| Due to the flexible bonding ability,different microstructures can be formed in carbon-based nano-surfaces and multi-phase combinations of several structures.In particular,carbon nano-surfaces containing nano-size graphene crystallites can be manufactured in a controlled manner and integrate good mechanical,optical,electrical,and magnetic properties.Therefore,they show a broad application prospects in solid lubrication,micro-nano sensing,and friction-electrification.As a microscopic characterization method,the atomic force microscope(AFM)probe can accurately measure surface roughness,potential,and mechanical properties at the nanoscale;enhanced Raman spectroscopy based on AFM probes(TERS)can analyze the carbon surface structure at the nanoscale,exploring the mechanism of structural evolution in the process of surface deformation.Therefore,this study proposes to use atomic force probes as the core means to study the effect of graphene nanocrystals on the structure,morphology and properties of carbon films,and their bonding state on the surface of carbon nanoparticles.This study will provide direct experimental evidence for the formation and evolution laws of graphene nano crystallites,and provide an important reference for further regulation of the properties of graphene nano crystallite carbon film.Firstly,Graphene nano crystallite carbon films were grown using electron cyclotron resonance plasma,when graphene nanocrystals of different sizes were formed by adjusting the substrate bias.The effect of crystallite evolution on the surface morphology was studied using AFM mode.The average size of nanocrystals in carbon films ranged from 0.95 nm to1.85 nm,and the surface roughness Ra increased from 0.19 nm to 0.82 nm as the average nanocrystal size increased.The effect of graphene crystallite on the surface potential was analyzed using the Kelvin probe mode.The results show that as the degree of nanocrystals inside the carbon film increases,the edges of graphene nanocrystals increases,the quantum well effect from the edges increases,and the surface electronegativity also increases.The negative is enhanced and the relative surface potential is reduced from-120 mV to-192 mV.Next,the surface was scratched,and the changing rule of the scratch morphology was studied by AFM.The TERS mode of the probe can increase the resolution of the Raman spectrum from 1 ?m to 25 nm.The structure of the scratched area was characterized,and the evolution mechanism of graphene nano crystallite during scratching was obtained.The results show that the peak ratio ID/IG inside the scratch is 2.6 greater than 1.6 measured from the original carbon film,which may be due to the increase in the size of the graphene layer inside the scratch.Finally,the van der Waals' s force inside the graphene crystallite was destroyed by liquid phase stripping method,and the independent dispersed graphene nano crystallite was found by Raman spectroscopy and AFM test.Combined with transmission electron microscopy observations,the structural changes of graphene nano crystallite particles were explored.The results show that the particle size of the carbon film particles has increased after the liquid phase stripping treatment.It may be that the van der Waals force in the graphene nanocrystalline particles is destroyed,causing a part of the folded graphene atomic layer to expand.Time has no obvious effect on the separation effect of nanocrystals.The graphene nanocrystal particles are not obtained in the existing method,and the test needs to be further improved. |
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