Proton Conducting Sol-Gel Materials

Fuel-cells allow the efficient conversion of chemical to electrical energy. The currently commercially used membranes need an aqueous phase for the proton transport and are therefore limited to temperatures below the boiling point of water. A higher operating temperature would increase the tolerance of the platinum catalyst to carbon monoxide poisoning. The development of water-free polymer electrolyte membranes (PEM) with good proton conduction at high temperatures would be a breakthrough in the fuel cell technology. Nitrogen-containing heterocylcles can act as proton-carriers and can therefore replace the aqueous phase in the membrane. The underlying project deals with the preparation of sol-gel materials with triazole in mesostructured pores. It is expected that the proton conduction along the channels filled with heterocycles will be increased. The incorporation of the heterocylces will be performed either directly by using triazole containing amphiphiles or indirectly by infiltration of triazole in the pores of a pre-formed mesostructured material. The proton conductivity of materials will be measured on samples prepared in the form of pellets. The last part of the project deals with the preparation of membranes. The systems with the best results in respect to proton conductivity will be optimized for the preparation of flexible membranes. This will be attempted by three different strategies. The first approach uses silanes that contain a polymerizable organic group that allows the formation of an organic network in addition to the inorganic network formed by the sol-gel process. The second approach uses bis-silanes that are bridged by a polymer and allow the preparation of an inorganic-organic hybrid network. In the last approach membranes will be formed by in-situ sol-gel reactions in a polymer solution followed by a slow drying procedure.