Proton-conducting sol-gel hybrids containing heteropoly acids

Organically modified silicate/heteropoly acid hybrids were made through a s ol-gel process from ethoxy silane functionalised by polypropylene glycol of various chain lengths. Heteropoly acids were incorporated as a source of p rotons. The gels with a high heteropoly acid loading show protonic conducti vities of about 10(-3) S/cm at room temperature. The process of crystallisa tion and agglomeration of Keggin units was followed by X-ray diffraction an d infrared spectroscopy. The membranes were applied in a direct methanol fu el cell at room temperature. (C) 2001 Elsevier Science B.V. All rights rese rved.