DFT investigation of CO2 hydrogenation to methanol over Ir-doped Cu surface

In this work, density functional theory (DFT) calculations have been employed to investigate the adsorption properties and reaction process of CO2 hydrogenation to CH3OH on Cu-based catalyst surface with different Ir doping ratios. During the reverse water-gas shift (RWGS) pathway, CO2 firstly hydrogenates to trans-COOH. Next, trans-COOH isomerizes to cis-COOH, which will dissociate to CO+OH subsequently. Then CO(2 )will consecutively hydrogenate to HCO, H2CO, H3CO and the target product H3COH. The results show that the formation of CO+OH is the rate-determining step for Ir3Cu6(111), while the rate-determining step for Ir6Cu3(111) and IrMLCu(111) is the formation of HCO, where the energy barriers to be overcome are 1.21 eV, 1.35 eV and 1.34 eV, respectively. In addition, the dissociation of H(2 )is almost spontaneous on IrCu(111) surfaces, which will provide a large amount of H source for the reaction. Overall, this work shows that the change of Ir doping ratio on the surface of Cu catalyst has an pronounced effect on the hydrogenation of CO2 to methanol, especially on IrMLCu(111) surface. Our results are helpful to provide some references for the design and modification of synthetic noble metal Ir doped Cu-based catalyst.