Suspension Plasma Sprayed ZnO Coatings for CO2 Gas Detection

Hollow spherical ZnO, prepared by hydrothermal synthesis method with a soft template, was dispersed in deionized water to form a uniform suspension. The micromorphology, phase composition and UV absorbance of ZnO powder were analyzed by SEM, EDS, XRD and UV-Vis. The ZnO coatings were deposited on Al2O3 substrates equipped with Pt electrodes to fabricate gas sensors by suspension plasma spraying. The effects of CO2 concentration and relative humidity (RH) on the gas sensing properties of the ZnO coatings at room temperature (similar to 25 degrees C) were studied, and the gas sensing mechanism was discussed. The experimental results elucidate two results: First, the response value rises with the increase of CO2 concentration under the condition of constant RH; second, the responses for concentrations of 3, 4, 5% CO2 rise with RH increasing from 0-60%. Under the condition of 400 ppm CO2, the response rises from 6.87-57.92, with an increase of RH from 20-80%.

Automated summary

Hollow spherical ZnO was prepared and fabricated into gas sensors using suspension plasma spraying. The study shows that the gas sensing properties of the ZnO coatings increase with the increase of CO2 concentration and relative humidity at room temperature.