Electrolyte-Free, H2S-Sensitive Microdiode Using a WO3/IrO2 Junction and Au Catalyst

Abstract

The H2S gas sensing performance based on a WO3/IrO2 diode assisted by gold (Au)-catalyst is investigated. Intermolecular force, similar to Van Der Waal interaction, initiates interstitial-water in IrO2 film to be H+-dipoled permanently. H+ and e(-) produce reversible redox reactions, which control conductivity by utilizing proton-electron double injection. As a result of the catalysis contributed from Au dopant-like particles distributed uniformly on the microdiode bulk surface, the barrier height between the surface of WO3-based microdiode and the reference gas molecules will be decreased in response upon exposure to H2S gas and therefore improve conductometric change significantly. The preliminary dc analysis of the microdiode has revealed repeatable and durable results. Such a microdiode can work stably for a long time without significant signal deterioration.