An anion exchange membrane (AEM) is a semipermeable membrane generally made from ionomers and designed to conduct anions but reject gases such as oxygen or hydrogen.
An important example is the hydroxide anion exchange membrane used to separate the electrodes of a direct methanol fuel cell (DMFC)[1] or direct-ethanol fuel cell (DEFC).
Poly(fluorenyl-co-aryl piperidinium) (PFAP)-based anion exchange materials (electrolyte membrane and electrode binder) with high ion conductivity and durability under alkaline conditions has been demonstrated for use to extract hydrogen from water.
Its yield is about 1.2 times that of commercial proton-exchange membrane technology (6 A/cm2), and it does not require the use of expensive rare-earth elements.
The system works by increasing the specific surface area.