Tungstic Acid Titanium Oxide Nanotubes for Proton Exchange Membrane Fuel Cell

Among various two-dimensional materials, titanium oxide nanotubes (TiO2 nanotubes) are stable and environmentally friendly, and their electronic, optical, and dielectric properties can be tuned by surface modification. Researchers used tungstic acid covalently bonded to titanium oxide nanotubes (W-TNT) for the first time as an ion-exchange filler for the fabrication of proton exchange composite membranes. The tungstate group (H2WO4) contains exchangeable protons similar to the sulfonic acid group (SO3H) and can also be used as an ion exchanger.

Two-dimensional (2D) nanostructured materials, such as nanotubes, nanorods or fibers, have the additional advantage of reduced fuel crossover due to their very large specific surface area and anisotropic structure. In addition, ion exchange groups (TNT) on the surface of sulfonated titanium dioxide - titanium dioxide nanotubes have been used as fillers for the preparation of composite membranes and have been shown to outperform non-functionalized fillers.

Therefore, tungstate groups are recommended as ion exchange materials for proton conduction. Grafting tungstate groups on the surface of TiO2 nanotubes is expected to contribute to the Grotthuss and hopping mechanisms of ion conduction. The nanocomposite membranes consisted of different concentrations of fillers (2%, 4%, 6%, 8%) in SPEEK matrix and the effect of feed ratio was evaluated in terms of water absorption, proton conductivity and ion exchange capacity.

The degree of sulfonation is an important parameter for the synthesis of SPEEK, which is also estimated from the integral values of1 H-NMR. The degree of sulfonation was determined by the comparative integration of different aromatic signals.

A lower degree of sulfonation leads to a smaller proton conductivity, while a higher degree of sulfonation leads to water swelling of the membrane. Therefore, the degree of sulfonation should be moderate.

Cited paper: Elumalai V, Deenadhayalan T, Kathleen Asitha A, et al. Preparation of tungstic acid functionalized titanium oxide nanotubes and its effect on proton exchange membrane fuel cell[J]. SN Applied Sciences, 2019, 1(4): 1-12.

• < Prev
• Next >