CO ₂ Reduction Catalysis over Transition Metal-Functionalized Graphene Pyridinic Nitrogen Systems

The electrocatalytic CO 2 reduction technology can convert greenhouse gases into more valuable products such as formic acid, which helps mitigate global warming and realize resource recycling. Nitrogen-doped graphene holds immense application potential in the electrocatalytic CO 2 reduction reaction. This work employs density functional theory (DFT) calculations to investigate the adsorption capacity, catalytic efficiency, and reaction mechanism of graphene pyridine nitrogen-coordinated Fe, Co, Ni, and V complexes during the catalytic CO 2 reduction process. Analysis of bond length and bond angle changes of these four complexes during CO 2 reduction shows that the bond lengths range from 1.87Å to 2.01Å, indicating their adsorption capacity. Gibbs free energy calculations reveal that the optimal electrocatalytic reduction of CO 2 is achieved for the Co-coordinated system with an overpotential of -0.30 V (where CO 2 molecules are activated via the coordination of their C atoms to the Co active sites), followed by the Fe-coordinated system with an overpotential of -0.34 V. DFT calculations demonstrate that the rate-determining steps for Fe and Ni-coordinated pyridine nitrogen graphene are the adsorption of the -COOH group, while those for Co and V are the adsorption of CO 2 molecules and the formation of HCOOH, respectively. Additionally, by comparing the DOS and PDOS of the four atomically doped catalysts, it is found that the Fe-coordinated pyridine nitrogen graphene exhibits significant cross-overlap with *COOH, resulting in excellent adsorption of intermediates, thereby revealing the catalytic activity of the Fe-coordinated pyridine nitrogen graphene catalyst.