Preparation And Research The Properties Of Doped Carbon-based And Sulfur-based Nanomaterials

Since the late 20 th century,nanotechnology has been highly favored by national research groups as a hot spot in the new frontier field.In particular,the semiconductor materials with outstanding photoelectric properties obtain a series of excellent fluorescence properties,catalytic activity and biocompatibility as a result of the reduction of dimension,and has been widely used in photochemistry,electrochemistry,optoelectronics,electro-optical,sensing,catalysis,and medicine-take fields of physics,chemistry,material and medicine.At the present stage,the two-dimensional carbon-based materials represented by graphene have been a hot topic,the work of which mainly focused on low-dimensional transformation and doping.Among the rest,research of the doping of graphene quantum dots(GQDs)is still in developing stage,and there is room for further expansion of the type of dopant elements Therefore.It is of great significance to study the effect of different element doping on the structure and performance of graphene.In addition,the sulfur-based semiconductor materials have the similar structure,properties and function with the graphene,the low-dimensional nano research is of great significance to the development of the graphene and Graphene-like materials.The following several aspects have been researched in this thesis:1.Using the hydrothermal synthesis technology,potassium-doped graphene quantum dots(K-GQDs),boron-doped graphene quantum dots(B-GQDs)and manganese-doped graphene quantum dots(Mn-GQDs)were prepared by using sucrose as carbon source with potassium hydroxide,boric acid and manganese acetate used as K,B and Mn doping sources,respectively.The morphology of quantum dots doped with different elements was characterized by transmission electron microscopy(TEM)and atomic force microscopy(AFM).The results showed that the incorporation of heteroatoms did not affect the hexagonal crystal structure of GQDs.And the size of doped and pure GQDs are similar,less than 10 nm.A series of phase characterization such as X-ray diffraction(XRD),Raman spectroscopy(Raman),Fourier infrared spectrum(FTIR)and X-ray photoelectron spectroscopy(XPS)confirmed that the doped of impurity atoms is effective,and the doped GQDs were prepared successfully.The examination of the photon spectroscopy(PL and PLE)show that the introduction of the impurity(K,B,Mn)is effective and adjusts the band gap of the graphene,showing a unique fluorescence characteristics.2.Using the ultrasonic stripping technology,NbSe2 and MoS2 are used as raw materials respectively,the raw material is miscible with NMP(N-methylpyrrolidone)ultrasonically after fully physically milled prior to reaction,the Selenium quantum dots(SeQDs)and MoS2 quantum dots(MoS2QDs)are obtained by centrifugation.The external appearance characterization of TEM,AFM and scanning electron microscope(SEM)showed that SeQDs and MoS2 QDs are spherical and have the same hexagonal crystal structures as GQDs.The characterization such as XRD,FTIR,Raman,XPS confirmed that the SeQDs and MoS2 QDs can be got through ultrasonic stripping method.By the optical performance characterization(PL&PLE,UV-vis,ultraviolet light),the fluorescence characteristics,absorption spectral characteristics and excitation wavelength dependence of SeQDs and MoS2 QDs also have certain similarities with GQDs.