Facile Synthesis of ZnO/g-C3N4 with Enhanced Photocatalytic Performance for the Reduction of Cr(VI) in Presence of EDTA Under Visible Light Irradiation

The ZnO/g-C3N4 composite was synthesized through facile one step calcination method using urea and zinc acetate dehydrate precursors. A series of techniques, TGA (Thermogravimetric Analysis), XRD (X-ray Diffraction), FTIR (Fourier Transform Infrared), BET (Brunauer-Emmett-Teller) surface area, SEM (Scanning Electron Microscopy), TEM (Transmission Electron Microscopy), XPS (X-ray Photoelectron Spectroscopy), UV-Visible DRS (Diffuse Reflection Spectroscopy), PL (Photoluminescence) and EIS (Electrochemical Impedance Spectroscopy) were used to evaluate the physicochemical and optical properties of composites. In the presence of sacrificial electron donor EDTA, ZnO/g-C3N4 photocatalyst gave better visible light response photocatalytic reduction ability against Cr(VI). The enhanced photocatalytic performance of ZnO/gC(3)N(4) photocatalyst could be ascribed to the addition of ZnO. The heterojunction effects between ZnO and g-C3N4 result in better photogenerated charge separation and slower e(-)-h(+) pairs recombination, which was confirmed from PL, EIS and UV-Visible DRS. The influence of various factors such as ZnO amount in the composite, synthesis calcination condition, catalytic dosage, initial concentration of Cr(VI), EDTA concentration and solution pH have been optimized for the photocatalytic Cr(VI) reduction. Moreover, ZnO/g-C3N4 composite showed modest stability after five cycle. Furthermore, the reaction mechanisms and pathways for Cr(VI) reduction by ZnO/g-C3N4 were proposed. [GRAPHICS] .