Catalyst free rutile phase TiO<inf>2</inf> nanorods as efficient hydrogen sensor with enhanced sensitivity and selectivity

Using a low-cost hydrothermal method, we demonstrated the fabrication of phase pure rutile phase high-density vertically aligned TiO2 nanorods-based catalyst-free hydrogen (H2) gas sensor. The synthesized TiO2 nanorods on FTO are decorated with the aluminum interdigitated electrode pattern for electrical measurements. TiO2 nanorods-based hydrogen sensor showed the optimum response of ∼53.18% at 150 ppm H2 concentration relative to air at 100 °C. The measured response and recovery time of TiO2 nanorods are 85 and 620 s, respectively. The TiO2 nanorods-based H2 gas sensor showed a relatively better response, good reproducibility, and stability at moderate temperatures, i.e., 50 and 100 °C. The electrochemical impedance measurements showed a small variation in the surface characteristics of TiO2 nanorods before and after exposing H2 gas. The carrier lifetime at 50 °C and 100 °C at 150 ppm are 5 μs and 3 μs, respectively. Interestingly, H2 selectivity is also observed against H2S, CO, and NH3 gases, suggesting that high-density vertically aligned TiO2 nanorods can be a good candidate for efficient hydrogen sensing at relatively low temperatures.