Preparation And Photocatalytic Properties Of Titania/g-C₃N₄ Complexes

Photocatalytic technology has attracted much attention because it can degrade organic pollutants into non-toxic and harmless substances such as CO2 and H2O,which helps to solve the problem of water pollution caused by industrial development.Graphitic carbon nitride(g-C3N4)affects its practical value due to its small specific surface area and high recombination rate of photogenerated carriers.In this paper,g-C3N4/TiO2 composites were modified with strong acid and the effects of different mass ratios of g-C3N4 and TiO2 on the photocatalytic performance were discussed.(1)Using melamine as the precursor,the g-C3N4 material was prepared by thermal polymerization.The composites with different mass ratios of g-C3N4/TiO2 were modified with sulfuric acid by hydrothermal method,and the modified composites had more pore structures.The composite material with a mass ratio of g-C3N4/TiO2 of 9/1 has a lower band gap and photo-generated electron-hole recombination rate,and the reaction rate constant of degrading methyl blue is 5.09 times that of bulk g-C3N4.(2)The g-C3N4/TiO2 with a mass ratio of 8/2 was modified with sulfuric acid and hydrochloric acid at a high temperature of 150℃.The protonation caused the collapse of the g-C3N4 structure and the fragmentation of the surface lamellae,which made the composite material have more photocatalytic reactions.the active site.The high-temperature acid modification effectively widens the band gap of the composites and reduces the recombination rate of photogenerated carriers.Photocatalytic experiments showed that sulfuric acid protonation greatly improved the photocatalytic performance of the composites.The reaction rate constant for the degradation of methyl blue was 14 times that of the blank control group,and the reaction rate constant for the degradation of ciprofloxacin was 8.11 times that of the deionized water treatment.(3)Using TiCl4 as precursor and ethanol as solvent,g-C3N4/TiO2 composites with different mass ratios were prepared by solvothermal method.Nano-TiO2 particles are uniformly attached to the g-C3N4 layered structure.The g-C3N4/TiO2 composite with a mass ratio of 2/1 has a lower band gap and photo-generated electron-hole recombination rate,and the reaction rate constant of TG1-2 for degrading methyl blue is three times that of TG1-4.(4)Ternary g-C3N4/TiO2/ZnO composites were prepared by hydrothermal modification with sulfuric acid and hydrochloric acid.After hydrothermal modification with hydrochloric acid,the bulk g-C3N4 was etched into a special sheet-like wrinkled layer The nanostructures of TiO2 and ZnO are deposited and stacked on the g-C3N4 nanosheets.The hydrochloric acid modification effectively widens the band gap of the composites.The degradation experiment of ciprofloxacin showed that the degradation reaction rate constant of the ternary composite treated with hydrochloric acid was 3.78 times that of g-C3N4.