Nafion®/mordenite composite membranes for improved direct methanol fuel cell performance

Composite polymer proton exchange membranes (PEM) were prepared by solution recasting. The composite membranes formed are based on Nafion incorporating a silane functionalized zeolite, mordenite, as an additive. The composite membranes were placed within a single cell DMFC and compared to an MEA featuring a standard Nafion 125 μm membrane. The impact of mordenite particle size, the choice of the silane functionalizing agent and the membrane preparation procedure are investigated. A composite ion exchange membrane which featured Nafion and a ground mordenite which was functionalized using glycidoxypropyltrimethoxysilane achieved a power density that outperformed a standard Nafion MEA under all conditions.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (120 K)Download as PowerPoint slideResearch highlights▶ Nafion/mordenite membranes perform better when the surface of the inorganic moiety is functionalized with a silane coupling agent. ▶ DMFC performance falls when the inorganic moiety is allowed to settle out of solution. ▶ If the solution is allowed to settle out of solution it can form a compact layer at one side of the membrane which blocks the effective movement of protons through the MEA. ▶ The new membrane out performs a standard Nafion membrane.