Fabrication of hierarchical copper sulfide/bismuth tungstate p-n heterojunction with two-dimensional (2D) interfacial coupling for enhanced visible-light photocatalytic degradation of glyphosate.

Hierarchical copper sulfide/bismuth tungstate (CuS/BiWO) p-n junction with two-dimensional (2D) interfacial coupling were prepared through a two-step hydrothermal method. The as-prepared samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, diffuse reflectance spectroscopy, photoluminescence spectroscopy, photocurrent and electrochemical impedance spectroscopy. CuS nanoplates anchored on the surface of hierarchical BiWO microspheres consisting of BiWO nanosheets to form a CuS/BiWO p-n junction photocatalyst. The photocatalytic activity of glyphosate degradation over CuS/BiWO under 44 W light-emitting diode (LED) light irradiation (λ > 400 nm) was investigated. The results indicate that the CuS/BiWO heterojunctions display higher photocatalytic activity than pure CuS and BiWO. The improved photocatalytic activity of the CuS/BiWO heterostructures can be attributed to strong visible light absorption and enhanced separation of photogenerated charge carriers by the internal electric field near the interface of the p-n junction. In addition, the CuS/BiWO p-n junction photocatalysts consisting of nanosheets are beneficial for the transport of photoexcited charge carriers, thus resulting in the increase of the photocatalytic activity of glyphosate degradation. This work provides the new avenue for the development and design p-n junction materials for photocatalytic applications.