An overview on the recent developments of Ag-based electrodes in the electrochemical reduction of CO2 to CO
Conversion of aqueous CO2 into CO through the electrochemical reduction reaction (ERR) suffers from poor selectivity and low current density with the classic Ag-based catalysts due to the inert nature of CO2 and the low activity of the active sites. Recently, it has been reported that nanostructured catalysts can display very distinctive behavior compared to their bulk counterparts. To explore the reasons behind this, the latest developments in Ag-based nanostructured materials in the CO2 ERR are summarized into six aspects in this review: (1) the size effect, (2) the morphology effect, (3) the porous effect, (4) the alloying effect, (5) the support effect, and (6) the surface modification effect. In particular, Ag-based alloy catalysts could exhibit a superior catalytic activity and long-term stability owing to the synergistic effect. Besides, the morphology of Ag-based alloy catalysts could also be controlled through adjusting their compositions. From the current literature survey we find that the maximum FE for CO obtained from Ag-based nanocatalysts reaches as high as 99.3%, which is a breakthrough over that from the traditional Ag foil. This review aims to offer a comprehensive understanding of Ag-based nanostructured catalysts in the CO2 ERR and consequently improve the catalyst design for active and selective electro-reduction of CO2 to CO.