Ethanol Sensing Characteristics of ZnO Nanostructures Impregnated by Gold Colloid

2008 ◽  
Vol 55-57 ◽  
pp. 293-296 ◽  
Author(s):  
E. Wongrat ◽  
P. Pimpang ◽  
N. Mangkorntong ◽  
Supab Choopun
Keyword(s):  
Thermal Oxidation ◽  
Operating Temperature ◽  
Heating Temperature ◽  
Chemical Reduction ◽  
Zinc Powder ◽  
Optimum Operating ◽  
Zno Nanostructures ◽  
Gold Colloid ◽  
Optimum Operating Temperature ◽  
Ethanol Sensing

ZnO nanostructures were synthesized by thermal oxidation reaction from zinc powder and then impregnated by gold colloid. The gold colloid was prepared by chemical reduction technique and had red color. The heating temperature and sintering time of thermal oxidation were 700 °C and 24 hours, respectively under oxygen atmosphere. The morphology of ZnO nanostructures and ZnO impregnated gold colloid were studied by field emission scanning electron microscope (FE-SEM). The diameter and length of pure ZnO and ZnO impregnated gold colloid were about the same value and were in the range of 100-500 nm and 2.0-7.0 µm, respectively. The ethanol sensing properties of ZnO impregnated by gold colloid were tested in ethanol atmosphere at ethanol concentrations of 1000 ppm and at an operating temperature of 260-360 °C. It was found that the sensitivity and response time were improved for gold impregnated sensor with an optimum operating temperature of 300°C due to the enhanced reaction between the ethanol and the adsorbed oxygen at an optimum temperature.

Xylene-sensing of Fe2(MoO4)3 nanoplates prepared via a hydrothermal method

2017 ◽  
Vol 10 (03) ◽  
pp. 1750022 ◽  
Author(s):  
Mengying Xu ◽  
Zhidong Lin ◽  
Wenying Guo ◽  
Yuyuan Hong ◽  
Ping Fu ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Hydrothermal Process ◽  
Optimum Operating ◽  
Average Crystalline Size ◽  
Optimum Operating Temperature ◽  
Recovery Times ◽  
Response And Recovery ◽  
Simple Hydrothermal Process

Fe2(MoO4)3 nanoplates were prepared via a simple hydrothermal process. The average crystalline size of these nanoplates is 85.8[Formula: see text]nm. The sensor based on Fe2(MoO4)3 shows a high gas sensing performance to xylene. The response of Fe2(MoO4)3 sensor is 25.9–100[Formula: see text]ppm xylene at optimum operating temperature of 340[Formula: see text]C. The response and recovery times to 100[Formula: see text]ppm xylene are 4 and 10[Formula: see text]s, respectively. Furthermore, the Fe2(MoO4)3 sensor exhibits remarkable selectivity detection of xylene gas with negligible responses to toluene and benzene. Therefore, the Fe2(MoO4)3 is a promising material for the detection of xylene gas sensors.

TUNGSTEN-DOPED TiO2 NANOLAYERS WITH IMPROVED CO2 GAS SENSING PROPERTIES FOR ENVIRONMENTAL APPLICATIONS

2017 ◽  
Vol 24 (Supp02) ◽  
pp. 1850024 ◽  
Author(s):  
MALIHEH SABERI ◽  
ALI AKBAR ASHKARRAN
Keyword(s):  
Electron Microscopy ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Sol Gel ◽  
Optimum Operating ◽  
Optimum Operating Temperature ◽  
Sensing Properties ◽  
Vis Spectroscopy ◽  
Gas Sensing Properties ◽  
Tungsten Concentration

Tungsten-doped TiO2 gas sensors were successfully synthesized using sol–gel process and spin coating technique. The fabricated sensor was characterized by field emission scanning electron microscopy (FE-SEM), ultraviolet visible (UV–Vis) spectroscopy, transmission electron microscopy (TEM), X-Ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Gas sensing properties of pristine and tungsten-doped TiO2 nanolayers (NLs) were probed by detection of CO2 gas. A series of experiments were conducted in order to find the optimum operating temperature of the prepared sensors and also the optimum value of tungsten concentration in TiO2 matrix. It was found that introducing tungsten into the TiO2 matrix enhanced the gas sensing performance. The maximum response was found to be (1.37) for 0.001[Formula: see text]g tungsten-doped TiO2 NLs at 200[Formula: see text]C as an optimum operating temperature.

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.

Role of Toluene and Carbon Dioxide on Sulfur Recovery Efficiency in Claus Process

2014 ◽  
Author(s):  
Salisu Ibrahim ◽  
Marie Chardonneau ◽  
Ahmed S. AlShoaibi ◽  
Ashwani K. Gupta
Keyword(s):  
Carbon Dioxide ◽  
Operating Temperature ◽  
Optimum Operating ◽  
Recovery Efficiency ◽  
Sulfur Recovery ◽  
Optimum Operating Temperature ◽  
Claus Process ◽  
Acid Gas ◽  
Reactor Temperature

Examination of the effect of toluene and carbon dioxide accompanying acid gases (mainly H2S) in the sulfur recovery process is very critical to determine the optimum operating temperature for enhanced sulfur recovery. Experimental and simulation were used to quantify the conversion efficiency with the addition of different amounts of toluene and carbon dioxide/toluene mixtures to the H2S gas stream. The results showed similar trends between predictions and experimental data, which revealed a decrease in conversion efficiency with increase in toluene or carbon dioxide/toluene addition to the H2S gas stream in a reactor. Further simulations were carried out to seek for the effect of toluene and CO2 addition to acid gas stream on the more favorable operating temperature of the reactor. The results showed that toluene increases the optimum reactor temperature at which enhanced sulfur recovery occurs, whereas it reduces the optimum operating temperature in the presence of CO2. The presence of toluene and CO2 in the acid gas stream affects the sulfur recovery efficiency by altering the optimum temperature of the reactor. These results reveal the importance of reactor temperature and its excursion on sulfur recovery in a Claus process. The effect of mean reactor temperature and its role on detailed chemical speciation from within the reactor as well as the role of key species formed in the process on sulfur recovery are presented.

scholarly journals Acetone Sensing Properties and Mechanism of SnO2 Thick-Films

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3425 ◽  
Author(s):  
Yanping Chen ◽  
Hongwei Qin ◽  
Yue Cao ◽  
Heng Zhang ◽  
Jifan Hu
Keyword(s):  
Molecular Dynamics ◽  
Dft Calculation ◽  
Operating Temperature ◽  
Thick Films ◽  
Optimum Operating ◽  
Acetone Molecule ◽  
Optimum Operating Temperature ◽  
Molecular Dynamics Calculations ◽  
Calculation Results ◽  
Sensing Characteristics

In the present work, we investigated the acetone sensing characteristics and mechanism of SnO2 thick-films through experiments and DFT calculations. SnO2 thick film annealed at 600 °C could sensitively detect acetone vapors. At the optimum operating temperature of 180 °C, the responses of the SnO2 sensor were 3.33, 3.94, 5.04, and 7.27 for 1, 3, 5, and 10 ppm acetone, respectively. The DFT calculation results show that the acetone molecule can be adsorbed on the five-fold-coordinated Sn and oxygen vacancy (VO) sites with O-down, with electrons transferring from acetone to the SnO2 (110) surface. The acetone molecule acts as a donor in these modes, which can explain why the resistance of SnO2 or n-type metal oxides decreased after the acetone molecules were introduced into the system. Molecular dynamics calculations show that acetone does not convert to other products during the simulation.

meso-Tetraphenylporphine as a prochiral solvating agent (pro-CSA): A physicochemical study

2020 ◽  
Vol 24 (01n03) ◽  
pp. 320-329 ◽  
Author(s):  
Jan Labuta ◽  
Shinsuke Ishihara ◽  
Jonathan P. Hill
Keyword(s):  
Exchange Rate ◽  
Operating Temperature ◽  
Variable Temperature ◽  
Enantiomeric Excess ◽  
Optimum Operating ◽  
Valuable Insight ◽  
Optimum Operating Temperature ◽  
Factors Affecting ◽  
Line Shapes ◽  
Nmr Techniques

Meso-tetraphenylporphine (TPP) can be used as a prochiral chiral solvating agent (pro-CSA) for NMR detection of enantiomeric excess (ee) of chiral organic acids, in this study 2-phenoxypropionic acid (PPA). The pro-CSA sensing mechanism is unique in that it does not depend on formation of diastereomers. Here we discuss the factors affecting construction of the calibration curves ([Formula: see text] observed linearity between induced chemical shift non-equivalency and ee) including temperature, guest exchange rate and binding strength. We have employed various NMR techniques including variable temperature NMR, titration experiments and analyses of NMR spectral line shapes. It is confirmed that optimization of ee sensing conditions is required for each TPP/acid guest pair. For the TPP/PPA host–guest system, an optimum operating temperature is -32[Formula: see text] C with an acceptable range from -28[Formula: see text] C to -50[Formula: see text] C. The upper bound is due to complete diprotonation of TPP by PPA and the lower bound is due to the limit of PPA guest exchange rate at TPP’s binding site [Formula: see text] s[Formula: see text]. These findings, typical for porphyrin-type diprotonated pro-CSAs, yields valuable insight for design of the next generation of ee sensing molecules.

Prepare and Formaldehyde Sensing Properties of Hollow Nanofibers In2O3

2014 ◽  
Vol 941-944 ◽  
pp. 479-482
Author(s):  
Chang Bai Liu ◽  
Xing Yi Liu
Keyword(s):  
Operating Temperature ◽  
Optimum Operating ◽  
Hollow Nanofibers ◽  
Optimum Operating Temperature ◽  
X Ray ◽  
Sensing Properties ◽  
Response And Recovery ◽  
Formaldehyde Sensing ◽  
Hollow Nanofiber ◽  
Synthesized Materials

Hollow nanofiber In2O3 is synthesized by electrospinning. The as-synthesized materials are characterized by scanning electron microscope (SEM) and X-ray power diffraction (XRD). The formaldehyde sensing properties of the devices using In2O3 films are investigated at different operating temperatures. The results reveal that the response of hollow nanofiber In2O3 sensor is about 2.5 to 1 ppm formaldehyde at the optimum operating temperature of 270°C. The response and recovery time is about 3 s and 19 s, respectively. Moreover, sensor possesses a good selectivity to some common gas.

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