Fig. 5

Proposed synergetic mechanism for the hydrogenation of CO₂ to formate. The activation of CO₂ can be achieved through a weakly bonded carbamate zwitterion intermediate at the gold–Schiff base interface, and then hydrogenated by H species to give formate with the help of gold nanoclusters. The electron-rich gold surface is speculated to be beneficial for the hydrogenation of CO₂, since it can offer a more negative hydride and lead to a higher reactivity of nucleophilic attack to the carbon center of CO₂