Influence of $$\text {RGO/TiO}_{2}$$ RGO/TiO 2 nanocomposite on photo-degrading Rhodamine B and Rose Bengal dye pollutants

Abstract

Reduced graphene oxide/titanium oxide-nanostructured composite (RGO/\(\text {TiO}_{2})\) was prepared by combining Hummer’s synthesized graphene oxide and solvothermally synthesized \(\text {TiO}_{2}\) nanoparticles (\(\text {TiO}_{2})\) through a facile ultrasonication-mediated mechanical mixing method. Structural and morphological evidences from XRD and SEM results confirmed that the as-prepared \(\text {TiO}_{2}\) composed of mixed phases, anatase phase with body centred tetragonal crystal structured prism-like architecture, rutile phase with primitive tetragonal crystal-structured bipyramid-like architecture and hence, \(\text {RGO/TiO}_{2}\) system exhibited the similar structural and morphological features. Band gap energy of \(\text {RGO/TiO}_{2}\) was reduced from 2.98 to 2.91 eV due to the presence of RGO and hence, the light absorption range was extended to visible region. In addition, RGO acted as the electron acceptor and hence, the separation efficiency of photo-generated electron–hole pairs increased effectively, and this prevented the recombination process in \(\text {RGO/TiO}_{2}\) system. Thus, \(\text {RGO/TiO}_{2}\) system exhibited greater efficiency towards degrading Rhodamine B (RhB) and Rose Bengal (RB) dye pollutants than bare \(\text {TiO}_{2}\) under sonophotocatalytic condition with natural sunlight irradiation. The possible mechanisms responsible for the enhanced efficiency are explained in this study using appropriate characterization techniques.