Nanoporous TiO2 thin film based conductometric H2 sensor

Abstract Nanoporous titanium dioxide (TiO 2 ) based conductometric sensors have been fabricated and their sensitivity to hydrogen (H 2 ) gas has been investigated. A filtered cathodic vacuum arc (FCVA) system was used to deposit ultra-smooth Ti thin films on a transducer having patterned inter-digital gold electrodes (IDTs). Nanoporous TiO 2 films were obtained by anodization of the titanium (Ti) thin films using a neutral 0.5% (wt) NH 4 F in ethylene glycol solution at 5 V for 1 h. After anodization, the films were annealed at 600 °C for 8 h to convert the remaining Ti into TiO 2 . The scanning electron microscopy (SEM) images revealed that the average diameters of the nanopores are in the range of 20 to 25 nm. The sensor was exposed to different concentrations of H 2 in synthetic air at operating temperatures between 100 °C and 300 °C. The sensor responded with a highest sensitivity of 1.24 to 1% of H 2 gas at 225 °C.