Interfacial Water Activation via Reconstruction‐Induced Sites for pH‐Universal Electroreduction of CO 2

ABSTRACT Renewable electricity‐driven electroreduction of CO 2 into formate represents one of the most commercially attractive routes for carbon valorization, yet Bi‐based catalysts often suffer from unstable surface states under reaction conditions. Here, we exploit this intrinsic instability to construct an interfacial Cs/Cl dual‐modified Bi nanoflower catalyst via an in situ electrochemical surface reconstruction strategy, which delivers high formate selectivity across a broad pH window, including acidic, neutral, and alkaline media. In situ spectroscopic analysis and theoretical calculations reveal that Cs/Cl dual‐modification fundamentally serves as synergistic sites by reconfiguring the interfacial electronic environment, accelerating water dissociation, and stabilizing *OCHO intermediates, thereby steering the reaction pathway toward formate. Furthermore, pairing CO 2 reduction with methanol oxidation in a two‐electrode configuration enables the simultaneous electrosynthesis of formate at both electrodes under low cell voltages, offering a dual‐value coproduction strategy for carbon utilization and biomass upgrading. This work establishes interfacial water activation via reconstruction‐induced dual‐sites as a powerful design principle for next‐generation CO 2 reduction electrocatalysts.