石墨烯及二氧化钛孔道内小分子扩散的反应分子动力学模拟

摘要

The reaction and diffusion of small organic molecules in confined spaces are hot issues in the field of nanoscale diffusion.Based on the nano-confined space composed of graphene or anatase titanium dioxide(101)thin layers,the diffusion and transport of common small organic molecules(benzene,phenol,methane)were explored by the molecular dynamics simulation with reactive force field(ReaxFF).The effects of pore materials and confined space size on the diffusion and density distribution of small molecules were examined.The results show that the small molecules in the confined space tend to accumulate near the surface of the pore material. With the increase of nano-slit width,the diffusion coefficients of benzene and phenol molecules show the tendency to increase at first and then decrease in the graphene interlayer,while these coefficients in methane system express monotone decreasing.The diffusion of phenol molecules in the titanium dioxide(101)interlayer is severely restricted indicating that the chemical reaction during the transfer process leads to the slow dow n of diffusion.%受限空间内有机小分子的反应、扩散传递是纳微尺度扩散传递领域的研究热点.以石墨烯或锐钛矿二氧化钛(101)薄层组成的纳米受限空间为研究对象,采用基于反应力场(Reax FF)的分子动力学方法研究了工业应用中常见有机小分子(苯、苯酚、甲烷)在受限空间内的扩散传递行为.模拟中分别研究了孔道材料、受限空间尺寸对小分子扩散及密度分布的影响.结果表明:受限空间内的有机小分子趋向于在孔道材料表面积聚,苯和苯酚分子的扩散系数在石墨烯孔道内随着孔道宽度的增加都呈现出先增后减的趋势,而甲烷分子的扩散系数随着孔道宽度的增加单调减小;二氧化钛孔道内苯酚分子由于发生化学反应扩散明显受阻,说明传递过程中的化学反应会导致扩散过程明显减慢.