Cu₂O-CuSe（Cu₂Se）/g-C₃N₄ Composite Materials Promote The Degradation Of Methylene Blue By Fenton-like Excitation Of H₂O₂ Induced By Visible Light

In recent years,chiogroup compounds of copper metal have been proved to be excellent Fenton-like catalysts,which can be used to induce FENTon-like degradation of organic pollutants by H₂O₂under visible light.Graphite phase carbon nitride（g-C₃N₄）as a two-dimensional non-metallic semiconductor material,with other semiconductors or metals It is considered as an important means to significantly improve the photocatalytic efficiency.In this study,cuprous oxide was used as a soft template and selenized with selenium water to explore the suitable solution system and the proportion of selenium water.The photocatalytic oxidation experiment was conducted to test the degradation efficiency of methylene blue（MB）of samples,and a relatively reasonable synthesis method was found based on the experimental results.Finally,Cu₂O/CuSe（Cu₂Se）yolk shell structure（CC）was synthesized.Because selenium water does not selenize Cu2O completely during selenization,the specific composition of CC material is Cu₂O,CuSe and Cu₂Se.Graphite phase carbon nitride（g-C₃N₄）was prepared by using melamine as raw material.A small amount of g-C₃N₄was synthesized in the outer layer of egg yolk shell,and the method and ratio of synthesis were explored.The composite material prepared in this experiment has the advantages of simple preparation method,low cost,high photocatalytic oxidation degradation efficiency of methylene blue（MB）,stable and continuous degradation of MB under dark and light conditions.The specific morphology of Cu₂O/CuSe（Cu₂Se）/g-C₃N₄（CC-G）composite was observed by scanning electron microscope（SEM）and transmission electron microscope（TEM）,and the specific chemical element distribution in the composite was detected,and the powder X-ray diffraction（XRD）was used.X-ray photoelectron spectroscopy（XPS）,Fourier transform infrared spectroscopy（FT-IR）,UV-VIS diffuse reflectance spectroscopy（UV-VIS）characterized the structure,elemental composition,chemical states,functional groups and optical properties of the composites.A 300W power xenon lamp simulates sunlight,and a small amount of hydrogen peroxide and CC-G composite materials constitute a synergistic system.The optimal compound ratio of g-C₃N₄is selected by the degradation capacity of the system.The degradation efficiency of MB in the optimal system was close to 100%within 80 min,which was much higher than that of the two parent materials（CC and g-C₃N₄）,and slightly higher than that of other g-C₃N₄composites.The catalytic performance of the material under dark condition was tested,and the possibility of catalytic degradation of MB under the actual light-dark cycle was discussed.The main active substances of the materials in the visible light induced Fenton-like reaction（photogenerated holes in the light reaction and hydroxyl radicals in the dark reaction）were detected and determined by radical stripping experiment combined with electron paramagnetic resonance（EPR）experiment.The recombination of photoluminescence（PL）was analyzed qualitatively.The XRD of the composite after four cycles of catalytic oxidation was tested.It was found that the composition of the CC shell changed,and the corresponding peak of some original univalent copper ions disappeared.Finally,the possible photocatalytic oxidation reaction mechanism of CC-G-X（X is the mass ratio of g-C₃N₄and CC before compounding,and X%is denoted as X）was deduced from the above experimental conclusions.In this study,a small amount of g-C₃N₄was successfully introduced into semiconductor materials.The two parent materials performed relatively poorly in the degradation of MB by Fenton-like fenton-induced H₂O₂induced by visible light,but after special composite experiments,the materials showed excellent degradation ability of MB.A stable CuSe hexagonal sheet（Cu₂Se）/g-C₃N₄heterojunction structure was formed locally in the yolk shell,which promoted the separation of photogenerated electron holes in the local area of the shell.In addition,the degradation of MB was promoted by H₂O₂Fenton-like excitation under visible light and dark conditions.The effects of different composite g-C₃N₄methods on the degradation efficiency of MB were also investigated.The position of g-C₃N₄in the complex system is coincident with the actual complex quantity.The degradation rate of the same system plays a decisive role.