Influence of temperature and humidity on the electrical sensing of Pt/WO₃ thin film hydrogen gas sensor

Abstract

Platinum catalyst loaded tungsten oxide (Pt/WO₃) is a promising candidate as a hydrogen gas sensor material, which can detect it through optical and electrical sensing. The sensor, which can detect the hydrogen gas stably in various environments, is strongly demanded. In this study, we prepared the Pt/WO₃ thin film by the sol–gel method and evaluate the dependence of the hydrogen gas sensing property on measuring temperature and humidity. Hydrogen gas sensing property of Pt/WO₃ thin film was evaluated by measuring the electrical conductivity with humid (0–100% of relative humidity) hydrogen gas exposure at various temperatures. The sensing property was declined in humid atmospheres because the water molecule adsorbing on the film surface disturbed the catalytic reaction between hydrogen and Pt surface. In addition, the catalytic combustion of hydrogen molecule on Pt was also disturbed by the adsorbed water. However, the heating at 60°C can remove the effect of water molecule and the film can detect hydrogen gas stably. From these results, it was considered that the degradation of sensor response in humid atmosphere was mainly dominated by adsorbing water on Pt catalyst surface.