Construction of Z-Scheme Bi2WO6/g-C3N4 Heterojunction Photocatalysts with Enhanced Visible-Light Photocatalytic Activity

Highly efficient visible-light-induced Z-scheme Bi2WO6/g-C3N4 heterojunction photocatalysts were synthesised by means of a simple hydrothermal method. The prepared Bi2WO6/g-C3N4 composite materials were characterised by means of X-ray diffraction, UV-vis diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, and photoluminescence. The photocatalytic activity of the Bi2WO6/g-C3N4 composite materials was determined through the degradation of Rhodamine B (RhB) solution as a target pollutant. The results of the experiment revealed that the active species O-2(center dot-) and h(+) play a crucial role in the scavenging system. The Bi2WO6/g-C3N4 composites showed an obviously improved photocatalytic performance compared with pure g-C3N4 and Bi2WO6 in the RhB degradation under visible light irradiation. The 10 wt-% Bi2WO6/g-C3N4 displayed the highest photocatalytic activity, and could completely degrade RhB within 75 min. It gave a reaction rate constant of 0.0439 min(-1), which is 5.22 and 2.58 times higher than pure Bi2WO6 and g-C3N4, respectively. The intimate contact interface between the Bi2WO6 and g-C3N4 leads to effective separation of charge carriers and hinders the recombination efficiency of electrons and holes. Hence the photocatalytic activities of the Bi2WO6/g-C3N4 composite materials are significantly improved.