The electron buffer effect for advanced electrocatalysis.

The electronic structure of catalysts often undergoes irreversible transformation during electrocatalysis at applied potential, significantly impacting their activity and stability. Recent studies have revealed the critical role of the electron buffer effect in enhancing electrocatalytic performance. Conceptually analogous to a pH buffer, this effect involves the dynamic regulation of electron density at active sites through reversible electron transfer with a functional support. It helps stabilize the optimal valence states of active sites, mitigates over-oxidation or over-reduction, and optimizes the adsorption/desorption behavior of key reaction intermediates. These insights underscore the need for a deeper atomic-level understanding of dynamic electronic structure design. This review systematically elaborates the fundamental mechanisms and distinctive features of the electron buffer effect, categorizes the relevant buffer materials into metal-based and nonmetal-based systems, and highlights their crucial roles in key electrocatalytic reactions. Finally, current challenges and future prospects concerning the precise manipulation and characterization of electron buffer effects are discussed, providing guidance for the rational design of advanced materials in highly efficient electrocatalysis.