不同结构石墨烯纳米带吸附NH3的第一性原理研究

A First Principle Study on Adsorption of NH3 by Graphene Nanoribbons with Different Structure

为了进一步提高基于石墨烯的气敏传感器对NH3的传感性能,采用第一性原理方法,研究了NH3与不同结构扶手椅型石墨烯纳米带(AGNR)的相互作用,通过计算吸附能、电荷转移和灵敏度,分析NH3在单层AGNR(MAGNR)结构上的最稳定吸附位置,以及3种含氧官能团(羟基、羧基、环氧基)的修饰对传感性能的影响。在此基础上,研究MAGNR结构、双层AGNR(BAGNR)结构、含氧官能团修饰AGNR(MGO)结构以及MAGNR与MGO堆叠结构(MGO-MAGNR)对NH3的传感性能。结果表明:NH3在MAGNR结构碳六环的中心位置吸附最稳定,吸附能(-0.36 eV)和电荷转移量(-4×10^-21 C)最小;羟基、羧基、环氧基的修饰会使MAGNR结构对NH3的吸附能分别减小0.39、0.21和0.19 eV,传感性能增强;相对于MAGNR结构,BAGNR结构对NH3的灵敏度始终小于0.1,传感性能降低;相对于MAGNR、MGO、BAGNR这3种结构,NH3在MGO-MAGNR结构上的吸附能更小,传感性能更好。

The interaction between NH3 and armchair graphene nanoribbons(AGNR)with different structures is studied by the first principle method to further improve the sensing performance of graphene-based gas sensors to NH3.The most stable adsorption position of NH3 on the monolayer-AGNR(MAGNR)structure and the effects of the modification to three oxyfunctional groups(hydroxyl,carboxyl,epoxy)on the sensing performance are analyzed by calculating the adsorption energy,charge transfer and sensitivity.On this basis,the sensing performances of MAGNR structure,bilayer AGNR structure(BAGNR),MAGNR structure modified by oxyfunctional groups(MGO)and MGO,MAGNR stacking structure(MGO-MAGNR)to NH3 are studied.Results show that the adsorption of NH3 is the most stable,and the adsorption energy(-0.36 eV)and the charge transfer(-4×10^-21 C)are respectively the smallest at the center of the carbon hexagon on the MAGNR structure.Modifications of hydroxyl、carboxyl and epoxy reduce the adsorption energy of MAGNR structure to NH3 by 0.39 eV,0.21 eV and 0.19 eV,respectively,and enhance the sensing performance.Compared with the MAGNR structure,the sensitivity of the BAGNR structure to NH3 is always less than 0.1,and the sensing performance is reduced.Compared with the three structures of MAGNR、MGO and BAGNR,NH3 has a smaller adsorption energy on the MGO-MAGNR structure,and better sensing performance.