摘要
为提高h-MoS2对NO的气敏性,采用第一性原理研究了 X(X=La、Ce、Pr和Nd)对h-MoS2的稳定性、吸附特性、功函数和伏安特性的影响.研究结果表明:X(X=La、Ce、Pr和Nd)取代Mo原子后得到的形成能均为负,说明掺杂体系容易形成且稳定存在.同时X掺杂后的h-MoS2布居数相比于未掺杂前的大,也说明掺杂有利于体系稳定.NO吸附在La、Ce原子顶部位置的吸附能为-1.215 eV、-1.225 eV,吸附距离分别为2.475 Å、2.854 Å,具有明显的化学吸附特征.同时Hirshfeld转移电荷分别为0.213e和0.325 e,具有明显的受体特征,提高了气敏性.La和Ce掺杂后能明显改变功函数的大小,也说明La和Ce能提高h-MoS2对NO的气敏性.施加电场后能有效提高Pr掺杂体系的吸附强度,增大Hirshfeld转移电荷,对功函数的改变最大,所以电场对Pr掺杂体系的影响非常明显.通过分析掺杂体系的伏安特性曲线,La、Ce两掺杂体系的电流分别由0增大到5.3 μA和4.8 μA,而Pr、Nd两掺杂体系的电流分别由0增大到2.2 μA和1.2 μA,所以La、Ce掺杂对于体系敏感性的影响比较明显.
Abstract
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.
基金项目
山东省重点研发计划(202054361)
山东省产品质量检验研究院标准化项(2019ZJKY028)
吉林省重点研发计划项目(ZY20200526147)
国家科技期刊平台
NSTL
万方数据