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

• CO 2 hydrogenation to methanol via RWGS pathway on Ir-doped Cu surface was studied by DFT. • The dissociation of H 2 is almost spontaneous on three IrCu(111) surfaces. • H 2 CO byproduct is easy to produce on Ir 3 Cu 6 (111) and Ir 6 Cu 3 (111) surfaces, while it is suppressed on Ir ML Cu(111) surface. In this work, density functional theory (DFT) calculations have been employed to investigate the adsorption properties and reaction process of CO 2 hydrogenation to CH 3 OH on Cu-based catalyst surface with different Ir doping ratios. During the reverse water-gas shift (RWGS) pathway, CO 2 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, H 2 CO, H 3 CO and the target product H 3 COH. The results show that the formation of CO+OH is the rate-determining step for Ir 3 Cu 6 (111), while the rate-determining step for Ir 6 Cu 3 (111) and Ir ML Cu(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 CO 2 to methanol, especially on Ir ML Cu(111) surface. Our results are helpful to provide some references for the design and modification of synthetic noble metal Ir doped Cu-based catalyst. The RWGS pathway of CO 2 hydrogenation to methanol on the Ir 3 Cu 6 (111) catalyst, where the hydrogen will dissociate spontaneously. The trace doping of Ir on Cu(111) is more favorable to the reaction.