Nafion

About: Nafion is a research topic. Over the lifetime, 9110 publications have been published within this topic receiving 320865 citations.

Perfluorosulfonated membrane (Nafion): FT-IR study of the state of water with increasing humidity

Abstract: A detailed study of the Nafion–water system has been performed using water sorption isotherm, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and FT-IR with the aim of investigating the state of water in the Nafion membrane. The last technique in particular can yield valuable information on molecular interactions, especially those involving water molecules. The first water molecules interact with sulfonic groups, forming hydronium H3O+ and –SO3- ions, while the following water molecules aggregate with H3O+ to form counter-ion clusters with five or six water molecules. Increasing the water content promotes cluster growth and cluster aggregation with the formation of a continuous water phase, where for every four molecules of water one has two hydrogen bonds, and each of the other three only one. All the sorption, calorimetric and infrared data agree with the proposed model of two non-interacting phase systems: the water-phase and the perfluoro-phase with sulfonic groups at the interphase. The only observed effects of water on Nafion polymer are sulfonic group dissociation and partial destruction of crystallinity associated in polymer swelling.

On the micro-, meso-, and macroporous structures of polymer electrolyte membrane fuel cell catalyst layers.

Abstract: In this work, N2 adsorption was employed to investigate the effects of carbon support, platinum, and ionomer loading on the microstructure of polymer electrolyte membrane fuel cell catalyst layers (CLs). Brunauer−Emmett−Teller and t-plot analyses of adsorption isotherms and pore-size distributions were used to study the microstructure of carbon supports, platinum/carbon catalyst powders, and three-component platinum/carbon/ionomer CLs. Two types of carbon supports were chosen for the investigation: Ketjen Black and Vulcan XC-72. CLs with a range of Nafion ionomer loadings were studied in order to evaluate the effect of an ionomer on the CL microstructure. Regions of adsorption were differentiated into micropores associated with the carbon primary particles ( 50 nm). Ketjen Black was found to possess a significant fraction of micropores, 25% of the total pore volume,...