Electrochemical CO 2 Reduction to C 1 Products on Single Nickel/Cobalt/Iron‐Doped Graphitic Carbon Nitride: A DFT Study

Electrocatalytic CO 2 reduction reaction (CRR) is one of the most promising strategies to convert greenhouse gases to energy sources. Herein, the CRR was applied towards making C 1 products (CO, HCOOH, CH 3 OH, and CH 4 ) on g‐C 3 N 4 frameworks with single Ni, Co, and Fe introduction; this process was investigated by density functional theory. The structures of the electrocatalysts, CO 2 adsorption configurations, and CO 2 reduction mechanisms were systematically studied. Results showed that the single Ni, Co, and Fe located from the corner of the g‐C 3 N 4 cavity to the center. Analyses of the adsorption configurations and electronic structures suggested that CO 2 could be chemically adsorbed on Co‐C 3 N 4 and Fe‐C 3 N 4 , but physically adsorbed on Ni‐C 3 N 4 . The H 2 evolution reaction (HER), as a suppression of CRR, was investigated, and results showed that Ni‐C 3 N 4 , Co‐C 3 N 4 , and Fe‐C 3 N 4 exhibited more CRR selectivity than HER. CRR proceeded via COOH and OCHO as initial protonation intermediates on Ni‐C 3 N 4 and Co/Fe‐C 3 N 4 , respectively, which resulted in different C 1 products along quite different reaction pathways. Compared with Ni‐C 3 N 4 and Fe‐C 3 N 4 , Co‐C 3 N 4 had more favorable CRR activity and selectivity for CH 3 OH production with unique rate‐limiting steps and lower limiting potential.