The Preparation and Characterization of Pt/Fe Electrocatalyst for Direct Methanol Oxidation

1994 ◽  
Vol 368 ◽  
Author(s):  
Chaoying Ma ◽  
A. D. Kowalak ◽  
Changmo Sung
Keyword(s):  
Methanol Oxidation ◽  
Chemical Method ◽  
Reaction System ◽  
Pt Catalyst ◽  
Reaction Conditions ◽  
X Ray ◽  
Transmission Electron ◽  
Scan Rate ◽  
Direct Methanol

ABSTRACTPt/Fe electrocatalysts (Pt/Fe) supported on Vulcan XC-72 carbon black were prepared by chemical method. The formation of Pt/Fe clusters was confirmed by transmission electron microscopy (TEM) and energy dispersive x-ray spectrometry (EDXS). The electrochemical efficiency and durability of the catalysts for direct methanol oxidation were compared with the catalyst containing Pt only (Pt) under the same reaction conditions of 1 M CH3OH in 0.1 M H2SO4 electrolyte solution. The current density for the Pt/Fe is three times of that of the Pt catalyst. Effects of various factors on the behavior of the catalysts, such as reaction time during preparation, order of the addition of the chemicals into the reaction system, methanol concentration, activation per unit Pt, scan rate for cyclic voltammograph, were examined.

scholarly journals Characterization of ferrite nanoparticles for preparation of biocomposites

2017 ◽  
Vol 8 ◽  
pp. 1257-1265 ◽  
Author(s):  
Urszula Klekotka ◽  
Magdalena Rogowska ◽  
Dariusz Satuła ◽  
Beata Kalska-Szostko
Keyword(s):  
Chemical Method ◽  
Ferrite Nanoparticles ◽  
Chemical Activity ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Wet Chemical Method ◽  
X Ray ◽  
Transmission Electron ◽  
Wet Chemical

Ferrite nanoparticles with nominal composition Me0.5Fe2.5O4 (Me = Co, Fe, Ni or Mn) have been successfully prepared by the wet chemical method. The obtained particles have a mean diameter of 11–16 ± 2 nm and were modified to improve their magnetic properties and chemical activity. The surface of the pristine nanoparticles was functionalized afterwards with –COOH and –NH2 groups to obtain a bioactive layer. To achieve our goal, two different modification approaches were realized. In the first one, glutaraldehyde was attached to the nanoparticles as a linker. In the second one, direct bonding of such nanoparticles with a bioparticle was studied. In subsequent steps, the nanoparticles were immobilized with enzymes such as albumin, glucose oxidase, lipase and trypsin as a test bioparticles. The characterization of the nanoparticles was acheived by transmission electron microscopy, X-ray diffraction, energy dispersive X-ray and Mössbauer spectroscopy. The effect of the obtained biocomposites was monitored by Fourier transform infrared spectroscopy. The obtained results show that in some cases the use of glutaraldehyde was crucial (albumin).

Preparation and Characterization of Pt/Superfine Mesocarbon Microbead Powers Electrocatalysts

2005 ◽  
Vol 3 (3) ◽  
pp. 358-360 ◽  
Author(s):  
Jia Rong-Li ◽  
Wang Cheng-Yang ◽  
Zhu Bin
Keyword(s):  
Reduction Method ◽  
Direct Methanol Fuel Cells ◽  
Electrochemical Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Platinum Particles ◽  
Platinum Electrocatalyst ◽  
Direct Methanol

Superfine mesocarbon microbead powders (SFMCMBs) as the new supports for platinum electrocatalysts were first investigated. The Pt∕SFMCMB electrocatalysts were prepared by an impregnation-reduction method, with hexachloroplatinic acid as the platinum precursor and formaldehyde as the reducing agent. The catalysts were characterized with x-ray diffraction (XRD), field emission gun transmission electron microscope (TEM), and electrochemical analysis. TEM photos showed the platinum particles were dispersed uniformly on the surface of SFMCMBs and there existed a little aggregation of platinum particles in the Pt∕SFMCMB catalysts. The TEM photos showed the existence of the platinum on the supports where the average platinum particle size were 4-6nm. The electrochemical analysis proved that SFMCMBs are excellent candidates to be used as the support of platinum electrocatalyst for methanol electrochemical oxidation as the potential catalyst candidate for direct methanol fuel cells (DMFCs).

LINEAR AND NONLINEAR OPTICAL PROPERTIES OF GOLD NANOPARTICLES STABILIZED WITH POLYVINYL ALCOHOL

2011 ◽  
Vol 20 (04) ◽  
pp. 467-475 ◽  
Author(s):  
MISHA HARI ◽  
SANTHI ANI JOSEPH ◽  
NITHYAJA BALAN ◽  
MATHEW S ◽  
RAVI KUMAR ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Polyvinyl Alcohol ◽  
Nonlinear Optical ◽  
Chemical Method ◽  
Excitation Wavelength ◽  
X Ray ◽  
Nonlinear Optical Absorption ◽  
Transmission Electron ◽  
532 Nm

The nonlinear optical absorption of gold nanoparticles dispersed in polyvinyl alcohol (Au:PVA) is investigated using open aperture Z-scan technique. Au :PVA nanocomposite material is synthesized by chemical method. The characterization of the material is done by UV/Vis absorption spectroscopy, transmission electron microscopy and X-ray diffractometry (XRD). It is observed that the nature of the nonlinear absorption depends on the excitation wavelength. The optical limiting capability of the sample is also demonstrated at a wavelength of 532 nm.

Synthesis and Characterization of a New Amino-Functionalized PMO Material

2013 ◽  
Vol 712-715 ◽  
pp. 271-279
Author(s):  
Fei Ding ◽  
Shuang Xi Liu
Keyword(s):  
Electron Microscopy ◽  
Solid State Nmr ◽  
Alkyl Chain ◽  
Reaction System ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Xrd Patterns

A new organic silicane which is bridged by a long amino-functionalized alkyl chain was prepared and used as the precursor in the synthesis of a series of PMO materials. The organic silicane was added into the reaction system in CH2Cl2and the PMO materials were prepared by a simple stirring method under acidic condition, with a nonionic surfactantBrij 76 as template. To find the proper synthesis condition, the time of stirring and the proportion of organic silicane and TEOS were varied. Liquid and solid state NMR, X-ray diffraction (XRD) patterns, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and N2-physisorption properties were used to characterize the structures.

scholarly journals Solvent-Free Mechanochemical Synthesis and Characterization of Nickel Tellurides with Various Stoichiometries: NiTe, NiTe2 and Ni2Te3

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1959
Author(s):  
Matjaž Kristl ◽  
Sašo Gyergyek ◽  
Srečo D. Škapin ◽  
Janja Kristl
Keyword(s):  
Electron Microscopy ◽  
Magnetic Measurements ◽  
Ferromagnetic Behavior ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
X Ray ◽  
Transmission Electron ◽  
Energy Consuming ◽  
Tga And Dsc

The paper reports the synthesis of nickel tellurides via a mechanochemical method from elemental precursors. NiTe, NiTe2, and Ni2Te3 were prepared by milling in stainless steel vials under nitrogen, using milling times from 1 h to 12 h. The products were characterized by powder X-ray diffraction (pXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), vibrating sample magnetometer (VSM), UV-VIS spectrometry, and thermal analysis (TGA and DSC). The products were obtained in the form of aggregates, several hundreds of nanometers in size, consisting of smaller nanosized crystallites. The magnetic measurements revealed a ferromagnetic behavior at room temperature. The band gap energies calculated using Tauc plots for NiTe, NiTe2, and Ni2Te3 were 3.59, 3.94, and 3.70 eV, respectively. The mechanochemical process has proved to be a simple and successful method for the preparation of binary nickel tellurides, avoiding the use of solvents, toxic precursors, and energy-consuming reaction conditions.

Comparison of Hydroxyapatite Synthesized under Different Conditions

2006 ◽  
Vol 510-511 ◽  
pp. 814-817 ◽  
Author(s):  
Li Rong Mo ◽  
Yu Bao Li ◽  
Guo Yu Lv ◽  
Ji Dong Li ◽  
Li Zhang
Keyword(s):  
Sodium Phosphate ◽  
Chemical Method ◽  
Calcium Nitrate ◽  
Reaction System ◽  
Xrd Analysis ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Before And After

In this paper, using sodium phosphate and calcium nitrate as reagents, nano-hydroxyapatite (n-HA) was synthesised under 8 conditions. The morphology and crystallinity of these prepared HA were investigated by Transmission Electron Microscope (TEM) and X-ray diffraction pattern (XRD). The Ca/P molar ratio of n-HA was tested by chemical method. In order to find a better way to obtain purer nano-hydroxyapatite, the phases transition and purification of these 8 samples before and after sintering at 1000°C were compared. The results indicated that all these samples showed similar, poorly crystallized apatite structures before sintering. The adding order between calcium and phosphate would affect the crystallinity, structure and Ca/P molar ratio of hydoxyapatite significantly. XRD analysis showed that adding sodium phosphate into calcium nitrate could gain more HA phase after sintering at 1000°C. The pH of reaction system had obvious effects on the structure of hydroxyapatite. Besides the pH of reactants also affected the structure of hydoxyapatite.

Preparation and Characterization of Copper Dendrite Like Structure by Chemical Method

2013 ◽  
Vol 678 ◽  
pp. 27-31 ◽  
Author(s):  
Chinna Kannaiyan Senthil Kumaran ◽  
Santhanam Agilan ◽  
Dhayalan Velauthapillai ◽  
Natarajan Muthukumarasamy ◽  
Mariyappan Thambidurai ◽  
...  
Keyword(s):  
Chemical Method ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Copper Particles ◽  
Transmission Electron ◽  
Simple Chemical ◽  
High Yields

Abstract Copper particles are prepared at room temperature using a simple chemical method. The method used is capable of giving high yields. In this method sodium borohydride is used as a reducing agent and poly vinly pyrrolidone (PVP) as a capping reagent. The prepared copper particles are characterized by X-ray diffraction method and Energy dispersive x-ray analysis (EDX). The scanning electron microscopy (SEM) images show the formation of dendrite like structures. The transmission electron microscope (TEM) studies also conform the formation of dendrite structures.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Surfactant involved in Copper Sulfide Nanocrystallites Synthesis

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Claudia Maria Simonescu ◽  
Valentin Serban Teodorescu ◽  
Camelia Capatina
Keyword(s):  
Copper Sulfide ◽  
X Ray Diffraction ◽  
Reaction Parameters ◽  
Reaction Conditions ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Shape Of Nanoparticles ◽  
Tem Transmission Electron Microscopy ◽  
Shape And Size

This paper presents the obtaining of copper sulfide CuS (covelite) from Cu(CH3COO)2.H2O and thioacetamide (TAA) system. The reaction was conducted in presence or absence of sodium-bis(2-ethylhexyl) sulfosuccinate (Na-AOT). The effects of various reaction parameters on the size and on the shape of nanoparticles have been examined. CuS obtained was characterized by X ray diffraction, IR spectroscopy, TEM � transmission electron microscopy and SAED selected area electron diffraction. The influence of surfactant to the shape and size of CuS (covellite) nanocrystals was established. The size of the nanocrystals varied from 10-60 nm depending on the reaction conditions such as quantity of surfactant.

Mn-Mo-O Catalysts for Methanol Oxidation. I. Preparation and Characterization of the Catalysts

1992 ◽  
Vol 57 (12) ◽  
pp. 2529-2538 ◽  
Author(s):  
Krasimir Ivanov ◽  
Penka Litcheva ◽  
Dimitar Klissurski
Keyword(s):  
Methanol Oxidation ◽  
Solution Concentration ◽  
Alkaline Media ◽  
Acidic Media ◽  
Chemical Methods ◽  
X Ray ◽  
Ph Values ◽  
Precipitate Composition

Mn-Mo-O catalysts with a different Mo/Mn ratio have been prepared by precipitation. The precipitate composition as a function of solution concentration and pH was studied by X-ray, IR, thermal and chemical methods. Formation of manganese molybdates with MnMoO4.1.5H2O, Mn3Mo3O12.2.5H2O, and Mn3Mo4O15.4H2O composition has been supposed. It is concluded that pure MnMoO4 may be obtained in both acid and alkaline media, the pH values depending on the concentration of the initial solutions. The maximum Mo/Mn ratio in the precipitates is 1.33. The formation of pure Mn3Mo4O15.4H2O is possible in weakly acidic media. This process is favoured by increasing the concentration of initial solutions.

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