Chromium-driven lattice oxygen activation in high-entropy oxide for efficient oxygen evolution reaction

The sluggish kinetics of the oxygen evolution reaction (OER) remains one of the major bottlenecks limiting the efficiency of water electrolysis for sustainable hydrogen production. Although high-entropy oxides (HEOs) have emerged as promising noble-metal-free electrocatalysts because of their tunable electronic structures and multimetal synergistic effects, most reported HEO catalysts still follow the conventional adsorbate evolution mechanism (AEM), which suffers from intrinsic scaling relationships and high reaction barriers. Activating the lattice oxygen oxidation mechanism (LOM) has recently been recognized as an effective strategy to overcome these limitations, yet rationally regulating lattice oxygen activity without sacrificing structural stability remains a major challenge.

Recently, a research team led by Prof. Renhong Li from Zhejiang Sci-Tech University and Dr. Mingwu Tan from A*STARrationally designed a self-supported high-entropy oxide electrocatalyst and clarified the dual regulatory roles of high-valent Cr species in triggering LOM to accelerate OER kinetics and maintaining structural stability. The results were published in Chinese Journal of Catalysis (DOI: 10.1016/s1872-2067(26)65069-3).

Cr performs three core functions during the lattice oxygen activation process in high-entropy oxide: (1) Electronic structure modulation: high-valent Cr serves as an electron regulator to induce charge redistribution within the lattice, downshift metal d-band center, weaken metal-oxygen (M–O) covalency and stabilize high-valent active species; (2) Triggering selective metal leaching and surface reconstruction: the charge redistribution triggered by Cr drives the selective dissolution of Mo species in the form of soluble MoO₄²⁻, which in-situ generates abundant oxygen vacancies and induces controllable surface reconstruction to form metal oxyhydroxide active phases with superior catalytic activity; (3) Facilitating lattice oxygen participation in OER: the enriched oxygen vacancies reduce the binding energy of lattice oxygen, enabling lattice oxygen to directly participate in O−O coupling for oxygen production via the LOM pathway, and the consumed lattice oxygen is replenished by electrolyte OH⁻ to regenerate the catalytic active structure.

This work establishes a clear structure-electronic structure-reaction pathway relationship for high-entropy oxide electrocatalysts and demonstrates that high-valent metals can effectively trigger lattice oxygen participation by simultaneously regulating electronic structure and surface reconstruction. The findings provide new mechanistic insights into lattice oxygen activation and offer a rational strategy for designing next-generation high-performance electrocatalysts for sustainable hydrogen production and renewable energy conversion.

About the Journal

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top one journals in Applied Chemistry with a current SCI impact factor of 17.2. The Editors-in-Chief are Profs. Can Li and Tao Zhang.

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