Room-temperature hydrogen sensing performance of Nb2O5 nanorod arrays

Nb2O5 nanorod arrays with a hexagonal phase were in situ grown on Nb foil via a facile hydrothermal method. The aspect ratio and spacing of the Nb2O5 nanorods increased upon an increase in the reaction temperature. A pair of platinum electrodes was deposited on the surface of the Nb2O5 nanorod arrays to form a hydrogen sensor. The sensor based on Nb2O5 nanorod arrays exhibited a fast and highly-sensitive hydrogen response with a sensitivity of 74.3% and a response time of 28 s toward 6000 ppm of H-2 at room temperature. The Nb2O5 nanorod arrays also showed good selectivity of H-2 against C2H6O, CO and NH3. The hydrogen sensing performance can be attributed to the reaction between chemisorbed oxygen species and H-2. The Nb2O5 nanorods have a high aspect ratio, leading to an increase in the chemisorbed oxygen species on the surface of the [001] orientated nanorods. Moreover, arrays with a vertical structure have low quantities of junctions, which allow oxygen ions to diffuse more easily.