Molecular Dynamics Simulation Of Photocatalytic Auxiliary Cutting Of Graphene

Graphene is a allotrope of carbon atom with hexagonal honeycomb structure.It is the sole stable two-dimensional material in nature.combining with excellent mechanical,electrical and thermal properties,graphene is a promising material for new generation of semiconductor instead of silicon and has broad application prospects in many fields.However,the biggest obstacle of graphene to the realize of semiconductor function at present is its zero band gap characteristic,which makes graphene have not semiconductor characteristics without special edge structure and non-composite materials.Therefore,ultra-precision processing method is needed to change this feature into special edge structure with armchair edge or zigzag edge..There are many methods for cutting graphene such as photolithography,electron beam processing,AFM cutting,etc..To overcome the low precision or high cost of these methods,this paper proposes a new photocatalytic oxidation technology assisted precision cutting method based on the mechanical cutting of graphene.The main research work is as following:(1)The molecular dynamics model of cutting graphene was established by LAMMPS.base the simulation,the edge morphology and defect types of graphene were observed when diamond tips cut graphene with different directions.Also the material energy of graphene and cutting force was analysized in detailedly.The simulation results show that the mechamical cutting ofgraphene presents previous anisotropy.When the edge is cut along the armchair direction,the cutting edge is rough with open carbon chain,and the system energy and the cutting force is small;While the edge is cut along the zigzag direction,it is easy to appear smooth edge with closed carbon chain.The system energy and the cutting force is large.(2)The feasibility and chemical reaction rate of photocatalytic oxidizing graphene were studied.By calculating the Gibbs free energy of the photocatalytic reaction,is the study judged whether the chemical reaction can spontaneously proceed or not at normal temperature,and the energy barrier of the chemical reaction is calculated.According to the thermodynamic parameters,the Gibbs free energy of the photocatalytic oxidizing graphene reaction becomes-1139.89 kJ/mol under the condition of 298 K temperature.It indicates that the reaction has the possibility of spontaneously proceeding in the positive direction under this condition.The calculation of transition state shows the first step of the photocatalytic reaction is highest.(3)The promotion of mechanical action on photocatalytic oxidizing reaction was studied.The model of photocatalytic reaction of graphene with different edge structure is established.The photocatalytic reaction simulation shows the reaction barrers of graphene with mechanical cutting defects are lower than that of regular edges.Both carbon chain and SW defects can decrease the reaction barrer.It indicates that the mechanical action can promote the photocatalytic chemcial oxidation rate.