Room temperature H2 sensing using functionalized GaN nanotubes with ultra low activation energy

A single-step synthesis route of square shaped wurtzite GaN nanotubes is reported by a quasi-vapor–solid process with detailed growth kinetics involving surface energies and Ga mobility along different crystalline facets. A wet chemical route is used for the functionalization of GaN nanotubes with Pt nanoclusters of average diameter ∼1.6 (0.4) nm in order to instigate the formation of localized Schottky barrier, responsible for carrier transport in the sensing process. Catalytically enhanced dissociation of molecular H2 down to the lowest detection limit of 25 ppm at room temperature, as compared to those of reported GaN systems has been shown. We report, for the first time, a very low activation energy value of 29.4 meV which will be useful in practical sensing of H2 at room temperature without any application of bias.

► Anomaly of square faceted nanotube for GaN having hexagonal symmetry is resolved. ► Growth mechanism of nanotube formation is provided for the first time. ► Functionalization with Pt nanoparticles of ∼1.6 (0.4) nm in a wet chemical route. ► Lowest ever reported detection limit of 25 ppm hydrogen at room temperature. ► Lowest ever reported activation energy value of 29.4 meV.