Highly selective electrocatalytic reduction of CO 2 to HCOOH over an in situ derived Ag-loaded Bi 2 O 2 CO 3 electrocatalyst.

The electrochemical reduction of CO 2 to HCOOH is considered one of the most appealing routes to alleviate the energy crisis and close the anthropogenic CO 2 cycle. However, it remains challenging to develop electrocatalysts with high activity and selectivity towards HCOOH in a wide potential window. In this regard, Ag/Bi 2 O 2 CO 3 was prepared by an in situ electrochemical transformation from Ag/Bi 2 O 3 . The Ag/Bi 2 O 2 CO 3 catalyst achieves a faradaic efficiency (FE) of over 90% for HCOOH in a wide potential window between -0.8 V and -1.3 V versus the reversible hydrogen electrode (RHE). Moreover, a maximum FE of 95.8% and a current density of 15.3 mA cm -2 were achieved at a low applied potential of -1.1 V. Density functional theory (DFT) calculations prove that the high catalytic activity of Ag/Bi 2 O 2 CO 3 is ascribed to the fact that Ag can regulate the electronic structure of Bi, thus facilitating the adsorption of *OCHO and hindering the adsorption of *COOH. This work expands the in situ electrochemical derivatization strategy for the preparation of electrocatalysts.