Enhanced Interface with Strong Charge Delocalization toward Ultralow Overpotential CO₂ Electroreduction

The construction of an interface has been demonstrated as one of the most insightful strategies for designing efficient catalysts toward electrochemical CO₂ reduction (CO₂RR). However, the weak interfacial interaction and inherent instability inevitably hinder a further performance enhancement in CO₂RR attributable to the interface effect. Herein, 2 nm Ag nanoclusters (Ag NCs) are embedded onto CeO₂ nanospheres (CeO₂ NSs) with highly interconnected porosity (Ag NCs@CeO₂ NSs) to exclusively study the pure interface effect toward CO₂RR. The enhanced Ag-CeO₂ pure interface endows Ag NCs@CeO₂ NSs with a remarkably larger current density, significantly higher Faraday efficiency (FE), and energy efficiency as compared to Ag NCs, CeO₂ NSs, and the one with Ag NCs dispersed on CeO₂ nanoparticles. More importantly, an impressively high CO FE of over 70.0% is achieved at an ultralow overpotential (η) of 146 mV. The free energy and differential charge calculations, coupled with X-ray photoelectron spectroscopy results jointly imply that the effective initiation of CO₂RR to CO at a lower η over Ag NCs@CeO₂ NSs derives from the enhanced interface-induced charge delocalization, which enhances the electron transfer ability toward *COOH intermediate, thus overcoming the energy barrier demanded for the rate-determining step.