Photocatalytic reduction of CO2 to methanol by Cu2 O/TiO2 heterojunctions

Abstract

The conversion of CO2 to low-carbon fuels using solar energy is considered an economically attractive and environmentally friendly route. The development of novel catalysts and the use of solar energy via photocatalysis are key to achieving the goal of chemically reducing CO2 under mild conditions. TiO2 is not very effective for the photocatalytic reduction of CO2 to low-carbon chemicals such as methanol (CH3 OH). Thus, in this work, novel Cu2 O/TiO2 heterojunctions that can effectively separate photogenerated electrons and holes were prepared for photocatalytic CO2-to-CH3 OH. More visible light-active Cu2 O in the Cu2 O/TiO2 heterojunctions favors the formation of methanol under visible light irradiation. On the other hand, under UV-Vis irradiation for 6 h, the CH3 OH yielded from the photocatalytic CO2-to-CH3 OH by the Cu2 O/TiO2 heterojunctions is 21.0–70.6 µmol/g-catalyst. In contrast, the yield of CH3 OH decreases with an increase in the Cu2 O fraction in the Cu2 O/TiO2 heterojunctions. It seems that excess Cu2 O in Cu2 O/TiO2 heterojunctions may lead to less UV light exposure for the photocatalysts, and may decrease the conversion efficiency of CO2 to CH3 OH.