Engineering and modeling the effect of Mg doping in TiO2 for enhanced photocatalytic reduction of CO2 to fuels

Abstract

Mg-Doped TiO₂ nanoparticles were prepared via a modified sonothermal method, and their photocatalytic activities were investigated for the reduction of CO₂ with H₂O. The structural properties of the prepared catalysts with varying Mg doping levels were studied by UV-vis spectroscopy, N₂ adsorption–desorption, XRD, SEM, TEM, and XPS. CO, H₂, CH₃OH, and CH₄ were the major products observed with a maximum production rate of 29.2, 28.7, 5910.0 and 2.3 μmol g⁻¹ h⁻¹, respectively. Preferable Mg doping sites in TiO₂ nanoparticles and interaction of CO₂ with Mg-doped TiO₂ were studied computationally. Modeling revealed that (101) facets and junctions of (101)/(101) and (001)/(101) facets are the preferred locations of surface Mg atoms. Adsorption of CO₂ proceeds in the bent carbonate and hydrocarbonate forms. The increased activity of Mg-doped TiO₂ is explained by the close proximity of surface Mg reaction sites to the positions of photogenerated electrons on (101) facets.