ZnO–TiO2/rGO heterostructure for enhanced photodegradation of IC dye under natural solar light and role of rGO in surface hydroxylation.

To overcome the limitations of ZnO as a photocatalyst, the present work reports a ternary nanocomposite (ZnO–TiO2/rGO) with a high photocatalytic activity under direct natural solar light irradiation. Reduced graphene oxide (rGO) was obtained after bio-reduction of GO using pomegranate peels. Techniques of FE-SEM, TEM, XRD, FTIR, UV–Vis DRS, Raman and PL were used for characterization purpose. The ternary nanocomposite exhibited a high photocatalytic activity towards the degradation of indigo carmine dye, resulting in an efficiency of 92% within 150 min under sunlight illumination. Accordingly, the hybridization of ZnO with TiO2 and rGO improves light absorption, promotes high separation of photogenerated charges, and solves the photocorrosion drawback of ZnO, leading to a better stability and reusability of the nanocomposite. Particularly, the prepared rGO allowed certain hydrophilicity and a better surface hydroxylation. In view of that, a comprehensive photocatalytic mechanism was proposed and discussed, referred to experiments showing the effect of holes and •OH scavengers. The findings revealed that the developed rGO hybridized with ZnO–TiO2 heterojunction can be a promising candidate for removing environmental contaminations using natural solar light. [ABSTRACT FROM AUTHOR]