Why is formate synthesis insensitive to copper surface structures?
Experiments have revealed that formate synthesis from carbon dioxide and hydrogen is structure insensitive to copper catalyst surfaces, while the reverse formate decomposition reaction is structure sensitive. The present ab initio density functional theory (DFT) calculations show that the reaction of CO2 with surface atomic hydrogen initially leads to the formation of unstable monodentate formate, which has similar adsorption energies on Cu(111), Cu(100), and Cu(110). The structure of the transition state is similar to that of monodentate formate. It is also shown that gaseous CO2 is directly reacted with surface hydrogen, as suggested by previous experiments. The position of the similar transition state and the direct reaction mechanism well explain the similar energetic pathways, that is, the structure insensitivity.