scholarly journals Design and Fabrication of High Activity Retention Al-Based Composite Powders for Mild Hydrogen Generation

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3328 ◽  
Author(s):  
Cuiping Wang ◽  
Kairui Lin ◽  
Yuheng Liu ◽  
Xinren Chen ◽  
Hongwei Zou ◽  
...  
Keyword(s):  
Hydrogen Generation ◽  
Calculated Phase Diagram ◽  
Distilled Water ◽  
X Ray Diffraction ◽  
Good Resistance ◽  
Composite Powders ◽  
Rich Phase ◽  
X Ray ◽  
Resistance To Oxidation ◽  
Cu Additive

Al–Bi–Sn–Cu composite powders for hydrogen generation were designed from the calculated phase diagram and prepared by the gas atomization process. The morphologies and structures of the composite powders were investigated using X-ray diffraction (XRD) and a scanning electron microscope (SEM) equipped with energy-dispersive X-ray (EDX) spectroscopy, and the results indicate that the Cu additive enhanced the phase separation between the Al-rich phase and the (Bi, Sn)-rich phase. The hydrogen generation performances were investigated by reacting the materials with distilled water. The Al–Bi–Sn–Cu powders reveal a stable hydrogen generation rate, and the Al–10Bi–7Sn–3Cu (wt%) powder exhibits the best hydrogen generation performance in 50 °C distilled water which reaches 856 mL/g in 800 min. In addition, the antioxidation properties of the powders were also studied. The Al–10Bi–7Sn–3Cu (wt%) powder has a good resistance to oxidation and moisture, which shows great potential for being the hydrogen source for fuel cell applications.

Synthesis and Structure of Titania Nanotubes For Hydrogen Generation

2013 ◽  
Vol 741 ◽  
pp. 84-89 ◽  
Author(s):  
Sangworn Wantawee ◽  
Pacharee Krongkitsiri ◽  
Tippawan Saipin ◽  
Buagun Samran ◽  
Udom Tipparach
Keyword(s):  
Oxalic Acid ◽  
Hydrogen Generation ◽  
Ammonium Fluoride ◽  
Photocurrent Density ◽  
Sodium Sulphate ◽  
Titania Nanotubes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dc Power ◽  
Anodic Voltage

Titania nanotubes (TiO2NTs) working electrodes for hydrogen production by photoelectrocatalytic water splitting were synthesized by means of anodization method. The electrolytes were the mixtures of oxalic acid (H2C2O4), ammonium fluoride (NH4F), and sodium sulphate (VI) (Na2SO4) with different pHs. A constant dc power supply at 20 V was used as anodic voltage. The samples were annealed at 450 °C for 2 hrs. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) were used to characterized TiO2NTs microstructure. TiO2NTs with diameter of 100 nm were obtained when pH 3 electrolyte consisting of 0.08 M oxalic acid, 0.5 wt% NH4F, and 1.0 wt% Na2SO4was used. Without external applied potential, the maximum photocurrent density was 2.8 mA/cm2under illumination of 100 mW/cm2. Hydrogen was generated at an overall photoconversion efficiency of 3.4 %.

scholarly journals Synthesis and Characterization of K-Ta Mixed Oxides for Hydrogen Generation in Photocatalysis

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Beata Zielińska ◽  
Ewa Mijowska ◽  
Ryszard J. Kalenczuk
Keyword(s):  
Diffuse Reflectance ◽  
Hydrogen Generation ◽  
Mixed Oxides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Photocatalytic Hydrogen Generation ◽  
Irregular Structure ◽  
Transmission Electron

K-Ta mixed oxides photocatalysts have been prepared by impregnation followed by calcination. The influence of the reaction temperature (450°C–900°C) on the phase formation, crystal morphology, and photocatalytic activity in hydrogen generation of the produced materials was investigated. The detailed analysis has revealed that all products exhibit high crystallinity and irregular structure. Moreover, two different crystal structures of potassium tantalates such as KTaO3and K2Ta4O11were obtained. It was also found that the sample composed of KTaO3and traces of unreacted Ta2O5(annealed at 600°C) exhibits the highest activity in the reaction of photocatalytic hydrogen generation. The crystallographic phases, optical and vibronic properties were examined by X-ray diffraction (XRD) and diffuse reflectance (DR) UV-vis and resonance Raman spectroscopic methods, respectively. Morphology and chemical composition of the produced samples were studied using a high-resolution transmission electron microscope (HR-TEM) and an energy dispersive X-ray spectrometer (EDX) as its mode.

scholarly journals Mechanochemical Synthesis of Fluorapatite-Zinc Oxide (FAp-ZnO) Composite Nanopowders

ISRN Ceramics ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Bahman Nasiri-Tabrizi ◽  
Abbas Fahami
Keyword(s):  
Zinc Oxide ◽  
Average Crystallite Size ◽  
Structural Features ◽  
Morphological Features ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
Remarkable Change ◽  
X Ray ◽  
Process Characterization ◽  
Ft Ir

Fluorapatite-zinc oxide (FAp-ZnO) composite nanopowders were successfully prepared via mechanochemical process. Characterization of the products was carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) analysis, energy dispersive X-ray spectroscopy (EDX), and field-emission scanning electron microscopy (FE-SEM) techniques. Results revealed that in the absence of ZnO which produced by hydrothermal method, the single-phase FAp had high-crystalline structure with appropriate morphological features. Furthermore, after 5 h of milling in the presence of 5 wt.% ZnO, FAp-5 wt.% ZnO, composite nanopowders with no impurity phase was obtained. Structural studies illustrated that the milling up to 5 h was not accompanied by a remarkable change in the structural features. Moreover, the gained composite powders presented an average crystallite size of about 40 nm for FAp. The FE-SEM observations indicated that the experimental outcome had a cluster-like structure which consisted of several small particles. Finally, results propose a new approach to prepare commercial amounts of novel FAp-based composite nanopowders with high quality and suitable structural and morphological features.

scholarly journals Phase Formation and Magnetic Properties of Melt Spun and Annealed Nd-Fe-B Based Alloys with Ga Additions

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 497
Author(s):  
Shchetinin ◽  
Aggrey ◽  
Bordyuzhin ◽  
Savchenko ◽  
Gorshenkov ◽  
...  
Keyword(s):  
Magnetic Property ◽  
Amorphous Phase ◽  
Melt Spinning ◽  
Fluorescence Analysis ◽  
Structural Transformations ◽  
X Ray Diffraction ◽  
Rich Phase ◽  
X Ray ◽  
Melt Spun ◽  
Property Changes

The structural transformations and magnetic property changes of the Nd16.2FebalCo9.9Ga0.5B7.5 (SG1, SG2) and Nd15.0FebalGa2.0B7.3 (SG3) nanocomposite alloys obtained by melt spinning in the as-quenched state and after annealing at a temperature range of 560–650 °C for 30 min were studied. The methods used were X-ray diffraction analysis, magnetic property measurements, TEM studies, X-ray fluorescence analysis and Mössbauer spectroscopy. Amorphous phase and crystalline phase Nd2Fe14B (P42/mnm) were observed in the alloy after melt spinning. The content of the amorphous phase ranged from 20% to 50% and depended on the cooling rate. Annealing of the alloys resulted in amorphous phase crystallization into Nd2Fe14B and led to the increased coercivity of the alloys up to 1840 kA/m (23.1 kOe) at 600 °C annealing for 30 min. The alloy with the maximum coercivity had a grain size of the Nd2Fe14B phase ≈50–70 nm with an Nd-rich phase between grains.

CoO-Co2P composite nanosheets as highly active catalysts for sodium borohydride hydrolysis to generate hydrogen

2020 ◽  
Vol 13 (06) ◽  
pp. 2051025
Author(s):  
Hongyan Liu ◽  
Qianyu Shi ◽  
Yumei Yang ◽  
Ya-Na Yu ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Sodium Borohydride ◽  
Hydrogen Generation ◽  
Sodium Hypophosphite ◽  
X Ray Diffraction ◽  
Water Displacement ◽  
X Ray ◽  
Highly Active ◽  
Naoh Solution ◽  
Adsorption Desorption ◽  
Hydrolysis Of

In this paper, CoO[Formula: see text]Co2P composite nanocatalysts as highly active catalysts were successfully prepared for catalytic hydrolysis of sodium borohydride (NaBH[Formula: see text] to generate hydrogen. For catalyst preparation, pre-synthesized Co(OH)2 nanosheets were uniformly mixed with sodium hypophosphite (NaH2PO[Formula: see text] and then treated through vapor-phase phosphorization process. For characterization, field-emission scanning electron microscopy (FE-SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), N2 adsorption–desorption measurement and X-ray photoelectric spectroscopy (XPS) were carried out, and traditional water-displacement method was performed to measure the hydrogen generation rate (HGR). It was found that component and catalytic activity of the composites were greatly affected by the ratio of Co(OH)2 to NaH2PO2. When the ratio was 2:1, the obtained catalyst composed of CoO and Co2P presented the highest HGR up to 3.94[Formula: see text]L min[Formula: see text] g[Formula: see text] using a 2[Formula: see text]wt.% NaBH[Formula: see text][Formula: see text]wt.% NaOH solution at [Formula: see text]C, and the apparent activation energy was detected as low as 27.4[Formula: see text]kJ mol[Formula: see text]. Additionally, the optimum CoO[Formula: see text]Co2P catalyst still retains 60% of the initial activity after recycling four times.

scholarly journals Preparation of Zirconium Carbide-Zirconium Silicide Composite Powders by Solid Reaction of Zr and SiC Powders

2020 ◽  
Vol 26 (3) ◽  
pp. 348-351
Author(s):  
Yingxin CHEN ◽  
Shoujun WU ◽  
Shaojun MA ◽  
Xiao ZHAO ◽  
Baowei CAO
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Diffusion Layer ◽  
Zirconium Carbide ◽  
X Ray Diffraction ◽  
Solid Reaction ◽  
Composite Powders ◽  
X Ray ◽  
Zirconium Silicide ◽  
Scanning Electron

In the present work, zirconium carbide-zirconium silicide composite powders were prepared by solid reaction using Zr and SiC powders as reactants. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results showed that, after treatment at 800 ºC, the produced zirconium carbide-zirconium silicide diffusion layer was very thin and mainly consisted of ZrC and ZrSi2. After treatment above 900 ºC, the produced phases were mainly consisted of ZrC and ZrSi2, plus less ZrSi.

Local structure and defects in ultrahigh-temperature materials of borosilicon carbonitride

2008 ◽  
Vol 23 (6) ◽  
pp. 1642-1646 ◽  
Author(s):  
Kazuhiro Yamamoto ◽  
Naoya Tsuganezawa ◽  
Shin-ichi Makimura ◽  
Daigo Sawa ◽  
Shin-ichi Nakahigashi ◽  
...  
Keyword(s):  
Structural Changes ◽  
Hexagonal Boron Nitride ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relative Peak Intensity ◽  
Resistance To Oxidation ◽  
Infrared Measurements ◽  
Void Defects ◽  
Ultrahigh Temperature ◽  
X Ray Absorption

We have investigated structural changes of amorphous borosilicon carbonitride materials with atomic ratios of B/Si/C of 2/3/6 and 4/3/6 calcined at several temperatures. The boron K-edge x-ray absorption spectra showed that the structures of both hexagonal boron nitride ([BN3] unit) with nitrogen-void defects ([BN2] and [BN1] units) and boron oxide existed in the samples, and the relative peak intensity due to the [BN3] unit became stronger by increasing the calcined temperature. It is thought that the well-developed B–N chain and the borosilicate glass coating lead to the high resistance to oxidation at high temperature. X-ray diffraction and infrared measurements followed the x-ray absorption near-edge spectroscopy findings.

Microstructure and Distribution of Low Content Elements in AlNiCo 9

2017 ◽  
Vol 898 ◽  
pp. 1669-1674 ◽  
Author(s):  
Bin Shao ◽  
Bing Bing Li ◽  
Chun Hong Li ◽  
Yi Long Ma ◽  
Qiang Zheng ◽  
...  
Keyword(s):  
Magnetic Force ◽  
Magnetic Domain ◽  
Magnetic Force Microscope ◽  
X Ray Diffraction ◽  
Rich Phase ◽  
X Ray ◽  
Al Content ◽  
Transmission Electron ◽  
Titanium Sulfide ◽  
High Al Content

The microstructure and the chemistry distribution of AlNiCo 9 samples were characterized by the X-ray diffraction, magnetic force microscope, field emission scanning electron microscopy and transmission electron microscope. An interface of a high Al content was formed near the FeCo-rich phases with a size of about 30 nm. S elements mainly combined with Ti to form titanium sulfide bars with the length between 70-150 μm, while S elements was not confirmed in the nanostructured FeCo-rich phase and AlNi-rich phase. Si and Nb preferably existed in the NiAl-rich phase, and a higher content Nb near the Cu precipitate boundary was observed. Moreover, the magnetic domain structure of AlNiCo 9 was also studied.

scholarly journals X-ray diffraction analysis of products sintered from isostatically pressed leaded bronze powders

2019 ◽  
Vol 298 ◽  
pp. 00037 ◽  
Author(s):  
Evgeny Ageev ◽  
Anton Pereverzev
Keyword(s):  
Phase Composition ◽  
Diffraction Analysis ◽  
Sintered Sample ◽  
Distilled Water ◽  
X Ray Diffraction ◽  
X Ray

This article presents a study of the phase composition of samples sintered from isostatically pressed leaded bronze electroerosion powders obtained in distilled water. It is identified that the main phases in the sintered sample are Cu, Zn2SnO4, Pb(Cu2O2), PbO, Fe3O4.

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