CO2 Hydrogenation to CH3OH on Metal-Doped TiO2(110): Mechanisms, Strain Effect and A New Thermodynamic-Kinetic Relation

To develop low temperature catalysts for CO2 to methanol, CO2 hydrogenation to methanol on Znx@TiO2(110) (x = 0-2) was explored using density functional calculations and microkinetic simulations. The reaction mechanisms on the three model systems were determined and it is shown that Zn2@TiO2(110) is most active. The most favorable pathway on Zn2@TiO2(110) is identified and CO2 + H to HCOO is found to be the rate-controlling step. It is demonstrated that there is a linear relation (named AEB relation) between the adsorption energies of the initial states and the barriers for the controlling step on the 17 systems studied. Calculations on strained surfaces show that the AEB relation exists within ±1% strain, which is an effective way to improve catalytic activity. Sr2@TiO2(110) and -1% strained CaZn and ZnCu doped TiO2(110) are potential good low temperature catalysts and deserve experimental testing.