Efficient Electrochemical Reduction of CO2 to CO by Ag-Decorated B-Doped g-C3N4: A Combined Theoretical and Experimental Study

Abstract

Electrochemical CO2 reduction (ECR) has received great attention in energy conversion and CO2 mitigation. In recent years, graphitic carbon nitride (g-C3N4) has been regarded as a very promising support for metal nanoparticles (NPs) for many catalytic reactions. In this work, we reported the silver- (Ag) loaded boron-doped g-C3N4 nanocomposite (Ag-B-g-C3N4) for efficient ECR to CO by a joint first-principles study and experimental work. Theoretical simulation demonstrated that the B dopant and Ag NPs could be easily incorporated into g-C3N4. The introduction of Ag NPs and the B atom could greatly decrease the adsorption free energy for the *COOH intermediate generation. Meanwhile, an electron-rich region at the Ag-B-g-C3N4 interface was observed, contributing to improved electrical conductivity and electron transport. B-g-C3N4 could not exhibit the obvious enhancement of ECR performance, while the Ag-B-g-C3N4 catalyst with an average Ag diameter of 4.95 nm exhibited a total current density of 2.08 mA cm–2 and a CO Faradaic efficiency (FECO) of 93.2% under the potential of −0.8 V vs the reversible hydrogen electrode (RHE), indicating that Ag is the only active center. Ag-B-g-C3N4 also displayed excellent stability without any deactivation in a 12-h electrocatalysis. This work revealed the mechanism of electrocatalytic CO2 reduction over metal- (Ag) and nonmetal- (B) modified g-C3N4, which paves the way for broader application of the g-C3N4 nanocomposite in electrocatalytic reactions.