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One of the most significant drawbacks of metal oxide (MOS) based chemiresistive gas sensors is the requirement of high operating temperature (250–450 °C), which results in significant power consumption and shorter lifetime. To develop room temperature (21±2 °C) MOS chemiresistive gas sensors, the sensing performance of different MOS nanostructures (i.e., tin (IV) oxide (SnO2) nanoparticles (NPs), indium (III) oxide (In2O3) NPs, zinc oxide (ZnO) NPs, tungsten trioxide (WO3) NPs, copper oxide (CuO) nanotubes (NTs), and indium tin oxide (In90Sn10O3 (ITO)) NPs) were systematically investigated toward different toxic industrial chemicals (TICs) (i.e., nitrogen dioxide (NO2), ammonia (NH3), hydrogen sulfide (H2S), carbon monoxide (CO), sulfur dioxide (SO2) and volatile organic compounds (VOCs) (i.e., acetone (C3H6O), toluene (C6H5CH3), ethylbenzene (C6H5CH2CH3), and p-xylene (C6H4(CH3)2)) in the presence and absence of 400 nm UV light illumination. Sensing performance enhancement through photoexcitation is strongly dependent on the target analytes. Under 400 nm UV photoexcitation at 76.0 mW/cm2 intensity, room temperature (21±2 °C) NO2 sensing was readily achieved where SnO2 NPs exhibited the highest sensor response (S = 474.4 toward 10 ppmm (parts per million by mass)) with good recovery followed by ZnO NPs > In2O3 NPs > ITO NPs. Meanwhile, indirect bandgap n-type WO3 NPs showed limited NO2 sensing performance under illumination, whereas p-type CuO NTs showed relatively good sensing response. The most significant improvements in SnO2 compared to other MOS nanoparticles might be attributed to the highest number of photogeneration electrons, which rapidly reacted with adsorbed species to enhance the reaction kinetics. WO3 NPs showed a unique sensing response toward aromatic compounds (e.g., ethylbenzene and p-xylene) under UV illumination, where maximum sensitivity was achieved under 36 mW/cm2 irradiation. Changing light intensity from 0.0 to 36.4 mW/cm2, WO3 showed 15.4-fold and 6.3-fold enhancement in sensing response toward 25 ppmm ethylbenzene and 100 ppmm p-xylene, respectively. 400 nm optical excitation has a limited effect on the sensing performance toward CO, SO2, toluene, and acetone.
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UV-Light-Tunable p-/n-Type Chemiresistive Gas Sensors Based on Quasi-1D TiS3 Nanoribbons: Detection of Isopropanol at ppm Concentrations
The growing demand of society for gas sensors for energy-efficient environmental sensing stimulates studies of new electronic materials. Here, we investigated quasi-one-dimensional titanium trisulfide (TiS3) crystals for possible applications in chemiresistors and on-chip multisensor arrays. TiS3 nanoribbons were placed as a mat over a multielectrode chip to form an array of chemiresistive gas sensors. These sensors were exposed to isopropanol as a model analyte, which was mixed with air at low concentrations of 1–100 ppm that are below the Occupational Safety and Health Administration (OSHA) permissible exposure limit. The tests were performed at room temperature (RT), as well as with heating up to 110 °C, and under an ultraviolet (UV) radiation at λ = 345 nm. We found that the RT/UV conditions result in a n-type chemiresistive response to isopropanol, which seems to be governed by its redox reactions with chemisorbed oxygen species. In contrast, the RT conditions without a UV exposure produced a p-type response that is possibly caused by the enhancement of the electron transport scattering due to the analyte adsorption. By analyzing the vector signal from the entire on-chip multisensor array, we could distinguish isopropanol from benzene, both of which produced similar responses on individual sensors. We found that the heating up to 110 °C reduces both the sensitivity and selectivity of the sensor array.
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- Award ID(s):
- 1849206
- PAR ID:
- 10426419
- Date Published:
- Journal Name:
- Sensors
- Volume:
- 22
- Issue:
- 24
- ISSN:
- 1424-8220
- Page Range / eLocation ID:
- 9815
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.3390/s22249815
