scholarly journals α-MnO2 Nanowires as Potential Scaffolds for a High-Performance Formaldehyde Gas Sensor Device

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 860
Author(s):  
Ahmad Umar ◽  
Ahmed A. Ibrahim ◽  
Rajesh Kumar ◽  
Hassan Algadi ◽  
Hasan Albargi ◽  
...  
Keyword(s):  
High Performance ◽  
Average Length ◽  
Average Diameter ◽  
Xrd Pattern ◽  
Sensor Device ◽  
Recovery Times ◽  
Response And Recovery ◽  
Uniform Diameter ◽  
Gas Response ◽  
Mno2 Nanowires

Herein, we report a chemi-resistive sensing method for the detection of formaldehyde (HCHO) gas. For this, α-MnO2 nanowires were synthesized hydrothermally and examined for ascertaining their chemical composition, crystal phase, morphology, purity, and vibrational properties. The XRD pattern confirmed the high crystallinity and purity of the α-MnO2 nanowires. FESEM images confirmed a random orientation and smooth-surfaced wire-shaped morphologies for as-synthesized α-MnO2 nanowires. Further, the synthesized nanowires with rounded tips had a uniform diameter throughout the length of the nanowires. The average diameter of the α-MnO2 nanowires was found to be 62.18 nm and the average length was ~2.0 μm. Further, at an optimized temperature of 300 °C, the fabricated HCHO sensor based on α-MnO2 nanowires demonstrated gas response, response, and recovery times of 19.37, 18, and 30 s, respectively.

Star-Fruit-Shaped CuO Structures for High Performance Ethanol Gas Sensor Device

2021 ◽  
Vol 13 (4) ◽  
pp. 724-733
Author(s):  
Ahmad Umar ◽  
Ahmed A. Ibrahim ◽  
Rajesh Kumar ◽  
Hassan Algadi ◽  
Hasan Albargi ◽  
...  
Keyword(s):  
Gas Sensor ◽  
High Performance ◽  
Crystal Size ◽  
Gas Sensing ◽  
Sensor Applications ◽  
Sensor Device ◽  
Star Fruit ◽  
Micro Structures ◽  
Gas Response ◽  
Structural Crystal

In this paper, star-fruit-shaped CuO microstructures were hydrothermally synthesized and subsequently characterized through different techniques to understand morphological, compositional, structural, crystal, optical and vibrational properties. The formation of star-fruit-shaped structures along with some polygonal and spherical nanostructures was confirmed by FESEM analysis. XRD data and Raman spectrum confirmed the monoclinic tenorite crystalline phase of the CuO with crystal size 17.61 nm. Star-fruit-shaped CuO microstructures were examined for ethanol gas sensing behavior at various operating temperatures and concentrations. The gas response of 135% was observed at the optimal temperature of 225 °C. Due to excellent selectivity, stability and re-usability, the as-fabricated sensor based on star-fruit-shaped CuO micro-structures may be explored for future toxic gas sensor applications.

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 Facile Chemical Bath Synthesis of SnS Nanosheets and Their Ethanol Sensing Properties

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2581 ◽  
Author(s):  
Wei Shan ◽  
Zhengqian Fu ◽  
Mingsheng Ma ◽  
Zhifu Liu ◽  
Zhenggang Xue ◽  
...  
Keyword(s):  
High Performance ◽  
Gas Sensing ◽  
Raw Materials ◽  
Orthorhombic Phase ◽  
Ethanol Vapor ◽  
Fast Response ◽  
Sensing Applications ◽  
Recovery Times ◽  
Response And Recovery ◽  
Ethanol Sensing

Tin(II) monosulfide (SnS) nanosheets were synthesized using SnCl4•5H2O and S powders as raw materials in the presence of H2O via a facile chemical bath method. Orthorhombic phase SnS nanosheets with a thickness of ~100 nm and lateral dimensions of 2~10 μm were obtained by controlling the synthesis parameters. The formation of a SnO2 intermediate is key to the valence reduction of Sn ions (from IV to II) and the formation of SnS. The gas sensors fabricated from SnS nanosheets exhibited an excellent response of 14.86 to 100 ppm ethanol vapor when operating at 160 °C, as well as fast response and recovery times of 23 s and 26 s, respectively. The sensors showed excellent selectivity for the detection of ethanol over acetone, methanol, and ammonia gases, which indicates the SnS nanosheets are promising for high-performance ethanol gas sensing applications.

scholarly journals Rapid and Facile Synthesis of High-Performance Silver Nanowires by a Halide-Mediated, Modified Polyol Method for Transparent Conductive Films

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1139
Author(s):  
Lin Cao ◽  
Qin Huang ◽  
Jie Cui ◽  
Huaijun Lin ◽  
Wei Li ◽  
...  
Keyword(s):  
High Performance ◽  
Silver Nanowires ◽  
Average Length ◽  
Average Diameter ◽  
Silver Nanowire ◽  
Polyol Method ◽  
Synthesis Process ◽  
Transparent Conductive Films ◽  
Conductive Films ◽  
Modified Polyol Method

Silver nanowires are receiving increasing attention as a kind of prospective transparent and conductive material. Here, we successfully synthesized high-performance silver nanowires with a significantly decreased reaction time by a modified polyol method. The synthesis process involved the addition of halides, including NaCl and NaBr, to control the release rate of Ag+ ions, as Cl− and Br− ions react with Ag+ ions to form AgCl and AgBr with different solubilities. As a result, Ag+ ions could be slowly released by graded dissolution, and the formation of silver nanowires was promoted. The results showed that the concentration of the added halides played an important role in the morphology of the final product. High-quality silver nanowires with an average diameter of 70 nm and average length of 21 μm were obtained by optimizing the reaction parameters. Afterwards, a simple silver nanowire coating was applied in order to fabricate the transparent conductive films. The film that was based on the silver nanowires provided a transmittance of 91.2% at the 550 nm light wavelength and a sheet resistance of about 78.5 Ω·sq−1, which is promising for applications in flexible and transparent optoelectronic devices.

UNIAXIALLY ALIGNED In2O3 NANOFIBERS BASED SENSORS WITH FAST RESPONSE TO ETHANOL

2012 ◽  
Vol 24 (02) ◽  
pp. 105-109
Author(s):  
Hang Liu ◽  
Hui-Tao Fan ◽  
Xiu-Juan Xu ◽  
Tong Zhang
Keyword(s):  
Magnetic Field ◽  
Operating Temperature ◽  
Average Diameter ◽  
Fast Response ◽  
Optimum Operating ◽  
Optimum Operating Temperature ◽  
Electrospinning Method ◽  
Aligned Nanofibers ◽  
Recovery Times ◽  
Response And Recovery

Uniaxially aligned In2O3 nanofibers are prepared by magnetic-field-assisted electrospinning method. The average diameter of the gained nanofibers is about 90 nm. The optimum operating temperature of the sensor based on the uniaxially aligned In2O3 nanofibers to ethanol is 120°C, the response and recovery times of the sensor are 0.4 s and 3 s, respectively. Compared with the randomly deposited nanofibers, the uniaxially aligned nanofibers show much rapider response.

scholarly journals Ethanol Gas Sensitivity Sensor Based on Roughened POF Taper of Modified Polypyrrole Films

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 989 ◽  
Author(s):  
Wenyi Liu ◽  
Yanjun Hu ◽  
Yulong Hou
Keyword(s):  
Low Cost ◽  
High Sensitivity ◽  
Chemical Oxidation ◽  
Gas Sensitivity ◽  
Polypyrrole Films ◽  
Shape Structure ◽  
Recovery Times ◽  
Bending Radius ◽  
Response And Recovery ◽  
Gas Response

The three polypyrrole (PPy) films with different mixture ratios, namely PPy1, PPy2, and PPy3, were synthesized by chemical oxidation with pyrrole and ferric chloride (FeCl3). The roughened plastic optical fiber (POF) taper assembled PPy films (POF-PPy1, POF-PPy2, and POF-PPy3) were facilely prepared and bent U shape structure for testing ethanol gas at room temperature. The morphologies of the PPy films and the roughened POF taper were studied using electron microscopy. The effect of the three PPy films on the gas response was investigated and the results showed that the POF-PPy2 exhibited a high sensitivity of 5.08 × 10−5 dB/ppm. The detection limit of the sensor was 140 ppm and its response and recovery times were 5 s and 8 s, respectively. The results also showed that as the bending radius decreased, the response and recovery times gradually shortened, while the output power increased. In addition, the proposed sensor has advantages of a low cost and simple structure.

NOx Gas Sensing Properties of Fe-Doped ZnO Nanoparticles

2020 ◽  
Vol 12 (6) ◽  
pp. 908-914 ◽  
Author(s):  
Ahmad Umar ◽  
M. Alduraibi ◽  
Omar Al-Dossary
Keyword(s):  
Gas Sensors ◽  
Zno Nanoparticles ◽  
Gas Sensing ◽  
Hydrothermal Process ◽  
Gas Sensing Properties ◽  
Recovery Times ◽  
Different Temperatures ◽  
Response And Recovery ◽  
Doped Zno ◽  
Gas Response

Herein, NOx, i.e., nitric oxide (NO) and nitrogen dioxide (NO2), gas sensors were fabricated using iron (Fe)-doped ZnO nanoparticles prepared via the facile hydrothermal process. The synthesized Fe-doped ZnO nanoparticles were analyzed through several techniques that revealed the well-crystallinity and dense growth of nanoparticles with the typical diameters of 25 ± 5 nm. The synthesized nanoparticles were utilized as a prospective material for the fabrication of NOx gas sensors operating at different temperatures, i.e., 350 °C, 400 °C, and 450 °C. The detailed sensing performances revealed that the optimum and most suitable sensing temperature for the fabricated sensors is 400 °C. In presence of 10 ppm NO gas, the fabricated sensor exhibited the highest gas response of 1.35 with a response (tresponse) and recovery (trecovery) time of 44 s and 402 s, respectively. Similarly, the fabricated NO2 gas sensor, in presence of 10 ppm gas shows the highest gas response of 1.33 with a response and recovery times of 50 s and 281 s, respectively. The presented results demonstrate that Fe-doped ZnO nanomaterials are capable to fabricate efficient NOx gas sensors.

Fabrication of p-Type Co3O4 Nanofiber Sensors for Ultra-Low H2S Gas Detection at Low Temperature

2021 ◽  
Vol 21 (4) ◽  
pp. 2626-2632
Author(s):  
Phan Hong Phuoc ◽  
Le Thi Hong ◽  
Nguyen Tat Thang ◽  
Nguyen Hong Hanh ◽  
Chu Manh Hung ◽  
...  
Keyword(s):  
Low Temperature ◽  
Gas Sensing ◽  
Average Diameter ◽  
Xrd Analysis ◽  
Practical Applications ◽  
Recovery Times ◽  
Nanocrystalline Structures ◽  
Chip Fabrication ◽  
On Chip ◽  
Gas Response

In the current work, we report the on-chip fabrication of a low-temperature H2S sensor based on p-type Co3O4 nanofibers (NFs) using the electrospinning method. The FESEM images show the typical spider-net like morphologies of synthesized Co3O4 NFs with an average diameter of 90 nm formed on the comb-like electrodes. The EDX data indicate the presence of Co and O elements in the NFs. The XRD analysis results confirm the formation of single-phase cubic spinel nanocrystalline structures (Fd3 m) for the synthesized Co3O4 NFs. The Raman results are in agreement with the XRD data through the presence of five typical vibration modes of the nanocrystalline Co3O4. The gas sensing properties of the fabricated Co3O4 NF sensors are tested to 1 ppm H2S within a temperature range of 150 °C to 450 °C. The results indicate a highest sensor response to 1 ppm H2S with the gas response of aproximately 2.1 times and the gas response/recovery times of 75 s/258 s at a low temperature of 250 °C. The fabricated sensor also demonstrates good selectivity and a low detection limit of 18 ppb. The overall results suggest a simple and effective fabrication process for the p-type Co3O4 NF sensor for practical applications in detecting H2S gas at low temperature.

scholarly journals Synthesis, Characterization, and Hydrogen Gas Sensing of ZnO/g-C3N4 Nanocomposite

2021 ◽  
Vol 10 (1) ◽  
pp. 3
Author(s):  
Arif Ibrahim ◽  
Uzma Bano Memon ◽  
Siddartha Prakash Duttagupta ◽  
Raman R. K. Singh ◽  
Arindam Sarkar
Keyword(s):  
Electron Microscopy ◽  
Gas Sensing ◽  
Hydrogen Gas ◽  
X Ray Diffraction ◽  
Material Synthesis ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Recovery Times ◽  
Response And Recovery ◽  
Gas Response

In this paper, the preparation of the ZnO/g-C3N4 nanocomposite is discussed. The synthesis of nanocomposite is performed by the direct pyrolysis of the precursor (zinc acetate hexahydrate). The material synthesis is validated by different characterization tools, such as X-ray Diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM). The SEM and TEM analysis revealed the formation of nanorods on g-C3N4 support. The gas sensing property of the ZnO/g-C3N4 was studied for various concentrations of hydrogen gas. Response and recovery times were recorded by the sensor.

scholarly journals Tin Disulfide-Coated Microfiber for Humidity Sensing with Fast Response and High Sensitivity

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 648
Author(s):  
Aijie Liang ◽  
Jingyuan Ming ◽  
Wenguo Zhu ◽  
Heyuan Guan ◽  
Xinyang Han ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
Small Diameter ◽  
High Sensitivity ◽  
Large Change ◽  
Small Variation ◽  
Response Speed ◽  
Fast Response ◽  
Tin Disulfide ◽  
Recovery Times ◽  
Response And Recovery

Breath monitoring is significant in assessing human body conditions, such as cardiac and pulmonary symptoms. Optical fiber-based sensors have attracted much attention since they are immune to electromagnetic radiation, thus are safe for patients. Here, a microfiber (MF) humidity sensor is fabricated by coating tin disulfide (SnS2) nanosheets onto the surface of MF. The small diameter (~8 μm) and the long length (~5 mm) of the MF promise strong interaction between guiding light and SnS2. Thus, a small variation in the relative humidity (RH) will lead to a large change in optical transmitted power. A high RH sensitivity of 0.57 dB/%RH is therefore achieved. The response and recovery times are estimated to be 0.08 and 0.28 s, respectively. The high sensitivity and fast response speed enable our SnS2-MF sensor to monitor human breath in real time.

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