Transport properties of fast proton conducting mesoporous silica xerogels

Abstract

Abstract Mesoporous acid-free silica xerogels exhibiting a proton conductivity of 2.0×10 −2 Scm −1 at 80 ◦ C and 81% RH is reported for the first time.The proton conductivity values, lower cost and higher hydrophilicity of mesoporous silica xerogels make them potential substitutes for Nafionmembranes in proton exchange membranes fuel cells (PEMFCs).© 2007 Elsevier B.V. All rights reserved. Keywords: Fuel cells; Proton exchange membranes; Silica xerogels; Mesoporosity 1. Introduction Proton conducting materials have attracted much attentionbecause of their potential use in clean-energy fields such as fuelcells [1], capacitors [2], proton sensors [3], and ion-exchange-membranes [1]. The series of perfluorosulfonate ionomers suchas Nafion are the most well-known proton conductive mate-rials and serve as ion-exchange membranes due to their highproton conductivity [1]. However, their conductivity decreasesat temperatures higher than 80 ◦ C because of their inabilityto retain water, instability at high temperature (above 100