One-step synthesis of a WO3-CuS nanosheet heterojunction with enhanced photocatalytic performance for methylene blue degradation and Cr(VI) reduction

BACKGROUND The photocatalytic activity of a pristine semiconductor is unsatisfactory due to the rapid recombination of photogenerated electrons and holes. Constructing composite photocatalysts has proven to be an effective method to suppress electron-hole recombination. The composites composed of two materials usually are synthesized through a two-step process. However, in this work, a simple one-step solvothermal method employing an homogeneous reaction system was adopted to synthesize a tungsten trioxide (WO3)-copper sulfide (CuS) nanosheet heterojunction with enhanced photocatalytic properties. RESULTS The formation of the WO3-CuS heterojunction was confirmed by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray and X-ray photoelectron spectroscopy analysis. The composites showed improved visible light harvesting ability, and enhanced photoelectric and photocatalytic properties compared with pure WO3. The optimized composite displayed a photocurrent almost five-fold greater than the sum of the photocurrents of WO3 and CuS, and had superior performance for methylene blue (MB) degradation and hexavalent chromium [Cr(VI)] reduction. The MB degradation and Cr(VI) reduction efficiencies were both improved when they co-existed in the photocatalytic system. Interferential ions Cl- and NO3- were much less effective in the degradation of MB than in the reduction of Cr(VI). CONCLUSIONS Improved photocatalytic activity was achieved after coupling CuS with WO3, due to the enhanced visible light absorption and efficient electron-hole separation. Photogenerated holes were found to be the dominant reactive species in the MB photodegradation process. A synergistic effect existed between MB degradation and Cr(VI) reduction. Interferential ions Cl- and NO3- had much greater effect on Cr(VI) reduction than MB degradation. (c) 2019 Society of Chemical Industry