Ceria-Optimized Oxygen-Species Exchange in Hierarchical Bimetallic Hydroxide for Electrocatalytic Water Oxidation.

The utilization of rare earth elements to regulate the interaction between catalysts and oxygen-containing species holds promising prospects in the field of oxygen electrocatalysis. Through structural engineering and adsorption regulation, it is possible to achieve high-performance catalytic sites with a broken activity-stability tradeoff. Herein, this work fabricates a hierarchical CeO 2 /NiCo hydroxide for electrocatalytic oxygen evolution reaction (OER). This material exhibits superior overpotentials and enhanced stability. Multiple potential-dependent experiments reveal that CeO 2 promotes oxygen-species exchange, especially OH - ions, between catalyst and environment, thereby optimizing the redox transformation of hydroxide and the adsorption of oxygen-containing intermediates during OER. This is attributed to the reduction in the adsorption energy barrier of Ni to *OH facilitated by CeO 2 , particularly the near-interfacial Ni sites. The less-damaging adsorbate evolution mechanism and the CeO 2 hierarchical shell significantly enhance the structural robustness, leading to exceptional stability. Additionally, the observed "self-healing" phenomenon provides further substantiation for the accelerated oxygen exchange. This work provides a neat strategy for the synthesis of ceria-based complex hollow electrocatalysts, as well as an in-depth insight into the co-catalytic role of CeO 2 in terms of oxygen transfer.