Highly selective Hydrogen sensing by applying characteristic frequency at room temperature: Case study on TiO2–PdO hydrogen sensor

Abstract

We report highly selective and reliable room temperature H₂ sensing using TiO₂–PdO heterostructure thin film based chemiresistive sensors in comparison with PdO thin film sensor. Gas sensing studies show higher sensitivity and better selectivity towards H₂ gas in the range 0.1 %–1% for TiO₂–PdO heterostructure thin film sensor compared to PdO sensor. Based on gas analysis results of the surface species formed, H₂ sensing mechanism is suggested. Temperature dependance of sensor response, repeatability, reproducibility, long term stability and humidity dependence studies at room temperature on TiO₂–PdO sensor show satisfactory performance promising viability for portable, hand held H₂ sensors. In addition to the advantages of heterostructure for better gas selectivity, increase in selectivity for room temperature sensor is shown using transient impedance measurements at characteristic frequency related to the target gas. Study suggests applying characteristic frequency measurements as a superior technique for obtaining high selectivity for portable H₂ sensor.