scholarly journals Hydrothermal Synthesis and Structural Characterization of NiO/SnO2Composites and Hydrogen Sensing Properties

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Chao Wei ◽  
Bin Bo ◽  
Fengbo Tao ◽  
Yuncai Lu ◽  
Shudi Peng ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Power Transformer ◽  
Transformer Oil ◽  
Photoelectron Spectra ◽  
X Ray ◽  
Hydrogen Sensing ◽  
Sensing Material ◽  
P Type ◽  
Surface Morphologies ◽  
Gas Response

Pure SnO2and NiO doped SnO2nanostructures were successfully synthesized via a simple and environment-friendly hydrothermal method. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectra (XPS) were used to investigate the crystalline structures, surface morphologies and microstructures, and element components and their valences of the as-synthesized samples. Furthermore, planar chemical gas sensors based on the synthesized pure SnO2and NiO/SnO2composites were fabricated and their sensing performances to hydrogen, an important fault characteristic gas dissolved in power transformer oil, were investigated in detail. Gas sensing experiments indicate that the NiO/SnO2composites showed much higher gas response and lower working temperature than those of pure SnO2, which could be ascribed to the formation of p-n heterojunctions between p-type NiO and n-type SnO2. These results demonstrate that the as-synthesized NiO/SnO2composites a promising hydrogen sensing material.

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.

scholarly journals Pd-Doped SnO2-Based Sensor Detecting Characteristic Fault Hydrocarbon Gases in Transformer Oil

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Weigen Chen ◽  
Qu Zhou ◽  
Tuoyu Gao ◽  
Xiaoping Su ◽  
Fu Wan
Keyword(s):  
Molecular Orbital ◽  
Online Monitoring ◽  
Gas Sensing ◽  
Power Transformer ◽  
Transformer Oil ◽  
Orbital Energy ◽  
Hydrocarbon Gases ◽  
X Ray ◽  
Molecular Orbital Energy ◽  
Highest Occupied Molecular Orbital

Methane (CH4), ethane (C2H6), ethylene (C2H4), and acetylene (C2C2) are important fault characteristic hydrocarbon gases dissolved in power transformer oil. Online monitoring these gaseous components and their generation rates can present the operational state of power transformer timely and effectively. Gas sensing technology is the most sticky and tricky point in online monitoring system. In this paper, pure and Pd-doped SnO2nanoparticles were synthesized by hydrothermal method and characterized by X-ray powder diffraction, field-emission scanning electron microscopy, and energy dispersive X-ray spectroscopy, respectively. The gas sensors were fabricated by side-heated preparation, and their gas sensing properties against CH4, C2H6, C2H4, and C2H2were measured. Pd doping increases the electric conductance of the prepared SnO2sensors and improves their gas sensing performances to hydrocarbon gases. In addition based on the frontier molecular orbital theory, the highest occupied molecular orbital energy and the lowest unoccupied molecular orbital energy were calculated. Calculation results demonstrate that C2H4has the highest occupied molecular orbital energy among CH4, C2H6, C2H4, and C2H2, which promotes charge transfer in gas sensing process, and SnO2surfaces capture a relatively larger amount of electric charge from adsorbed C2H4.

Synthesis of Co3O4 Multilayer Nanosheet Material and its Promising Gas Sensing Property

2014 ◽  
Vol 937 ◽  
pp. 231-236 ◽  
Author(s):  
Ming Li Yin ◽  
Sheng Zhong Liu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
Annealing Treatment ◽  
Solution Concentration ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sensing Material ◽  
Ethanol Resistance ◽  
Structure Morphology ◽  
P Type

Co3O4multilayer nanosheets were synthesized by a hydrothermal method and a post annealing treatment process. The effect of solution concentration and ratio on the morphology of Co3O4precursor was studied. The crystalline structure, morphology and elemental composition of Co3O4multilayer nanosheets were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy technologies. When exposed to reducing gas such as ethanol, resistance of Co3O4multilayer nanosheet sensor increases quickly, demonstrating that the Co3O4multilayer nanosheets are p-type conductivity. For 100 ppm alcohol at 240 °C, the sensor response is as high as 32, indicating that the powder of Co3O4multilayer nanosheets is a very promising low-powder gas sensing material.

scholarly journals A Hydrogen Gas Sensor Based on TiO2 Nanoparticles on Alumina Substrate

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2483 ◽  
Author(s):  
Siti Mohd Chachuli ◽  
Mohd Hamidon ◽  
Md. Mamat ◽  
Mehmet Ertugrul ◽  
Nor Abdullah
Keyword(s):  
Tio2 Nanoparticles ◽  
Gas Sensor ◽  
Operating Temperature ◽  
Hydrogen Gas ◽  
Optimum Operating ◽  
Optimum Operating Temperature ◽  
X Ray ◽  
Semiconductor Gas Sensor ◽  
Sensing Material ◽  
P Type

High demand of semiconductor gas sensor works at low operating temperature to as low as 100 °C has led to the fabrication of gas sensor based on TiO2 nanoparticles. A sensing film of gas sensor was prepared by mixing the sensing material, TiO2 (P25) and glass powder, and B2O3 with organic binder. The sensing film was annealed at temperature of 500 °C in 30 min. The morphological and structural properties of the sensing film were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The gas sensor was exposed to hydrogen with concentration of 100–1000 ppm and was tested at different operating temperatures which are 100 °C, 200 °C, and 300 °C to find the optimum operating temperature for producing the highest sensitivity. The gas sensor exhibited p-type conductivity based on decreased current when exposed to hydrogen. The gas sensor showed capability in sensing low concentration of hydrogen to as low as 100 ppm at 100 °C.

Direct preparation and microstructure investigation of p-type transparent conducting Ga-doped SnO2 thin films

2010 ◽  
Vol 25 (S1) ◽  
pp. S36-S39 ◽  
Author(s):  
Tieying Yang ◽  
Xiubo Qin ◽  
Huan-hua Wang ◽  
Quanjie Jia ◽  
Runsheng Yu ◽  
...  
Keyword(s):  
Thin Films ◽  
Rf Magnetron Sputtering ◽  
Photoelectron Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fine Microstructure ◽  
Direct Preparation ◽  
Sno2 Thin Films ◽  
P Type ◽  
Reactive Rf Magnetron Sputtering

Transparent p-type conducting Ga-doped SnO2 thin films were prepared using reactive rf-magnetron sputtering. Good p-type conduction was directly realized without the need of postdeposition annealing. The p-type conductivity was found to be very sensitive to the growth condition and process, suggesting that the carrier behavior is strongly related to the fine microstructure of the films. The microstructures of the films were characterized using synchrotron X-ray diffraction and specular reflectivity techniques. The valence state of the Ga dopant was measured from X-ray photoelectron spectra to explain the origin of net holes presented in the films.

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 High Performance Acetylene Sensor with Heterostructure Based on WO3 Nanolamellae/Reduced Graphene Oxide (rGO) Nanosheets Operating at Low Temperature

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 909 ◽  
Author(s):  
Zikai Jiang ◽  
Weigen Chen ◽  
Lingfeng Jin ◽  
Fang Cui ◽  
Zihao Song ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Gas Sensor ◽  
High Performance ◽  
Gas Sensing ◽  
Hybrid Nanocomposites ◽  
Transformer Oil ◽  
X Ray ◽  
Reduced Graphene ◽  
Sensing Performance

The development of functionalized metal oxide/reduced graphene oxide (rGO) hybrid nanocomposites concerning power equipment failure diagnosis is one of the most recent topics. In this work, WO3 nanolamellae/reduced graphene oxide (rGO) nanocomposites with different contents of GO (0.5 wt %, 1 wt %, 2 wt %, 4 wt %) were synthesized via controlled hydrothermal method. X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analyses-derivative thermogravimetric analysis-differential scanning calorimetry (TG-DTG-DSC), BET, and photoluminescence (PL) spectroscopy were utilized to investigate morphological characterizations of prepared gas sensing materials and indicated that high quality WO3 nanolamellae were widely distributed among graphene sheets. Experimental ceramic planar gas sensors composing of interdigitated alumina substrates, Au electrodes, and RuO2 heating layer were coated with WO3 nanolamellae/reduced graphene oxide (rGO) films by spin-coating technique and then tested for gas sensing towards multi-concentrations of acetylene (C2H2) gases in a carrier gas with operating temperature ranging from 50 °C to 400 °C. Among four contents of prepared samples, sensing materials with 1 wt % GO nanocomposite exhibited the best C2H2 sensing performance with lower optimal working temperature (150 °C), higher sensor response (15.0 toward 50 ppm), faster response-recovery time (52 s and 27 s), lower detection limitation (1.3 ppm), long-term stability, and excellent repeatability. The gas sensing mechanism for enhanced sensing performance of nanocomposite is possibly attributed to the formation of p-n heterojunction and the active interaction between WO3 nanolamellae and rGO sheets. Besides, the introduction of rGO nanosheets leads to the impurity of synthesized materials, which creates more defects and promotes larger specific area for gas adsorption, outstanding conductivity, and faster carrier transport. The superior gas sensing properties of WO3/rGO based gas sensor may contribute to the development of a high-performance ppm-level gas sensor for the online monitoring of dissolved C2H2 gas in large-scale transformer oil.

scholarly journals Sputtered SnO2/ZnO Heterostructures for Improved NO2 Gas Sensing Properties

Chemosensors ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 67 ◽  
Author(s):  
Bharat Sharma ◽  
Ashutosh Sharma ◽  
Monika Joshi ◽  
Jae-ha Myung
Keyword(s):  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
Operating Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Response Recovery ◽  
No2 Gas Sensor ◽  
Highly Sensitive ◽  
Gas Sensing Properties ◽  
Gas Response

A highly sensitive and selective NO2 gas sensor dependent on SnO2/ZnO heterostructures was fabricated using a sputtering process. The SnO2/ZnO heterostructure thin film samples were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Sensors fabricated with heterostructures attained higher gas response (S = 66.9) and quicker response-recovery (20 s, 45 s) characteristics at 100 °C operating temperature towards 100 ppm NO2 gas efficiently in comparison to sensors based on their mono-counterparts. The selectivity and stability of SnO2/ZnO heterostructures were studied. The more desirable sensing mechanism of SnO2/ZnO heterostructures towards NO2 was described in detail.

Enhanced Gas Sensing of Tin Dioxide Based Sensor for Indoor Formaldehyde Application

2021 ◽  
Vol 16 (2) ◽  
pp. 337-342
Author(s):  
Gaoqi Zhang ◽  
Fan Zhang ◽  
Kaifang Wang ◽  
Shanyu Liu ◽  
Ying Wang ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Tin Dioxide ◽  
Gas Sensing ◽  
Fast Response ◽  
Sensing Material ◽  
Gas Sensing Properties ◽  
Recovery Times ◽  
Response And Recovery ◽  
Formaldehyde Sensing ◽  
Gas Response

Indoor formaldehyde detection is of great important at present. Using efficient solvothermal method, nanosheet-constructed and nanorod-constructed hierarchical tin dioxide (SnO2) microspheres were successfully synthesized in this work and used for the gas sensing material for indoor formaldehyde application. The as-prepared two kinds of SnO2 gas sensing materials were applied to fabricate the gas sensors and formaldehyde gas sensing experiments were carried out. The HCHO gas sensing tests indicate that the gas response of the nanosheet-constructed SnO2 microspheres is about 1.7 times higher than that of the nanorod-constructed SnO2 microspheres. In addition, both of the two SnO2 based gas sensors show almost fast response and recovery time to HCHO gas. For the nanosheet-constructed microspheres, the response value is estimated to be 32.0 at 350 °C to 60 ppm formaldehyde gas, while the response and recovery times are 7 and 5 s, respectively. The simple and efficient preparation method and improved gas sensing properties show that the as-synthesized hierarchical SnO2 microsphere that is constructed by a large amount of nanosheets exhibits significant potential application for the indoor formaldehyde sensing.

scholarly journals CTAB-Assisted Hydrothermal Synthesis of WO3Hierarchical Porous Structures and Investigation of Their Sensing Properties

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Dan Meng ◽  
Guosheng Wang ◽  
Xiaoguang San ◽  
Yanbai Shen ◽  
Guodong Zhao ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Nitrogen Adsorption ◽  
Fast Response ◽  
Photoelectron Spectra ◽  
Porous Structures ◽  
X Ray ◽  
Transmission Electron ◽  
Hierarchical Porous ◽  
Adsorption Desorption ◽  
Higher Sensitivity

WO3hierarchical porous structures were successfully synthesized via cetyltrimethylammonium bromide- (CTAB-) assisted hydrothermal method. The structure and morphology were investigated using scanning electron microscope, X-ray diffractometer, transmission electron microscopy, X-ray photoelectron spectra, Brunauer-Emmett-Teller nitrogen adsorption-desorption, and thermogravimetry and differential thermal analysis. The result demonstrated that WO3hierarchical porous structures with an orthorhombic structure were constructed by a number of nanoparticles about 50–100 nm in diameters. The H2gas sensing measurements showed that well-defined WO3hierarchical porous structures with a large specific surface area exhibited the higher sensitivity compared with products without CTAB at all operating temperatures. Moreover, the reversible and fast response to H2gas and good selectivity were obtained. The results indicated that the WO3hierarchical porous structures are promising materials for gas sensors.

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