Bismuth yttrium oxide (BiYO3) photocatalysts doped with different Cu amounts were synthesized via a hydrothermal method, characterized and applied for the photocatalytic reduced CO2 to formic acid under the visible light irradiation. The particle size of Cu/BiYO3 was smaller than that of BiYO3, and the surface area of BiYO3 was increased from 6.75 m(2)/g to 18.64 m(2)/g when the Cu doping amount of was 2.0%. The FT-Raman results reveal the formation of oxygen vacancies after doping with Cu, which suppressed the charge recombination, and the electrochemical impedance spectroscopy (EIS) proved that the Cu/BiYO3 has a better electronic transmission capacity. The HCOOH amount of photocatalytic reduction of CO2 was 2.04 mu mol/mL by using 2.0% Cu/BiYO3 as photocatalyst, which was 2.2 times than that of BiYO3. The highly improved performance of the 2.0% Cu/BiYO3 can be ascribed to the increased surface area, increased light absorption, and efficient charge separation. (C) 2016 Elsevier B.V. All rights reserved.