Synthesis Of Graphene And Graphene/Carbon Nanocomposites

Carbon nanomaterials,including one-dimensional(1D)carbon nanotube(CNTs),carbon nanofibers(CNFs),and two-dimensional(2D)graphene,have been proven to be used in various fields because of excellent thermal conductivity,electrical conductivity,and mechanical properties.However,both 2D graphene and/or 1D CNTs and CNFs can form irreversible agglomerates because of the van der Waals interactions,which This will greatly reduce electrochemical properties.It has been demonstrated that assembling low-dimensional carbon materials into 3D hybrid structures could hinder re-agglomeration by reducing van der Waals interactions among GNs or CNTs and consequently better harness the inherent attributes of the lower dimensional materials for macroscopic applications.3D structures have been indicated to show excellent physical chemistry properties,which have attracted great attention in energy storage and nanoelectronics.Understanding the effect of process parameters is critical for production of large-area and high-quality graphene by low-pressure chemical pressure deposition on Cu.We investigate that the hydrogen concentrations and the growth pressure are critical parameters that affect the quality and morphology of graphene.Scanning electron microscopy(SEM)shows that suitable hydrogen concentration contributes to controlling the morphology of graphene.Raman spectra indicate that the graphene synthesized at low pressure exhibit superior quality and monolayer of graphene.We successfully prepared spiral carbon nanofibers based on graphene through exploration of experimental conditions.we investigated the effect of experimental parameters on the morphology and quality of carbon nanofibers by changing the growth temperature,growth time,and the flow of benzene.Studies have shown that when the graphene precursor is the same with each other,the optimal parameters for fabricating three-dimensional graphene/carbon nanofiber composites can be concluded: The growth temperature was 1100°C,the carbon source flow was 100 sccm,and the growth time was 7 min.Integration of two-dimensional graphene and one-dimensional carbon nanotubes(CNTs)to create potentially useful 3D mesoscopic carbon structures with enhanced properties relative to the original materials is very desirable.Here,we report a novel and simple route using chemical vapor deposition(CVD)methods to fabricate bead-like nitrogen-doped CNT/graphene composites(NCNT/G)via a simple pyrolysis of the N-rich melamine in the presence of graphene oxide(GO)as a substrate using a Mn-Ni-Co ternary catalyst.The three dimensional NCNT/G hybrids have unique network structures,moderate graphitization,high specific surface area,good mesoporosity,and N doping,which makes them promising materials for applications in energy storage and conversion.