Fast proton-conducting ceramic membranes derived from ferroxane nanoparticle-precursors as fuel cell electrolytes

Ceramic membranes derived from carboxylate-ferroxane nanoparticles are shown to yield high power (5.21 mW cm−2) and current (16.5 mA cm−2) densities in a working membrane electrode assembly, comparable to those obtained using untreated Nafion® membranes. The ceramic membranes have a high density of surface hydroxyl sites, conducting protons by a mechanism consistent with Grotthuss diffusion that is nearly insensitive to humidity over a range of 33–100% RH.