Theoretical study on highly efficient reduction of CO₂ by in-situ produced hydrogen using Al under mild hydrothermal conditions

A theoretical study with quantum chemistry calculations was performed to investigate highly efficient reduction of CO₂ to formic acid using Al under mild hydrothermal conditions. All the structures of the reactants, products and transition states were optimized by B3LYP functional using the extended 6-311 + G(3df,2p) basis set. The formation of HAlOH species, an intermediates in the reaction of Al with H₂O, was calculated firstly. The formation of HCOO^- was simulated subsequently. Our theoretical results showed that Al-H is a key intermediate species in the highly efficient reduction of CO₂ to formic acid using Al under mild hydrothermal conditions, which demonstrated that the formation of formic acid is through an SN2-like mechanism.