Ling Xiao, Bonn Mischa, Parekh Sapun H, Domke Katrin F
Department of Molecular Spectroscopy, Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany.
Angew Chem Int Ed Engl. 2016 Mar 14;55(12):4011-5. doi: 10.1002/anie.201600219. Epub 2016 Feb 19.
The connection between the nanoscale structure of two chemically equivalent, yet morphologically distinct Nafion fuel-cell membranes and their macroscopic chemical properties is demonstrated. Quantification of the chemical interactions between water and Nafion reveals that extruded membranes have smaller water channels with a reduced sulfonic acid head group density compared to dispersion-cast membranes. As a result, a disproportionally large amount of non-bulk water molecules exists in extruded membranes, which also exhibit larger proton conductivity and larger water mobility compared to cast membranes. The differences in the physicochemical properties of the membranes, that is, the chemical constitution of the water channels and the local water structure, and the accompanying differences in macroscopic water and proton transport suggest that the chemistry of nanoscale channels is an important, yet largely overlooked parameter that influences the functionality of fuel-cell membranes.
证明了两种化学等效但形态不同的全氟磺酸（Nafion）燃料电池膜的纳米级结构与其宏观化学性质之间的联系。对水与Nafion之间化学相互作用的定量分析表明，与分散浇铸膜相比，挤出膜具有更小的水通道，磺酸头基密度降低。因此，挤出膜中存在数量不成比例的大量非本体水分子，与浇铸膜相比，其还表现出更高的质子传导率和更大的水迁移率。膜的物理化学性质差异，即水通道的化学组成和局部水结构，以及随之而来的宏观水和质子传输差异表明，纳米级通道的化学性质是影响燃料电池膜功能的一个重要但在很大程度上被忽视的参数。
