scholarly journals Preparation of Tin Oxide Quantum Dots in Aqueous Solution and Applications in Semiconductor Gas Sensors

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 240 ◽  
Author(s):  
Jianqiao Liu ◽  
Weiting Xue ◽  
Guohua Jin ◽  
Zhaoxia Zhai ◽  
Jiarong Lv ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Quantum Dots ◽  
Grain Size ◽  
Gas Sensors ◽  
Tin Oxide ◽  
Photoelectron Spectroscopy ◽  
Fluorescence Emission ◽  
X Ray ◽  
Average Grain Size ◽  
Semiconductor Gas Sensors

Tin oxide quantum dots (QDs) were prepared in aqueous solution from the precursor of tin dichloride via a simple process of hydrolysis and oxidation. The average grain size of QDs was 1.9 nm. The hydrothermal treatment was used to control the average grain size, which increased to 2.7 and 4.0 nm when the operating temperatures of 125 and 225 °C were employed, respectively. The X-ray photoelectron spectroscopy (XPS) spectrum and X-ray diffraction analysis (XRD) pattern confirmed a rutile SnO2 system for the QDs. A band gap of 3.66 eV was evaluated from the UV-VIS absorption spectrum. A fluorescence emission peak was observed at a wavelength of 300 nm, and the response was quenched by the high concentration of QDs in the aqueous solution. The current-voltage (I-V) correlation inferred that grain boundaries had the electrical characteristics of the Schottky barrier. The response of the QD thin film to H2 gas revealed its potential application in semiconductor gas sensors.

scholarly journals γ-Radiation Enhanced Luminescence of Thiol-Capped Quantum Dots in Aqueous Solution

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 506 ◽  
Author(s):  
Shuquan Chang ◽  
Xian Wu ◽  
Jianzhang Lan ◽  
Zheng Li ◽  
Xiaohong Zhang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Quantum Dots ◽  
Photoelectron Spectroscopy ◽  
Fluorescence Emission ◽  
High Energy ◽  
Γ Radiation ◽  
X Ray ◽  
Fluorescence Efficiency ◽  
High Fluorescence ◽  
Xrd Patterns

Quantum dots (QDs) have attracted great attention due to their unique optical properties. High fluorescence efficiency is very important for their practical application. In this study, we report a simple and efficient strategy to enhance the photoluminescence of water-dispersed thiol-capped QDs using γ-radiation. Three kinds of QDs with different surface ligands and cores (MPA-CdTe, MPA-CdSe and Cys-CdTe) were fabricated and irradiated by high-energy γ-ray in an aqueous solution. Their photoluminescence intensities were significantly enhanced after irradiation, which were closely related to the radiation dose and the structure of QDs. The positions of the fluorescence emission peaks did not shift obviously after irradiation. The mechanism of photoluminescence enhancement was discussed based on the results of photoluminescence (PL) spectra, UV-visible light absorption (UV-vis) spectra, transmission electron microscope (TEM), X-ray diffraction (XRD) patterns, Fourier transform infrared (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS). This method can be employed to uniformly treat large batches of QDs at room temperature and without other chemicals.

Research on Solvothermal Synthesis of Phase Composition Controllable Nanocrystalline TiO2 Powders

2011 ◽  
Vol 284-286 ◽  
pp. 820-824
Author(s):  
Mei Jun Li ◽  
Wen Bin Cao
Keyword(s):  
Aqueous Solution ◽  
Grain Size ◽  
Phase Composition ◽  
Absorption Edge ◽  
Photoelectron Spectroscopy ◽  
Solvothermal Synthesis ◽  
X Ray ◽  
Light Yellow ◽  
Photocatalytic Activities ◽  
Visible Light Photocatalytic

N-doped TiO2 powders have been prepared by solvothermal synthesis using TiCl3 aqueous solution as precursor. The as-synthesized powders are composed of anatase and rutile and show light-yellow in color. The grain size is ranged from 10.3 nm to 19.1 nm by Scherrer's method and the specific surface area is ranged from 21 m2/g to 122 m2/g. X-ray photoelectron spectroscopy (XPS) results indicate that N atoms have been doped into the lattice of TiO2. Ti-N bonding and radical groups such as ×OH were detected on the surface of the powders. The synthesized N-doped TiO2 powders shows excellent visible-light photocatalytic activities and their absorption edge have been red-shifted to 560 nm.

Photoluminescence and I–V characteristics of ZnS grown on silicon nanoporous pillar array

2008 ◽  
Vol 23 (1) ◽  
pp. 121-126 ◽  
Author(s):  
Hai Jun Xu ◽  
He Shun Jia ◽  
Zhi Tao Yao ◽  
Xin Jian Li
Keyword(s):  
Grain Size ◽  
Photoelectron Spectroscopy ◽  
Heterogeneous Reaction ◽  
Optical And Electrical Properties ◽  
X Ray Diffraction ◽  
Pillar Array ◽  
X Ray ◽  
Patterned Surface ◽  
Forward Current ◽  
Average Grain Size

Silicon nanoporous pillar array (Si-NPA) is a silicon hierarchical structure with regularly patterned surface morphology. Through a heterogeneous reaction process, zinc sulfide nanocrystallites (nc-ZnS) were grown onto Si-NPA and a unique heterostructure of ZnS/Si-NPA was obtained. The formation of wurtzite nc-ZnS was proved by x-ray diffraction, and the average grain size was evaluated to be ∼18 nm. X-ray photoelectron spectroscopy disclosed that as-grown nc-ZnS was well separated from Si-NPA by a SiO2 thin layer of ∼1.3 nm. The photoluminescence (PL) spectrum of ZnS/Si-NPA showed that in addition to the two red PL bands peaked at ∼648 and ∼705 nm observed in Si-NPA, three other PL bands peaked at ∼365, ∼418, and ∼472 nm were observed and attributed to the PL from nc-ZnS. It was also demonstrated that as-prepared ZnS/Si-NPA heterostructure could exhibit good rectification characteristic featured by a high forward current density of ∼75 mA/cm2 at 2 V and high reverse breakdown voltage of ∼10 V. Our results indicated that ZnS/Si-NPA might be a valuable heterostructure nanosystem to be further probed for achieving enhanced optical and electrical properties.

Preparation of Fluorine Doped Tin Oxide Film by Ultrasonic Spray Pyrolysis

2011 ◽  
Vol 695 ◽  
pp. 594-597 ◽  
Author(s):  
Yang Ren ◽  
Gao Yang Zhao ◽  
Jie Shen
Keyword(s):  
Spray Pyrolysis ◽  
Tin Oxide ◽  
Photoelectron Spectroscopy ◽  
Large Scale ◽  
Spray Pyrolysis Technique ◽  
Ultrasonic Spray Pyrolysis ◽  
Stannic Chloride ◽  
X Ray ◽  
Ultrasonic Spray ◽  
Average Grain Size

Fluorine doped tin oxide (FTO) film is one of the most promising transparent conducting materials. It can be used for Low-E glasses, thin film solar cells, displays, etc. FTO film can be fabricated by various techniques. The technique of sol-gel combined with ultrasonic spray pyrolysis gives the possibility to produce high-quality large-scale FTO films. In this paper, the FTO sol is successfully prepared using pentahydrate stannic chloride (SnCl4•5H2O), hydrogen fluoride (HF) and methanol. Using the FTO sol, FTO films are prepared by ultrasonic spray pyrolysis technique. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) are used to characterize the FTO films coated on glass substrates. Results indicate that the as-deposited films are polycrystalline SnO2 phase with tetragonal crystal structure, and that the average grain size for the samples is 160nm. The optical and electrical properties of the FTO film are also analyzed.

Effect of Composition on the Morphology and Hardness of Nanostructured Cu Based Composite and Alloy Powders/Granules Produced by High Energy Mechanical Milling

2007 ◽  
Vol 29-30 ◽  
pp. 143-146 ◽  
Author(s):  
Aamir Mukhtar ◽  
De Liang Zhang ◽  
C. Kong ◽  
P. R. Munroe
Keyword(s):  
Grain Size ◽  
Mechanical Milling ◽  
Alloy Powder ◽  
High Energy ◽  
Al2o3 Nanoparticles ◽  
X Ray ◽  
Fine Powders ◽  
Average Grain Size ◽  
Powder Particles

Cu-(2.5 or 5.0vol.%)Al2O3 nanocomposite balls and granules and Cu-(2.5vol.% or 5.0vol.%)Pb alloy powder were prepared by high energy mechanical milling (HEMM) of mixtures of Cu and either Al2O3 or Pb powders. It was observed that with the increase of the content of Al2O3 nanoparticles from 2.5vol.% to 5vol.% in the powder mixture, the product of HEMM changed from hollow balls into granules and the average grain size and microhardness changed from approximately 130nm and 185HV to 100nm and 224HV, respectively. On the other hand, HEMM of Cu–(2.5 or 5.0vol.%) Pb powder mixtures under the same milling conditions failed to consolidate the powder in-situ. Instead, it led to formation of nanostructured fine powders with an average grain size of less than 50nm. Energy dispersive X-ray mapping showed homogenous distribution of Pb in the powder particles in Cu–5vol.%Pb alloy powder produced after 12 hours of milling. With the increase of the Pb content from 2.5 to 5.0 vol.%, the average microhardness of the Cu-Pb alloy powder particles increases from 270 to 285 HV. The mechanisms of the effects are briefly discussed.

scholarly journals Succinic acid in aqueous solution: connecting microscopic surface composition and macroscopic surface tension

2014 ◽  
Vol 16 (39) ◽  
pp. 21486-21495 ◽  
Author(s):  
Josephina Werner ◽  
Jan Julin ◽  
Maryam Dalirian ◽  
Nønne L. Prisle ◽  
Gunnar Öhrwall ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Surface Tension ◽  
Succinic Acid ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Md Simulations ◽  
Vapor Interface ◽  
X Ray ◽  
Ph Values ◽  
Microscopic Surface

The water–vapor interface of aqueous solutions of succinic acid, where pH values and bulk concentrations were varied, has been studied using surface sensitive X-ray photoelectron spectroscopy (XPS) and molecular dynamics (MD) simulations.

scholarly journals Effect of synthesis conditions  on  methylene blue adsorption capacity of electrochemically preparated graphene

2020 ◽  
Vol 9 (3) ◽  
pp. 9-14
Author(s):  
Hao Pham Van ◽  
Linh Ha Xuan ◽  
Oanh Phung Thi ◽  
Hong Phan Ngoc ◽  
Huy Nguyen Nhat ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Adsorption Capacity ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Graphene Nanosheets ◽  
Electrochemical Exfoliation ◽  
X Ray ◽  
Synthesis Conditions ◽  
Mb Adsorption

This report presents the effect of synthesis conditions on the synthesis of graphene nanosheets via electrochemical exfoliation method for adsorbing methylene blue from aqueous solution. Oxygen-containing functional groups and defects in the material were characterized by Raman and X-ray photoelectron spectroscopy (XPS). As a result, by using voltage of 15 V, (NH4)2SO4 (5%, 250 mL) and KOH (7.5%, 250 mL), the obtained material showed the highest MB adsorption capacity due to the high densities of oxygen-containing groups and defects comparison to other conditions.

Synthesis and characterization of homogeneous lead-substituted tin oxide with the (110) face of rutile structure

2000 ◽  
Vol 15 (10) ◽  
pp. 2076-2079
Author(s):  
Chika Nozaki ◽  
Takashi Yamada ◽  
Kenji Tabata ◽  
Eiji Suzuki
Keyword(s):  
Electron Microscopy ◽  
Tin Oxide ◽  
Photoelectron Spectroscopy ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
Rutile Structure ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Synthesis of a rutile-type lead-substituted tin oxide with (110) face was investigated. The characterization was performed by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive x-ray spectroscopy, infrared spectroscopy, x-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller surface area measurements. The homogeneous rutile-type lead-substituted tin oxide was obtained until 4.1 mol% of tin was substituted with lead. The surface of obtained oxide had a homogeneously lead-substituted (110) face.

scholarly journals Dislocations in Grain Boundary Regions: The Origin of Heterogeneous Microstrains in Nanocrystalline Materials

2019 ◽  
Vol 51 (1) ◽  
pp. 513-530 ◽  
Author(s):  
Zhenbo Zhang ◽  
Éva Ódor ◽  
Diana Farkas ◽  
Bertalan Jóni ◽  
Gábor Ribárik ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Nanocrystalline Materials ◽  
Md Simulation ◽  
High Pressure Torsion ◽  
Md Simulations ◽  
Line Profile Analysis ◽  
Misfit Dislocations ◽  
X Ray ◽  
Average Grain Size

Abstract Nanocrystalline materials reveal excellent mechanical properties but the mechanism by which they deform is still debated. X-ray line broadening indicates the presence of large heterogeneous strains even when the average grain size is smaller than 10 nm. Although the primary sources of heterogeneous strains are dislocations, their direct observation in nanocrystalline materials is challenging. In order to identify the source of heterogeneous strains in nanocrystalline materials, we prepared Pd-10 pct Au specimens by inert gas condensation and applied high-pressure torsion (HPT) up to γ ≅ 21. High-resolution transmission electron microscopy (HRTEM) and molecular dynamic (MD) simulations are used to investigate the dislocation structure in the grain interiors and in the grain boundary (GB) regions in the as-prepared and HPT-deformed specimens. Our results show that most of the GBs contain lattice dislocations with high densities. The average dislocation densities determined by HRTEM and MD simulation are in good correlation with the values provided by X-ray line profile analysis. Strain distribution determined by MD simulation is shown to follow the Krivoglaz–Wilkens strain function of dislocations. Experiments, MD simulations, and theoretical analysis all prove that the sources of strain broadening in X-ray diffraction of nanocrystalline materials are lattice dislocations in the GB region. The results are discussed in terms of misfit dislocations emanating in the GB regions reducing elastic strain compatibility. The results provide fundamental new insight for understanding the role of GBs in plastic deformation in both nanograin and coarse grain materials of any grain size.

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