Al-doped ZnO for highly sensitive CO gas sensors

Hjiri, M.; Mır, L. El; Leonardi, Salvatore Gianluca; Pistone, Alessandro; Mavilia, Letterio; Neri, G.

doi:10.1016/j.snb.2014.01.068

Cited by 358 publications

(144 citation statements)

References 31 publications

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“…Together with nitrogen dioxide, CO is considered one of the most dangerous pollutant gases. Prolonged exposure to concentrations higher than 50-70 ppm of CO may cause death [13]. Many different nanostructures based on pure and doped ZnO have been investigated as sensitive materials for CO monitoring [13,[76][77][78].…”

Section: Carbon Monoxidementioning

confidence: 99%

Two-Dimensional Zinc Oxide Nanostructures for Gas Sensor Applications

Leonardi

2017

Chemosensors

159

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Two-dimensional (2D) nanomaterials, due to their unique physical and chemical properties, are showing great potential in catalysis and electronic/optoelectronic devices. Moreover, thanks to the high surface to volume ratio, 2D materials provide a large specific surface area for the adsorption of molecules, making them efficient in chemical sensing applications. ZnO, owing to its many advantages such as high sensitivity, stability, and low cost, has been one of the most investigated materials for gas sensing. Many ZnO nanostructures have been used to fabricate efficient gas sensors for the detection of various hazardous and toxic gases. This review summarizes most of the research articles focused on the investigation of 2D ZnO structures including nanosheets, nanowalls, nanoflakes, nanoplates, nanodisks, and hierarchically assembled nanostructures as a sensitive material for conductometric gas sensors. The synthesis of the materials and the sensing performances such as sensitivity, selectivity, response, and recovery times as well as the main influencing factors are summarized for each work. Moreover, the effect of mainly exposed crystal facets of the nanostructures on sensitivity towards different gases is also discussed.

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Section: Carbon Monoxidementioning

confidence: 99%

Two-Dimensional Zinc Oxide Nanostructures for Gas Sensor Applications

Leonardi

2017

Chemosensors

159

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“…16)22) The use of Al is environmentally and industrially favorable because Al is abundant and inexpensive compared to noble metals such as Pt, Pd, and Au. However, the role played by Al atoms in the improvement of the sensing performance of Al-doped ZnO gas sensors remains unclear because the doped Al acts as a donor in ZnO, changing not only the electronic properties but also the microstructure of the ZnO, such as grain size, shape, and degree of orientation.…”

Section: )2)mentioning

confidence: 99%

“…Meanwhile, Navale et al 21) concluded that surface defects formed by Al doping play an important role in the enhancement of the gas sensing response, according to electron paramagnetic resonance measurements and diffuse reflectance spectroscopy. Hjiri et al 16) and Guan et al 17) reported the formation of an Al-related secondary phase on the surface of ZnO nanoparticles due to heavy Al doping, and suggested the possi-bility that the secondary phase acts as a catalyst to improve the sensing performance of the gas sensors. Meanwhile, the effects of the atomic arrangement of the exposed sample surface on the sensing properties have not been adequately investigated for Aldoped ZnO, even though the surface atomic arrangement of a sensor body is known to affect the sensing performance.…”

Section: )2)mentioning

confidence: 99%

Gas sensing properties of <i>c</i>-axis-oriented Al-incorporated ZnO films epitaxially grown on (11-20) sapphire substrates using pulsed laser deposition

Adachi

Watanabe

Saito

et al. 2016

J. Ceram. Soc. Japan

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Al-incorporated ZnO films with various Al concentrations were prepared using pulsed laser deposition on the (11 20) face of sapphire substrates, and their gas sensing properties were evaluated. The use of c-axis-oriented epitaxial films with the same thickness suppressed the influence of the surface-to-volume ratio and surface atomic arrangements on the sensing properties, clarifying the role of Al doping in the improvement of ZnO gas sensors. The results of ethanol gas sensing measurements indicated that Al doping significantly improved the sensing response and response time of the ZnO gas sensors. The formation of Al-related impurity phases and/or non-equilibrium defects induced by Al doping improved the sensing performance. On the other hand, changes in the grain size did not significantly affect the sensing response.

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“…According to [23,27], this compensation is achieved through the introduction of electrons in the doped-ZnO conduction band, favored by the band gap narrowing, increasing concentration of free electrons. As a consequence, an increase in conductivity and in sensing properties of the doped oxide have been observed [23,27]. The charge compensation mechanism is presented in Equation A, written considering the Kröger-Vink notation [28].…”

Section: Catalyst Characterizationmentioning

confidence: 99%

Pure and Al-doped ZnO obtained by the modified Pechini method applied in ethanolic transesterification of cottonseed oil

et al. 2017

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Pure zinc oxide (ZnO) and 5% Al-doped ZnO (ZNAL) were synthesized using the modified Pechini method and characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Raman spectroscopy, infrared spectroscopy and UV-visible spectroscopy. XRF confirmed the theoretical stoichiometry, while XRD and Raman spectroscopy indicated that Al 3+ was incorporated into the ZnO wurtzite lattice with no secondary phases, leading to a decrease in the band gap value and to a meaningful increase of the Lewis basic sites. Pure and doped ZnO were used as catalysts in the ethylic transesterification of cottonseed oil using a factorial design to determine the best synthesis conditions. Oil conversion into biodiesel was evaluated by viscosity measurements and 1 H NMR spectroscopy. The results analyzed by factorial design indicated that the catalyst type and temperature were the determinant factors in the conversion indices. The highest basicity of the ZNAL lead to a significant increase of the catalytic potential, reaching a reduction of the oil viscosity next to 71% at 130 °C and greater than 85% at 200 °C.

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Al-doped ZnO for highly sensitive CO gas sensors

Cited by 358 publications

References 31 publications

Two-Dimensional Zinc Oxide Nanostructures for Gas Sensor Applications

Two-Dimensional Zinc Oxide Nanostructures for Gas Sensor Applications

Gas sensing properties of <i>c</i>-axis-oriented Al-incorporated ZnO films epitaxially grown on (11-20) sapphire substrates using pulsed laser deposition

Pure and Al-doped ZnO obtained by the modified Pechini method applied in ethanolic transesterification of cottonseed oil

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