In situ synthesis of three-dimensional core–shell structure Bi2WO6/BiOCl and photocatalytic degradation of trinitrotoluene wastewater

Bi2WO6/BiOCl nanocomposites with three-dimensional core–shell structure were synthesized by a two-step hydrothermal method. The compounds were characterized by XRD, SEM, TEM, HR-TEM, EDX, SAED, XPS, PL, UV–Vis DRS, photoelectrochemical, and photodegradation experiments. The result showed that the catalytic activity of Bi2WO6/BiOCl nanocomposites was significantly better than that of Bi2WO6 and BiOCl. The effect of the amount of Bi2WO6 on the properties of the composite was studied. The result showed that the Bi2WO6/BiOCl with three-dimensional core–shell structure had the highest photocatalytic degradation efficiency for TNT, and the degradation rate reached 90% after 180 min of visible light irradiation. In the degradation process of TNT, the reaction rate of 4.5 Bi2WO6/BiOCl is the highest, which is 0.20057 min−1. After 4 cycles, the degradation rate of TNT by 4.5 Bi2WO6/BiOCl remained at 80%. The free radical trapping experiments showed that the holes and superoxide anions played a major role in the photocatalytic degradation of TNT wastewater by 4.5 Bi2WO6/BiOCl. Based on the results of free radical trapping experiment, Mott-Schottky test, and ultraviolet–visible diffuse reflection spectroscopy, the reaction mechanism of enhancing photocatalytic activity was proposed.