scholarly journals The Influence of Nb on the Synthesis of WO3 Nanowires and the Effects on Hydrogen Sensing Performance

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2332 ◽  
Author(s):  
Dario Zappa
Keyword(s):  
Electron Microscope ◽  
High Performance ◽  
Low Cost ◽  
Portable Devices ◽  
Monoclinic Crystal ◽  
Electronic Noses ◽  
X Ray ◽  
Hydrogen Sensing ◽  
Monoclinic Crystal Structure ◽  
Research Activities

Hydrogen sensing is becoming one of the hottest topics in the chemical sensing field, due to its wide number of applications and the dangerousness of hydrogen leakages. For this reason, research activities are focusing on the development of high-performance materials that can be easily integrated in sensing devices. In this work, we investigated the influence of Nb on the sensing performances of WO3 nanowires (NWs) synthetized by a low-cost thermal oxidation method. The morphology and the structure of these Nb-WO3 nanowires were investigated by field emission scanning electron microscope (FE-SEM), high-resolution transmission electron microscope (HR-TEM), X-ray diffraction (XRD), Raman and X-ray photoelectron (XPS) spectroscopies, confirming that the addition of Nb does not modify significantly the monoclinic crystal structure of WO3. Moreover, we integrated these NWs into chemical sensors, and we assessed their performances toward hydrogen and some common interfering compounds. Although the hydrogen sensing performances of WO3 nanowires were already excellent, thanks to the presence of Nb they have been further enhanced, reaching the outstanding value of more than 80,000 towards 500 ppm @ 200 °C. This opens the possibility of their integration in commercial equipment, like electronic noses and portable devices.

PHAX-SCAN: Functional integration of a Scanning Electron Microscope and an energy-dispersive x-ray analyser

1989 ◽  
Vol 47 ◽  
pp. 56-57
Author(s):  
Marc H. Peeters ◽  
Max T. Otten
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
Functional Integration ◽  
Energy Dispersive ◽  
X Rays ◽  
X Ray ◽  
High Speed Analysis ◽  
Scanning Electron

Over the past decades, the combination of energy-dispersive analysis of X-rays and scanning electron microscopy has proved to be a powerful tool for fast and reliable elemental characterization of a large variety of specimens. The technique has evolved rapidly from a purely qualitative characterization method to a reliable quantitative way of analysis. In the last 5 years, an increasing need for automation is observed, whereby energy-dispersive analysers control the beam and stage movement of the scanning electron microscope in order to collect digital X-ray images and perform unattended point analysis over multiple locations.The Philips High-speed Analysis of X-rays system (PHAX-Scan) makes use of the high performance dual-processor structure of the EDAX PV9900 analyser and the databus structure of the Philips series 500 scanning electron microscope to provide a highly automated, user-friendly and extremely fast microanalysis system. The software that runs on the hardware described above was specifically designed to provide the ultimate attainable speed on the system.

scholarly journals Characterization of CuO/n-Si heterojunction solar cells produced by thermal evaporation

2018 ◽  
Vol 36 (4) ◽  
pp. 668-674 ◽  
Author(s):  
Reşit Özmenteş ◽  
Cabir Temirci ◽  
Abdullah Özkartal ◽  
Kadir Ejderha ◽  
Nezir Yildirim
Keyword(s):  
Solar Cells ◽  
Band Gap ◽  
Thermal Evaporation ◽  
Front Surface ◽  
Band Gap Energy ◽  
Monoclinic Crystal ◽  
Photovoltaic Properties ◽  
X Ray ◽  
Heterojunction Solar Cells ◽  
Monoclinic Crystal Structure

AbstractCopper(II) oxide (CuO) in powder form was evaporated thermally on the front surface of an n-Si (1 0 0) single crystal using a vacuum coating unit. Structural investigation of the deposited CuO film was made using X-ray difraction (XRD) and energy dispersive X-ray analysis (EDX) techniques. It was determined from the obtained results that the copper oxide films exhibited single-phase CuO properties in a monoclinic crystal structure. Transmittance measurement of the CuO film was performed by a UV-Vis spectrophotometer. Band gap energy of the film was determined as 1.74 eV under indirect band gap assumption. Current-voltage (I-V) measurements of the CuO/n-Si heterojunctions were performed under illumination and in the dark to reveal the photovoltaic and electrical properties of the produced samples. From the I-V measurements, it was revealed that the CuO/n-Si heterojunctions produced by thermal evaporation exibit excellent rectifying properties in dark and photovoltaic properties under illumination. Conversion efficiencies of the CuO/n-Si solar cells are comparable to those of CuO/n-Si produced by other methods described in the literature.

scholarly journals Nanosheets of CuCo2O4 As a High-Performance Electrocatalyst in Urea Oxidation

2019 ◽  
Vol 9 (4) ◽  
pp. 793 ◽  
Author(s):  
Camila Zequine ◽  
Fangzhou Wang ◽  
Xianglin Li ◽  
Deepa Guragain ◽  
S.R. Mishra ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Nickel Foam ◽  
Low Cost ◽  
Agricultural Waste ◽  
Bifunctional Catalyst ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electroactive Material

The urea oxidation reaction (UOR) is a possible solution to solve the world’s energy crisis. Fuel cells have been used in the UOR to generate hydrogen with a lower potential compared to water splitting, decreasing the costs of energy production. Urea is abundantly present in agricultural waste and in industrial and human wastewater. Besides generating hydrogen, this reaction provides a pathway to eliminate urea, which is a hazard in the environment and to people’s health. In this study, nanosheets of CuCo2O4 grown on nickel foam were synthesized as an electrocatalyst for urea oxidation to generate hydrogen as a green fuel. The synthesized electrocatalyst was characterized using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The electroactivity of CuCo2O4 towards the oxidation of urea in alkaline solution was evaluated using electrochemical measurements. Nanosheets of CuCo2O4 grown on nickel foam required the potential of 1.36 V in 1 M KOH with 0.33 M urea to deliver a current density of 10 mA/cm2. The CuCo2O4 electrode was electrochemically stable for over 15 h of continuous measurements. The high catalytic activities for the hydrogen evolution reaction make the CuCo2O4 electrode a bifunctional catalyst and a promising electroactive material for hydrogen production. The two-electrode electrolyzer demanded a potential of 1.45 V, which was 260 mV less than that for the urea-free counterpart. Our study suggests that the CuCo2O4 electrode can be a promising material as an efficient UOR catalyst for fuel cells to generate hydrogen at a low cost.

Preparation, Crystal Structure, and Properties of the Lanthanoid Carbides Ln4C7 with Ln = Ho, Er, Tm, and Lu

1996 ◽  
Vol 51 (5) ◽  
pp. 646-654 ◽  
Author(s):  
Ralf Czekalla ◽  
Wolfgang Jeitschko ◽  
Rolf-Dieter Hoffmann ◽  
Helmut Rabeneck
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Magnetic Ordering ◽  
Monoclinic Crystal ◽  
X Ray ◽  
Neutron Powder Diffraction Data ◽  
Monoclinic Crystal Structure ◽  
Arc Melting ◽  
Structure Factors ◽  
Hydrolysis Of

The isotypic carbides Ln4C7 (Ln = Ho, Er, Tm, Lu) were prepared by arc-melting of the elemental components, followed by annealing at 1300 °C. The positions of the metal and of some carbon atoms of the monoclinic crystal structure of LU4C7 were determined from X-ray powder data, and the last carbon positions were found and refined from neutron powder diffraction data: P21/c, a = 360.4(1), b = 1351.4(3), c = 629.0(2) pm, β = 104.97(2)°, Z = 2, R = 0.026 for 429 structure factors and 15 positional parameters. The structure contains isolated carbon atoms with octahedral lutetium coordination and linear C3-units, with C-C bond lengths of 132(1) and 135(1) pm. This carbide may therefore be considered as derived from methane and propadiene. The hydrolysis of LU4C7 with distilled water yields mainly methane and propine, while the hydrolyses of the corresponding holmium and erbium carbides resulted in relatively large amounts of saturated and unsaturated C2-hydrocarbons in addition to the expected products methane and propine. The structure comprises two-dimensionally infinite NaCl-type building elements, which are separated by the C3-units. It may be described as a stacking variant of a previously reported structure of HO4C7, now designated as the a-modification. The Lu4C7-type β -modification was obtained at higher temperatures. Its structure was refined by the Rietveld method from X-ray powder data to a residual R = 0.037 for 320 F values and 15 positional parameters. Lu4C7 is Pauli paramagnetic; β -HO4C7 and Er4C7 show Curie-Weiss behavior with magnetic ordering temperatures of less than 20 K.

Low-Cost Synthesis and Morphology Control of Magnesium Oxysulfate Hydrate Whiskers

2014 ◽  
Vol 936 ◽  
pp. 986-991
Author(s):  
Chuan Hui Gao ◽  
Li Ding ◽  
Yu Min Wu ◽  
Chuan Xing Wang ◽  
Jun Xu
Keyword(s):  
Electron Microscope ◽  
Raw Materials ◽  
Low Cost ◽  
Hydrothermal Process ◽  
Control Agent ◽  
Raw Material ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Magnesium Oxysulfate

A low-cost raw material, bittern obtained from the production process of sea salt, was used to prepare magnesium oxysulfate hydrate (MgSO4·5Mg (OH)2·2H2O, abbreviated as 152MOS) whiskers via hydrothermal synthesis with ammonia and magnesium sulfate as the other starting raw materials. The bittern was firstly filtered and then used directly without de-coloring. X-ray powder diffraction (XRD), transmission electron microscope (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscope (SEM) were employed to investigate the composition and morphology of the products. It was found that the 152MOS whiskers synthesized from bittern at 190°C for 3 hours exhibited fanlike morphology. The formation of the fanlike whiskers was inhibited and most of the whiskers presented as single fibers when ethanol was used as crystal control agent in the hydrothermal process. From the two-dimensional steps observed at tips of the whiskers, a possible growth mechanism was speculated that it was the extension of dislocations that made the growth of the whiskers.

About the crystalline structure of vanadates Ca1.5±0.1Mn0.5±0.1V2O7 and Ca1.5Cd0.5V2O7

2018 ◽  
Vol 33 (3) ◽  
pp. 246-255
Author(s):  
V.D. Zhuravlev ◽  
A.P. Tyutyunnik ◽  
A.Yu. Chufarov ◽  
N.I. Lobachevskaja ◽  
Yu. A. Velikodnyi ◽  
...  
Keyword(s):  
Homogeneity Region ◽  
Powder Diffraction Data ◽  
Compound I ◽  
Monoclinic Crystal ◽  
Conventional Solid State Reaction ◽  
Space Group ◽  
X Ray ◽  
Triclinic System ◽  
Monoclinic Crystal Structure ◽  
Calcium Cations

The crystal structures of Ca1.5Mn0.5V2O7 (I) and Ca1.5Cd0.5V2O7 (II) synthesized by the citrate method and by a conventional solid-state reaction, respectively, were determined using X-ray powder diffraction data. It was found that the compound I has a monoclinic crystal structure a = 4.88563(9) Å, b = 11.21279(22) Å, c = 5.69643(11 Å), β = 96.376(7)°, V = 310.132(10) Å3 (space group P21/c), Z = 2). Compound I has a narrow homogeneity region Ca1.5±0.1Mn0.5±0.1V2O7. The vanadate Ca1.5Cd0.5V2O7 crystallizes in the triclinic system with the parameters a = 6.66139(6) Å, b = 6.93019(7) Å, c = 7.02211(6) Å, α = 85.4404(9)°, β = 63.7505(7)°, γ = 82.5515(10)° и V = 288.201(5) Å3 (space group P$\bar 1$, Z = 2). It is one of the formulations of the primary solid solution, formed as a result of the substitution of part of the calcium cations for cadmium cations in Ca2V2O7.

A Low Cost Rejuvenation of Old G.E. and Picker X-Ray Generators

1983 ◽  
Vol 27 ◽  
pp. 293-297
Author(s):  
G. Raykhtsaum ◽  
P. Georgopoulos
Keyword(s):  
Solid State ◽  
High Voltage ◽  
High Performance ◽  
Low Cost ◽  
The United States ◽  
Control Device ◽  
State Control ◽  
X Ray ◽  
Tube Current ◽  
Control Devices

General Electric (G.E.) and Picker generators are currently installed in many research laboratories all over the United States. These units are old and do not satisfy the modern requirements for X-ray generators. Instabilities of high voltage and tube current complicate the experiment. To maintain G.E. and Picker generators is becoming more and more expensive due to the high cost of vacuum tubes and replacement parts. To replace old generators with new high performance commercial units can cost even more and requires additional adaptations. In the present paper another alternative is proposed, which assumes the replacement of vacuum tube mA and KV controls with solid state circuits using the old G.E. or Picker high voltage transformers. This alternative allows rejuvenation of old generators without difficulties of reinstallation and does not require adaptations to the existing experimental X-ray equipment. The combination of old high voltage transformers with modern solid state control devices provides high performance at low cost. For this purpose the control device was designed and is described below.

Facile hydrothermal synthesis of ternary CeO2–SnO2/rGO nanocomposite for supercapacitor application

2020 ◽  
Vol 13 (02) ◽  
pp. 2051005 ◽  
Author(s):  
Godlaveeti Sreenivasa Kumar ◽  
Somala Adinarayana Reddy ◽  
Hussen Maseed ◽  
Nagireddy Ramamanohar Reddy
Keyword(s):  
Electron Microscope ◽  
Specific Capacitance ◽  
High Performance ◽  
High Specific Capacitance ◽  
Energy Storage And Conversion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Supercapacitor Application ◽  
Transmission Electron ◽  
One Step

In this work, we present the synthesis of a ternary CeO2–SnO2/rGO nanocomposite by using a facile one-step hydrothermal method. The as-synthesized composite was structural, chemical, morphological, elemental information studied by using different characterization techniques X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDAX) and transmission electron microscope (TEM). The CeO2–SnO2/rGO exhibited an excellent specific capacitance of 156[Formula: see text]F[Formula: see text][Formula: see text] at 0.5[Formula: see text]A/g in the presence of 3 M KOH solution. The synergic effect of CeO2, SnO2 and graphene composite coated on Ni foam endowed a high specific capacitance than their individual compounds. This work suggests that the novel ternary composite is a promising candidate for the high performance electrochemical energy storage and conversion systems.

Preparation and Activity Evaluation of the Novel Cu/TiO2 Nanometer Photocatalytic Materials

2020 ◽  
Vol 12 (7) ◽  
pp. 1027-1033
Author(s):  
Yingchun Miao ◽  
Xiaolin Xu ◽  
Kaiquan Liu ◽  
Shiwen Yu ◽  
Yaqin Wang ◽  
...  
Keyword(s):  
Electron Microscope ◽  
High Performance ◽  
Oxygen Demand ◽  
Butyl Alcohol ◽  
Copper Sheet ◽  
Tertiary Butyl ◽  
X Ray ◽  
Synthesis Conditions ◽  
Energy Dispersion Spectrometer ◽  
Cefazolin Sodium

In this paper, the Cu/TiO2 thin film catalysts were prepared by alcoholthermal method with copper sheet as the carrier. In order to improve the degradation rate of antibiotic (cefazolin sodium), the synthesis conditions of Cu/TiO2 thin films were optimized. The physicochemical properties and activity were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray energy dispersion spectrometer (EDX), infrared spectrometer (FTIR), X-ray photoelectron spectrometer (XPS), high performance liquid chromatography (HPLC), chemical oxygen demand (COD) and spectrophotometry. The results show that the Cu/TiO2 catalyst had a uniform thickness of ∼200 nm and the particle size was about 0.4 nm, and the heterojunction between copper and anatase titanium dioxide has was successfully prepared. It can be found that when the dosage of TiF4 was 0.016 g, the tertiary butyl alcohol was 40 ml, the oven temperature was 130 °C, the oven reaction time was 24 h, the calcination temperature was 180 °C, and the calcination time was 2 h, the formed Cu/TiO2 catalyst can reach 58.1% for 3 h under visible light, with the photocatalytic degradation of 20 μg · mL–1 cefazolin sodium aqueous solution.

Electron density, disorder and polymorphism: high-resolution diffraction studies of the highly polymorphic neuralgic drug carbamazepine

2016 ◽  
Vol 72 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Ioana Sovago ◽  
Matthias J. Gutmann ◽  
Hans Martin Senn ◽  
Lynne H. Thomas ◽  
Chick C. Wilson ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Diffraction Data ◽  
Structural Formula ◽  
Orthorhombic Crystal ◽  
Monoclinic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Monoclinic Crystal Structure

Analysis of neutron and high-resolution X-ray diffraction data on form (III) of carbamazepine at 100 K using the atoms in molecules (AIM) topological approach afforded excellent agreement between the experimental results and theoretical densities from the optimized gas-phase structure and from multipole modelling of static theoretical structure factors. The charge density analysis provides experimental confirmation of the partially localized π-bonding suggested by the conventional structural formula, but the evidence for any significant C—N π bonding is not strong. Hirshfeld atom refinement (HAR) gives H atom positional and anisotropic displacement parameters that agree very well with the neutron parameters. X-ray and neutron diffraction data on the dihydrate of carbemazepine strongly indicate a disordered orthorhombic crystal structure in the space groupCmca, rather than a monoclinic crystal structure in space groupP21/c. This disorder in the dihydrate structure has implications for both experimental and theoretical studies of polymorphism.

Sign in / Sign up

Export Citation Format

Share Document