Modification of the surface of Ga2O3 with rare-earth elements enhanced the evolution of CO as a reduction product in the photocatalytic conversion of CO2 using H2O as an electron donor under UV irradiation in aqueous NaHCO3 as a pH buffer, with the rare-earth species functioning as a CO2 capture and storage material. Isotope experiments using (CO2)-C-13 as a substrate clearly revealed that CO was generated from the introduced gaseous CO, In the presence of the NaHCO3 additive, the rare-earth (RE) species on the Ga2O3 surface are transformed into carbonate hydrates (RE2(CO3)(3).nH2O) and/or hydroxycarbonates (RE2(OH)(2(3-4))(CO3)(x)) which are decomposed upon photo irradiation. Consequently, Ag-loaded Yb-modified Ga2O3 exhibits much higher activity (209 mu mol h(-1) of CO) than the pristine Ag-loaded Ga2O3. The further modification of the surface of the Yb-modified Ga2O3 with Zn Thus, we successfully achieved an efficient Ag-loaded Yb- and Zn-modified controllable selectivity, suitable for use in artificial photosynthesis.