Coupling Interfacial Electron Polarization with Carbonate-Mediated Proton Relay for Efficient CO2-to-CO Electrocatalysis

Abstract

Electrocatalytic CO2 reduction (ECR) driven by renewable electricity is a pivotal route for carbon neutrality, but it is constrained by the sluggish kinetics of CO2 activation and proton transfer. Herein, we report a dual-regulation strategy utilizing a CdCO3/AgCl nanowire (NW) heterojunction to break these constraints. The catalyst achieves an outstanding CO Faradaic efficiency (FE) of 97.1 % with a partial current density of -121 mA/cm2 at -1.0 V vs. RHE, while maintaining excellent operational stability. Operando spectroscopy and DFT calculations confirm a synergistic mechanism of electronic and microenvironmental regulation. The heterointerface induces electron transfer from CdCO3 to AgCl, rendering the AgCl surface electron enriched. This optimizes the electronic structure to facilitate the activation of CO2 and stabilizes the key *COOH intermediate. The interfacial carbonate groups function as pivotal proton relays to accelerate the interfacial proton flux and optimize the local *H availability on the AgCl NWs surface. This effectively synchronizes the proton supply with electron transfer, substantially lowering the energy barrier for the rate-determining proton-coupled electron transfer (PCET) step. This work presents a generalizable design principle for engineering interface-activated electrocatalysts via synergistic electronic and microenvironmental modulation.