Photocatalytic reduction of CO2 into methanol and ethanol over conducting polymers modified Bi2WO6 microspheres under visible light

Bi2WO6 hierarchical hollow microspheres (HHMS) modified with different conducting polymers (polyaniline, polypyrrole, and polythiophene) were successfully synthesized by 'in situ' deposition oxidative polymerization method, and evaluated as photocatalysts for the photocatalytic reduction of CO2 with H2O to methanol and ethanol. It was found that the introduction of conducting polymers obviously decreased the recombination of photogenerated electron-hole pairs, thus promoting the photocatalytic activity of Bi2WO6. Among the as-fabricated photocatalysts, polythiophene modified Bi2WO6 (PTh/Bi2WO6) exhibited the best photoelectronic and photocatalytic performance, due to the narrow band gap and good charge mobility of polythiophene. The results demonstrate that the methanol and ethanol yield over PTh/Bi2WO6 was 56.5 and 20.5 mu mol g(cat)(-1) in 4h, respectively. The total yield of hydrocarbons is 2.8 times higher than that over pure Bi2WO6. It is noted that the catalyst exhibits good recyclability and stability. After five consecutive runs, the PTh/Bi2WO6 catalyst shows no significant loss of photocatalytic activity. The possible photocatalytic mechanism was proposed which is beneficial for further improving the activity of photocatalysts. The approach described in this study provides a simple and reliable strategy for the rational design of efficient visible light-driven photocatalysts for photoreduction of CO2 to hydrocarbons. (C) 2015 Elsevier B.V. All rights reserved.