scholarly journals SnO2/TiO2 Thin Film n-n Heterostructures of Improved Sensitivity to NO2

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6830
Author(s):  
Piotr Nowak ◽  
Wojciech Maziarz ◽  
Artur Rydosz ◽  
Kazimierz Kowalski ◽  
Magdalena Ziąbka ◽  
...  
Keyword(s):  
Thin Film ◽  
Operating Temperature ◽  
Incidence Geometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Langmuir Blodgett ◽  
Response Recovery ◽  
Low Concentrations ◽  
Highly Sensitive ◽  
Recovery Times

Thin-film n-n nanoheterostructures of SnO2/TiO2, highly sensitive to NO2, were obtained in a two-step process: (i) magnetron sputtering, MS followed by (ii) Langmuir-Blodgett, L–B, technique. Thick (200 nm) SnO2 base layers were deposited by MS and subsequently overcoated with a thin and discontinuous TiO2 film by means of L–B. Rutile nanopowder spread over the ethanol/chloroform/water formed a suspension, which was used as a source in L–B method. The morphology, crystallographic and electronic properties of the prepared sensors were studied by scanning electron microscopy, SEM, X-ray diffraction, XRD in glancing incidence geometry, GID, X-ray photoemission spectroscopy, XPS, and uv-vis-nir spectrophotometry, respectively. It was found that amorphous SnO2 films responded to relatively low concentrations of NO2 of about 200 ppb. A change of more than two orders of magnitude in the electrical resistivity upon exposure to NO2 was further enhanced in SnO2/TiO2 n-n nanoheterostructures. The best sensor responses RNO2/R0 were obtained at the lowest operating temperatures of about 120 °C, which is typical for nanomaterials. Response (recovery) times to 400 ppb NO2 were determined as a function of the operating temperature and indicated a significant decrease from 62 (42) s at 123 °C to 12 (19) s at 385 °C A much smaller sensitivity to H2 was observed, which might be advantageous for selective detection of nitrogen oxides. The influence of humidity on the NO2 response was demonstrated to be significantly below 150 °C and systematically decreased upon increase in the operating temperature up to 400 °C.

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.

Acetylene Sensing by ZnO/TiO2 Nanoparticles

2020 ◽  
Vol 15 (1) ◽  
pp. 41-45 ◽  
Author(s):  
Zhi-Cheng Zhong ◽  
Zhao-Jun Jing ◽  
Kui-Yuan Liu ◽  
Tong Liu
Keyword(s):  
Gas Sensors ◽  
Operating Temperature ◽  
Sol Gel ◽  
Fast Response ◽  
X Ray Diffraction ◽  
Uniform Size ◽  
X Ray ◽  
Recovery Times ◽  
Response And Recovery ◽  
Hydrothermal Methods

We adopted the sol–gel and hydrothermal methods to prepare the TiO2 nanomaterials doped with ZnO. We adopted X-ray diffraction, scanning electron microscopy, and the Brunauer–Emmett–Teller method to investigate the materials’ structures and morphologies. The results showed that the prepared TiO2 nanomaterials had uniform size and good dispersibility. Gas sensors were fabricated and their performances in acetylene sensing were assessed. The results show that the sensor prepared with the ZnO/TiO2 nanomaterial doped with 10 wt% ZnO gave fast response and recovery times for acetylene gas at different concentrations. When the operating temperature was 280 °C, the gas sensor detected 200 ppm acetylene gas with a response sensitivity of 9.9, a response time of 5 s, and a recovery time of 2 s.

scholarly journals A highly sensitive fluorescent sensor for Al3+ detection based on luminescent Eu(III)-β-dicetonate complexes

2021 ◽  
Vol 63 (11) ◽  
pp. 47-50
Author(s):  
Thi Hien Dinh ◽  
◽  
Thi Mai Huong Phan ◽  
Duc Manh Nguyen ◽  
Luu Tung Quan Nguyen ◽  
...  
Keyword(s):  
Exchange Resin ◽  
Anion Exchange Resin ◽  
Fluorescent Sensor ◽  
X Ray Diffraction ◽  
Sodium Complex ◽  
Simple Process ◽  
X Ray ◽  
Low Concentrations ◽  
Highly Sensitive ◽  
The Eu

The structure of the Eu(III) complexes were determined by single-crystal X-ray diffraction. The results showed that these complexes exist as a heteronuclear of Eu(III)-Na(I) in which ion Eu3+ is coordinated through eight oxygen atoms of four β-dixetone ligands. The authors found that the monomeric europium-sodium complex displays a very strong red emission with a quantum yield up to 47.5% at λex=370 nm. The authors have successfully designed a simple process to put the Eu(III) complexes on anion exchange resin to create Resin-EuTFNB and Resin-EuTFPB materials. The products have a luminescent intensity that is stronger than that of the precursor complexes due to the removal of the coordination solvents in these complexes. Initially, using these materials to test the ability to recognise Al3+ ion at low concentrations, Resin-EuTFNB and Resin-EuTFPB played a role as a sensing chemosensor based on turn-off mechanism. In the future, they are expected to detect Al3+ion in the biological system.

Structural and Acetone Sensing Properties of La-Doped Porous In2O3 Nanospheres by Hydrothermal Synthesis

2014 ◽  
Vol 1053 ◽  
pp. 177-180
Author(s):  
Dan Han ◽  
Peng Song ◽  
Qi Wang ◽  
Hui Hui Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Operating Temperature ◽  
X Ray Diffraction ◽  
Acetone Concentration ◽  
X Ray ◽  
Recovery Times ◽  
Response And Recovery ◽  
La Doped ◽  
Scanning Electron

The La-doped porous In2O3 nanospheres were prepared by a simple hydrothermal method, and La3+ accounted for 3 mol% of the In3+. The La exists and has been doped in the lattice of In2O3 characterized respectively by the means of energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), the morphology of the samples with uniform nanospheres observed by field-emission scanning electron microscopy (FESEM). Moreover, the sensor exhibits higher response properties compared with pure porous In2O3 nanospheres towards different acetone concentration at operating temperature 300 °C. The response and recovery times is about 13 s and 8 s to 50 ppm acetone.

Ultra-Sensitive H2S Gas Sensor Based on WO3 Nanocubes with Low Operating Temperature

2018 ◽  
Vol 939 ◽  
pp. 133-140
Author(s):  
Zhan Hong Li ◽  
Ji Xie ◽  
Xiao Bing Hu ◽  
Cheng Chen ◽  
Li Li Xie ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Operating Temperature ◽  
Threshold Limit Value ◽  
X Ray Diffraction ◽  
X Ray ◽  
Limit Value ◽  
Response Recovery ◽  
Excellent Selectivity ◽  
Higher Sensitivity ◽  
Scanning Electron

WO3 nanostructure with nanocube morphology was synthesized through acidification of Na2WO4·2H2O, which were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the result of the present work implied that the sensor fabricated by nanocube WO3 could detect the level of 330 ppb H2S, which is much lower than the threshold limit value of 10 ppm. Compared with other results, the nanocube WO3 sensor shows higher sensitivity, excellent selectivity and faster response/recovery to H2S. Especially, the best operating temperature of this nanocube WO3 for H2S detection is 100 °C.

scholarly journals Ultrafast Growth of h-MoO3 Microrods and Its Acetone Sensing Performance

Surfaces ◽  
2020 ◽  
Vol 4 (1) ◽  
pp. 9-16
Author(s):  
Giovana T. Santos ◽  
Anderson A. Felix ◽  
Marcelo O. Orlandi
Keyword(s):  
Molybdenum Trioxide ◽  
Metastable Phase ◽  
Fast Response ◽  
X Ray Diffraction ◽  
X Ray ◽  
Response Recovery ◽  
Lower Detection ◽  
Recovery Times ◽  
Fine Control ◽  
Ppm Level

Hexagonal molybdenum trioxide (h-MoO3) was synthesized by microwave-assisted hydrothermal method, allowing an ultrafast growth of unidimensional microrods with well-faceted morphology. The crystalline structure of this metastable phase was confirmed by X-ray diffraction (XRD) and Raman spectroscopy. Scanning electron microscopy (SEM) showed that hexagonal microrods can be obtained in one minute with well-defined exposed facets and the fine control of morphology. Sensing tests of the acetone biomarker revealed that the h-MoO3 microrods exhibit, at low ppm level, good sensor signal, fast response/recovery times, selectivity to different interferent gases, and a lower detection limit of 400 ppb.

Highly Sensitive H2 Sensors Based on Pd- and PdO-Decorated TiO2 Thin Films at Low-Temperature Operation

2016 ◽  
Vol 675-676 ◽  
pp. 277-280 ◽  
Author(s):  
Benjarong Samransuksamer ◽  
Tula Jutarosaga ◽  
Mati Horprathum ◽  
Anurat Wisitsoraat ◽  
Pitak Eiamchai ◽  
...  
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
Chemical Element ◽  
Operating Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Highly Sensitive ◽  
Dc Reactive Magnetron Sputtering ◽  
Very High

Abstract In this work, the low-temperature H2-sensing properties of palladium (Pd) and palladium oxide (PdO) nanoparticles decorated titanium dioxide (TiO2) thin film were studied. The TiO2 thin films were prepared by the dc reactive magnetron sputtering. The Pd and PdO nanoparticles were sputtered on the top surface of TiO2 surface in order to enhance the sensitivity to the H2 gas. Morphologies, crystal structures, and chemical element of the examiner samples were investigated by the field-emission scanning electron microscopy (FE-SEM), grazing-incident X-ray diffraction (GIXRD), and X-ray photoelectron spectroscopy (XPS), respectively. The effects of the Pd and PdO nanoparticles on H2-sensing performance of TiO2 were investigated over a low concentration range of 150-3,000 ppm H2 at 50-250°C-operating temperatures. This result exhibited that the PdO decorated on TiO2 surface showed very high response to H2 at a low operating temperature of 150°C.

scholarly journals Aligned Grid Shaped NiO Nanowires for Humidity Sensing at Room Temperature

2020 ◽  
Author(s):  
Masoumeh Mohammadi ◽  
Mohammad Almasi-Kashi ◽  
Somayeh Fardindoost ◽  
Azam Iraji zad
Keyword(s):  
Room Temperature ◽  
Ionic Conduction ◽  
X Ray Diffraction ◽  
Ac Impedance Spectroscopy ◽  
Humidity Sensing ◽  
Electrodeposition Process ◽  
X Ray ◽  
Response Recovery ◽  
Recovery Times ◽  
Sensing Characteristics

Abstract A grid configuration based on the aligned nickel oxide nanowire (NiO NW) for humidity sensing were fabricated through the oxidation of ferromagnetic nickel NWs prepared by a template-assisted electrodeposition process. Their structure and elemental compositions were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and energy-dispersive X-ray analyses (EDAX). The room-temperature humidity sensing behavior of the NiO NWs was investigated successfully based on DC and AC impedance spectroscopy (IS) method in frequencies range 10 Hz to 2 MHz. The sensors showed excellent humidity sensing characteristics such as a high response of about 66 with rather rapid response-recovery times about 9 and 2 s for 90%RH, and good stability. The equivalent circuits were simulated for impedance responses to humidity in the range of 40–90% RH. According to the results, ionic conduction via NW-NW junctions as well as NW-electrode interfaces in the grid configuration is responsible for sensing behavior.

scholarly journals Preparation, Characterization, and Mechanistic Understanding of Pd-Decorated ZnO Nanowires for Ethanol Sensing

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Xiao Deng ◽  
Shengbo Sang ◽  
Pengwei Li ◽  
Gang Li ◽  
Fanqin Gao ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Operating Temperature ◽  
Zno Nanowires ◽  
X Ray Diffraction ◽  
X Ray ◽  
Recovery Times ◽  
Response And Recovery ◽  
New Perspective ◽  
Ethanol Sensing ◽  
Higher Sensitivity

ZnO nanowires (ZnO-NWs) and Pd-decorated ZnO nanowires (Pd-ZnO-NWs) were prepared by hydrothermal growth and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). When used for gas sensing, both types of nanowires showed a good selectivity to ethanol but a higher sensitivity and lower operating temperature were found with Pd-ZnO-NWs sensors comparing to those of ZnO-NWs sensor. When exposed to 200 ppm ethanol, our ZnO-NWs sensor showed a sensitivity of about 2.69 at 425°C whereas 1.3 at. % Pd-ZnO-NWs sensor provided a 57% more detection sensibility at 325°C. In addition, both response and recovery times of Pd-ZnO-NWs sensors were significantly reduced (9 s) comparing to the ZnO-NWs. Finally, Pd-ZnO-NWs sensor also showed a much lower detection limit of about 1 ppm. The sensing mechanism of Pd-ZnO-NWs sensors has also been clarified, thereby providing a new perspective for further improvement of the sensing performance of ethanol sensors.

Hydrogen Sensing Properties of Dye-Sensitized TiO2 Nanotube Array

2011 ◽  
Vol 492 ◽  
pp. 296-299 ◽  
Author(s):  
Liang Huang ◽  
Yun Han Ling ◽  
Yu Qing Zhuo ◽  
Fu Jian Ren
Keyword(s):  
Electrochemical Anodization ◽  
X Ray Diffraction ◽  
Nanotube Array ◽  
X Ray ◽  
Simulated Solar Light ◽  
Hydrogen Sensing ◽  
Dye Sensitized ◽  
Solar Light Irradiation ◽  
Low Concentrations ◽  
Highly Sensitive

A dye-sensitized TiO2 nanotube array (DST) was fabricated by electrochemical anodization in an aqueous organic electrolyte and immersed into ethanol containing N719 dye. The crystal phase and microstructure of the TiO2 nanotube array (TNTA) were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The UV-Vis spectra of the DST were characterized by diffuse reflectance spectra (DRS). The hydrogen sensitivity of the as-prepared sample was tested at room temperature under Xe-lamp (simulated solar light) irradiation. It was found that the sensor was highly sensitive to low concentrations of hydrogen as an application in air quality control.

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