| Photocatalytic technology can utilize the energy generated by natural sunlight to decompose hydrogen from water,and often be used to treat industrial and domestic sewage,which has the advantages of high efficiency and low energy consumption.Therefore,photocatalysis has a good application prospect in environmental management.The g-C3N4 is regarded as one of the most promising photocatalytic materials because of its suitable band gap,excellent stability and photoelectric performance.However,due to its own defects,the photocatalytic activity of g-C3N4 is restricted,which limits the use of g-C3N4 in the photocatalytic range.In this paper,the binary composite photocatalysts based on g-C3N4 were constructed by direct calcining and in situ growth methods,so as to enhance the photocatalytic performance of g-C3N4.The structure,morphology and properties of binary photocatalysts were characterized and analyzed theoretically.In addition,the photodegradation properties of binary materials were evaluated,and the catalytic principle in the photoreaction process was studied.The details of this article are as follows:?1?Different ratios of g-C3N4/In2O3 composite materials were synthesized by two-step calcination.XRD,FTIR and TEM characterization results confirmed the existence of heterojunction in the composite,and also showed that the introduction of In2O3 did not affect the structure of g-C3N4.In addition,compared with g-C3N4,the bandgap width of g-C3N4/In2O3was smaller,indicating that the optical response range of g-C3N4/In2O3 was larger than that of g-C3N4.According to the photocurrent and impedance characterization,the separation efficiency of carriers in g-C3N4/In2O3-30%was faster and the charge transfer resistance was smaller,so the photocatalytic performance of g-C3N4/In2O3 binary materials was enhanced.Among them,when the light shined for two hours,the removal efficiency of g-C3N4/In2O3-30%on methyl orange?MO?could reach 90.5%,and the performance was stable.?2?A series of Z-scheme g-C3N4/Bi2O3 binary materials with large specific surface area were successfully obtained by one-step calcining.In the light reaction,the photodegradation performance of g-C3N4/Bi2O3 material to methyl orange?MO?was better than that of g-C3N4and Bi2O3 monomer.Among them,after two hours of light irradiation,the MO removal efficiency of g-C3N4/Bi2O3-1%could reach 91.8%.The key to the enhancement of photocatalytic activity were that the large specific surface area of g-C3N4/Bi2O3 binary materials enlarged the absorption of visible light and the photogenerated charge migration adopted the Z-scheme mechanism.In addition,the free radical capture experiment confirmed that the main active groups in the g-C3N4/Bi2O3 photoreaction system are h+,·O2-and·OH.This work provides a cost-effective strategy for advanced photocatalyst design and dye treatment in wastewater.?3?The mpg-C3N4/SnO2 composite photocatalyst with high photocatalytic performance was synthesized by in-situ growth method.The structure,morphology and properties of mpg-C3N4/SnO2 were analyzed by means of XRD,XPS and SEM.The photodegradation performance of mpg-C3N4/SnO2 was found to be excellent through the photodegradation of RhB in the photoreaction.After two hours of light irradiation,the best removal effect of RhB was mpg-C3N4/SnO2-20%,and the removal efficiency was 93.1%.The enhanced catalytic activity of mpg-C3N4/SnO2 could be attributed to its own mesoporous structure and the heterostructure formed between mpg-C3N4 and SnO2.In addition,the possible photocatalytic mechanism of mpg-C3N4/SnO2 photocatalyst was studied by ESR test and free radical trapping experiment. |
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