Jackson Grayson L, Perroni Dominic V, Mahanthappa Mahesh K
Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States.
Department of Chemical Engineering & Materials Science, University of Minnesota , 421 Washington Avenue, S.E., Minneapolis, Minnesota 55455, United States.
J Phys Chem B. 2017 Oct 12;121(40):9429-9436. doi: 10.1021/acs.jpcb.7b06366. Epub 2017 Oct 3.
Nanoporous proton-transporting media are critical components in fuel cells and other electrochemical devices, yet general molecular design criteria for new materials with enhanced performance remain obscure. Aqueous lyotropic liquid crystals (LLCs) comprise a platform for detailed studies of the molecular-level features governing proton transport in monodisperse, water-filled nanopores lined with well-defined chemical functionalities. We report new alkylsulfonic acid LLCs that exhibit H conductivities as high as σ = 380 mS/cm at 80 °C, which rival those of more acidic, perfluorinated polymers, thus demonstrating that the acidity of the pore functionality is not the sole determinant of proton transport. Direct experimental comparisons of LLCs with convex and concave nanopores of similar dimensions indicate that H conductivities therein sensitively depend on the hydration state of the acid functionalities and the pore curvature. These experiments suggest that judicious manipulation of pore curvature provides a new means for optimizing the activities of proton-exchange membranes and nanoporous solid acid catalysts.
纳米多孔质子传输介质是燃料电池和其他电化学装置的关键组件，但具有增强性能的新材料的一般分子设计标准仍不明确。水性溶致液晶（LLC）为详细研究在具有明确化学功能的单分散、充满水的纳米孔中质子传输的分子水平特征提供了一个平台。我们报道了新型烷基磺酸LLC，其在80°C时的H电导率高达σ = 380 mS/cm，可与酸性更强的全氟聚合物相媲美，从而表明孔功能的酸度不是质子传输的唯一决定因素。对具有相似尺寸的凸形和凹形纳米孔的LLC进行直接实验比较表明，其中的H电导率敏感地取决于酸性官能团的水合状态和孔曲率。这些实验表明，明智地控制孔曲率为优化质子交换膜和纳米多孔固体酸催化剂的活性提供了一种新方法。
