Efficient Electrochemical CO2 Reduction Using AgN3 Single-Atom Sites Embedded in Free-Standing Electrodes for Flow Cell Applications.

Abstract

The electrochemical reduction of CO₂ into valuable chemicals presents a promising strategy for carbon utilization; however, it remains challenging due to low activity, poor selectivity and stability of existing catalysts. In this study, we report the fabrication of free-standing silver single-atom catalysts (Ag SACs) designed for the efficient conversion of CO₂ to carbon monoxide (CO) at high current densities in a bicarbonate electrolyzer. The Ag single atoms dispersed within a carbon matrix, forming Ag-N₃ active sites for the electrocatalytic CO₂ reduction reaction (CO₂ RR). The catalytic activity and stability of the free-standing Ag SACs are evaluated at a current density of 100 mA cm^-2, demonstrating prolonged electrolysis with consistent Faradaic efficiency for CO production. Density functional theory calculations revealed that the Ag-N₃ active site significantly lowers the energy barriers for the CO₂ absorption step compared to Ag-Ag and Ag-Ni sites, facilitating CO₂ activation and contributing to enhanced catalytic activity and stability during CO₂ reduction. Detailed analysis of the electronic structure and coordination environment further validates the superior performance of the Ag-N₃ site in the free-standing Ag SACs, underscoring their effectiveness in CO₂ electroreduction. These findings highlight the potential of the free-standing Ag SACs to advance CO₂ reduction technologies, offering enhanced efficiency and selectivity for CO₂ conversion.