Enhanced photocatalytic removal of Cr(VI) over 0D/2D anatase/graphene and its synergism with organic pollutants under visible light irradiation

In this study, a novel anatase/graphene (0D/2D)-based composite photocatalyst is synthesized through a facile hydrothemal method using graphene oxide (GO), titanium sulfate (Ti(SO ₄ ) ₂ ) and hydrazine hydrate (N ₂ H ₄ ·H ₂ O) as precursors. The study reveals that the surface-dispersed anatase nanoparticles adhere well to the flake-like graphene. Compared with pure anatase nanoparticles, the anatase/graphene composite showed a significantly modified crystal structure in the crystallinity of the anatase phase and surface area. The involvement of graphene also dramatically enhanced the absorption of visible light and provided a shift in the absorption edge towards red wavelengths. From the analysis of the fluorescence spectra, it is demonstrated that the recombination dynamics of the photogenerated charge (electron-hole) pairs can be effectively inhibited by the compounded graphene and hence improve the efficiency of the charge carrier separation. The dramatically improved reduction of Cr(VI) is achieved through the visible light photocatalytic activity provided by the anatase/graphene composite. The rate of the reaction measured for the composite is 4.83-fold and 9.78-fold greater than that of the pure anatase under ultraviolet and visible light irradiation, respectively. Moreover, the synergism of the RhB degradation with the reduction of Cr(VI) also dramatically improves the latter. Additionally, we present an analysis of a potential alternate system for the improvement of photocatalytic activity.