Highly Active NaTaO3‐Based Photocatalysts for CO2 Reduction to Form CO Using Water as the Electron Donor

Doped NaTaO3 (NaTaO3:A, where A=Mg, Ca, Sr, Ba, or La) has arisen as a highly active photocatalyst for CO2 reduction to simultaneously form CO, H2, and O2 using water as the electron donor when used with an Ag cocatalyst, under UV irradiation, and with 1 atm (0.1 MPa) of CO2. The ratio of the number of reacted electrons/holes was almost unity, indicating that water was consumed as the electron donor. A liquid‐phase reduction method for loading of the Ag cocatalyst was superior to photodeposition and impregnation methods. The Ag cocatalyst‐loaded NaTaO3:Ba was the most active photocatalyst in water with no required additives. The addition of bases, such as hydrogencarbonate, was effective to enhance the CO formation for Mg‐, Ca‐, Sr‐, Ba‐, and La‐doped NaTaO3 photocatalysts with an Ag cocatalyst. Ca‐ and Sr‐doped NaTaO3 photocatalysts showed especially high activity along with the Ba‐doped photocatalyst in the aqueous NaHCO3 solution. The selectivity for the CO formation [CO/(CO+H2)] on Ca‐, Sr‐, and Ba‐doped NaTaO3 photocatalysts with Ag cocatalyst reached around 90 %.