Fabrication of TiN/TiO ₂ Nanotube‐Based Heterostructure for Hydrogen Sensing Applications

ABSTRACT An effective room‐temperature hydrogen gas sensor based on a Pd/TiN/TiO ₂ nanotube heterostructure is demonstrated. A novel ion beam deposition method is used to form a TiN/TiO ₂ heterostructure on TiO ₂ nanotubes formed by electrochemical anodization. Comprehensive physical characterization is performed, and x‐ray photoelectron spectroscopy reveals the presence of an oxynitride component within the TiN conformal layer. Current‐voltage measurements, via deposited Pd electrodes, show rectifying behavior in the TiN/TiO ₂ heterostructures, confirming barrier formation at the interface, while the bare TiN film displays ohmic behaviour. Upon exposure to 1% H ₂ , a substantial current enhancement is observed, whose magnitude depends on the TiN thickness. The enhanced sensing response is attributed to catalytic H ₂ dissociation at the Pd electrodes and the subsequent modulation of the barrier formed at the TiN/TiO ₂ interface. These findings confirm that the dominant sensing mechanism originates from barrier height modulation at the interface. AC impedance spectroscopy suggests that the oxynitride interlayer enhances electronic conductivity and reduces charge recombination by creating a strong static electric field within the space charge region. The TiN/TiO ₂ nanotube system offers a promising platform for sensitive and reliable room‐temperature hydrogen detection through advanced interfacial engineering in solid‐state gas sensors.