Synthesis and characterization of BiPO4/g-C3N4 nanocomposites with significantly enhanced visible-light photocatalytic activity for benzene degradation

Abstract

In order to enhance the photocatalytic activity of g-C₃N₄ in the visible light region, BiPO₄/g-C₃N₄ nanocomposites photocatalysts with different BiPO₄ contents were prepared through a hydrothermal method including calcination. Through N₂ adsorption–desorption measurements, BiPO₄/g-C₃N₄ showed a large surface area (172.9 m² g⁻¹) and small pore diameter and the incorporation of BiPO₄ caused a red-shift of g-C₃N₄ in the visible light region by UV-vis diffuse reflection spectroscopy. The photocatalytic degradation of benzene over BiPO₄/g-C₃N₄ was investigated. Degradation of benzene could be achieved up to 73% in 2 wt% BiPO₄/g-C₃N₄ photocatalysts under optimum reaction conditions, which was 6 times more when compared with pure g-C₃N₄ at the same conditions. The improved photoactivity of BiPO₄/g-C₃N₄ could be ascribed to its effective separation of photogenerated hole–electron pairs between BiPO₄ and g-C₃N₄. Furthermore, the BiPO₄/g-C₃N₄ photocatalysts showed excellent stability. By using an in situ FTIR technique, ethyl acetate, carboxylic acid and aldehyde could be regarded as the intermediate products, and CO₂ and H₂O were produced as the final products. Through electron spin resonance (ESR), OH˙ and O₂˙⁻ were examined in the photocatalytic degradation of benzene.