UCL Discovery

Abstract

This paper describes the synthesis and characterization of a novel mesostructured solid electrolyte composite material, denoted meso-SiO2-C12EO10OH-CF3SO3H. A lyotropic non-ionic surfactant-triflic acid-silicate liquid crystal is used as a supramolecular template for a one-pot synthesis of the material. Within this structure, the oligoethyleneoxide head groups of the non-ionic surfactant that is imbibed within the channels of hexagonal mesoporous silica act in a crown-ether-like fashion towards the protons. The structure and dynamics of the silicate-oligo(ethylene oxide)surfactant-triflic acid co-assembly has been studied via several analytical techniques. These methods include polarized optical microscopy (POM), powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), multinuclear nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric analysis (TGA), and Fourier transform (FT) Raman spectroscopy. Together these results imply that the protons coordinate to the oxygen atoms of the ethylene oxide units on the non-ionic surfactant and the compound has the structural integrity of the silicified liquid crystal. AC impedance spectroscopy was used to determine the proton conductivity of the meso-SiO2-C12EO10OH-CF3SO3H composite material at different relative humidity values giving some insight into its potential utility as a proton conducting solid electrolyte in a proton-exchange membrane fuel cell.