Study On Preparation By Dehalogenation And Electrochemical Performance Of New Types Of Carbon Materials

Because of their unique electron orbital characteristics,carbon forms a very diverse array of bonded hybrids,so that carbon can build materials that vary in performance from zero to three dimensions.In recent years,methods of preparing carbon materials are emerging in an endless stream,and more and more studies on their properties,especially in energy-related fields,have been conducted.In view of the excellent properties of carbon materials such as hardness,optical properties,electrical conductivity and surface and interface properties,the authors prepared new types of carbon nanomaterials by basic dehalogenation of halogen-containing carbon sources under various conditions,its electrochemical properties were studied,and the mechanism of basic dehalogenation at room temperature was also studied by first principles.The main work is as follows:1.Density Functional Theory at room temperature strong base dehalogenation reaction mechanism was studied.Carbon materials were prepared by strong alkaline dehalogenation reaction at room temperature.Carbonization was achieved by manual grinding with highly halogenated polymer PVDC as a carbon source,and some uncyclized carbon sites showed high activity.Coupling with heteroatoms to achieve the preparation of doped carbon materials.We use 2,2-dichlorobutane instead of long-chain PVDC to simulate the dechlorination and doping mechanism of PVDC by Gaussian.The calculated results show that PVDC has two steps of dehalogenation under alkaline conditions at room temperature,with activation barriers of 1.38 kcal/mol and 11.69 kcal/mol.We used NH3 to simulate heteroatom doping with an energy barrier of 36.99 kcal/mol.2.The NP was successfully incorporated into the carbon chain by dehalogenation and calcined to obtain NP-doped C3N4.The solvothermal method is used to dehalogenate hexachlorocyclotriphosphazene and melamine under certain conditions to realize the preparation of NP-doped carbon materials,and the high-temperature calcination of NP-doped carbon materials is used to achieve the purpose of hydrogen evolution by photoelectrocatalytic decomposition of water.Theoretical calculations show that NP doping makes the band gap of C3N4 smaller,the spectral response range increases,and the carrier transmission rate is enhanced.Experimental results show that the photocurrent response current of NP doped C3N4 is significantly higher than that of pure carbon nitride.The bandgap decreases from 2.7 eV to 2.3 eV,and the hydrogen evolution overpotential in the bright field decreases to 0.25 V.In summary,the preparation of doped carbon material by dehalogenation reaction is a new efficient and practical method,and it has very important applications in the photo-electrocatalysis and energy storage.