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

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