scholarly journals Ethanol Sensors Based on Porous In2O3 Nanosheet-Assembled Micro-Flowers

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3353
Author(s):  
Wenbo Qin ◽  
Zhenyu Yuan ◽  
Hongliang Gao ◽  
Fanli Meng
Keyword(s):  
Electron Microscopy ◽  
Gas Sensor ◽  
Gas Sensing ◽  
Hydrothermal Time ◽  
Hydrothermal Conditions ◽  
Step Method ◽  
Detection Range ◽  
Transmission Electron ◽  
Porous Nanosheets ◽  
One Step

By controlling the hydrothermal time, porous In2O3 nanosheet-assembled micro-flowers were successfully synthesized by a one-step method. The crystal structure, microstructure, and internal structure of the prepared samples were represented by an x-ray structure diffractometry, scanning electron microscopy, and transmission electron microscopy, respectively. The characterization results showed that when the hydrothermal time was 8 h, the In2O3 nano materials presented a flower-like structure assembled by In2O3 porous nanosheets. After successfully preparing the In2O3 gas sensor, the gas sensing was fully studied. The results show that the In2O3 gas sensor had an excellent gas sensing response to ethanol, and the material prepared under 8 h hydrothermal conditions had the best gas sensing property. At the optimum working temperature of 270 °C, the highest response value could reach 66, with a response time of 12.4 s and recovery time of 10.4 s, respectively. In addition, the prepared In2O3 gas sensor had a wide detection range for ethanol concentration, and still had obvious response for 500 ppb ethanol. Furthermore, the gas sensing mechanism of In2O3 micro-flowers was also studied in detail.

scholarly journals Facile Hydrothermal Synthesis of Two-Dimensional Porous ZnO Nanosheets for Highly Sensitive Ethanol Sensor

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Lai Van Duy ◽  
Nguyen Hong Hanh ◽  
Dang Ngoc Son ◽  
Pham Tien Hung ◽  
Chu Manh Hung ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Gas Sensing ◽  
Fast Response ◽  
Two Dimensional ◽  
Ethanol Sensor ◽  
X Ray ◽  
Transmission Electron ◽  
Porous Nanosheets ◽  
Composition And Structure ◽  
Zno Nanosheets

Two-dimensional porous ZnO nanosheets were synthesized by a facile hydrothermal method for ethanol gas-sensing application. The morphology, composition, and structure of the synthesized materials were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, powder X-ray diffraction, and high-resolution transmission electron microcopy. Results showed that the synthesized ZnO materials were porous nanosheets with a smooth surface and a thickness of 100 nm and a large pore size of approximately 80 nm. The as-prepared nanosheets, which had high purity, high crystallinity, and good dispersion, were used to fabricate a gas sensor for ethanol gas detection at different operating temperatures. The porous ZnO nanosheet gas sensor exhibited a high response value of 21 toward 500 ppm ethanol at a working temperature of 400°C with a reversible and fast response to ethanol gas (12 s/231 s), indicating its potential application. We also discussed the plausible sensing mechanism of the porous ZnO nanosheets on the basis of the adopted ethanol sensor.

Facile and green synthesis of amino-functionalized carbon nanodots for biomedical applications

2019 ◽  
Vol 12 (04) ◽  
pp. 1950062
Author(s):  
Zhongyan Gao ◽  
Qiang Ding ◽  
Qizhi Diao ◽  
Zhongying Guan ◽  
Biqiong Liu
Keyword(s):  
Electron Microscopy ◽  
Biomedical Applications ◽  
Carbon Nanodots ◽  
Excitation Wavelength ◽  
Pine Needle ◽  
Step Method ◽  
X Ray ◽  
Transmission Electron ◽  
One Step ◽  
Scanning Electron

Considering the high interests and concerns in regards to quantum dots (QDs), their properties and applications, this paper presents highly photoluminescent amino-functionalized carbon QDs which were prepared via a simple one-step method developed directly from pine needle. They were characterized by X-ray powder diffraction, photoluminescence (PL), UV-Vis diffused reflectance spectra, transmission electron microscope and scanning electron microscopy. These carbon QDs show strong and stable PL, which is dependent on excitation wavelength. The intense PL under longer excitation wavelength and excellent bioactivities suggest they can be used for biomedical applications due to its high photostability and biocompatibility.

scholarly journals Controlled Synthesis of Hierarchically Assembled Porous ZnO Microspheres with Enhanced Gas-Sensing Properties

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Shengsheng You ◽  
Haojie Song ◽  
Jing Qian ◽  
Ya-li Sun ◽  
Xiao-hua Jia
Keyword(s):  
Electron Microscopy ◽  
Gas Sensing ◽  
Hexagonal Phase ◽  
Trisodium Citrate ◽  
Zinc Hydroxide ◽  
Scanning Calorimetry ◽  
Sensing Properties ◽  
Transmission Electron ◽  
Porous Nanosheets ◽  
Gas Sensing Properties

The ZnO microspheres constructed by porous nanosheets were successfully synthesized by calcinating zinc hydroxide carbonate (ZHC) microspheres obtained by a sample hydrothermal method. The samples were characterized in detail with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric and differential scanning calorimetry (TG-DSC). The results indicated that the prepared ZnO microspheres were well crystalline with wurtzite hexagonal phase. The effects of reaction time, temperature, the amount of trisodium citrate, and urea on the morphology of ZnO microspheres were studied. The formation mechanism of porous ZnO microspheres was discussed. Furthermore, the gas-sensing properties for detection of organic gas of the prepared porous ZnO microspheres were investigated. The results indicated that the prepared porous ZnO microspheres exhibited high gas-sensing properties for detection of ethanol gas.

Synthesis, Characterization and Catalytic Properties of Monometal/SiO2 and Bimetal/SiO2 Hollow Spheres with Mesoporous Structure

NANO ◽  
2017 ◽  
Vol 12 (12) ◽  
pp. 1750148 ◽  
Author(s):  
Xinzhi Sun ◽  
Fanglin Du
Keyword(s):  
Electron Microscopy ◽  
Hollow Spheres ◽  
Mesoporous Structure ◽  
Hydrogen Atmosphere ◽  
Hydrothermal Conditions ◽  
Reaction Conditions ◽  
Transmission Electron ◽  
One Step ◽  
Temperature Programmed

Monometallic M1(M[Formula: see text] Ni/Cu/Fe/Co) silicates and bimetallic Ni–M2(M[Formula: see text] Cu/Fe/Co) silicates hollow spheres with mesoporous structure and the controllable morphology have been synthesized successfully via one-step sacrificial template method under hydrothermal conditions. The catalysts were obtained by reducing the corresponding silicates in situ under the hydrogen atmosphere at a certain temperature. All the silicates and the catalysts M1/SiO2 and Ni–M2/SiO2 hollow spheres have been characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and temperature-programmed reduction (TPR) thoroughly and systematically. The morphology and reaction conditions of bimetallic Ni–M2 silicates hollow spheres depend on the second metal M2, which has been verified by SEM, TEM and XRD. From the results, it can be concluded that bimetallic silicates possess better physical properties in favor of the catalytic activity. Bimetallic Ni–M2/SiO2 hollow spheres had higher catalytic property than the monometallic M1/SiO2 and the conversion of nitrobenzene could reach 100% within 3[Formula: see text]h using Ni–Cu/SiO2 and Ni–Fe/SiO2 hollow spheres as catalysts.

The Microstructure and Growth Behavior of Bi2Fe4O9 Superfine Particles Synthesized by Hydrothermal Method

2018 ◽  
Vol 281 ◽  
pp. 78-83
Author(s):  
Hai Peng Song ◽  
Qi Sun ◽  
Yuan Yu Wang
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Method ◽  
Phase Structure ◽  
Ostwald Ripening ◽  
Growth Behavior ◽  
Hydrothermal Time ◽  
Orthorhombic Structure ◽  
Hydrothermal Conditions ◽  
Hydrothermal Temperature ◽  
Transmission Electron

In this work, Bi2Fe4O9superfine particles were prepared by hydrothermal method and effects of hydrothermal conditions on the microstructure of Bi2Fe4O9, especially the concentration of OH-([OH-]) in initial solutions, were investigated. The results showed that [OH-] had obvious influences on the growth of Bi2Fe4O9under the same hydrothermal temperature and hydrothermal time. Phase structure of Bi2Fe4O9unchanged with the increase of [OH-] and maintained orthorhombic structure. Besides, the microstructure of Bi2Fe4O9was carefully studied through transmission electron microscopy (TEM). The results suggested that the mechanism of Bi2Fe4O9growth was Ostwald ripening. In conclusion, Bi2Fe4O9superfine particles with good morphology and microstructure can be successfully synthesized when the concentration of OH-is 2 mol/L and hydrothermal conditions are 240 °C for 6h.Keywords: Bi2Fe4O9, hydrothermal method, phase structure, growth mechanism Topic code numbers: C2

DUMBBELL-SHAPED ZnO NANORODS: GROWTH AND CHARACTERIZATION

2011 ◽  
Vol 10 (01n02) ◽  
pp. 87-92 ◽  
Author(s):  
N. RAJKUMAR ◽  
M. PRABHU ◽  
K. RAMACHANDRAN
Keyword(s):  
Electron Microscopy ◽  
Large Scale ◽  
Zno Nanorods ◽  
Growth Direction ◽  
Hexagonal Structure ◽  
X Ray Diffraction ◽  
Step Method ◽  
Structural Morphology ◽  
Transmission Electron ◽  
One Step

A novel one-step method to synthesize large-scale uniform dumbbell-shaped ZnO nanorods is presented here. The structural morphology was investigated by using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy analyses. The prepared dumbbells with diameter of 300 nm and length of 1.5 μm possess hexagonal structure with preferable [001] growth direction. The UV–vis absorption spectra show blueshift for smaller nanoparticles and redshift for bigger dumbbell-shaped ZnO nanorods.

Hydrothermal synthesis, characterization and gas sensing of Bi2MoxW1−xO6

2020 ◽  
Vol 13 (06) ◽  
pp. 2051032
Author(s):  
Li Zhang ◽  
Chengwen Song ◽  
Xiaoxing Zhang ◽  
Zhemin Shi ◽  
Jingkun Xiao
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Good Sensitivity ◽  
Good Property ◽  
X Ray ◽  
Transmission Electron ◽  
One Step ◽  
Sensing Application

Bi2MoxW[Formula: see text]O6 microspheres are synthesized by simple one-step hydrothermal method and the morphological characterizations are performed by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), BET, scanning electron microscopy (SEM), transmission electron microscopy (TEM). The gas sensing of Bi2WO6, Bi2MoO6 and Bi2MoxW[Formula: see text]O6 is investigated. It can be concluded that the sensor of Bi2MoxW[Formula: see text]O6 has the same good sensitivity as pure Bi2MoO6 and Bi2WO6 to alcohol. It is noteworthy that the operating temperature of Bi2Mo[Formula: see text]W[Formula: see text]O6 is 200∘C which is lower than that of pure Bi2WO6 or Bi2MoO6 (240∘C), so Bi2MoxW[Formula: see text]O6 show its good property for alcohol gas sensing application.

A novel additive-free oxides–hydrothermal approach for monazite-type LaPO4nanomaterials with controllable morphologies

2010 ◽  
Vol 43 (5) ◽  
pp. 990-997 ◽  
Author(s):  
Jie Ma ◽  
Qingsheng Wu
Keyword(s):  
Electron Microscopy ◽  
Treatment Time ◽  
Synthesis Temperature ◽  
Molar Ratio ◽  
Hydrothermal Conditions ◽  
Typical Sample ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Hydrothermal Approach

A facile oxides–hydrothermal (O–HT) method is demonstrated to prepare high-purity monazite-type LaPO4nanomaterials. In this approach, La2O3and P2O5powder are first directly used as precursors under additive-free hydrothermal conditions. The as-prepared samples are characterized with X-ray diffraction, Fourier transform IR spectroscopy, thermogravimetry, scanning electron microscopy, transmission electron microscopy (high-resolution TEM, energy dispersive spectroscopy) and selected-area electron diffraction. The typical sample obtained at 433 K in 24 h comprises uniform single-crystal nanofibres with a diameter of ∼15–28 nm and an aspect ratio of 30–50. The influences of treatment time, synthesis temperature and P/La molar ratio are investigated. The phase transition from hexagonal hydrate to monoclinic anhydrous lanthanum phosphate and the growth process of nanofibres are revealed by the experimental results. The formation mechanism of the monoclinic LaPO4is discussed. The result indicates that the P/La ratio does not influence the composition and crystal phase but changes the morphology of the product in the O–HT system.

scholarly journals Electrophoretic deposition of Au NPs on CNT networks for sensitive NO<sub>2</sub> detection

2014 ◽  
Vol 3 (2) ◽  
pp. 245-252 ◽  
Author(s):  
E. Dilonardo ◽  
M. Penza ◽  
M. Alvisi ◽  
C. Di Franco ◽  
D. Suriano ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
Spectroscopic Characterization ◽  
Core Diameter ◽  
Au Nps ◽  
Transmission Electron ◽  
P Type ◽  
Reducing Gases ◽  
The Impact

Abstract. In the present study, Au-surfactant core-shell colloidal nanoparticles (NPs) with controlled dimension and composition were synthesized by sacrificial anode electrolysis. Transmission electron microscopy (TEM) revealed that Au NPs core diameter is between 8 and 12 nm, as a function of the electrosynthesis conditions. Moreover, surface spectroscopic characterization by X-ray photoelectron spectroscopy (XPS) analysis confirmed the presence of nanosized gold phase. Controlled amounts of Au NPs were then deposited electrophoretically on carbon nanotube (CNT) networked films. The resulting hybrid materials were morphologically and chemically characterized using TEM, SEM (scanning electron microscopy) and XPS analyses, which revealed the presence of nanoscale gold, and its successful deposition on CNTs. Au NP/CNT networked films were tested as active layers in a two-pole resistive NO2 sensor for sub-ppm detection in the temperature range of 100–200 °C. Au NP/CNT exhibited a p-type response with a decrease in the electrical resistance upon exposure to oxidizing NO2 gas and an increase in resistance upon exposure to reducing gases (e.g. NH3). It was also demonstrated that the sensitivity of the Au NP/CNT-based sensors depends on Au loading; therefore, the impact of the Au loading on gas sensing performance was investigated as a function of the working temperature, gas concentration and interfering gases.

A Novel Tungsten Trioxide Based Gas Sensor for Indoor Formaldehyde Detection

2021 ◽  
Vol 16 (3) ◽  
pp. 363-367
Author(s):  
Gaoqi Zhang ◽  
Fan Zhang ◽  
Kaifang Wang ◽  
Tao Tian ◽  
Shanyu Liu ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Gas Sensor ◽  
Indoor Air ◽  
Gas Sensing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sensing Material ◽  
Transmission Electron ◽  
Gas Sensing Properties ◽  
Gas Response

Accurate and real-time detection of formaldehyde (HCHO) in indoor air is urgently needed for human health. In this work, a ceramic material (WO3·H2O) with unique structure was successfully prepared using an efficient hydrothermal method. The crystallinity, morphology and microstructure of the as-prepared sensing material were analyzed by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) as well as transmission electron microscope (TEM). The characterization results suggest that the as-prepared sample is composed of square-like nanoplates with uneven surface. Formaldehyde vapor is utilized as the target gas to investigate gas sensing properties of the synthesized novel nanoplates. The testing results indicate that the as-fabricated gas sensor exhibit high gas response and excellent repeatability to HCHO gas. The response value (Ra/Rg) is 24.5 towards 70 ppm HCHO gas at 350 °C. Besides, the gas sensing mechanism was described.

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