Pure and 3-12 at. % Pr-doped In2O3 macroporous spheres were fabricated by ultrasonic spray pyrolysis and their acetone-sensing characteristics under dry and humid conditions were investigated to design humidity-independent gas sensors. The 12 at. % Pr-doped In2O3 sensor exhibited approximately the same acetone responses and sensor resistances at 450 °C regardless of the humidity variation, whereas the pure In2O3 exhibited significant deterioration in gas-sensing characteristics upon the change in the atmosphere, from dry to humid (relative humidity: 80%). Moreover, the 12 at. % Pr-doped In2O3 sensor exhibited a high response to acetone with negligible cross responses to interfering gases (NH3, CO, benzene, toluene, NO2, and H2) under the highly humid atmosphere. The mechanism for the humidity-immune gas-sensing characteristics was investigated by X-ray photoelectron and diffuse reflectance infrared Fourier transform spectroscopies together with the phenomenological gas-sensing results and discussed in relation with Pr3+/Pr4+ redox pairs, regenerative oxygen adsorption, and scavenging of hydroxyl groups.
Bibliographical noteFunding Information:
This research was supported by the International Research & Development Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, and Future Planning (MSIP) of Korea (NRF-2017K1A3A1A49069947) and the Industrial Strategic Technology Development Program (10073068, Development of Miniaturized 10 mW TVOC/Alcohol Dual Gas Sensor and Module using Non-Silicon AAO Ceramic Substrate) funded By the Ministry of Trade, Industry & Energy (MOTIE, Korea).
© 2019 American Chemical Society.
- cyclic redox reactions
- humidity dependence
- indium oxide
- oxide semiconductor gas sensor
ASJC Scopus subject areas
- Materials Science(all)