氢修饰石墨烯纳米带压电性质的第一性原理研究

采用第一性原理计算方法, 系统研究了不同宽度、不同边缘修饰模式的间隔氢吸附锯齿型石墨烯纳米带的压电性质. 结构优化和结合能计算表明, 氢修饰石墨烯纳米带结构稳定. 氢原子间隔排列的吸附使得纳米带中的相邻碳原子成键及电荷状态不同, 导致拉伸时纳米带中六元碳环的正负电荷中心不再重合, 产生宏观电极化. 纳米带宽度越宽, 包含六元碳环数目越多, 则拉伸时纳米带长度方向上电偶极矩密度越大, 其压电性能越强. 另外, 边缘原子电荷状态决定了无拉伸时纳米带的初始电偶极矩密度, 其大小可以通过改变边缘氢原子的修饰模式来有效调控. 关键词： 石墨烯纳米带 第一性原理 修饰改性 压电性质

First-principles study on the piezoelectric properties of hydrogen modified graphene nanoribbons

This paper focuses on the piezoelectric properties of zigzag graphene nanoribbons with hydrogen selective modifications by first-principles calculations. The structures of hydrogen modified graphene nanoribbons are optimized and the calculated hydrogen binding energies indicate that these structures are very stable. Owing to the hydrogen atom selective adsorption, the adjacent carbon atoms have different charge states and breaking inversion symmetries of nonpiezoelectric graphene. So, the positive charge centers and the negative charge centers of the hexatomic carbon ring in these structures separate from each other under uniaxial tensile strain, inducing the macroscopical electric polarization. Furthermore, the gradient of strain induced dipole moment density is related to ribbon width, i.e., the wider the ribbon, the better the piezoelectric property is. Besides, the dipole moment density of hydrogen selective modified graphene nanoribbons without strain could be controlled by changing the edge modification configuration of hydrogen atoms effectually.