Synthesis and characterization of nitrogen-doped TiO 2 coatings on reduced graphene oxide for enhancing the visible light photocatalytic activity

Nitrogen-doped TiO2 coatings on reduced graphene oxide were prepared via a sonochemical synthesis and hydrothermal process. The nanocomposites showed improved photocatalytic activity due to their large specific surface areas (185–447 m2/g), the presence of TiO2 in the anatase phase, and a quenched photoluminescence peak. In particular, GN3-TiO2 (nitrogen-doped TiO2 coatings on rGO with 3 ml of titanium (IV) isopropoxide) exhibited the best photocatalytic efficiency and degradation rate among the materials prepared. With nitrogen-doped on the reduced graphene oxide surface, the photocatalytic activity is enhanced approximately 17.8 times compared to that of the pristine TiO2. The dramatic enhancement of activity is attributed to the nitrogen contents and rGO effectively promoting charge-separation efficiency and providing abundant catalytically active sites to enhance the reactivity. The composites also showed improved pollutant adsorption capacity, electron–hole pair lifetime, light absorption capability, and absorbance of visible light.