Elaborated Reaction Pathway of Photothermal Catalytic CO2 Conversion with H2O on Gallium Oxide-Decorated and -Defective Surfaces

Abstract

Ga2O3-decorated and -defective surface models based on anatase TiO2 have been established. The thermodynamic reaction pathways, including protonation, deoxygenation and hydroxylation steps, during CO2 conversion with H2O to C1 products were calculated. The calculation results demonstrate that a Ga2O3 cocatalyst enhances the selective adsorption of CO2 and slightly weakens the competitive adsorption of H2O. The promotion effect of Ga2O3 on the subsequent reaction depends on the availability of protons and electrons. Free-energy calculations revealed that the basic functional site generated by Ga2O3 not only suppresses the back reaction of the OH group after H2O directly provides protons but also maintains the surface defect oxygen vacancy (VO), which promotes the reaction thermodynamics but tends to be consumed in the process. Additionally, Ga2O3 decoration promotes VO formation, and the coexistence of Ga2O3 and VO further decreases the reaction rate-determining step energy barrier, promoting C1 production.