Titanium oxide tungstate nanotubes could improve fuel cell performance. The chemical oxidative stability of the tungstate-functionalized sulfonated poly ether ether ketone (SPEEK) membranes is one of the key requirements for the durability and performance of the fuel cells, which was estimated using Fenton's reagent method.

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.

Ion exchange capacity is a vital property of ionic membranes, and this property is enhanced with the addition of ion-exchange materials. The IEC value of pure SPEEK membranes is 1.9 meq g^-1 due to the contribution of sulfonate group (SO₃H). increasing the content of tungstate titanium oxide nanotubes (W-TNT) in sulfonated poly ether ether ketone (SPEEK) membranes could improve the fuel cell ion-exchange capacity.

Titanium oxide nanotubes (TNT) were synthesized by hydrothermal method and covalently grafted with tungstic acid (ion exchange group) on their surface. The synthesized tungstate functionalized TNT (W-TNT) was characterized by SEM, TEM, and XRD analysis, and the successful grafting of the tungstate group was confirmed by FTIR and solid-state NMR techniques.