Visible Light Driven ZnMoO4/BiFeWO6/rGO Z-Scheme Photocatalyst for the Degradation of Anthraquinonic Dye

The Z-scheme zinc molybdate/bismuth iron tungstate/reduced graphene oxide (ZnMoO4/BiFeWO6/rGO, ZM/BFW/rGO) ternary composite photocatalyst was prepared with rGO acting as an electron transmission mediator. The physicochemical properties of the materials were characterized by using a range of techniques such as SEM, TEM, EDS, FTIR, Raman, BET, TGA, and UV-vis DRS. The optical properties of the materials showed that ZM/BFW/rGO absorbed more visible light than the pristine ZnMoO4 (ZM) and BiFeWO6 (BFW). Thermal analysis showed enhanced stability of the ternary composite due to incorporation of thermally stable ZM. The composite material was used for photocatalytic degradation of 30 mg L-1 anthraquinonic acid blue 25 (AB 25) as the model pollutant under visible light irradiation. A degradation efficiency of 98% was achieved after 180 min degradation using ZM/BFW/rGO, while ZM and BFW showed only 24% and 36% dye removal efficiencies. About 70% total organic carbo (TOC) was attained with a ternary composite photocatalyst. The enhanced degradation was attributed to the formation of a Z-scheme between the two catalysts, visible light absorption, and the presence of high rGO that aided in electron mediation and shuttling. The photocatalyst also showed high stability with 89% removal efficiency after four cycles of repeated usage. The results of this work provide an alternative method for effective removal of dyes from wastewater and may be explored for large-scale application in the future.