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Suzuki TT, Ohgaki T, Adachi Y, Sakaguchi I, Nakamura M, Ohashi H, Aimi A, Fujimoto K. Ethanol Gas Sensing by a Zn-Terminated ZnO(0001) Bulk Single-Crystalline Substrate. ACS OMEGA 2020; 5:21104-21112. [PMID: 32875247 PMCID: PMC7450640 DOI: 10.1021/acsomega.0c02750] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 07/27/2020] [Indexed: 05/31/2023]
Abstract
Metal oxide semiconductor gas sensors have been widely studied for the selective detection of various gases with trace concentrations. The identification of the reaction scheme governing the gas sensing response is crucial for further development; however, the mechanism of ethanol (EtOH) gas sensing by ZnO is still controversial despite being one of the most intensively studied target gas and sensing material combinations. In this work, for the first time, the detailed mechanism of EtOH sensing by ZnO is studied by using a bulk single-crystalline substrate, which has a well-defined stoichiometry and atomic arrangement, as the sensing material. The sensing response is substantial on the ZnO substrate even with a millimeter-size thickness, and it becomes larger with resistance of the substrate. The large sensing response is described in terms of the adsorption/desorption of the oxygen species on the substrate surface, namely, oxygen ionosorption. The valence state of the ionosorbed oxygen involved in EtOH sensing is identified to be O2- regardless of the temperature. The increase in the sensing response with the temperature is attributed to the enhanced oxidation rate of the EtOH molecule on the surface as analyzed by pulsed-jet temperature-programmed desorption mass spectrometry, which has been newly developed for analyzing surface reactions in simulated working conditions.
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Affiliation(s)
- Taku T. Suzuki
- National
Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Takeshi Ohgaki
- National
Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Yutaka Adachi
- National
Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Isao Sakaguchi
- National
Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Minoru Nakamura
- Department
of Pure and Applied Chemistry, Tokyo University
of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Hideyuki Ohashi
- Department
of Pure and Applied Chemistry, Tokyo University
of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Akihisa Aimi
- Department
of Pure and Applied Chemistry, Tokyo University
of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Kenjiro Fujimoto
- Department
of Pure and Applied Chemistry, Tokyo University
of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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