Modulating Intermediate Adsorption and Interfacial Water Structure via Alkali Cations for Enhanced Electrocatalytic C–N Coupling to Formamide

Abstract

Modulating the electrode–electrolyte interfacial microenvironment has emerged as an effective strategy to steer electrocatalytic reaction pathways, yet its role in interfacial C–N coupling remains largely unexplored. Herein, we propose a cation-dependent interfacial microenvironment regulation strategy to enhance electrocatalytic C–N coupling toward formamide synthesis by engineering intermediate assembly and interfacial water structure. Notably, the formamide synthesis performance exhibits a clear linear dependence on alkali metal cation radius, following the trend of Li+ < Na+ < K+. Using Cu-based perovskite La2CuO4 as a proof-of-concept catalyst, K+–containing electrolytes achieve a high formamide yield rate of 250 μmol h–1 cm–2 and a Faradaic efficiency of 30%, representing 2.5– and 2.0–fold enhancements compared with Li+- and Na+-based systems, respectively. Theoretical calculations and in situ spectroscopic analyses reveal that K+ most effectively strengthens the interaction between *OCH2 and *NH2 intermediates by reducing their p-orbital energy gap, thereby lowering the energy barrier for *NH2CH2O formation. Meanwhile, K+ reorganizes the interfacial hydrogen-bonding network to regulate interfacial water structure, facilitating proton-coupled electron transfer and increasing active-site exposure. Extending this strategy across diverse perovskite catalysts highlights the generality of alkali metal cation-mediated microenvironment engineering in promoting electrocatalytic C–N coupling toward value-added chemicals.