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-C₄, Fe-N₄, and Fe-Si₄ 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-C₄ 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-Si₄ catalyst had a stronger ability to activate CO₂ molecules as well as stronger catalytic performance compared with the Fe-C₄ and Fe-N₄ catalysts, which was mainly attributed to the synergistic catalytic effect between the doped Si atoms and the Fe metal atom.