Unraveling active sites regulation and temperature-dependent thermodynamic mechanism in photothermocatalytic CO2 conversion with H2O.

In the photothermal synergistic catalytic conversion of CO₂ and H₂O, the catalyst harnesses solar energy to accumulate heat, thereby elevating the reaction system's temperature. The influence of this temperature effect on surface chemical reactions remains an underexplored area. Here the impact of temperature on the surface-level thermodynamic reactions and conversion of CO₂ with H₂O on oxide semiconductors at the atomic scale was investigated using first-principle calculations. 13 different metal oxides and 5 transition metal clusters were used to introduce surface functional sites on the TiO₂ supporting catalyst. The potential metal oxide cocatalysts that could be most beneficial to the following conversion of CO₂ by H₂O were initially screened by calculating the degrees of promotion of CO₂ adsorption and activation of surface H to provide protons. The proton donation and hydrogen evolution difficulty from H₂O were further analyzed, identifying transition metal cocatalysts that promote direct CO₂ hydrogenation. Upon introducing bifunctional sites to facilitate adsorption and reduction, the production of CH₃OH and CH₄ could be further enhanced through the facilitation of the proton donation process of H₂O. The results of Gibbs free-energy calculations revealed that increasing temperature enhances the reaction thermodynamics for each C1 product formation at different surface sites to varying degrees. These findings offer valuable theoretical insights for designing and regulating active sites on oxide semiconductor surfaces for efficient photothermal catalytic CO₂ reduction by H₂O. [ABSTRACT FROM AUTHOR]