Photocatalytic High-Quality Edge Formation Mechanism For Nanocutting Graphene

Graphene,a new two-dimensional nanomaterial with excellent physical and chemical properties,is considered to be an ideal material to replace silicon as the next generation of semiconductors.However,the application of graphene in the semiconductor field is greatly limited by its zero band gap.To overcome this problem,the band gap of graphene can be opened up by using nanoprobes to cut graphene and process it into nanoribbons of a certain width.Although several graphene processing methods have emerged,such as nanoparticle etching,energy beam processing,mask lithography and AFM mechanical scribing,all of these methods have difficulty in obtaining high-quality edge structures.In order to solve this problem,this project used AFM mechanical scribing as the basis for cutting graphene using a photocatalytic assisted approach.The structure evolution mechanism of graphene cut edges by nanoprobes was revealed from an atomic perspective by investigating the scribing process of graphene cut by probes through molecular dynamics methods,and the photocatalytic oxidation reaction of the scribed graphene films was studied.The main studies are as follows:（1）An experimental model of nanoprobe scribing of monolayer graphene films was established by Lammps.The effects of different scribing depths and scribing speeds on the scribing force,scribing edge shape and atomic isoelectric force were analysed.The simulation results showed that as the scribing depth increased,the graphene edge deformation increased,the scratch width increased,the number of defects increased and the force on the probe increased.And the local stress concentration location of graphene edge would first appear crack damage.Scribing speed had less influence on the scribing process.Therefore,the degree of graphene plastic deformation mainly increased with the increase of the scratching depth.（2）Scribing tests on graphene films were carried out by atomic force microscopy（AFM）.The results showed that the transverse force（probe graphene film）was about1865n N and the transverse force（probe silicon substrate）was about 165n N for a downward probe load of 2.7n N,and about 3588n N and 567n N for a downward probe load of 16.25n N.The transverse force of the probe increased with increasing downward pressure.The transverse force of the probe during the scribing process was mainly due to the force between the probe and graphene.（3）A photocatalytic etching test was carried out on graphene films to investigate the effect of mechanical cutting defects on the promotion of graphene photocatalytic oxidation.The experimental results showed that the new element O was detected by the energy spectrum analyser and the typical defect peak of graphene appeared in the Raman spectrum at 1350 cm^-1.This indicated that the photocatalytic oxidation reaction occurred on the surface of graphene and that graphene with mechanically cut edges was more prone to photocatalytic oxidation reactions.