Hydrothermal synthesis of Cu2WS4 as a visible-light-activated photocatalyst in the reduction of aqueous Cr(VI)

An inexpensive and less pollutive hydrothermal method, which was based on the autoclave-sealed reactions of CuCl, Na2WO4·2H2O and thioacetamide in mixed solution of equal volume of water and ethanol at 190 °C for 72 h, was employed to synthesize Cu2WS4. X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and N2 adsorption-desorption isotherms indicated that the as-synthesized product was body-centered tetragonal structure Cu2WS4 (I-Cu2WS4) submicron crystallites with a BET specific surface area of 2.199 m2/g. UV-vis diffuse reflectance spectrum suggested that the as-synthesized I-Cu2WS4 submicron crystallites had a direct bandgap of about 2.15 eV. Besides, the as-synthesized I-Cu2WS4 submicron crystallites exhibited considerably high photocatalytic activity in the reduction of aqueous Cr(VI) under visible-light (λ>420 nm) irradiation.