Ultrafast and Reversible Gas-Sensing Properties of ZnO Nanowire Arrays Grown by Hydrothermal Technique

Sinha, Madhumita; Mahapatra, Rajat; Mondal, Bittagopal; Maruyama, Toru; Ghosh, Ranajit

doi:10.1021/acs.jpcc.5b11012

Cited by 111 publications

(41 citation statements)

References 48 publications

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“…This is consistence with the most accepted sensing mechanism model proposed in the literature for pristine metal oxides including SnO 2 [46]. According to this model (Figure 13a), when SnO 2 film is exposed to air, oxygen molecules are adsorbed at the surface and form oxygen ions [47,48] (in our case O 2 − is formed because the operating temperature is 160 • C [11]), thus extracting electrons from the conduction band. As a result of this electron transfer, a depletion layer is formed and the film electrical resistance is increased.…”

Section: Gas Sensing Mechanismsupporting

confidence: 81%

“…Therefore, the depletion layer narrows and the film electrical resistance decreases [46]. surface and form oxygen ions [47][48] (in our case O2 ‾ is formed because the operating temperature is 160°C [11]), thus extracting electrons from the conduction band. As a result of this electron transfer, a depletion layer is formed and the film electrical resistance is increased.…”

Section: Gas Sensing Mechanismmentioning

confidence: 85%

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Influence of Mg Doping Levels on the Sensing Properties of SnO2 Films

Bendahmane

Tomić

Touidjen

et al. 2020

Sensors

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This work presents the effect of magnesium (Mg) doping on the sensing properties of tin dioxide (SnO2) thin films. Mg-doped SnO2 films were prepared via a spray pyrolysis method using three doping concentrations (0.8 at.%, 1.2 at.%, and 1.6 at.%) and the sensing responses were obtained at a comparatively low operating temperature (160 °C) compared to other gas sensitive materials in the literature. The morphological, structural and chemical composition analysis of the doped films show local lattice disorders and a proportional decrease in the average crystallite size as the Mg-doping level increases. These results also indicate an excess of Mg (in the samples prepared with 1.6 at.% of magnesium) which causes the formation of a secondary magnesium oxide phase. The films are tested towards three volatile organic compounds (VOCs), including ethanol, acetone, and toluene. The gas sensing tests show an enhancement of the sensing properties to these vapors as the Mg-doping level rises. This improvement is particularly observed for ethanol and, thus, the gas sensing analysis is focused on this analyte. Results to 80 ppm of ethanol, for instance, show that the response of the 1.6 at.% Mg-doped SnO2 film is four times higher and 90 s faster than that of the 0.8 at.% Mg-doped SnO2 film. This enhancement is attributed to the Mg-incorporation into the SnO2 cell and to the formation of MgO within the film. These two factors maximize the electrical resistance change in the gas adsorption stage, and thus, raise ethanol sensitivity.

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Section: Gas Sensing Mechanismsupporting

confidence: 81%

Section: Gas Sensing Mechanismmentioning

confidence: 85%

Influence of Mg Doping Levels on the Sensing Properties of SnO2 Films

Bendahmane

Tomić

Touidjen

et al. 2020

Sensors

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show abstract

“…It is important to note that the chemisorbed oxygen species are strongly dependent on the operating temperature. For example, at operating temperatures below 130 °C, chemisorption of the stabilised takes place, while at operating temperatures between 130 and 300 °C, O − is stabilised and chemisorbed onto the sensing material surface, and at operating temperatures higher than 300 °C, the stable O 2− is chemisorbed 36,40 . In the system reported herein, an operating temperature of 350 °C was employed for the detection of NH 3 , and so we could assume that O 2− was chemisorbed onto pure ZnO NPs- based sensor surface according to the following reaction:…”

Section: Resultsmentioning

confidence: 99%

A highly responsive NH3 sensor based on Pd-loaded ZnO nanoparticles prepared via a chemical precipitation approach

Mhlongo

Motaung

Cummings

et al. 2019

Sci Rep

103

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The gas-detecting ability of nanostructured ZnO has led to significant attention being paid to the development of a unique and effective approach to its synthesis. However, its poor sensitivity, cross-sensitivity to humidity, long response/recovery times and poor selectivity hinder its practical use in environmental and health monitoring. In this context, the addition of noble metals, as dopants or catalysts to modify the ZnO surface has been examined to enhance its sensing performance. Herein, we report preparation of Pd-loaded ZnO nanoparticles via a chemical precipitation approach. Various Pd loadings were employed to produce surface-modified ZnO nanostructure sensors, and their resulting NH 3 sensing capabilities both in dry and humid environments were investigated. Through a comparative gas sensing study between the pure and Pd-loaded ZnO sensors upon exposure to NH 3 at an optimal operating temperature of 350 °C, the Pd-loaded ZnO sensors were found to exhibit enhanced sensor responses and fast response/recovery times. The influence of Pd loading and its successful incorporation into ZnO nanostructure was examined by X-ray diffraction, high resolution-transmission electron microscopy, and X-ray photoelectron spectroscopy. XPS studies demonstrated that in all samples, Pd existed in two chemical states, namely Pd° and Pd 2+ . The possible sensing mechanism related to NH 3 gas is also discussed in detail.

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“…The rst step represents the common reaction of the ZnO NRs with reducing gases. 27,28 Oxygen molecules are surface adsorbed from the environment and trap the free electrons from the surface. Oxygen ions form, which react with the reducing gases.…”

Section: Discussionmentioning

confidence: 99%

New strategy for magnetic gas sensing

et al. 2016

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A new-concept approach to room temperature magnetic gas sensing has been developed, based on newly\ud designed Co/ZnO hybrid nanostructures. The sensor prototype has been demonstrated to be sensitive,\ud reversible, fast and scalable. In this work, the role of the Co/ZnO surface and interface in the gas-sensing\ud mechanism has been clarified. In order to attain a comprehensive understanding of the physics governing\ud the remarkable properties of the Co/ZnO stack, an extensive electronic and structural investigation has been\ud carried out. The reaction at room temperature with target gases involves the surface and the lateral faces of\ud the ZnO nanorods, with the formation of structural defects and vacancies. In particular, it has been\ud discovered that the stress enhancement as well as the change in the polarizability of the ZnO nanorods are\ud transduced by Co in a change of its magnetization. The interplay between these phenomena may provide\ud versatile approaches to tune the intrinsic electronic,magnetic and optical properties of the hybrid nanostructure

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Ultrafast and Reversible Gas-Sensing Properties of ZnO Nanowire Arrays Grown by Hydrothermal Technique

Cited by 111 publications

References 48 publications

Influence of Mg Doping Levels on the Sensing Properties of SnO2 Films

Influence of Mg Doping Levels on the Sensing Properties of SnO2 Films

A highly responsive NH3 sensor based on Pd-loaded ZnO nanoparticles prepared via a chemical precipitation approach

New strategy for magnetic gas sensing

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