质子交换膜离子传输通道中水合质子结构及形成机理的研究

Hydrated proton is the basic and smallest structure of the proton transport across proton exchange membrane (PEM), thus there is great effect of the hydrated proton size on the proton flux. However, little light has been shed on the structure and the formation mechanism of hydrated proton in the ion transport channel of the membrane. Molecular dynamics method has an advantage in the simulation of the inter-molecular potential energy and the molecular movement. Thus the method is used to study the transportation of proton and water in the PEM. It is very important to accurately simulate the induced polarization effect resulted from the charged particle, thus we propose a method that the partial charges of the related atoms is adjusted every time step. Meanwhile, the extensive experiments on PEM provide plenty of data for the validation of the simulation results. Based on the simulation results, the stable structure, probability distribution and the transition mechanism of the hydrated protons are investigated to elucidate the effect of the size of the ion transport channel on the hydration number of the proton; the effects of different condition are also studied to clarify the interaction of the hydrated proton structure and the channel size; the corresponding proton conductivity is then analyzed to explore the inhibition mechanism, then the proton transfer in the ion transport channel could be modeled. The project will provide theoretical guidance for the improvement and design of the proton transport channel, the regulation of the hydrated proton structure and the development of highly conductive proton exchange membrane.

水合质子作为质子交换膜中最小质子传递单元，其尺寸直接影响质子传递通量，而人们对于膜内水合质子结构及形成机理的认识不十分明晰。分子动力学方法能有效地模拟分子间作用及其运动规律，故本项目采用该方法模拟质子和水分子在质子交换膜中的传递过程，创新地提出动态调节各原子电荷量，使带电粒子产生的诱导极化效应得到准确描述，这是准确模拟质子在膜内传递的关键，大量的实验研究也为模拟结果准确性的验证提供了数据支持；进而探究离子传递通道尺寸对质子水合数的影响，探明水合质子的稳定结构及分布规律，阐释各类型水合质子结构的形成机理及其相互转化规律；探索不同条件对水合质子结构和通道形貌的影响，提出对水合质子结构与离子传递通道尺寸间耦合作用规律进行研究，揭示影响质子传导率的关键因素，并构建描述质子在膜通道中的输运模型。本项目的实施为离子传输通道的改善和设计、水合质子尺寸的调控并开发出高质子传导性能的膜材料提供理论指导。

水合质子作为质子交换膜中最小质子传递单元，其尺寸直接影响质子传递通量，而人们对于膜内水合质子结构及形成机理的认识不十分明晰。分子动力学方法能有效地模拟分子间作用及其运动规律，故本项目采用该方法模拟质子和水分子在质子交换膜中的传递过程，创新地提出通过探究离子水合结构阐明离子传输通道的传质机制，并通过构建一维拟质子交换膜通道模型，通过DFT方法优化带电基团的偏电荷量合理描述分子间相互作用，探究膜通道尺寸、功能基团等因素对质子水合数的影响，探明水合质子的稳定结构及分布规律，阐释各类型水合质子结构的形成机理及其相互转化规律；探索不同条件对水合质子结构和通道形貌的影响，提出对水合质子结构与离子传递通道尺寸间耦合作用规律进行研究，揭示影响质子传导率的关键因素，并构建描述质子在膜通道中的输运模型。本项目的实施为离子传输通道的改善和设计、水合质子尺寸的调控并开发出高质子传导性能的膜材料提供理论指导。