Ethanol-water mixtures, physicochemical

Water is the active medium of PEFCs. From a chemical point of view, water is the main product of the fuel cell reaction. It is the only product in hydrogen fuel cells. Cells supplied with direct methanol or ethanol as the fuel produce water and carbon dioxide in stoichiometric amounts. The low operating temperature implies that water is present in liquid form. It mediates direct electrostatic as well as colloidal interactions in solutions or ink mixtures containing ionomeric, electronic, and electrocatalytic materials. These interactions control phase separation and structural relaxation phenomena that lead to the formation of PEMs and CLs. Variations in water content and distribution, thus, lead to transformations in stable structures of these media, which incur modifications in their physicochemical properties. It is evident that many of the issues of understanding the structure and function of fuel cell components under operation are intimately linked to water fluxes and distribution. 

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