Surface Enriched Sulfonic Acid Ionic Clusters of Nafion Nanofibers as Long‐Range Interconnected Ionic Nanochannels for Anisotropic Proton Transportation: Phenomenon and Molecular Mechanism

Abstract

AbstractConstruction of long‐range interconnected ionic channels in proton exchange membranes (PEMs) is the key to realize anisotropic proton transportation. But, how to effectively modulate ionic channels at the molecular level still remains a great challenge for modern nanoenergy technology. Here, surface enriched sulfonic acid ionic clusters in Nafion (NF)/ZnO nanofibers are successfully designed and fabricated as long‐range interconnected ionic channels, in which the ZnO nanofiller (nano‐ZnO) act as an inducer to enable the spatial deformation and inversion of sulfonic acid groups in NF molecule from the inside to the surface of the NF/ZnO nanofibers, due to the strong intermolecular electrostatic interactions between nano‐ZnO and the CF2 of NF backbones. The phenomenon and molecular mechanism are visually confirmed by physicochemical analysis. Ultimately, the NF/ZnO nanofibers demonstrate the relative higher of proton conductivity up to 253.2 mS cm‐1 and power density of 115.72 mW cm‐2 than that of reported NF‐based PEMs. This study, for the first time, reveals that the surface enrichment of sulfonic acid ionic clusters is an efficient strategy to construct long‐range interconnected ionic channels in the NF‐based PEMs, proves that the formation of the ionic channels could be efficiently modulated by controlling the molecular activity and morphology of nanofiller.