The NO gas sensitivity of monolayer h-MoS2 modified by rare earth X(X=La,Ce,Pr,Nd)
In order to improve the NO gas sensitivity of h-MoS2,the effects of X(X=La,Ce,Pr,Nd)on the stability,adsorption characteristics,work function and V-I characteristics of h-MoS2 were studied by first principles.The results reveal that the formation energies of Mo substituted by X(X=La,Ce,Pr,Nd)are all negative,indicating that the doping system is easy to form and stable.Simultaneously,the Mulliken population of h-MoS2 after X doping is larger than that before doping,which also indicates that doping is conducive to the stability of the system.The adsorption energies of NO on the top of La and Ce are-1.215 eV,-1.225 eV,and the adsorption distances are 2.475 Å,2.854 Å respectively,which has obvious chemical adsorption charac-teristics.In the meantime,Hirshfeld charges are 0.213e and 0.325e,respectively,which has obvious receptor characteristics and improves gas sensitivity.La and Ce doping can obviously change work function,which also indicates that La and Ce can improve the NO gas sensitivity of h-MoS2.The electric field can effectively im-prove the adsorption strength of Pr doping system,increase the Hirshfeld charge,and change the work function.Therefore,the effect of electric field on Pr doping system is obvious.By analyzing the V-I curves of the doping systems,the currents of La and Ce doping systems increase from 0 to 5.3 μA and 4.8 μA,respectively.Howev-er,the currents of Pr and Nd doping systems increase from 0 to 2.2 μA and 1.2 μA,respectively.Therefore,the influence of La and Ce doping on the sensitivity of the system is obvious.
Monolayer h-MoS2First-principlesGas sensitivityAdsorption energyWork function
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