Temperature-Dependent NO<sub>2</sub> Sensing Mechanisms over Indium Oxide

Roso, Sergio; Degler, David; Llobet, Eduard; Bârsan, Nicolae; Urakawa, Atsushi

doi:10.1021/acssensors.7b00504

Cited by 76 publications

(59 citation statements)

References 13 publications

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“…The In 2 O 3 -based sensors generally respond to NO 2 since NO 2 molecules are negatively adsorbed on the oxide surface (Roso et al, 2017). The magnitude of NO 2 response of the pr-In 2 O 3 (n)-20 sensors was increased by the loading of a small amount of Au as shown in the previous section, which indicates that the highly dispersed Au nanoparticles loaded enhanced the amount of negatively charged NO 2 adsorbed on the oxide surface.…”

Section: Effects Of the Au Loading To Pr-in 2 O 3 (N) Powders On The mentioning

confidence: 55%

Improvement in NO2 Sensing Properties of Semiconductor-Type Gas Sensors by Loading of Au Into Porous In2O3 Powders

et al. 2019

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Porous (pr-) In 2 O 3 powders loaded with and without noble metals (Au, Pd, or Pt) were prepared by ultrasonic spray pyrolysis employing the PMMA microspheres as a template (typical particle size (ps): 28 or 70 nm with a diameter), and their NO 2 sensing properties were examined. The Au loading on the pr-In 2 O 3 was effective to increase the NO 2 response at lower operating temperature (≤200 • C), while the metal loading of Pd or Pt were hardly effective. In addition, a decrease in the PMMA microspheres (from 70 to 28 nm in ps) largely increased the NO 2 response, and an optimized amount of Au loaded on the pr-In 2 O 3 sensor was 1.0 wt%. The decrease in the thickness of the sensing layer improved the NO 2 response and response speed. It was suggested that the Au loading enhanced the amount of the negatively adsorbed NO 2 on the bottom part of the sensing layer, leading to the increase in the NO 2 response. Furthermore, the introduction of additional macropores (ps: 150 nm) to the 1.0 wt% Au loaded pr-In 2 O 3 sensor increased the response to a low concentration of NO 2 (0.025 ppm) at 30 • C. Therefore, it was found that easy gas diffusion from the surface to the bottom part of the sensing layer increased the effective concentration of NO 2 , and thus the NO 2 response was increased.

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Section: Effects Of the Au Loading To Pr-in 2 O 3 (N) Powders On The mentioning

confidence: 55%

Improvement in NO2 Sensing Properties of Semiconductor-Type Gas Sensors by Loading of Au Into Porous In2O3 Powders

et al. 2019

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“…Some baseline drift is present that is especially visible for NO 2 . This is due to the strong interaction of this oxidizing species with the gas sensitive film—which combined to the relatively low operating temperature of the sensor (i.e., 150 °C)—does not allow for a complete desorption of adsorbed species and baseline recovery during each cleaning phase [18]. …”

Section: Resultsmentioning

confidence: 99%

“…Additionally, ambient moisture facilitates the adsorption of NO 2 on the surfaces of indium oxide octahedra [6] or of indium oxide nanoparticles [18], further increasing sensor response and sensitivity to this species.…”

Section: Discussionmentioning

confidence: 99%

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Flexible Gas Sensors Employing Octahedral Indium Oxide Films

Alvarado

Navarrete

Romero

et al. 2018

Sensors

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Indium oxide octahedral nanopowders were obtained from an ionic precursor compound after an oxidation process conducted under a low-oxygen atmosphere. This method was found to produce contamination-free indium oxide nanomaterial with very similar morphological and crystalline properties to the one produced by vapor-phase transport, but at significantly lower temperatures and higher yield. The as-synthesized indium oxide was mixed to an organic vehicle and microdrop deposited to form a film bridging the interdigitated silver electrodes patterned on top of a flexible, polyimide (Kapton®), substrate. The gas sensing properties of the flexible chemoresistors towards ammonia vapors, hydrogen, and nitrogen dioxide were investigated. It was found that these sensors were remarkably sensitive to nitrogen dioxide at a low operating temperature of 150 °C. These results are consistent with the performance of vapor-phase transport synthesized indium oxide octahedra sensors on rigid, ceramic substrates. Therefore, the results presented here pave the way for the mass production of inexpensive gas sensors onto flexible substrates via additive manufacturing.

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“…Indium oxide is a wide-bandgap semiconducting material with a direct bandgap of around 2.8-2.9 eV. It has been extensively used as a transparent conductive oxide (TCO) in electronics, for photovoltaic devices, light emitting diodes and chemical sensors [3,4]. Nevertheless, the knowledge about sensing with In2O3 based devices is still insufficient.…”

Section: Published: 23 June 2019mentioning

confidence: 99%