Simple synthesis of a graphene-supported bismuth single-atom catalyst for the improved electrochemical reduction of CO2

Solving the problems of carbon dioxide (CO2) emissions and energy scarcity by the development of highly selective, cost-effective, and reliable catalysts for the electrochemical reduction of CO2 to useful carbon-based products would be very helpful. We report the synthesis of an efficient graphene-supported bismuth single-atom catalyst (BiSA-G) featuring a BiN4 coordination structure for this purpose. The synthesis used tannic acid as a multifunctional ligand and ammonia as a nitrogen dopant. Using a scalable coordination chemistry approach, BiN4 sites were uniformly dispersed on the graphene substrate and were found to have an outstanding ability for the conversion of CO2 to CO, with a high faradaic efficiency of 97.4% at −0.55 V (vs. RHE) and a high turnover frequency of 5230 h−1 along with outstanding stability. Density functional theory calculations confirmed that the BiN4 site serves as the dominant active center, simultaneously facilitating CO2 activation and the efficient formation of the crucial intermediate *COOH with a reduced free energy barrier. This discovery offers a new way for the atomic-scale design of high-efficiency catalysts for the electrochemical CO2 reduction reaction, potentially helping sustainable carbon use.