Preparation and photocatalytic properties CuS-Bi₂WO₆/carbon nanofibers composites

Chromium is a common heavy metal pollutant and extensively used in variety of industrial processes. CuS-Bi₂WO₆/CNFs (carbon nanofibers) composite photocatalysts with different CNFs content were prepared by solvothermal method to remove Cr(VI) from the aqueous solution. The crystal form, morphology, structure, elemental composition, surface functional groups and optical properties of the samples were characterized by XRD, SEM, TEM, FTIR, XPS, UV-Vis and PL. The photocatalytic degradation of Cr(VI) by CuS-Bi₂WO₆/CNFs composite materials was evaluated. The results show that the photocatalytic activity of the CuS-Bi₂WO₆/CNFs composite is obviously higher than that of the CuS、Bi₂WO₆ and CuS/Bi₂WO₆. Under visible light irradiation, 1%CuS-Bi₂WO₆/CNFs composites show higher photocatalytic degradation performance, and the reduction rate of Cr(VI) is 98% within 3 h. And 1%CuS-Bi₂WO₆/CNFs composites also show strong stability and recoverability after four cycles. In addition, the experimental results of active group capture show that hydroxyl radical (•OH), photogenerated hole (h⁺) and superoxide radical (•O₂⁻) are involved in the reduction of Cr(VI) on CuS-Bi₂WO₆/CNFs, and •O₂⁻ is the main active components of the system. The photocatalytic reaction mechanism was discussed. The research results show that the preparation of CuS-Bi₂WO₆/CNFs can be achieved by a simple and controllable solvothermal method, and it has confirmed the good prospects of CuS-Bi₂WO₆/CNFs composites in the treatment of hexavalent chromium.