Computational Evidence for Lewis Base-Promoted CO2 Hydrogenation to Formic Acid on Gold Surfaces

The mechanism and the effect of Lewis bases in gold-catalyzed CO2 hydrogenation to formic acid were investigated using first principle calculations. The calculations indicate that different types of gold surfaces are all capable of heterolytically splitting H2 by coupling with Lewis bases (e.g., NH3). The generated hydride and proton (in NH4) on gold surfaces can be concertedly transferred to CO2 with high reactivity. Furthermore, instead of the disfavored hydride transfer to the formate (HCOO) intermediate, the effective proton transfer from NH4 to HCOO provides an alternative pathway for the formation of formic acid.