A facile vapor deposition synthesis of g-C3N4/SiO2 nanocomposite with large specific surface area and enhanced photocatalytic activity

A core-shell g-C3N4/SiO2 nanocomposite was successfully synthesized by depositing g-C3N4, obtained from the sublimation of melamine and subsequent polymerization reaction in the gaseous phase, on the nano-silica. The as-prepared g-C3N4/SiO2 was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, N-2 adsorption-desorption, UV-vis diffuse reflectance spectroscopy. The visible-driven photocatalytic activity of g-C3N4/SiO2 was evaluated by the degradation of tetracycline. The results indicate that the specific surface area of g-C3N4/SiO2 is 97.32 m(2)/g, which is 6.74 times as high as that of bulk g-C3N4(14.44 m(2)/g). Compared to bulk g-C3N4, g-C3N4/SiO2 composite exhibits significantly enhanced photocatalytic activity for degradation of tetracycline and can degrade 72.7% of tetracycline within 60 min under visible-light irradiation. The photodegradation rate constant of tetracycline over g-C3N4/SiO2 is 7.2 times as high as that over bulk g-C3N4. The greatly enhanced photocatalytic activity of g-C3N4/SiO2 is due to coupling enlarged surface areas with the contribution of SiO2 in inhibition of the recombination of photo-induced electron-hole pair.