Preparation and visible light catalytic degradation of hollow urchin-like TiO2/N-GQDs composites on waste organic dyes

Abstract In order to enhance the visible light catalytic activity of TiO₂ by broadening its photoresponse range, the TiO₂/N-GQDs (TGs) composite catalysts with a three-dimensional hollow urchin-like structure were prepared by one-step hydrothermal method using potassium titanium oxalate and citric acid as raw materials. The microstructure and photoelectric properties of the synthesized TGs composites were analyzed through a series of characterizations, and the performance in degrading organic dyes under visible light was investigated. The results demonstrated that the prepared composites effectively enhanced the visible light absorption spectrum of TiO₂ by forming heterojunction, and the photocatalytic degradation efficiency of TGs composites on organic dyes was significantly improved than neat TiO₂. The degradation efficiency of organic dyes could reach 95.71% under visible light irradiation for 1 hour, which further increased to 99.39% after 2 hours. Additionally, the photocatalytic degradation process could be effectively accelerated under acid conditions. After 5 cycles of testing, the degradation efficiency of TGs composites on organic dyes was hardly reduced, indicating that they had great visible light catalytic activity and significant reusability.