Synthesis and Visible-Light Photocatalytic Activity of Carbon Spheres Decorated g-C3N4 Composites

A kind of carbon spheres decorated carbon nitride (C/g-C3N4) composite photocatalysts were successfully synthesized by hydrothermal method using glucose and g-C3N4 as raw materials. The structure, composition, morphology, specific surface area and optical properties of these photocatalysts were fully characterized by X-ray powder diffraction, scanning electron microscope, N, adsorption-desorption, ultraviolet-visible diffuse reflectance spectroscopy, surface photovoltage spectroscopy and electron paramagnetic resonance. The results showed that the carbon spheres with a diameter of about 20 nm were tightly present on the surface of g-C3N4. When the dosage ratio of glucose to g-C3N4 (mass fraction) was 1%, the composite photocatalyst was the best catalyst. Compared with g-C3N4, the specific surface area of g-C3N4 with 1% C (1% C/g-C3N4) was significantly increased, the visible light response range was expanded, and the separation efficiency of photogenerated electrons and holes of the catalyst was also improved. In addition, under the irradiation of a 400 W metal halide lamp with 420 nm filter, 87% of rhodamine B (10 mu mol.L-1) could be fully degraded by 1% C/g-C3N4 composite photocatalyst within 80 min. The efficiency of this catalyst was three times that of pure g-C3N4 under the same conditions and its stability was also good.