A hydrogen gas sensor employing vertically aligned TiO2 nanotube arrays prepared by template-assisted method

Vertically aligned TiO2 nanotube arrays for H2 gas sensor were fabricated by using atomic layer deposition combined with anodic aluminum oxide template. Morphology and crystalline structure of the TiO2 nanotubes were characterized, and gas sensing properties at low temperatures (<200 °C) were investigated. Uniform TiO2 nanotubes with anatase phase were synthesized to be vertically aligned on the substrate and electrically interconnected with each other. The TiO2 nanotube sensors were operated in air environment, and the highest magnitude of the gas response (Rair/Rgas) was determined to be ∼100 toward 1000 ppm H2/air at 100 °C. The sensor showed a very short response time (<1 s) and a high selectivity for H2 gas against several reducing gases including NH3, CO, and C2H5OH.