Ceria-driven synergistic nourishment of polarized silver overcoming the trade-off between faradaic efficiency and current density for CO2 electroreduction to CO

Abstract

Although the potential of microenvironment modulation to enhance electricity-driven CO₂ reduction has been recognized, substantial challenges remain, particularly in effectively integrating multiple favorable microenvironments. Herein, we synthesize CeO₂ with abundant oxygen vacancies to effectively disperse and anchor small-sized Ag₂O nanoparticles (Ag₂O/Vo-CeO₂). Vo-CeO₂ acts as a multifunctional modulator, regulating both the reaction microenvironment and the electronic structure of Ag sites, thereby boosting CO₂ reduction (CO₂RR) efficiency. Its strong CO₂ adsorption and H₂O dissociation capabilities facilitate the supply of CO₂ and active *H species to Ag sites. The electron-withdrawing effect of Vo-CeO₂ induces polarization at interfacial Ag sites, generating Ag^δ+ species that enhance CO₂ affinity and activation. Moreover, the electronic coupling between Vo-CeO₂ and Ag upshifts the d-band center of Ag, optimizing COOH binding and lowering the thermodynamic barrier of the potential-determining step. Ag₂O/Vo-CeO₂ delivers a consistently high Faraday efficiency (FE) of over 99% for CO production even at industrially current density (up to 365 mA cm⁻² herein), and the operational potential window spans an astonishing 1700 mV (FE >95%). The unprecedented activity, which overcomes the trade-off between the selectivity and current density for CO₂RR, outperforms state-of-the-art Ag-based catalysts reported to date. These findings offer a promising pathway to develop robust CO₂RR catalysts and present an engineering strategy for constructing the optimal microenvironment of active sites via the synergistic effects of multifunctional modulation.