Electronic engineering of spinels for advanced electrocatalysis.

Spinels represent promising candidates for clean energy electrocatalysis due to their abundance and electronic structure adjustability. However, their intrinsic catalytic activity remains limited. This review analyzes the fundamental correlations between the electronic structure and catalytic performance of spinel-based electrocatalysts. It elucidates the critical roles of coordination geometry, e.g., tetrahedral vs. octahedral sites, and the electronic configuration of active metal centers, including the d-band center position and spin state. The applications of these electronic structure modulation strategies across electrocatalytic reactions, encompassing the oxygen evolution reaction, oxygen reduction reaction, hydrogen evolution reaction, nitrogen reduction reaction, nitrate reduction reaction, carbon dioxide reduction reaction, and urea oxidation reaction, were further analyzed. Gaining insights from these diverse reaction systems, this review proposes a generalizable design paradigm for efficient spinel electrocatalysts: coordination engineering-d-band center optimization-spin state modulation. Finally, challenges in electronic-state control and future research frontiers are outlined, providing a robust mechanistic framework for the rational design of spinel electrocatalysts for sustainable energy technologies.