Formation of networked ZnO nanowires by vapor phase growth and their sensing properties with respect to CO

Park, Jae Young; Park, Yong Kuk; Kim, Sang Sub

doi:10.1016/j.matlet.2011.05.098

Cited by 23 publications

(14 citation statements)

References 15 publications

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“…The change in resistance during the adsorption or desorption process of H 2 species is likely to be caused by the alteration both in the width of the surface depletion layer of each In 2 O 3 nanotower and in the height of potential barriers built at the contacted junctions between two In 2 O 3 nanotowers. These two-fold effects may facilitate less response time and higher response to certain chemical species [45]. …”

Section: Resultsmentioning

confidence: 99%

In2O3 Nanotower Hydrogen Gas Sensors Based on Both Schottky Junction and Thermoelectronic Emission

2015

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Indium oxide (In2O3) tower-shaped nanostructure gas sensors have been fabricated on Cr comb-shaped interdigitating electrodes with relatively narrower interspace of 1.5 μm using thermal evaporation of the mixed powders of In2O3 and active carbon. The Schottky contact between the In2O3 nanotower and the Cr comb-shaped interdigitating electrode forms the Cr/In2O3 nanotower Schottky diode, and the corresponding temperature-dependent I-V characteristics have been measured. The diode exhibits a low Schottky barrier height of 0.45 eV and ideality factor of 2.93 at room temperature. The In2O3 nanotower gas sensors have excellent gas-sensing characteristics to hydrogen concentration ranging from 2 to 1000 ppm at operating temperature of 120–275 °C, such as high response (83 % at 240 °C to 1000 ppm H2), good selectivity (response to H2, CH4, C2H2, and C3H8), and small deviation from the ideal value of power exponent β (0.48578 at 240 °C). The sensors show fine long-term stability during exposure to 1000 ppm H2 under operating temperature of 240 °C in 30 days. Lots of oxygen vacancies and chemisorbed oxygen ions existing in the In2O3 nanotowers according to the x-ray photoelectron spectroscopy (XPS) results, the change of Schottky barrier height in the Cr/In2O3 Schottky junction, and the thermoelectronic emission due to the contact between two In2O3 nanotowers mainly contribute for the H2 sensing mechanism. The growth mechanism of the In2O3 nanotowers can be described to be the Vapor-Solid (VS) process.

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Section: Resultsmentioning

confidence: 99%

In2O3 Nanotower Hydrogen Gas Sensors Based on Both Schottky Junction and Thermoelectronic Emission

2015

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“…It is worth noticing that the sensing properties of such sensors have been reported and described in our previous study. 43 The second step for the preparation of the novel nanocomposite ZIF-8/Pd/ZnO NWs sensing device involves the synthesis of Pd NPs on ZnO NWs, using ALD. ALD is a vapor phase technique based on self-limiting reactions of precursor molecules with the substrate surface groups, enabling the preparation of nanomaterials controllable at the (sub)nanometer scale.…”

Section: Sensing Measurementsmentioning

confidence: 99%

High-Performance Nanowire Hydrogen Sensors by Exploiting the Synergistic Effect of Pd Nanoparticles and Metal–Organic Framework Membranes

Weber

Kim

Lee

et al. 2018

ACS Appl. Mater. Interfaces

Self Cite

157

110

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Herein, we report the fabrication of hydrogen gas sensors with enhanced sensitivity and excellent selectivity. The sensor device is based on the strategic combination of ZnO nanowires (NWs) decorated with palladium nanoparticles (Pd NPs) and a molecular sieve metal-organic framework (MOF) nanomembrane (ZIF-8). The Pd NPs permit the sensors to reach maximal signal responses, whereas the ZIF-8 overcoat enables for an excellent selectivity. Three steps were employed for the fabrication: (i) coating of a miniaturized sensor with vapor-grown ZnO NWs, (ii) decoration of these NWs with Pd NPs by atomic layer deposition, and (iii) partial solvothermal conversion of the tuned NWs surface to ZIF-8 nanomembrane. The microstructure and composition investigations of the ZIF-8/Pd/ZnO nanostructured materials confirmed the presence of both metallic Pd NPs and uniform ZIF-8 thin membrane layer. The integration of these nanomaterials within a miniaturized sensor device enabled the assessment of their performance for H detection at concentrations as low as 10 ppm in the presence of various gases such as CH, CH, CHOH, and CHCOCH. Remarkably high-response signals of 3.2, 4.7, and 6.7 ( R/ R) have been measured for H detection at only 10, 30, and 50 ppm, whereas no noticeable response toward other tested gases was detected, thus confirming the excellent H selectivity obtained with such a sensor design. The results obtained showed that the performance of gas sensors toward H gas can be greatly increased by both the addition of Pd NPs and the use of ZIF-8 coating, acting as a molecular sieve membrane. Furthermore, the presented strategy could be extended toward the sensing of other species by a judicious choice of both the metallic NPs and MOF materials with tuned properties for specific molecule detection, thus opening a new avenue for the preparation of highly selective sensing devices.

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“…1D nanostructured devices such as nanowires are more sensitive and selective due to their high aspect ratio giving rise to a large surface area. There are many gasses that can be detected by ZnO nanowires, such as NO [128], NO 2 [129], CO [130], NH 3 [127], H 2 [131], O 2 [132], and ethanol [133]. A resistor type NO 2 gas sensor based on the ZnO nanorod was reported by Oh et al [134] using a sonochemical route.…”

Section: Sensormentioning

confidence: 99%

Synthesis, Characterization, and Applications of ZnO Nanowires

Zhang

Ram

Stefanakos

et al. 2012

Journal of Nanomaterials

353

306

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ZnO nanowires (or nanorods) have been widely studied due to their unique material properties and remarkable performance in electronics, optics, and photonics. Recently, photocatalytic applications of ZnO nanowires are of increased interest in environmental protection applications. This paper presents a review of the current research of ZnO nanowires (or nanorods) with special focus on photocatalysis. We have reviewed the semiconducting photocatalysts and discussed a variety of synthesis methods of ZnO nanowires and their corresponding effectiveness in photocatalysis. We have also presented the characterization of ZnO nanowires from the literature and from our own measurements. Finally, a wide range of uses of ZnO nanowires in various applications is highlighted in this paper.

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Formation of networked ZnO nanowires by vapor phase growth and their sensing properties with respect to CO

Cited by 23 publications

References 15 publications

In2O3 Nanotower Hydrogen Gas Sensors Based on Both Schottky Junction and Thermoelectronic Emission

In2O3 Nanotower Hydrogen Gas Sensors Based on Both Schottky Junction and Thermoelectronic Emission

High-Performance Nanowire Hydrogen Sensors by Exploiting the Synergistic Effect of Pd Nanoparticles and Metal–Organic Framework Membranes

Synthesis, Characterization, and Applications of ZnO Nanowires

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