Modelling of proton diffusion in immobilised imidazole systems for application in fuel cells

The mobility of an excess proton has been studied in systems of immobilised imidazole under different conditions using quantum mechanical approaches coupled to a molecular mechanics force field in molecular dynamics. The system is a simple model for imidazole covalently bound to a mesoporous material. Such materials are intended to be used as an additive to a polymer electrolyte membrane for fuel cells. This theoretical work is focused on dynamic properties of the proton transport. The diffusion constant of the system is found to be in the order of magnitude of 10(-9) m(2) s(-1) and it is verified that the proton diffusion increases with increase in temperature or density. Further, the proton transport mechanism is investigated.