Interfacial charge transfer of hybrid (Fe3+/Fe2+)/SnO2/TiO2 composites for highly efficient degradation of chromium (VI) under ultra-violet light illumination via Z-scheme

A series of heterostructures (Fe3+/Fe2+) incorporated on SnO2/TiO2, SnO2 and TiO2 were prepared by the photochemical reduction method in neat water and 30% PriOH in water as a solvent medium and were characterized. XPS analysis confirmed the reduced state of Fe3+/Fe2+ on composite materials and introduced new additional energy level to diminish the recombination rate of photo-generated electron-hole pairs to photocatalytic reaction. The synergistic effect of SnO2/(Fe3+/Fe2+)/TiO2 composites is more efficient in pH 3, and the presence of organic sacrificial reagents like EDTA and citric acid to trap centre of holes created on the catalyst surface to degrade the Cr(VI) ion. The photocatalytic reduction of potassium dichromate is described by the pseudo-first order kinetic equation. Ternary SnO2/(Fe3+/Fe2+)/TiO2 composites were speculated to accelerate the effective separation of electron-hole (e‒/h+) pairs, and enhanced the transportation rate of ecb− to the pollutants improved the photocatalytic activity than the (Fe3+/Fe2+)/SnO2 and (Fe3+/Fe2+)/TiO2 binary components. [Display omitted] •(Fe3+/Fe2+) incorporated SnO2, TiO2, SnO2/TiO2 nanocomposites in water and H2O/PriOH (70/30% (v/v)) prepared by photochemical interfacial electron transfer method and characterized successfully.•Fe3+/Fe2+ ion on composites introduced a new energy level to diminish the recombination rate of photo-generated electron-holes pairs to photocatalytic reaction.•Ternary SnO2/(Fe3+/Fe2+)/TiO2 composites were speculated to accelerate the effective separation of electron-hole (e‒/h+) pairs and enhanced the transportation rate of ecb− to the pollutants, improved the photocatalytic activity than the (Fe2+/Fe3+)/SnO2 and (Fe2+/Fe3+)/TiO2 binary components.•The photocatalytic reduction of Cr (VI) ion has been performed using the optimum amount of catalyst, pH, and organic sacrificial reagents were studied in detail.