Structure-dependent room-temperature hydrogen sensing of Nb2O5 nanorods prepared by topological transformation process

Abstract

The development of reliable low-power-consumption hydrogen gas sensors is of great significance for the accurate detection of hydrogen leakage in the hydrogen-related industries. Nb2O5 nanomaterials have exhibited great potential for building highly selective hydrogen sensors owing to its outstanding hydrogen catalytic capability, but still suffer from relatively low hydrogen sensitivity at room temperature. Herein, the orthorhombic and hexagonal Nb2O5 nanorods with different defect states are prepared through a combined topological transformation process. The Nb2O5 nanorods with polycrystalline orthorhombic structures exhibit much higher room-temperature hydrogen response comparing with the single-crystalline hexagonal Nb2O5 nanorods. Moreover, both phases of the Nb2O5 nanorods exhibit certain amounts of oxygen vacancies, as well as the interstitial Nb4+ and related oxygen defects. The elimination of the Nb4+ and related oxygen defects can significantly enhance the surface reactivity of the Nb2O5 nanorods and improve the sensor response of the chemiresistor devices. The sensor based on the defect-modified orthorhombic Nb2O5 nanorods shows sensitive and highly selective room-temperature hydrogen sensing performance with the detection limit of 160 ppm. The structure-dependent hydrogen sensing behavior of the Nb2O5 nanorods can be attributed to the redox reaction between hydrogen and pre-adsorbed oxygens, which can be promoted by the superior gas adsorption and pathway effect of the orthorhombic Nb2O5 lattice.