶格畸变策略，通过使用一系列镧系元素（从Gd到Lu）作为主要的A位以及一系列碱金属（从Mg到Ba）作为A位替代物，来研究烧绿石对OER的几何效应。研究发现，A位与A位替代物之间的半径差越大，这些合金化烧绿石钌酸盐的晶格膨胀就越大，同时伴随着Ru─O键缩短、Ru─O─Ru键角增大以及[RuO]八面体的共价性增强。大的晶格膨胀还会导致A位快速浸出并形成保护性的RuO重构层，从而抑制金属的逐步溶解、晶格收缩以及由此导致的OER绝缘失活。由于晶格畸变的协同效应，畸变最大的LuBa烧绿石在电化学测试或PEMWE运行中均表现出最高的OER性能和最大的增强效果，证明了其在实际应用中的巨大潜力。
