TiO2 Nanotubes produced by two step anodization on hydrogen detection and electrical characterization

Hydrogen energy is one of the important candidates in the search for an alternative energy source to fossil fuels due to their environmental hazards. The fact that hydrogen, which is colorless and odorless, has flammable and explosive properties at concentrations above 4% makes hydrogen safety an important issue [1]. Therefore, sensors that can accurately detect low concentrations of hydrogen at low temperatures are needed for hydrogen safety. This will ensure the safe use of hydrogen in the production, transportation, storage, and technological and industrial applications [2]. Titanium dioxide (TiO₂), has attracted attention in many technological applications due to its advantages in structural properties. TiO₂ nanotube production has been evaluated in gas sensor research due to the convenience it provides in the surface area [3].

One of the methods used for the production of TiO2 nanotubes is the anodization method [4]. Unlike previous studies, the dual anodization method was preferred in this study. In order to prepare the electrolyte containing 0.5% NH₄F, 47.25 mL of ethylene glycol, 2.50 mL of ultrapure water, and 0.25 g of NH₄F were added to the mixture as a result of the stock solution calculation for a 50 g sample. Platinum (Pt) and titanium (Ti), used as cathodes, were immersed in the electrolyte. The first anodization step was applied at 20 °C, 60 V, for 2 hours, and the formation of TiO2 nanotubes was observed. The second anodization step was applied at 20 °C, 40 V, for 1 hour. Thanks to the two-stage anodization protocol, nanotubes with morphological integrity, high regularity, and homogeneous wall thickness were produced. SEM images and XRD analysis were performed on the produced nannotubes.

Following the anodization process, electrical characterization and gas tests were performed on the completed Ti/TiO2 nanotubes/Pt device. The results showed that the nanotubes produced by dual anodization had better performance.

This study was funded by The Scientific and Technological Research Council of Türkiye (TUBİTAK), Project Number: 123F411.