Enhanced sunlight photocatalytic activity and recycled Ag-N co-doped TiO2 supported by expanded graphite C/C composites for degradation of organic pollutants

Removing organic pollutants from wastewater is urgent for developing a sustainable ecological environment. A highly efficient visible light photocatalyst was synthesized through a sol-gel method using C/C composites (expanded graphite dipping in the phenol formaldehyde resin, EGC) coated with Ag, N co-doped TiO2. The as-prepared composites were characterized through scanning electron microscopy (SEM), X-ray diffraction (XRD), N-2 adsorption-desorption (BET), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible light diffuse reflectance spectroscopy (UV-Vis-DRS). The XRD and N-2 adsorption-desorption (BET) results revealed that the photocatalysts were composed of mesoporous structures mainly with anatase TiO2. The effects of Ag content and calcination temperature on the photocatalytic activity of Ag-N-TiO2/EGC photocatalysts were studied. The results showed that under visible light, the photocatalytic efficiencies of Ag-1.0-N-TiO2/EGC (550 A degrees C) obtained for the degradation of Rhodamine B (RB) and diesel are 7.4 times and 3.9 times higher, respectively, than those of N-TiO2/EGC with high mineralization. The enhanced photocatalytic activity of the Ag-N-TiO2/EGC composites was attributed to the porosity and flexible electron transport paths for formation of superoxide radicals. These characteristics assured Ag-N-TiO2/EGC photocatalyst as a high-efficiency photocatalytic material for organic pollutant degradation under visible light.