Novel hydrogen sensor based on p-type Ni:TiO₂ nanorods fabricated on ITO substrate

In the present work, Ni-doped TiO₂ nanorods were fabricated on indium tin oxide (ITO) coated glass substrate by a novel spray pyrolysis deposition route. The influence of pyrolytic temperature on the degree of crystallinity of the Ni:TiO₂ films was clearly reflected in the X-ray diffractograms. The promoting effect of ITO seed layer on Ni:TiO₂ film was reflected in the film prepared at 300 °C which show predominantly a (101) orientation corresponding to the c-axis of pure tetragonal anatase TiO₂. The evaluated optical band gap (E_g) of the films prepared at different temperature was in the range of 3.3–3.62 eV. The high E_g values confirmed the existence of TiO₂–Ni catalyst influence interaction. The morphology of the film optimized at 300 °C was almost rod shaped with large roughness favorable for sensing. The hydrogen sensing properties of the Ni:TiO₂ nanorod sensor was investigated. The Ni doped TiO₂ films exhibited a different p-type response to H₂. It was found that the sensor based on Ni:TiO₂ nanorod structure optimized at 300 °C exhibited good performance even at room temperature.