Electrolyte-free, H₂S-sensitive microdiode using a WO ₃/IrO₂ junction and Au catalyst

The H₂S gas sensing performance based on a WO ₃/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.