Synthesize And Photocatalytic Performance Under Visible Light Of The Copper Semiconductor/g-C₃N₄ Heterojunction

g-C₃N₄ as a novel non-metallic semiconductor material,composed of the elements C and N only,and wide forbidden band is about 2.7 eV,possess ability of visible light response.In recent years,many studies found that the g-C₃N₄ can be used for the decomposition of pollutants and photolysis splitting of water into hydrogen.However,due to the rapid recombination of photogenerated electron hole pairs on the surface of g-C₃N₄,the smaller specific surface area of g-C₃N₄,which leads to the visible photocatalytic performance of g-C₃N₄ is not strong.In order to improve the photocatalytic efficiency of g-C₃N₄,this paper use copper acetate,copper chloride and melamine as raw materials,preparation of the copper based semiconductor g-C₃N₄/Cu₃B₂O₆ and g-C₃N₄/CuS heterojunction composite photocatalytic materials.The photocatalytic performances of the g-C₃N₄/Cu₃B₂O₆ composites were evaluated by degrading methylene blue?MB?using H₂O₂as an oxidant under visible-light irradiation,and the g-C₃N₄/CuS by methyl orange?MO?.The active species involved in the photoreactions were examined via the trapping experiments by using radical scavengers,and the mechanism of photocatalytic degradation of organic pollutants also explored.The conclusions of this paper are as follows;?1?g-C₃N₄/Cu₃B₂O₆ was successfully synthesized by a liquid chemisorption and thermal post-treatment method,g-C₃N₄/CuS were synthesized by hydrothermal synthesis method respectively.The structure,morphology and optical response ability of the as-synthesized samples were characterized by X-raydiffraction?XRD?,fourier transform infrared?FTIR?,X-ray photoelectron spectra?XPS?,field-emission scanning electron microscopy?FE-SEM?,transmission electron microscope?TEM?,Brunauer-Emmett-Teller?BET?.characterization results shows that the two heterojunctions were successfully synthesized,copper semiconductor was loaded well on the lamellar g-C₃N_4,not monomer mixture of simple material,but by interfacial interactions formed good p-n heterojunction structure,with high specific surface and good response performance of light.?2?A series of experiments were used for investigate g-C₃N₄/Cu₃B₂O₆ photocatalytic activity of degrading methylene blue?MB?under visible-light irradiation.The photocatalytic results shows that the heterojunction photocatalyst can significantly improve the catalytic effect compare with pure g-C₃N₄ and Cu₃B₂O₆.It was found that 60%g-C₃N₄/Cu₃B₂O₆heterojunction exhibite the optimal capacity among the all contents g-C₃N₄ in degrading MB under visible-light,while the photodegradation rate of 20mg/L MB reached to 97%in 60minutes.And the influence condition of the visible light degrading MB under visible-light were investigated also,the results indicate that the larger amount add,the higher light degradation of methylene blue,alkaline environment conducive to the heterojunction in visible light on the degradation of methylene blue.In addition,through the cycle experiment,g-C₃N₄/Cu₃B₂O₆ showed good stability in the process of the light reaction.Free radicals capture experimental shows that the photogenerated h⁺and e^-were the main active species for MB photodegradation,the degradation mechanism may be under the irradiation of light,the electrons and holes of come into being on the valence band top and bottom of the conduction band of heterojunction degradated the methylene blue,the experimental results are consistent with the determination results of PL,ultraviolet visible?UV-vis?performance.?3?A series of experiments were used for investigate g-C₃N₄/CuS photocatalytic activity of degrading methyl orange?MO?under visible-light irradiation.The photocatalytic results shows that the heterojunction photocatalyst can significantly improve the catalytic effect compare with pure g-C₃N₄ and CuS.It was found that 60%g-C₃N₄/Cu₃B₂O₆heterojunction exhibite the optimal capacity among the all contents g-C₃N₄ in degrading MO under visible-light,while the photodegradation rate of 20mg/L MO reached to 95%in 30minutes.And the influence condition of the visible light degrading MB under visible-light were investigated also,the results indicate that the larger amount add,the higher light degradation of MO,the increase of initial concentration of MO will not affect the heterojunction photocatalytic activity.In addition,through the cycle experiment,g-C₃N₄/CuS showed good stability in the process of the light reaction.Free radicals capture experimental shows that the photogenerated h⁺was the main active species for MO photodegradation,the degradation mechanism was much the same with the mechanism of g-C₃N₄/Cu₃B₂O₆heterojunction degrade MB under visible-light.