Humidity-Independent Gas Sensors Using Pr-Doped In2O3 Macroporous Spheres: Role of Cyclic Pr3+/Pr4+ Redox Reactions in Suppression of Water-Poisoning Effect

Jun Sik Kim, Chan Woong Na, Chang Hoon Kwak, Hua Yao Li, Ji Won Yoon, Jae Hyeok Kim, Seong Yong Jeong, Jong Heun Lee

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43 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)25322-25329
Number of pages8
JournalACS Applied Materials and Interfaces
Issue number28
Publication statusPublished - 2019 Jun 24


  • cyclic redox reactions
  • humidity dependence
  • indium oxide
  • oxide semiconductor gas sensor
  • praseodymium

ASJC Scopus subject areas

  • Materials Science(all)


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