Abstract: Graphitic carbon nitride/titanium dioxide (g-C3N4/TiO2)hybrid photocatalysts were synthesized by heating mixtures of commercial TiO2 particles and melamine.The g-C3N4/TiO2 samples were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),transmission electron microscopy (TEM),low temperature nitrogen adsorption and UV-visible diffused reflectance spectroscopy (UV-vis DRS).The photocatalytic degradation of sulfamethazine (SMT) was investigated by using g-C3N4/TiO2 under visible light.The results show that TiO2 is distribute on layered structure of g-C3N4,and form g-C3N4/TiO2 with pore structure and larger specific surface areas.The g-C3N4/TiO2 has visible light response with absorption edge of 430 nm.When the dosage of g-C3N4/TiO2 is 0.2g/L,about 98.8; of SMT in solution is removed in 3 h with an initial concentration of 0.5 mg/L under visible light,much higher than g-C3N4 (57.8;) and TiO2 (9.7;).The results of active species trapping experiments reveal that the holes (h +) and superoxide radical (· O2-) make a major contribution in photocatalytic degradation of SMT by g-C3N4/TiO2.

Key words: Graphitic carbon nitride/titanium dioxide (g-C3N4/TiO2)hybrid photocatalysts were synthesized by heating mixtures of commercial TiO2 particles and melamine.The g-C3N4/TiO2 samples were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),transmission electron microscopy (TEM),low temperature nitrogen adsorption and UV-visible diffused reflectance spectroscopy (UV-vis DRS).The photocatalytic degradation of sulfamethazine (SMT) was investigated by using g-C3N4/TiO2 under visible light.The results show that TiO2 is distribute on layered structure of g-C3N4,and form g-C3N4/TiO2 with pore structure and larger specific surface areas.The g-C3N4/TiO2 has visible light response with absorption edge of 430 nm.When the dosage of g-C3N4/TiO2 is 0.2g/L,about 98.8; of SMT in solution is removed in 3 h with an initial concentration of 0.5 mg/L under visible light,much higher than g-C3N4 (57.8;) and TiO2 (9.7;).The results of active species trapping experiments reveal that the holes (h +) and superoxide radical (· O2-) make a major contribution in photocatalytic degradation of SMT by g-C3N4/TiO2.