Exfoliation, Modification And Properties On Hexagonal Boron Nitride And Graphite

The nanomaterial science and technology, which is a foundation of the development of high-technologies and new disciplines, has a large effect on various aspects of our country. The unique geometric morphology and physicochemical property of the inorganic nanomaterial have fundamentally determined their wide applications in different fields. Furthermore, the innovative and constructive doping and compounding of the nanomaterial expand the researches on nanomaterial in-depth in practical applications. Both the inorganic layered nanomaterials of hexagonal boron nitride (h-BN) and graphene (G) have a similar and unique structural feature, which lead to these two nanomaterials having a promising application in the field of photoelectricity. Transmission electron microscope-scanning tunneling microscope (TEM-STM) is an in-situ electrical property measurement system, which covers the modern electron microscopy techniques, micro and nano processing technologies and devices.Our paper selected hexagonal boron nitride nanosheets and graphite as the subjects, which were obtained through a modified liquid ultrasonic exfoliated method from the bulk hexagonal boron nitride and graphite, and the structure and morphology of the products were characterized by XRD. SEM. TEM. AFM and so on. On the basis of successful exfoliation of the above two nanomaterials. we carried out the researches on the modification of the hexagonal boron nitride nanosheets and graphene by doping and compounding. The doping and compounding nanomaterials are given as follows:(1) Doping fluorine element into hexagonal boron nitride nanosheets by a facile chemical solution method;(2) Synthesizing the compounds of BN@NiMoO4. G@MnO:, rGO@Ag:S and rGO@Cu7S4. Finally, we measured the properties of the products by TEM-STM. UV-Vis and PL. The in-situ electrical property tests show that both the fluorinated hexagonal boron nitride nanosheets and graphene have a good electrical conductivity, which determines their considerable applications in electronic devices field. The BN@NiMoO4shows an excellent optical property, which suggests it will be a novel photoelectric functional material. The main research results are listing as follows:1. The few-layered hexagonal boron nitride nanosheets were exfoliated from the bulk hexagonal boron nitride powder by a modified liquid ultrasonic exfoliated method. Via the systematic experiments, the best experiment program was obtained. The morphology and structure of the few-layered hexagonal boron nitride nanosheets were characterized by FE-SEM. TEM. AFM and so on. At last, the PL spectroscopy detection reveals the few-layered hexagonal boron nitride nanosheets have a certain optical property.2. The fluorinated few-layered hexagonal boron nitride nanosheets were obtained by doping fluorine element via a facile chemical solution method, which was obtained after various compared experiments. The existence of fluorine element was detected by the element characterizations of XPS and EDX. The TEM-STM in-situ electrical property test was applied to various hexagonal boron nitride nanosheets. The results show that the bulk hexagonal boron nitride powder shows its intrinsic electric insulation characteristic with no detectable current. Compared with the bulk hexagonal boron nitride, the exfoliated few-layered hexagonal boron nitride nanosheet has a weak electrical property. Interestingly, the fluorinated few-layered hexagonal boron nitride nanosheet displays an excellent semiconductor property, which suggests hexagonal boron nitride material is transformed from the insulator to a semiconductor through the effective doping of fluorine. This change may owe to the bandgap transition from indirect to direct. The remarkable change in conductive property makes hexagonal boron nitride will be a new functional material in the field of electronic devices. In the second part, BN@NiMoO4compound, which was synthesized by a high temperature solid phase sintering process, has an excellent optical property, making the hexagonal boron nitride nanomaterial could be used in the field of optics.3. The graphene was exfoliated from graphite by the modified liquid ultrasonic exfoliated method. The electrical performance of the graphene detected by the in-situ TEM-STM reveals graphene has a good electrical conductivity. Finally, we synthesized a G@MnO2heterostructure through a straightforward nanocrystal-seeds-directing hydrothermal method, prepared a compound of rGO@Ag2S by different methods of hydrothermal and pyrolysis, and got the rGO@Cu7S4compound by the hydrothermal route, then the morphology of the compounds were characterized by XRD. SEM. and TEM. etc.