Moving Toward The Application And Industrialization Of Graphene:Processes Of Graphite Formation And Graphitic Crystal Chemistry

Freestanding graphene and its applications has become the strategic path of the majority of all nations and nations in the present situation.It is a breakthrough point of election of its starting graphite and product quality control in preparation process of graphene,to reveal the applicability that the application areas of graphene are restricted by natural graphite determined under certain geological conditions.However,till now,little study has been done in the world.Flake graphite deposits are the main types of deposits in the world.The ore minerals are mainly coarse crystal flaky graphite,big flaky grapite and fine flaky graphite.Those typical deposits occur in early Precambrian Khondalite high-grade metamorphic rocks,and ore-hosting rocks are dominated by gneiss,altered marble,leptynite,granulite,amphibolite and migmatite.Vein graphite deposits result from the metamorphism of sedimentary rocks rich in carbonaceous matter or from precipitation from carbon-bearing fluids?or melts?.The latter process forms vein deposits which are structurally controlled and usually occur in granulites or igneous rocks.Amorphous graphite deposits are based on in late Precambrian epimetamorphic rock graphite deposits,which are formed in dynamic metamorphic belt of black rock sequence or coal seam contact metamorphism triggered by magma intrusion into coal measures.Natural graphite formation must combine carbonaceous matter and thermodynamic condition,and rocks enriched in carbon after graphitization process can form graphite ores.Thus,the condition of the formation of graphite ores is mainly thermodynamic condition,origin of carbon,organic beings and sedimentary formation.According to the conditions of the formation of graphite ores and characteristics of graphite mineralization,suggest three stages of metallogenic model including enrichment in carbon-organic carbon hot crystallization-carbonaceous and siliceous organic matter hydrothermal replacement.Thus,ore genesis of natural graphite is summarized by combination of origin of carbon + ore-bearing rock + thermodynamic condition + graphitization process,defined by the four factors of genetic model of natural graphite.The crystal structure,crystal characteristics and physicochemical characteristics are determined by genesis of natural graphite deposits and graphitization degree.Factors influencing on graphitization process for carbonaceous matter?temperature,pressure and heating time?are closely related to the metamorphism of rocks.The results of mineralogical characteristics of graphite samples from typical mines show that these graphite samples are 2H-type graphite,and in certain degree,contain 3R-type graphite.The lower degree of metamorphism,the smaller graphite crystal size,the greater the numbers of RH facies.The ordering degree of crystal structure and contents of carbon and hydrogen in graphite are associated with graphitization degree.Major factors influencing on physicochemical properties of natural graphite are degree of metamorphism or metamorphic facies and graphitization degree.The crystal morphology of the natural crystalloid graphites have an influence on the characteristics and properties of synthesised reduced graphene oxide?rGO?.However,few reports may have investigated this original natural graphite material for synthesised rGO.Important gaps in our knowledge include the lack of geological characteristics of graphites in different genetic types to constrain the raw material for graphene synthesis involved in deposition of the crystalline graphite deposits.In this regard,influence of graphite source on graphene synthesis is remain unknown.Meanwhile,documentation of natural graphite deposit constraint on industrialization of graphene is incomplete and important questions remain unanswered to constrain the industrialization of graphene materials.Important gaps in our knowledge include the lack of the genesis of natural graphite deposit to constrain the industrialization of graphene materials.Thus,this paper deals with a physical and mathematical model for the genesis of natural graphite deposit to constrain the industrialization of graphene materials.The model is express byG_geo= F?Bat,Flex,Bio,Cor,Com,Thermo?= ?Bat + ?Flex + ?Bio + ?Cor + ?Com + ?Thermo The model has important theoretical and practical significance to realize the industrialization of graphene materials.In election of its starting graphite and product quality control,it provided a theoretical basis for large-scale production and application of graphene,and also for invertors and developers of graphite mine,downstream new forward materials of graphene strategic positioning,and developing and utilizing graphene resources.This work aims at investigating the influence of graphite source on graphene synthesis.Reduced graphene oxides?rGOs?prepared from crystalline graphites in Liumao and Xiaodouling,China revealed that graphite with fine flake?GF?is much easier to oxidize than graphite with coarse flake?GC?,and is preferable for preparing single or double layer graphene because of a higher graphitisation degree,bigger specific surface area and smaller crystal size.rGO synthesised from GC exhibit high quality with a specific capacitance than that obtained from GC.Our findings also show that there are differences in fixed carbon content,origin of carbon,metamorphic facies,and geodynamic setting of ore deposit between GF and GC.Therefore,the genesis of graphite is a major factor influencing the material properties.Natural graphites were used to synthesise GrOs and rGOs.The study focused on?1?characterisation and comparison of the GrOs and rGOs prepared from the three types of graphite,?2?investigation of the effect of the crystal morphology on the oxidation process of GrO and the characteristics of the prepared rGO,and?3?Comparison of the processes of the three types of graphite formation.The characterisation of reduced graphene oxides?rGOs?prepared from natural flaky,lumpy,andamorphous graphites using Hummers method was investigated.The prepared graphite oxides?GrOs?and rGOs were characterised by X-ray diffraction,Fourier transform infrared spectroscopy,Raman spectroscopy,UV–vis spectroscopy,atomic force microscopy and electrochemical performance.The results showed that amorphous graphite was much easier to oxidise than lumpy and flaky graphites and was preferable for preparing single or double layer graphene because low graphitisation degree,high defect degree,high specific surface area and small crystal size were beneficial for?1?the oxidants to attack the exposed carbon atoms,?2?the intercalation of oxidants,and?3?the diffusion of oxidants between graphitic layers.In addition,rGO synthesised from amorphous graphite had the most defects and the smallest size of the in-plane sp2 domains compared to those obtained from the other two nature graphites.These investigations provided an effective strategy to select the suitable original natural graphite material based on the performance requirements of graphene.Cyclic voltammetry,galvanostatic charge-discharge and electrochemical impedance spectroscopy were used to estimate the supercapacitive performance of the graphene prepared from both kinds of graphite.The results show that the graphene prepared from both kinds of graphite possess electrical double-layer capacitive characteristics.The increasing of the oxidation degree of graphite oxide is beneficial to the supercapacitive perfoemance of the graphene,but the higher oxidation might lead to worse electronical resistivity.At the same oxidation condition,the higher thermal temperature leads to better cycle stability,but the specific capacity could increase fistly and then decrease with the thermal temperature.The supercapacitive performance of graphene prepared from crystalline graphite is slittily better than that of graphene prepared from microcrystalline graphite.Based on the result,recommendations were made in this paper,aiming to contribute development and utilization of graphene resources in the world.?1?Proactively organize government-owned enterprise groups for development and utilization of graphene resources;?2?Pay attention to the axis-wheeled industrial clusters under the global chain network;?3?Establish global advanced new graphene material database systems;?4?Divide global potential graphene resource into six resource economic zones and sixteen resource economic areas;?5?Adopt interregional coordinate policies for graphene resource development and utilization;?6?Improve the environmental regulations and industry standards;?7?Set up dynamic detection systems for development and utilization of graphene resources.