Simple synthesis of 3D flower-like g-C3N4/TiO2 composite microspheres for enhanced visible-light photocatalytic activity

3D flower-like g-C3N4/TiO2 composite microspheres (FCTCMs) were prepared by a simple solvothermal method and combined with a thermal treatment method. By controlling the amount of urea mixed with the 3D flower-like structure of TiO2 microspheres (FTMs), FCTCMs with different g-C3N4 loadings were prepared. Urea has two functions in the preparation process: one decomposes into gaseous substances during heat treatment at 550 degrees C to form g-C3N4 in the gap between nanosheets of TiO2 microspheres; and the other effectively protects the 3D flower-like structure of TiO2 microspheres (FTMs). The results of XRD, TEM, FT-IR, SEM and XPS indicate that g-C3N4 and TiO2 were connected in a surface-to-surface manner. Its photocatalytic performance was characterized by the degradation of methyl orange and methylene blue solution. The results show that the photocatalytic performance of FCTCMs under visible light was as twice as FTMs. The transient photocurrent responses and EIS results also indicate the increase in the number of photogenerated electron-hole pairs produced by FCTCMs.