2D reduced graphene oxide–titania nanocomposites synthesized under different hydrothermal conditions for treatment of hazardous organic pollutants

Abstract

Two-dimensional reduced graphene oxide–titania (RGO–TiO2) composites were prepared using a single-step hydrothermal method under various hydrothermal reaction conditions. The morphological and surface characteristics of the RGO–TiO2 composites and reference materials were determined. The RGO–TiO2 composites showed photocatalytic activity for the decomposition of two target pollutants that was superior to both pure TiO2 and RGO under fluorescent daylight lamp illumination. The photocatalytic activity of the RGO–TiO2 composite increased as the hydrothermal treatment time increased from 1 to 24h, but then it decreased as the time increased to 36h, which indicated the presence of an optimal treatment time. RGO–TiO2 composites activated by violet light-emitting diodes (LEDs) displayed lower decomposition efficiency than those activated by a daylight lamp, likely because of the lower light intensity of violet LEDs (0.2mW/cm2) when compared with that of the daylight lamp (1.4mW/cm2). However, the photocatalytic decomposition of the target pollutants using the RGO–TiO2 composite was more energy-efficient using the violet LEDs. The photocatalytic reaction rates increased as the residence time decreased, whereas the reverse was true for the decomposition efficiency.