Sulfonated polyether ether ketone/strontium zirconite@TiO2 nanocomposite membranes for direct methanol fuel cells
Nanocomposite membranes consisting of sulfonated perovskite-type strontium zirconite (sSrZrO3) and sSrZrO3@TiO2 nanofillers integrated into a sulfonated polyether ether ketone (SPEEK) matrix have been explored as ion-exchange membranes for direct methanol fuel cells (DMFCs). The perovskite fillers improved the thermal and oxidative stabilities of the SPEEK membranes. Due to the hygroscopic characteristics of sSrZrO3@TiO2, the SPEEK/sSrZrO3@TiO2 nanocomposite membrane adsorbed a large amount of water, which facilitated the dissolution of acid moieties and led to enhanced proton conductivity. The narrower channels formed in the SPEEK/sSrZrO3@TiO2 nanocomposite via the uniform distribution of sSrZrO3@TiO2 fillers in the SPEEK matrix restricted fuel transport and improved the selectivity ratio of proton conductivity to methanol permeation. A DMFC constructed with the SPEEK/sSrZrO3@TiO2 membrane offered superior power and current densities of 140 mW cm−2 and 639 mA cm−2, respectively, at 80 °C, compared to those obtained with a Nafion 117 membrane.