ABSTRACT
The development of efficient heterojunctions through a simple and facile method is an effective way to enhance the photocatalytic performance of bismuth-based oxide semiconductors for industrial applications. Here, the novel ï¬ower-like type II SnS2/Bi2WO6 heterostructure consisting of bismuth tungstate (Bi2WO6) nanosheets and tin bisulfide (SnS2) nanoplates was successfully designed and synthesized. The crystal structure, composition, morphology, and photoelectric properties of the heterostructure were systematically characterized. In addition, the photocatalytic activity of SnS2/Bi2WO6 was analyzed and compared with Bi2WO6 or SnS2 alone or physical mixture of SnS2 and Bi2WO6. 2%SnS2/Bi2WO6 presents a 3.1 times greater degradation rate constant (0.0065 min-1) than that of Bi2WO6 (0.0021 min-1) under low visible light irradiation (5.3 mW·cm-2, a 44 W LED), while SnS2 alone exhibits no photocatalytic effect toward glyphosate. Furthermore, 2%SnS2/Bi2WO6 maintains 93% of its original photocatalytic activity even after four cycles. The possible photocatalytic degradation pathway of glyphosate and photocatalytic mechanism are also proposed. The excellent photocatalytic performance of SnS2/Bi2WO6 is attributed to the decoration of SnS2 nanoplates on the surface of Bi2WO6, appropriate (113)/(020) ratio, increased visible-light absorption, and effective separation of photoinduced carriers. This paper reports a new methodology that can act as a reference basis to design and develop visible-light responsive photocatalysts with outstanding photocatalytic performance for carbon dioxide reduction, water splitting, and pollutant degradation.
ABSTRACT
Hierarchical copper sulfide/bismuth tungstate (CuS/Bi2WO6) 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 Bi2WO6 microspheres consisting of Bi2WO6 nanosheets to form a CuS/Bi2WO6 p-n junction photocatalyst. The photocatalytic activity of glyphosate degradation over CuS/Bi2WO6 under 44â¯W light-emitting diode (LED) light irradiation (λâ¯>â¯400â¯nm) was investigated. The results indicate that the CuS/Bi2WO6 heterojunctions display higher photocatalytic activity than pure CuS and Bi2WO6. The improved photocatalytic activity of the CuS/Bi2WO6 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/Bi2WO6 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.
