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 H₂ at room temperature. The Nb₂O₅ nanorod arrays also showed good selectivity of H₂ against C₂H₆O, CO and NH₃. The hydrogen sensing performance can be attributed to the reaction between chemisorbed oxygen species and H₂. 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.