In situ investigations on Bi-based electrocatalyst construction and reaction dynamic monitoring toward efficient CO2 reduction

Electrochemical CO2 reduction reaction (CO2RR) to high-value compounds has attracted considerable attention; however, studies on intrinsic active sites under operating conditions remain controversial. Herein, we report a Bi/Bi2O2CO3 thin-nanosheets electrocatalyst (denoted as Bi/BOC TNS), which gives a formate Faradaic efficiency of 92.1% and a formation rate of 845.2 μmol h−1 cm−2. A strong electron transfer at the interface induces a redistribution of local charge and enhances the interaction of interface polarization. The comprehensive investigations based on in situ experimental studies and density functional theory calculations confirm that the interface structure (Bi0−Biδ+) serves as the intrinsic active site toward CO2 to formate. Specifically, a water molecule undergoes dissociation to provide protons at Bi0, while the CO2∗ species adsorbed at Biδ+ experiences C−H formation to generate the key intermediate (∗OCHO). This work demonstrates the dynamic structure reconstruction of electrocatalyst and reveals the synergistic catalysis, which is of great significance for researches on highly efficient CO2RR electrocatalysts.