Role of nanoparticle size and surface chemistry on ion transport and nanostructure of perfluorosulfonic acid ionomer nanocomposites
Role of nanoparticle size and surface chemistry on ion transport and nanostructure of perfluorosulfonic acid ionomer nanocomposites
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DOI：
10.1039/d1sm01573g
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发表时间：
2022-03-07
期刊：
影响因子：
3.4
通讯作者：
Davis, Eric M.
中科院分区：
文献类型：
--
作者：
Domhoff, Allison;Wang, Xueting;Davis, Eric M.
在此，我们系统地研究了纳米二氧化硅（SiNP）的尺寸和表面化学对纳米颗粒分散状态的影响，以及由此产生的复合离聚体膜的形态和钒离子渗透率。具体来说，Nafion含有5%质量分数的二氧化硅颗粒，其公称直径范围从10纳米到100 μ m，具有磺酸和胺功能化表面。最值得注意的是，在标称直径为200nm的含有胺功能化SiNPs的离聚体膜上，观察到钒离子渗透率降低了80%。此外，与原始Nafion相比，这些膜的质子选择性几乎增加了400%。在特定标称直径内，钒离子渗透率的趋势被认为是表面化学的一个函数，例如，对于含有非功能化SiNPs的膜，观察到钒离子渗透率随着粒径的增加而增加，而对于含有胺功能化SiNPs的膜，它被认为保持相对恒定。总的来说，随着颗粒尺寸的增加，二氧化硅颗粒倾向于表现出更高程度的聚集。从小角度中子散射实验中，观察到所有复合膜疏水畴间距的增加，尽管颗粒尺寸和表面化学对离聚体离子畴间距有不同的影响。
Herein, we present a systematic investigation of the impact of silica nanoparticle (SiNP) size and surface chemistry on the nanoparticle dispersion state and the resulting morphology and vanadium ion permeability of the composite ionomer membranes. Specifically, Nafion containing a mass fraction of 5% silica particles, ranging in nominal diameters from 10 nm to >1 mu m and with both sulfonic acid- and amine-functionalized surfaces, was fabricated. Most notably, an 80% reduction in vanadium ion permeability was observed for ionomer membranes containing amine-functionalized SiNPs at a nominal diameter of 200 nm. Further, these membranes exhibited an almost 400% increase in proton selectivity when compared to pristine Nafion. Trends in vanadium ion permeability within a particular nominal diameter were seen to be a function of the surface chemistry, where, for example, vanadyl ion permeability was observed to increase with increasing particle size for membranes containing unfunctionalized SiNPs, while it was seen to remain relatively constant for membranes containing amine-functionalized SiNPs. In general, the silica particles tended to exhibit a higher extent of aggregation as the size of the particles was increased. From small-angle neutron scattering experiments, an increase in the spacing of the hydrophobic domains was observed for all composite membranes, though particle size and surface chemistry were seen to have varying impacts on the spacing of the ionic domains of the ionomer.