Non-oxide High-Entropy Ceramics for Oxygen Evolution Reaction: A Review

As fossil energy resources deplete and environmental challenges escalate, the development of clean energy technologies has gained global consensus. Among emerging strategies, electrochemical water splitting for hydrogen production stands out due to its zero-carbon emissions. However, the oxygen evolution reaction suffers from sluggish kinetics and typically depends on precious metal catalysts. Recently, non-oxygen anion (e.g., S, P, N, F, C, etc.) high-entropy ceramics (NOHECs), a subclass of high-entropy materials doped with diverse elements, have demonstrated significant OER potential, offering a cost-effective solution with high activity and excellent stability. This review delineates the synthesis methods for NOHECs from two distinct perspectives: liquid-phase synthesis routes and gas-phase synthesis routes. Subsequently, the catalytic mechanisms and performance breakthroughs of various NOHECs are reviewed in detail, which are categorized by the types of coordinated non-oxygen anions. Importantly, this review critically explores future research directions for these materials from multiple perspectives, including innovative synthetic routes, novel NOHEC designs, theoretical simulations, advanced material characterization techniques, industrial feasibility, and expanded applications. Ultimately, it aims to provide a theoretical foundation and technical references for the integration of NOHECs in energy conversion systems while highlighting promising pathways for further advancement in this rapidly evolving field.