Visible active N, S co-doped TiO2/graphene photocatalysts for the degradation of hazardous dyes

Abstract

Abstract Herein, we report the synthesis of nitrogen and sulphur co-doped TiO2/rGO nano composites (NST/x%-rGO, x = 2.5, 5, 7.5 & 10%) by facile single step hydrothermal method. The structural and morphological analyses of the synthesized composites were made by XRD, IR, XPS, SEM and TEM, while optical properties were studied by Raman and DRS-UV spectrophotometric techniques. Charge separation efficiency and the extent of recombination were investigated by EIS and photoluminescence (PL) studies. Photodegradation efficiency was evaluated by the de-colorization of congo red (CR), methylene blue (MB) and reactive orange 16 (RO16) dyes. For comparison purpose, TiO2/rGO (GT) and nitrogen, sulphur co-doped TiO2 (NST) were also synthesized, characterized and their photocatalytic activities were evaluated and compared. NST/5%-rGO exhibited the highest photocatalytic activity towards the degradation of all the three dyes under visible light. Improved optical absorption property and increased life time of the photogenerated charge carriers have been observed. Trapping experiments with different quenchers suggested that superoxide radicals (O2 −) were highly responsible for the degradation process compared to other species such as hydroxyl radicals (OH ) and photogenerated holes (h+).