Two-dimensional Materials Based Composites:A Study On Their Fabrication And Photocatalytic Performance For Organic Pollutants Degradation

With the rapid development of global economy and industrialization process,water pollution problems become increasingly serious.Among all the water pollution problems,organic pollutants have become one of the most difficult problems due to the widespread sources,large scale emissions,and great hazard.Therefore,how to conveniently and efficiently remove organic pollutants from wastewater has become a research hotspot.The advantages of photocatalysis on the use of solar energy such as economically efficient,renewable,and clean,are gradually being considered as a cost-effective approach to solve the severe environmental problems.The design and synthesis of high-performance and low-cost photocatalysts are the keys to the effective application of solar energy.Two-dimensional nanomaterials,as a new-type of nanomaterials,exhibit unique magnetic,optical,and mechanical properties and hold significant potential for real applications.In this dissertation,we synthesized several novel two-dimensional materials based composites with improved interface's photogenerated charge transport and separation and further boost the catalytic activity in photocatalysts.The fabricated materials were characterized by techniques of transmission electron microscopy(TEM),X-ray diffraction(XRD),infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),UV-vis diffuse reflectance spectroscopy(UV-vis),and photoluminescence(PL).),photocurrent(it)and so on.Degradation of organic pollutants such as bisphenol A(BPA),tetracycline hydrochloride(TC),2,4,6-trichlorophenol(2,4,6-TCP),and Rhodamine B(RhB)were investigated for the evaluating the photocatalytic activity of the catalysts.The specific research content is as follows:1.WS2QDs,one of the emerging extraordinary zero-dimensional(OD)TMD materials,were applied to the preparation of novel 0D/2D heterojunctions of the WS2 QDs/BiOCl nanosheets.The obtained WS2/BiOCl composites exhibited significantly enhanced visible-light-driven photocatalytic activity as compared with the pure BiOCl.The results indicated the holes(h+)and O2·-are the main active species generated by the catalysts under visible light irradiation.The enhanced photocatalytic performance could be due to the broad band absorption and up-conversion properties of the WS2 QDs as well as the band alignment and the strong coupling between the WS2 QDs and BiOCl NSs,leading to broadened light absorption range and enhanced efficiency for electron-hole paris' production and separation.These findings offer exciting opportunities using the extraordinary 2D TMD materials derived quantum dots for the fabrication of novel 0D/2D composites and may provide new insights into the application of the novel 0D/2D composites in catalysts.2.A novel biomimetic photocatalytic composite material TAPP/C3N4 was prepared using organic small molecule material 4-(tetraaminophenyl)porphyrin(TAPP)and urea.The results show that TAPP not only improves the absorption of light by the composite,but also promotes the photo excited electrons and reduces the electron-holes recombination probability.The g-C3N4 composite sensitized by TAPP shows excellent photocatalytic activity.When the TAPP inclusion amount reaches 1%,the composite material has the best degradation effect on organic pollutants,and the degradation effect on BPA is nearly 10 times higher than that of pure g-C3N4 in the same time.This achievement provides a theoretical basis for the development of new organic/organic composite photocatalysts.