Fabrication of effective visible-light-driven ternary Z-scheme ZnO-Ag-BiVO4 heterostructured photocatalyst for hexavalent chromium reduction

• Published in: Separation and purification technology Vol. 252; p. 117446
• Main Authors: Raja, A., Rajasekaran, P., Vishnu, B., Selvakumar, K., Yeon Do, Jeong, Swaminathan, M., Kang, Misook
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2020
• Subjects: Chromium(VI) reduction; Photocatalysis; Visible light; Z-scheme photocatalyst; ZnO-Ag-BiVO4; Chromium(VI) reduction; Z-scheme photocatalyst; Visible light; ZnO-Ag-BiVO4; Photocatalysis
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2020.117446

[Display omitted] •The nanochain plates like structured Ag-ZnO-BiVO4 nanocomposite were synthesized by hydrothermal method.•ZnO-Ag -BiVO4 is highly efficient in photoreduction of Cr(VI) under visible light.•The ZnO-Ag -BiVO4 nanocomposite is a stable and recyclable photocatalyst.•In ZnO-Ag-BiVO4 Z-scheme, Ag nanoparticles act as the charge transmission-bridge between ZnO and BiVO4. A simple hydrothermal technique was used for the synthesis of a ternary ZnO-Ag-BiVO4 nanocomposite. The morphology, structure and optical performance of ZnO-Ag-BiVO4 were analyzed by XPS, TEM, XRD, FT-IR, FE-SEM, PL, and DRS. The sharp peaks of ZnO-Ag-BiVO4 indicated the good crystalline nature of the photocatalyst. FE-SEM images depicted the hexagonal structure of ZnO and the plate-like structure of BiVO4. The heterostructured catalyst Ag-ZnO-BiVO4 is capable of reducing 20 ppm of Cr(VI) from potassium dichromate in 100 mL aqueous solution to 97% within 70 min under visible light. The first-order rate constant value of 0.0371 min−1 and a 97% reduction for the ZnO-Ag-BiVO4 catalyst show its maximum photoreduction efficiency. The optimum pH for effective Cr(VI) reduction on ZnO-Ag-BiVO4 is 5 and it is steady and recyclable. The photo generated electron acts mainly in the photocatalytic reduction of hexavalent chromium. The photocurrent analysis shows that the ZnO-Ag-BiVO4 composite material can enhance the photoexcited charge production, separation and migration, which improved the photocatalytic reduction of Cr(VI). Proposed Z-scheme mechanism of ternary ZnO-Ag-BiVO4 clearly explains the electron-hole separation and higher efficiency of this nanocomposite in the photoreduction.