Z-Scheme Heterojunction of SnS 2 /Bi 2 WO 6 for Photoreduction of CO 2 to 100% Alcohol Products by Promoting the Separation of Photogenerated Charges.

Using sunlight to convert CO 2 into solar fuel is an ideal solution to both global warming and the energy crisis. The construction of direct Z-scheme heterojunctions is an effective method to overcome the shortcomings of single-component or conventional heterogeneous photocatalysts for photocatalytic CO 2 (carbon dioxide) reduction. In this work, a composite photocatalyst of narrow-gap SnS 2 and stable oxide Bi 2 WO 6 were prepared by a simple hydrothermal method. The combination of Bi 2 WO 6 and SnS 2 narrows the bandgap, thereby broadening the absorption edge and increasing the absorption intensity of visible light. Photoluminescence, transient photocurrent, and electrochemical impedance showed that the coupling of SnS 2 and Bi 2 WO 6 enhanced the efficiency of photogenerated charge separation. The experimental results show that the electron transfer in the Z-scheme heterojunction of SnS 2 /Bi 2 WO 6 enables the CO 2 reduction reactions to take place. The photocatalytic reduction of CO 2 is carried out in pure water phase without electron donor, and the products are only methanol and ethanol. By constructing a Z-scheme heterojunction, the photocatalytic activity of the SnS 2 /Bi 2 WO 6 composite was improved to 3.3 times that of pure SnS 2 .