scholarly journals Growth Mechanisms of ZnO Micro-Nanomorphologies and Their Role in Enhancing Gas Sensing Properties

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1331 ◽  
Author(s):  
Ambra Fioravanti ◽  
Pietro Marani ◽  
Sara Morandi ◽  
Stefano Lettieri ◽  
Mauro Mazzocchi ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Functional Materials ◽  
Synthesis Process ◽  
Growth Mechanisms ◽  
Sensing Properties ◽  
Wet Chemical Synthesis ◽  
Gas Sensing Properties ◽  
Materials Used ◽  
Chemiresistive Gas Sensors

Zinc oxide (ZnO) is one of the main functional materials used to realize chemiresistive gas sensors. In addition, ZnO can be grown through many different methods obtaining the widest family of unique morphologies. However, the relationship between the ZnO morphologies and their gas sensing properties needs more detailed investigations, also with the aim to improve the sensor performances. In this work, seven nanoforms (such as leaves, bisphenoids, flowers, needles, etc.) were prepared through simple wet chemical synthesis. Morphological and structural characterizations were performed to figure out their growth mechanisms. Then, the obtained powders were deposited through screen-printing technique to realize thick film gas sensors. The gas sensing behavior was tested toward some traditional target gases and some volatile organic compounds (acetone, acetaldehyde, etc.) and compared with ZnO morphologies. Results showed a direct correlation between the sensors responses and the powders features (morphology and size), which depend on the specific synthesis process. The sensors can be divided in two behavioral classes, following the two main morphology kinds: aggregates of nanocrystals (leaves and bisphenoids), exhibiting best performances versus all tested gases and monocrystal based (stars, needle, long needles, flowers, and prisms).

The effect of Nb doping on hydrogen gas sensing properties of capacitor-like Pt/Nb-TiO2/Pt hydrogen gas sensors

2019 ◽  
Vol 806 ◽  
pp. 1052-1059 ◽  
Author(s):  
Zhong Li ◽  
ZhengJun Yao ◽  
Azhar Ali Haidry ◽  
Tomas Plecenik ◽  
Branislav Grancic ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Hydrogen Gas ◽  
Sensing Properties ◽  
Gas Sensing Properties ◽  
Hydrogen Gas Sensors ◽  
Nb Doping

scholarly journals Gas Sensing Properties of Mg-Incorporated Metal–Organic Frameworks

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3323 ◽  
Author(s):  
Jae-Hyoung Lee ◽  
Thanh-Binh Nguyen ◽  
Duy-Khoi Nguyen ◽  
Jae-Hun Kim ◽  
Jin-Young Kim ◽  
...  
Keyword(s):  
Pore Size ◽  
Gas Sensors ◽  
Gas Sensing ◽  
High Surface ◽  
Metal Organic Frameworks ◽  
Kinetic Properties ◽  
Sensing Properties ◽  
Sensing Applications ◽  
Gas Sensing Properties ◽  
Metal Organic

The gas sensing properties of two novel series of Mg-incorporated metal–organic frameworks (MOFs), termed Mg-MOFs-I and -II, were assessed. The synthesized iso-reticular type Mg-MOFs exhibited good crystallinity, high thermal stability, needle-shape morphology and high surface area (up to 2900 m2·g−1), which are promising for gas sensing applications. Gas-sensing studies of gas sensors fabricated from Mg-MOFs-II revealed better sensing performance, in terms of the sensor dynamics and sensor response, at an optimal operating temperature of 200 °C. The MOF gas sensor with a larger pore size and volume showed shorter response and recovery times, demonstrating the importance of the pore size and volume on the kinetic properties of MOF-based gas sensors. The gas-sensing results obtained in this study highlight the potential of Mg-MOFs gas sensors for the practical monitoring of toxic gases in a range of environments.

scholarly journals NOx Gas Sensing Properties and Mechanism of ZnO-Based Varistor-Type Gas Sensors

1999 ◽  
Vol 119 (2) ◽  
pp. 103-107 ◽  
Author(s):  
Takeo Hyodo ◽  
Keiko Okamoto ◽  
Yuji Takao ◽  
Yasuhiro Shimizu ◽  
Makoto Egashira
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Sensing Properties ◽  
Gas Sensing Properties

New Insight into Gas Sensing Properties of SnO2 and Cu2o/CuO Based Gas Sensors By Near Ambient Pressure XPS

2020 ◽  
Vol MA2020-01 (28) ◽  
pp. 2114-2114
Author(s):  
Mykhailo Vorokhta ◽  
Pavel Hozak ◽  
Ivan Khalakhan ◽  
Martin Vrnata ◽  
Ján Lančok ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Ambient Pressure ◽  
Sensing Properties ◽  
Ambient Pressure Xps ◽  
Gas Sensing Properties ◽  
Insight Into ◽  
Near Ambient Pressure Xps

scholarly journals Discriminable Sensing Response Behavior to Homogeneous Gases Based on n-ZnO/p-NiO Composites

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 785 ◽  
Author(s):  
Wen-Dong Zhou ◽  
Davoud Dastan ◽  
Jing Li ◽  
Xi-Tao Yin ◽  
Qi Wang
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Sol Gel ◽  
High Sensitivity ◽  
Oxide Semiconductor ◽  
Sensing Properties ◽  
Gas Sensing Properties ◽  
P Type ◽  
Type Response ◽  
Properties Of Composites

Metal oxide semiconductor (MOS) gas sensors have the advantages of high sensitivity, short response-recovery time and long-term stability. However, the shortcoming of poor discriminability of homogeneous gases limits their applications in gas sensors. It is well-known that the MOS materials have similar gas sensing responses to homogeneous gases such as CO and H2, so it is difficult for these gas sensors to distinguish the two gases. In this paper, simple sol–gel method was employed to obtain the ZnO–xNiO composites. Gas sensing performance results illustrated that the gas sensing properties of composites with x > 0.425 showed a p-type response to both CO and H2, while the gas sensing properties of composites with x < 0.425 showed an n-type response to both CO and H2. However, it was interesting that ZnO–0.425NiO showed a p-type response to CO but an discriminable response (n-type) to H2, which indicated that modulating the p-type or n-type semiconductor concentration in p-n composites could be an effective method with which to improve the discriminability of this type of gas sensor regarding CO and H2. The phenomenon of the special gas sensing behavior of ZnO–0.425NiO was explained based on the experimental observations and a range of characterization techniques, including XRD, HRTEM and XPS, in detail.

On the Role of Oxygen Vacancies in the Determination of the Gas-Sensing Properties of Tin-Oxide Nanowires

2006 ◽  
Vol 915 ◽  
Author(s):  
Roberto Mosca ◽  
Mingzheng Zha ◽  
Davide Calestani ◽  
Laura Lazzarini ◽  
Giancarlo Salviati ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Oxygen Vacancies ◽  
Gas Sensing ◽  
Oxide Nanowires ◽  
Sensing Properties ◽  
Sno2 Nanowires ◽  
Gas Sensing Properties ◽  
First Results ◽  
Depth Study

AbstractSnO2 nanowires have been recently employed in the “gas-sensors” field and excellent results of conductometric and optical tests on SnO2 nanowires-based gas sensors have been reported.However, the mechanism that controls the gas-sensing effect in metal oxides nanowires is not fully understood yet. Here the authors present the first results of an in-depth study about the influence of post growth treatments on the physical and gas sensing properties of SnO2 nanowires.In particular, SnO2 nanowires grown by a vapour transport technique were annealed in a oxygen-rich atmosphere and then characterized by different techniques to assess the influence of the treatment on the nanowires properties.The annealing in oxygen atmosphere is shown to strongly affect the PL and CL spectra, the electrical resistivity as well as the gas sensing properties of the nanowires. The obtained results are consistent with a reduction of the oxygen vacancies concentration induced by the O2 treatment and seem to confirm the role of these defects in affecting the gas response of SnO2 nanowires-based sensors.

Hierarchically designed ZnO nanostructure based high performance gas sensors

RSC Advances ◽  
2014 ◽  
Vol 4 (90) ◽  
pp. 49521-49528 ◽  
Author(s):  
Mohammad R. Alenezi ◽  
T. H. Alzanki ◽  
A. M. Almeshal ◽  
A. S. Alshammari ◽  
M. J. Beliatis ◽  
...  
Keyword(s):  
Gas Sensors ◽  
High Performance ◽  
Gas Sensing ◽  
High Surface ◽  
Hierarchical Nanostructures ◽  
Sensing Properties ◽  
Zno Nanostructure ◽  
Gas Sensing Properties

Enhanced gas sensing properties of ZnO were achieved by designing hierarchical nanostructures with high surface-to-volume ratios and more exposed polar facets.

Effect of Au Doped WO3 Gas Sensors for NO2 Detection

2011 ◽  
Vol 492 ◽  
pp. 308-311 ◽  
Author(s):  
Wu Bin Gao ◽  
Cheng Dong ◽  
Xu Liu ◽  
Yun Han Ling ◽  
Jia Lin Sun
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Point Contact ◽  
X Ray ◽  
Sensing Properties ◽  
Gas Sensing Properties ◽  
Tungsten Filaments ◽  
Gas Response ◽  
Contact Sensors

Gas sensor based on point contact tungsten trioxide (WO3) was prepared by in-situ induction-heating thermal oxidation of tungsten filaments. X-ray diffractometry (XRD) and field emission scanning electron microscopy (FESEM) were employed to analyze the phase and the morphology of the fabricated thin films. The results showed that the WO3films exhibited a monoclinic phase and were composed of hierarchical micro and nano crystals. The NO2(1-8 ppm) sensing properties of the point contact sensors based on Pure and Au-sputtering doped (2.5 at%) WO3films were investigated. The results showed that the gas sensing properties of the Au (2.5 at%) doped WO3sensors were superior to those of the undoped. The obtained point contact WO3sensor exhibited the maximum NO2gas response at 100°C.

scholarly journals Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases

2016 ◽  
Vol 7 ◽  
pp. 22-31 ◽  
Author(s):  
Elena Dilonardo ◽  
Michele Penza ◽  
Marco Alvisi ◽  
Cinzia Di Franco ◽  
Francesco Palmisano ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
Low Cost ◽  
Sol Gel ◽  
Zno Nanostructures ◽  
Sensing Properties ◽  
Gas Sensing Properties ◽  
Zno Powders ◽  
One Step ◽  
Chemiresistive Gas Sensors

A one-step electrochemical method based on sacrificial anode electrolysis (SAE) was used to deposit stabilized gold nanoparticles (Au NPs) directly on the surface of nanostructured ZnO powders, previously synthesized through a sol–gel process. The effect of thermal annealing temperatures (300 and 550 °C) on chemical, morphological, and structural properties of pristine and Au-doped ZnO nancomposites (Au@ZnO) was investigated. Transmission and scanning electron microscopy (TEM and SEM), as well as X-ray photoelectron spectroscopy (XPS), revealed the successful deposition of nanoscale gold on the surface of spherical and rod-like ZnO nanostructures, obtained after annealing at 300 and 550 °C, respectively. The pristine ZnO and Au@ZnO nanocomposites are proposed as active layer in chemiresistive gas sensors for low-cost processing. Gas-sensing measurements towards NO2 were collected at 300 °C, evaluating not only the Au-doping effect, but also the influence of the different ZnO nanostructures on the gas-sensing properties.

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