Measuring the surface diffusivity of argon in nanoporous carbon.
Measuring the surface diffusivity of argon in nanoporous carbon.
复制标题
测量纳米多孔碳中氩的表面扩散率。
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Yunfeng Shi
中科院分区：
文献类型：
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作者：
Xi Mi;Yunfeng Shi
气体在多孔介质中的扩散包括表面跳跃和非表面弹道/体扩散。遗憾的是，通常只测量总体扩散系数，而不分成不同的扩散模式。在这里，我们报道了一种利用分子动力学模拟来区分表面扩散和非表面扩散对纳米多孔碳中Ar扩散的贡献的数值方法。关键是根据吸附/解吸状态截断Ar的轨迹，从而根据扩散过程中的特定机制对质量通量进行归属。表面扩散系数和非表面扩散系数均随气体载量的增加而先增大后减小。然而，表面扩散系数和非表面扩散系数作为纳米孔网络的温度和气体-衬底亲和力的函数表现得非常不同。
Gas diffusion in porous media consists of surface hopping and non-surface ballistic/bulk diffusion. Unfortunately, only the overall diffusivity is usually measured, without being separated into various diffusion modes. Here, we report a numerical method to differentiate contributions from surface diffusion and non-surface diffusion for argon diffusion in nanoporous carbon using molecular dynamics simulations. The key is to truncate the argon trajectories based on the adsorption/desorption state, and thus attribute mass fluxes according to specific mechanisms during diffusion. Both the surface diffusivity and non-surface diffusivity increase and then decrease as a function of gas loading. Yet, surface diffusivity and non-surface diffusivity behave very differently as a function of the temperature and gas-substrate affinity of the nanoporous network.