| Graphene,as an emerging two-dimensional material,is hopeful to be the next generation of semiconductor materials with its good electronic properties.However,the zero bandgap structure formed by graphene Dirac points has greatly limited the practical application of graphene.Researchers have found that the graphene nanoribbon(GNR)formed by cutting graphene through atomic force microscopy(AFM)probes can successfully open the bandgap.However,the defects produced after cutting hinder the opening of the GNR bandgap.Therefore,in this paper,various defects generated at the back edge of cutting graphene are simulated in Materials Studio(MS)to analyze the effect of different defects on armchair graphene nanoribbons(AGNR),and introduced photo-modification technology to analyze the charge density of defected graphene nanoribbons(D-AGNR)to explore the electron exchange connection between photocatalytically formed oxhydryl and different kinds of defects.The main research contents of this paper are as follows:(1)Analyze and select boundary conditions,ensembles,and potential functions suitable for the model to ensure the validity and accuracy of the simulation results.Moreover,through theoretical research,the dispersion relationship of graphene and the edge state analysis results of GNR are obtained.At the same time,analyze and select the force field,functional and basis set suitable for MS simulation,and finally select the appropriate length and width of AGNR.(2)Different edge defects are obtained through Lammps simulation,namely single-vacancy defects,double-vacancy defects,hole defects,C-ring defects,and crack defects.MS simulation of different defects shows that the maximum energy required for the formation of hole defects is 40.964 e V.The minimum energy of Stone Wales(SW)defect formation is4.276 e V.Moreover,most of the defects cause the AGNR band gap to decrease,and the minimum band gap reaches 0.And through the calculation and analysis of the density of states of D-AGNR,it can be seen that the defects will lead to the increase of the density of states.Among them,the maximum density of crack defect state reaches 56.628,and the adsorption capacity is the strongest.Unfavorable defects can thus be eliminated by atomic adsorption and hydroxyl groups.(3)The electronic properties of AGNR under H atom adsorption were simulated,and it was found that the formation energy of defects after adsorption increased.Especially for hole defects,the maximum energy difference is 12 e V.At the same time,it is found that the bandgap generally increases after adsorption;for example,the Single Vacancy(SV)defect bandgap increases to 0.277 e V after the adsorption of H atoms.Therefore,adatoms make AGNR more favorable for practical applications.The influence of different types of defects on electron transport was explored,and it was found that defects in general lead to the decline of the electronic performance of AGNR,especially crack defects.The deeper and broader the crack defect,the worse the electronic performance.For instance,absence of 10 C atoms(C10)crack defects lead to the disappearance of the first platform,and the transmission value drops by 3times.Electron scattering and the quantum Hall effect are the main reasons for electronic performance degradation.(4)The influence of oxhydryl on the electron transfer of D-AGNR was analyzed.It was found that the color change of the image before and after adsorption of defects was the most obvious,and the electron transfer was the most.The image change of SW defect before and after adsorption is the least obvious,and the electron transfer is the least. |
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