Enhanced Interface with Strong Charge Delocalization toward Ultralow Overpotential CO Electroreduction.

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