Ultraviolet Photoactivated Room Temperature NO<sub>2</sub> Gas Sensor of ZnO Hemitubes and Nanotubes Covered with TiO<sub>2</sub> Nanoparticles
Prolonged exposure to NO<sub>2</sub> can cause lung tissue inflammation, bronchiolitis fibrosa obliterans, and silo filler’s disease. In recent years, nanostructured semiconducting metal oxides have been widely used to fabricate gas sensors because of their unique structure and...
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MDPI AG
2020-03-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/10/3/462 |
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| author | Hee-Jung Choi Soon-Hwan Kwon Won-Seok Lee Kwang-Gyun Im Tae-Hyun Kim Beom-Rae Noh Sunghoon Park Semi Oh Kyoung-Kook Kim |
| author_facet | Hee-Jung Choi Soon-Hwan Kwon Won-Seok Lee Kwang-Gyun Im Tae-Hyun Kim Beom-Rae Noh Sunghoon Park Semi Oh Kyoung-Kook Kim |
| author_sort | Hee-Jung Choi |
| collection | DOAJ |
| description | Prolonged exposure to NO<sub>2</sub> can cause lung tissue inflammation, bronchiolitis fibrosa obliterans, and silo filler’s disease. In recent years, nanostructured semiconducting metal oxides have been widely used to fabricate gas sensors because of their unique structure and surface-to-volume ratio compared to layered materials. In particular, the different morphologies of ZnO-based nanostructures significantly affect the detection property of NO<sub>2</sub> gas sensors. However, because of the large interaction energy of chemisorption (1−10 eV), metal oxide-based gas sensors are typically operated above 100 °C, overcoming the energy limits to attain high sensitivity and fast reaction. High operating temperature negatively affects the reliability and durability of semiconductor-based sensors; at high temperature, the diffusion and sintering effects at the metal oxide grain boundaries are major factors causing undesirable long-term drift problems and preventing stability improvements. Therefore, we demonstrate NO<sub>2</sub> gas sensors consisting of ZnO hemitubes (HTs) and nanotubes (NTs) covered with TiO<sub>2</sub> nanoparticles (NPs). To operate the gas sensor at room temperature (RT), we measured the gas-sensing properties with ultraviolet illumination onto the active region of the gas sensor for photoactivation instead of conventional thermal activation by heating. The performance of these gas sensors was enhanced by the change of barrier potential at the ZnO/TiO<sub>2</sub> interfaces, and their depletion layer was expanded by the NPs formation. The gas sensor based on ZnO HTs showed 1.2 times higher detection property than those consisting of ZnO NTs at the 25 ppm NO<sub>2</sub> gas. |
| first_indexed | 2024-04-14T08:05:00Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-04-14T08:05:00Z |
| publishDate | 2020-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Nanomaterials |
| spelling | doaj.art-226351a56bad48d48030481e848612122022-12-22T02:04:46ZengMDPI AGNanomaterials2079-49912020-03-0110346210.3390/nano10030462nano10030462Ultraviolet Photoactivated Room Temperature NO<sub>2</sub> Gas Sensor of ZnO Hemitubes and Nanotubes Covered with TiO<sub>2</sub> NanoparticlesHee-Jung Choi0Soon-Hwan Kwon1Won-Seok Lee2Kwang-Gyun Im3Tae-Hyun Kim4Beom-Rae Noh5Sunghoon Park6Semi Oh7Kyoung-Kook Kim8Department of Advanced Convergence Technology, and Research Institute of Advanced Convergence Technology, Korea Polytechnic University, 237 Sangidaehak-ro, Siheung-si 15073, KoreaDepartment of Advanced Convergence Technology, and Research Institute of Advanced Convergence Technology, Korea Polytechnic University, 237 Sangidaehak-ro, Siheung-si 15073, KoreaDepartment of Advanced Convergence Technology, and Research Institute of Advanced Convergence Technology, Korea Polytechnic University, 237 Sangidaehak-ro, Siheung-si 15073, KoreaDepartment of Nano & Semiconductor engineering, Korea Polytechnic University, 237 Sangidaehak-ro, Siheung-si 15073, KoreaDepartment of Advanced Convergence Technology, and Research Institute of Advanced Convergence Technology, Korea Polytechnic University, 237 Sangidaehak-ro, Siheung-si 15073, KoreaDepartment of Advanced Convergence Technology, and Research Institute of Advanced Convergence Technology, Korea Polytechnic University, 237 Sangidaehak-ro, Siheung-si 15073, KoreaDepartment of Software Convergence, and 1101B Gwanggeto-Bd, Sejong University, Neungdong-ro, Gwangjin-gu, Seoul 05006, KoreaDepartment of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, Michigan 48109, USADepartment of Advanced Convergence Technology, and Research Institute of Advanced Convergence Technology, Korea Polytechnic University, 237 Sangidaehak-ro, Siheung-si 15073, KoreaProlonged exposure to NO<sub>2</sub> can cause lung tissue inflammation, bronchiolitis fibrosa obliterans, and silo filler’s disease. In recent years, nanostructured semiconducting metal oxides have been widely used to fabricate gas sensors because of their unique structure and surface-to-volume ratio compared to layered materials. In particular, the different morphologies of ZnO-based nanostructures significantly affect the detection property of NO<sub>2</sub> gas sensors. However, because of the large interaction energy of chemisorption (1−10 eV), metal oxide-based gas sensors are typically operated above 100 °C, overcoming the energy limits to attain high sensitivity and fast reaction. High operating temperature negatively affects the reliability and durability of semiconductor-based sensors; at high temperature, the diffusion and sintering effects at the metal oxide grain boundaries are major factors causing undesirable long-term drift problems and preventing stability improvements. Therefore, we demonstrate NO<sub>2</sub> gas sensors consisting of ZnO hemitubes (HTs) and nanotubes (NTs) covered with TiO<sub>2</sub> nanoparticles (NPs). To operate the gas sensor at room temperature (RT), we measured the gas-sensing properties with ultraviolet illumination onto the active region of the gas sensor for photoactivation instead of conventional thermal activation by heating. The performance of these gas sensors was enhanced by the change of barrier potential at the ZnO/TiO<sub>2</sub> interfaces, and their depletion layer was expanded by the NPs formation. The gas sensor based on ZnO HTs showed 1.2 times higher detection property than those consisting of ZnO NTs at the 25 ppm NO<sub>2</sub> gas.https://www.mdpi.com/2079-4991/10/3/462room temperatureno<sub>2</sub> gas sensorzno hemitubetio<sub>2</sub> nanoparticleuv emitter |
| spellingShingle | Hee-Jung Choi Soon-Hwan Kwon Won-Seok Lee Kwang-Gyun Im Tae-Hyun Kim Beom-Rae Noh Sunghoon Park Semi Oh Kyoung-Kook Kim Ultraviolet Photoactivated Room Temperature NO<sub>2</sub> Gas Sensor of ZnO Hemitubes and Nanotubes Covered with TiO<sub>2</sub> Nanoparticles Nanomaterials room temperature no<sub>2</sub> gas sensor zno hemitube tio<sub>2</sub> nanoparticle uv emitter |
| title | Ultraviolet Photoactivated Room Temperature NO<sub>2</sub> Gas Sensor of ZnO Hemitubes and Nanotubes Covered with TiO<sub>2</sub> Nanoparticles |
| title_full | Ultraviolet Photoactivated Room Temperature NO<sub>2</sub> Gas Sensor of ZnO Hemitubes and Nanotubes Covered with TiO<sub>2</sub> Nanoparticles |
| title_fullStr | Ultraviolet Photoactivated Room Temperature NO<sub>2</sub> Gas Sensor of ZnO Hemitubes and Nanotubes Covered with TiO<sub>2</sub> Nanoparticles |
| title_full_unstemmed | Ultraviolet Photoactivated Room Temperature NO<sub>2</sub> Gas Sensor of ZnO Hemitubes and Nanotubes Covered with TiO<sub>2</sub> Nanoparticles |
| title_short | Ultraviolet Photoactivated Room Temperature NO<sub>2</sub> Gas Sensor of ZnO Hemitubes and Nanotubes Covered with TiO<sub>2</sub> Nanoparticles |
| title_sort | ultraviolet photoactivated room temperature no sub 2 sub gas sensor of zno hemitubes and nanotubes covered with tio sub 2 sub nanoparticles |
| topic | room temperature no<sub>2</sub> gas sensor zno hemitube tio<sub>2</sub> nanoparticle uv emitter |
| url | https://www.mdpi.com/2079-4991/10/3/462 |
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