Synthesis of WO3/g-C3N4 nanocomposite for photocatalytic CO2 reduction under visible light

Abstract

Greenhouse gas CO2 emitted through the burning of fossil fuels is a main cause of global warming. Among the different alternatives, photocatalytic conversion of CO2 using solar energy in the presence of highly efficient photocatalyst is most attractive for the production of solar fuels. In this work, graphitic carbon nitride (g-C3N4) dispersed tungsten oxide (WO3) to construct WO3/g-C3N4 heterojunction was synthesized through hydrothermal approach. The performance of photocatalysts were tested for photocatalytic CO2 reduction with CH4 to CO via dry reforming of methane (DRM) under visible light irradiation in a fixed bed photoreactor. The performance of composite catalysts was further tested for photo-catalytic CO2 reduction via H2O as reductant and bireforming of methane (BRM) under visible light irradiations. The maximum CO production of 310 µmol g-cat-1 h-1 was observed over WO3/g-C3N4 composite catalyst which is 2.95 and 8.85 folds higher than using pristine g-C3N4 and WO3 photocatalysts. Using BRM process, production of CO was further increased due to the addition of water into CO2-methane system. In general, significantly enhanced photocatalytic performance of composite catalyst was obviously due to Z-scheme heterojunction formation with efficient charge carrier separation and good band positions under visible light irradiation. The newly developed composite catalysts can effectively be used for recycling greenhouse gases to fuels using solar energy and would be beneficial for cleaner environment.