Synthesis and characterization of ZnS-based quantum dots to trace low concentration of ammonia

Abstract In the present work, a solution-based co-precipitation method has been adopted to synthesize pure and cobalt-doped ZnS quantum dots and characterized by XRD, SEM, TEM with EDX, FTIR and gas sensing properties. XRD analysis has shown a single phase of ZnS quantum dots having a zinc blend structure. TEM and XRD line broadening indicated that the average crystallite size in the sample is in the range of 2 to 5 nm. SEM micrographs show spherical-shaped quantum dots. FTIR studies show that cobalt has been successfully doped into the ZnS cubic lattice. EDX spectra have analyzed the elemental presence in the samples and it is evident that the spectra confirmed the presence of cobalt (Co), zinc (Zn), oxygen (O), and sulphur (S) elements only and no other impurities are observed. The ZnS-based quantum dot sensors reveal high sensitivity towards 50 ppm of ammonia vapors at an operating temperature of 70 °C. Hence, ZnS-based quantum dots can be a promising and quick traceable sensor towards ammonia sensing applications with good response and recovery time.

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Synthesis and characterization of silver oxide nanoparticles prepared by chemical bath deposition for NH3 gas sensing applications

Iraqi Journal of Science ◽

10.24996/ijs.2020.61.4.9 ◽

2020 ◽

pp. 772-779

Author(s):

Hajar H. Nayel ◽

Hamid S. AL-Jumaili

Keyword(s):

Thin Films ◽

Chemical Bath Deposition ◽

Silver Oxide ◽

Energy Gap ◽

Gas Sensing ◽

High Sensitivity ◽

Average Crystallite Size ◽

Xrd Analysis ◽

Oxide Thin Film ◽

Sensing Applications

Nano-silver oxide thin films with high sensitivity for NH3 gas were deposited on glass substrates by the chemical bath deposition technique. The preparations were made under different values of pH and deposition time at 70ᵒ C, using silver nitrate AgNO3 and triethanolamine. XRD analysis showed that all thin films werepolycrystalline with several peaks of silver oxides such as Ag2O, AgO and Ag3O4, with an average crystallite size that ranged between 31.7 nm and 45.8 nm, depending on the deposition parameters. Atomic force microscope (AFM) technique illustrated that the films were homogenous with different surface roughness and thegrain size ranged between 55.69 nm and 86.23 nm. The UV-Vis spectrophotometer showed that the optical direct energy gap ranged between 1.66 eV to 2.12 eV. The silver oxide thin film gives a high sensitivity of 70.12 for NH3 gas at 75°C operating temperature. This study shows that different types of silver oxides can beprepared by the CBD techniques, with the nanostructure to be used in gas sensors and optoelectronic applications.

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Effect of Zn Doping in CuO Octahedral Crystals towards Structural, Optical, and Gas Sensing Properties

Crystals ◽

10.3390/cryst10030188 ◽

2020 ◽

Vol 10 (3) ◽

pp. 188 ◽

Cited By ~ 2

Author(s):

Chandra Prakash Goyal ◽

Deepak Goyal ◽

Sinjumol K. Rajan ◽

Niranjan S. Ramgir ◽

Yosuke Shimura ◽

...

Keyword(s):

Work Function ◽

Surface Defects ◽

Gas Sensing ◽

Oxygen Adsorption ◽

Precipitation Method ◽

Zn Doping ◽

Sensor Resistance ◽

Sensing Applications ◽

Zinc Doping ◽

Co Precipitation

Monodispersed CuO octahedral crystals were successfully synthesized using a low-temperature co-precipitation method. Zinc doping in CuO created surface defects that enhanced oxygen adsorption on the surface crucial for gas sensing applications. Pure and Zn-doped CuO sensor films were realized using the doctor blade method. The sensor films showed selective response towards a low concentration of NO2 at a lower operating temperature of 150 °C. Doping with Zn causes the resistance of the sensor film to decrease due to the enhancement of charge carriers with an analogous improvement in the sensor response. The observed decrease in sensor resistance agreed well with the findings of the work function studies. Zinc doping resulted in an increase in work function by 180 meV which, after NO2 exposure, was found to increase by a further 130 meV, attributed to the oxidizing behavior of the test gas.

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Nanocrystalline Phosphors for Lighting and Detection Applications

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.1130 ◽

2010 ◽

Vol 654-656 ◽

pp. 1130-1133 ◽

Cited By ~ 4

Author(s):

Christopher J. Summers ◽

Hisham M. Menkara ◽

Richard A. Gilstrap ◽

Mazen Menkara ◽

Thomas Morris

Keyword(s):

Quantum Dots ◽

Quantum Dot ◽

Shell Growth ◽

Stokes Shift ◽

Thermal Quenching ◽

High Sensitivity ◽

In Situ Monitoring ◽

White Leds ◽

Sensing Applications ◽

Improved Stability

We report the development of new nanoparticle phosphors and quantum dot structures designed for applications to enhance the color rendering and efficiency of high brightness white LEDs, as well as for bio-sensing applications. The intrinsic problem of self-absorption, high toxicity, and high sensitivity to thermal quenching of conventional quantum dot systems has prevented their adoption to LED devices. Doped Cd-free quantum dots may circumvent these issues due to their distinct Stokes shift and improved stability at high temperature. We report on the modification of Mn-doped ZnSe/ZnS core-shell quantum dots for application to the (blue diode + yellow emitter) white LED system. Band gap tuning for 460 nm excitation, inorganic shell growth and in-situ monitoring for enhanced efficiency, and analysis of thermal stability will are reported.

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MWCNT Devices Fabricated by Dielectrophoresis: Study of Their Electrical Behavior Related to Deposited Nanotube Amount for Gas Sensing Applications

Journal of Integrated Circuits and Systems ◽

10.29292/jics.v10i1.400 ◽

2015 ◽

Vol 10 (1) ◽

pp. 13-20

Author(s):

Elisabete Galeazzo ◽

Marcos C. Moraes ◽

Henrique E. M. Peres ◽

Michel O. S. Dantas ◽

Victor G. C. Lobo ◽

...

Keyword(s):

Carbon Nanotubes ◽

Gas Sensing ◽

High Sensitivity ◽

Cost Effective ◽

Adsorbed Water ◽

Fast Response ◽

Process Time ◽

Electrical Behavior ◽

Glass Substrates ◽

Sensing Applications

Intensive research has been focused on investigating new sensing materials, such as carbon nanotubes (CNT) because of their promising characteristics. However, there are challenges related to their application in commercial devices such as sensitivity, compatibility, and complexity of miniaturization, among others. We report the study of the electrical behavior of devices composed by multi-walled carbon nanotubes (MWCNT) deposited between aluminum electrodes on glass substrates by means of dielectrophoresis (DEP), which is a simple and cost-effective method. The devices were fabricated by varying the DEP process time. Remarkable changes in their electric resistance were noticed depending on the MWCNT quantities deposited. Other electrical properties of devices such as high sensitivity, fast response time and stability are also characterized in humid environment. A humidity sensing mechanism is proposed on the basis of charge transfer between adsorbed water molecules and the MWNTC surface or between water and the glass surface.

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Electrochemical detection of white spot syndrome virus with a silicone rubber disposable electrode composed of graphene quantum dots and gold nanoparticle-embedded polyaniline nanowires

Journal of Nanobiotechnology ◽

10.1186/s12951-020-00712-4 ◽

2020 ◽

Vol 18 (1) ◽

Author(s):

Kenshin Takemura ◽

Jun Satoh ◽

Jirayu Boonyakida ◽

Sungjo Park ◽

Ankan Dutta Chowdhury ◽

...

Keyword(s):

Quantum Dots ◽

White Spot Syndrome Virus ◽

Graphene Quantum Dots ◽

High Sensitivity ◽

White Spot ◽

Sensing Matrix ◽

Disposable Electrode ◽

Sensing Applications ◽

Doped Graphene ◽

White Spot Syndrome

Abstract Background With the enormous increment of globalization and global warming, it is expected that the number of newly evolved infectious diseases will continue to increase. To prevent damage due to these infections, the development of a diagnostic method for detecting a virus with high sensitivity in a short time is highly desired. In this study, we have developed a disposable electrode with high-sensitivity and accuracy to evaluate its performances for several target viruses. Results Conductive silicon rubber (CSR) was used to fabricate a disposable sensing matrix composed of nitrogen and sulfur-co-doped graphene quantum dots (N,S-GQDs) and a gold-polyaniline nanocomposite (AuNP-PAni). A specific anti-white spot syndrome virus (WSSV) antibody was conjugated to the surface of this nanocomposite, which was successfully applied for the detection of WSSV over a wide linear range of concentration from 1.45 × 102 to 1.45 × 105 DNA copies/ml, with a detection limit as low as 48.4 DNA copies/ml. Conclusion The engineered sensor electrode can retain the detection activity up to 5 weeks, to confirm its long-term stability, required for disposable sensing applications. This is the first demonstration of the detection of WSSV by a nanofabricated sensing electrode with high sensitivity, selectivity, and stability, providing as a potential diagnostic tool to monitor WSSV in the aquaculture industry.

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XRD and Photoluminescence Properties of CaSO4:Dy Phosphor Synthesized by New Co-Precipitation Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.888.333 ◽

2017 ◽

Vol 888 ◽

pp. 333-337 ◽

Cited By ~ 1

Author(s):

Nadira Kamarudin ◽

Wan Saffiey Wan Abdullah ◽

Muhammad Azmi Abdul Hamid

Keyword(s):

Calcium Sulfate ◽

Average Crystallite Size ◽

Information Storage ◽

Precipitation Method ◽

Photoluminescence Properties ◽

Orthorhombic Crystal ◽

Phosphor Material ◽

X Ray ◽

Wide Range ◽

Co Precipitation

This paper presents the luminescence properties of dysprosium (Dy) doped calcium sulfate (CaSO4) phosphor material produced by co-precipitation technique with 0.1 - 0.5 mol% concentration of dopant. The crystallinity of the produced powder was studied using x-ray powder diffraction (XRD). The XRD spectrum shows high purity anhydrite CaSO4 phosphor material produced. The average crystallite size of 74 nm with orthorhombic crystal system was obtained. The luminescence behavior of produced CaSO4: Dy was studied using a photoluminescence (PL) spectrometer. The excitation and emission spectrum peaks associated with defects and vacancies of the phosphor material at claimed crystalline phase. The mixed peaks of excitation and emission that corresponds to micro and nano sized particle was shown for the produced powders. These properties show that the produced powders have wide range of luminescence detection with many electron traps ready for thermoluminescence (TL) information storage.

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Hybrid Quantum Dots/WS2 Nanowalls Bifunctional Devices for Efficient Optical and Gas Sensing Applications

ECS Meeting Abstracts ◽

10.1149/ma2020-02291958mtgabs ◽

2020 ◽

Vol MA2020-02 (29) ◽

pp. 1958-1958

Author(s):

Shin-Yi Tang ◽

Chun-Chuan Yang ◽

Teng-Yu Su ◽

Tzu-Yi Yang ◽

Shu-Chi Wu ◽

...

Keyword(s):

Quantum Dots ◽

Gas Sensing ◽

Sensing Applications

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Influence of ZrO2 Nanoparticles on the Microstructural Development of Cement Mortars with Limestone Aggregates

Applied Sciences ◽

10.3390/app9030598 ◽

2019 ◽

Vol 9 (3) ◽

pp. 598

Author(s):

Danna Trejo-Arroyo ◽

Karen Acosta ◽

Julio Cruz ◽

Ana Valenzuela-Muñiz ◽

Ricardo Vega-Azamar ◽

...

Keyword(s):

Xrd Analysis ◽

Sem Analysis ◽

Precipitation Method ◽

Zro2 Nanoparticles ◽

Microstructural Development ◽

Cement Ratio ◽

Cement Mortars ◽

Crystallite Sizes ◽

Co Precipitation ◽

Two Stages

In this research, the effect of the addition of zirconium oxide-synthesized nanoparticles on the microstructural development and the physical–mechanical properties of cement mortars with limestone aggregates was studied. Zirconia nanoparticles were synthesized using the co-precipitation method. According to XRD analysis, a mixture of tetragonal (t) and monoclinic (m) zirconia phases was obtained, with average crystallite sizes around 15.18 and 17.79 nm, respectively. Based on the ASTM standards, a mixture design was obtained for a coating mortar with a final sand/cement ratio of 1:2.78 and a water/cement ratio of 0.58. Control mortars and mortars with ZrO2 additions were analyzed for two stages of curing of the mortar—7 and 28 days. According to SEM analysis, mortars with ZrO2 revealed a microstructure with a high compaction degree and an increase in compressive strength of 9% on the control mortars. Due to the aggregates’ characteristics, adherence with the cement paste in the interface zone was increased. It is suggested that the reinforcing effect of ZrO2 on the mortars was caused by the effect of nucleation sites in the main phase C–S–H and the inhibition of the growth of large CH crystals, and the filler effect generated by the nanometric size of the particles. This produced a greater compaction volume, suggesting that faults are probably originated in the aggregates.

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Structural characterization, electrical properties and gas sensing applications of polypyrrole/Cu-Al2O3 hybrid nanocomposites

High Performance Polymers ◽

10.1177/0954008319899157 ◽

2020 ◽

Vol 32 (6) ◽

pp. 719-728 ◽

Cited By ~ 5

Author(s):

S Sankar ◽

K Parvathi ◽

MT Ramesan

Keyword(s):

Dielectric Constant ◽

Electron Microscope ◽

Electrical Properties ◽

Gas Sensing ◽

Xrd Analysis ◽

High Energy ◽

Dc Conductivity ◽

Hybrid Nanocomposites ◽

Ammonia Gas ◽

Sensing Applications

The present work focused on the synthesis of polypyrrole (PPy) wrapped nano copper-alumina (Cu-Al2O3) composite by an in situ polymerization of pyrrole in the presence of Cu-Al2O3 nanoparticles. The polymerized samples were systematically characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), high-resolution transmission electron microscope (HR-TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The properties such as AC and DC conductivity, dielectric constant, and ammonia gas sensing performance of PPy/Cu-Al2O3 composites were investigated in detail as a function of Cu-Al2O3 content. The FTIR spectra showed the existence of sharp and resolved infrared bands of nanoparticles in the PPy chain. The presence of the crystalline peaks of Cu-Al2O3 in the PPy matrix was confirmed from the XRD analysis. SEM images revealed the homogenous growth of Cu-Al2O3 in the polymer with the formation of spherically shaped particles. The HR-TEM observation showed that Cu-Al2O3 particles were dispersed at a nanometer level in the nanocomposites with a width of 30–60 nm. The glass transition temperature of composites obtained from DSC was found to be increased with increase in the content of nanoparticles. TGA analysis proved that the nano Cu-Al2O3 in the content in the composites acted as a mass transport barrier that retards the degradation of the product. The AC conductivity and dielectric constant of the nanocomposite showed that the maximum electrical properties were observed for the composite with 5 weight percentage loading of Cu-Al2O3. DC conductivity showed that the PPy/Cu-Al2O3 composites have higher electrical conductivity than PPy. The ammonia gas sensing property of the composites was significantly enhanced by the addition of Cu-Al2O3 nanoparticles. Therefore, the improved properties of synthesized PPy/Cu-Al2O3 nanocomposite can be useful for developing functional composite material for the fabrication of sensors, electronic devices, and high energy storage capacitors.

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