Structure Control And Photocatalytic Performance Of G-C₃N₄-Cu₂O

In this thesis,the g-C₃N₄-Cu₂O heterojunction was successfully prepared by hydrothermal reduction and high temperature calcination.The structure of g-C₃N₄-Cu₂O heterojunction was controlled by acidification of g-C₃N₄ and addition of surfactant PEG.X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,Fourier transform infrared spectroscopy（FTIR）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,N₂ adsorption desorption（BET）,The composition,structure and optical properties of the g-C₃N₄-Cu₂O heterojunction were characterized by UV-visible diffuse reflectance spectroscopy（DRS）and fluorescence spectroscopy（PL）.The contamination of methyl orange（MO）was modeled.Its photocatalytic properties explore reactive species through free capture experiments.A possible photocatalytic mechanism was proposed based on theory,characterization and experimentation.The main research contents of this article include:（1）The g-C₃N₄-Cu₂O heterojunction was prepared by hydrothermal reduction method and high-temperature calcination method.Its photocatalytic performance was obviously better than that of g-C₃N₄ and Cu₂O,and the photocatalysis of g-C₃N₄-Cu₂O（1:5）.The performance is better than other doping ratios,and the degradation rate can reach 84%within 30 minutes;decreasing the concentration of pollutants and increasing the concentration of catalyst can all promote degradation.After 5 cycles of experiments,no significant inactivation of g-C₃N₄-Cu₂O occurred.Free radical capture experiments show that photogenerated holes and superoxide radicals are the main active species for the photocatalytic degradation of methyl orange.The heterojunction structure extends the photoresponse range,promotes the effective separation of photoelectron-holes,and proposes a photocatalytic mechanism.（2）On the basis of g-C₃N₄-Cu₂O heterojunction,the acid-treated g-C₃N₄-Cu₂O heterojunction has higher photocatalytic stability.The degradation rate of MO after 5cycles is still 75%.Through characterization analysis,the acidified g-C₃N₄ has good dispersibility,forms a rich heterojunction interface with Cu₂O,generates more heterojunction active sites,improves light utilization and quantum efficiency,and thus enhances Its photocatalytic properties.（3）Based on the acidification treatment of g-C₃N₄,the structure of g-C₃N₄-Cu₂O heterostructure was controlled by the addition of surfactant PEG.The g-C₃N₄-Cu₂O heterojunction has higher photocatalytic performance and stability,and the removal rate of MO reaches 94%in 30 minutes.After 5 cycles,the degradation rate of MO is still 85%.Through characterization analysis,the PEG-controlled g-C₃N₄-Cu₂O heterojunction forms a richer heterojunction interface.More active sites of heterojunction promote the effective separation of photogenerated carriers and extend the range of photoresponse.Improve the quantum efficiency and light utilization,and further enhance the photocatalytic performance.