Characteristics of a Metal-loaded SnO₂/WO₃ Thick Film Gas Sensor for Detecting Acetaldehyde Gas

摘要

This study investigates the sensitivity of a gas sensor to volatile organic compounds (VOCs) at various operating temperatures and catalysts. Nano-sized powdered WO3 prepared by sol-gel and chemical precipitation methods was mixed with various metal oxides. Next, transition metals (Pt, Ru, Pd, and In) were doped on the surface of the mixture. Metal-WO3 thick films were prepared using the screen-printing method. The physical and chemical properties of the films were studied by SEM/EDS, XRD, and BET techniques. The measured sensitivity to VOCs is defined as the ratio (Ra/Rg) of resistance (Rair) of WO3 film in the air to resistance (Rgas) of WO3 film in a VOCs test gas. The sensitivity and selectivity of the films were tested with various VOCs such as acetaldehyde, formaldehyde, methyl alcohol, and BTEX. The thick WO3 film containing 1 wt % of Ru and 5 wt % of SnO2 showed the best sensitivity and selectivity to acetaldehyde gas at an operating temperature of 300 oC.