Catalytic combustion type hydrogen gas sensor using TiO2 and UV-LED

A thick film catalytic gas sensor operable at a temperature of 82 °C in the presence of UV-LED (ultra violet-light emitting diode) has been developed to measure hydrogen concentration in the range of 0.5–5%. The sensing material as a combustion catalyst consists of TiO2 (5 wt%) and Pd/Pt (20 wt%) supported on γ-Al2O3 powder. The reference material to compensate the heat capacity of it in a bridge circuit is γ-Al2O3 powder. A platinum heater and the sensor materials were formed on an alumina plate by a screen printing method, followed by heat treatment. The effect of UV irradiation in the presence of photocatalyst TiO2 on the sensor response, response and recovery time has been investigated. The reduction of operating temperature from 253 to 82 °C for hydrogen gas sensing in the presence of UV radiation is attributed to the enhanced activity of the chemisorbed oxygen ions which facilitate a higher rate of reaction between O2 and H2.