Fast and selective room-temperature hydrogen sensing of oxygen-deficient orthorhombic Nb₂O₅ nanobelts

The increasing demand for hydrogen as a clean and renewable energy source necessitates the development of efficient and reliable hydrogen sensing technologies. This study presents the preparation of oxygen-deficient orthorhombic Nb₂O₅ nanobelts for room-temperature chemiresistive hydrogen sensing. The nanobelts were synthesized by converting the H₃ONb₃O₈ nanobelts into orthorhombic Nb₂O₅ through a calcination-based topochemical transformation process. The content of oxygen vacancy defects in the nanobelts was effectively modified by post-annealing treatments, without introducing undesirable phase transition. The results revealed that the hydrogen sensing performance of Nb₂O₅ nanobelts is closely linked to the oxygen vacancy content. With optimal defect concentration, the proposed chemiresistive sensors demonstrated significantly enhanced room-temperature hydrogen response, achieving a sensor response of 10.3 and response time down to 28 s, to 5000 ppm hydrogen. The sensor also exhibited good selectivity against various interference gases, highlighting its great potential for fast and accurate hydrogen leak detection in practical applications.