Highly selective CO₂ photoreduction to CO over g-C₃N₄/Bi₂WO₆ composites under visible light

CO₂ is highly stable and therefore extremely difficult to be reduced at room temperature even by photocatalysis. Herein, a series of g-C₃N₄/Bi₂WO₆ composites have been synthesized through a facile in situ hydrothermal approach, which demonstrated greatly enhanced response to visible light, and consequently a remarkably enhanced CO₂ selective photoreduction to CO. The g-C₃N₄ content and synthesis parameters of these composites have been tuned to obtain the optimized photocatalytic activity with a peak CO production rate of 5.19 μmol g^-1 h^-1 under visible light irradiation at room temperature, which was 22 and 6.4 times that on pure g-C₃N₄ and Bi₂WO₆, respectively. Based on the matched band energy potentials between g-C₃N₄ and Bi₂WO₆ in the synthesized composites, a possible Z-scheme mechanism, which features a significantly promoted separation of photo-generated carriers under visible light irradiation by the composites, has been proposed to account for the distinctive CO₂ photoreduction performance.