Theory study on catalytic hydrogenation of CO2 to formic acid over Si, N-doped modified graphene quantum dots supported single atom Fe

Exploring suitable catalysts to catalyze the chemical transformation of CO2 molecules is essential to reduce CO2 levels. In this article, catalyst models of Fe-C-4, Fe-N-4, and Fe-Si-4 were constructed using the density functional theory (DFT) calculations, and the reaction mechanisms of CO2 hydrogenation over these three catalysts were calculated and analyzed. The results showed that the doping of N atoms lowered the energy barrier of the second hydrogenation step compared with that of Fe-C-4 catalyst, while the doping of Si atoms changed the electron distribution on the surface of the catalyst and formed new Si adsorption sites. And the Fe-Si-4 catalyst had a stronger ability to activate CO2 molecules as well as stronger catalytic performance compared with the Fe-C-4 and Fe-N-4 catalysts, which was mainly attributed to the synergistic catalytic effect between the doped Si atoms and the Fe metal atom.