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.