Highly efficient photocatalytic degradation and mineralization of 4-nitrophenol by graphene decorated ZnO

In the present study we have synthesized a series of ZnO–graphene composites with different initial amounts of graphene oxide by hydrazine assisted hydrothermal method. The structure, morphology, thermal, optical and electrochemical properties were characterized by XRD, Raman, SEM, TEM, thermogravimetry, photoluminescence, UV–visible spectroscopy and cyclic voltammetry measurements. The composites thus obtained were utilized as photocatalysts for degradation of aqueous organic pollutants under UV irradiation. We inferred that, photoperformance of the catalysts depends on the amount of graphene present in the composite. The composite with weight ratio of graphene oxide to zinc acetate as 1.4 % (ZG-3) has shown ~fivefold enhancement in the degradation rate (as compared to ZnO) of 4-nitrophenol. Further, the obtained results for the photocatalytic degradation and mineralization of 4-nitrophenol, rhodamine B, propranolol and 4-chlorophenol suggest the non-selectivity of ZnO–graphene photocatalyst. These composites have potential applications for wastewater treatment.