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

Surface strain and linear thermodynamic-kinetic relation are interesting topics in catalysis. Development of low temperature methanol catalysts of high activity and selectivity is of particularly importance for conversion of CO₂ to methanol. In the present paper 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 the 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 18 systems studied. Calculations on strained surfaces show that the AEB relation exists within ±1 % strain. Sr2@TiO₂(110) and -1 % strained CaZn and ZnCu doped TiO₂(110) are potential good low temperature catalysts and deserve experimental testing.