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Modification Of Multi-Walled Carbon Nanotubes By Microwave Digestion Method As Electrocatalyst Supports For Direct Methanol Fuel Cell Applications, Fang-Tzu Chuang
Modification Of Multi-Walled Carbon Nanotubes By Microwave Digestion Method As Electrocatalyst Supports For Direct Methanol Fuel Cell Applications, Fang-Tzu Chuang
Fang-Tzu Chuang
Multi-walled carbon nanotubes (MWCNTs) which were directly synthesized on carbon cloth were modified by a microwave digestion method in 5M HNO3 for supporting Pt nanoparticles. The characterizations of modified CNTs were carried out by TEM, XPS, FTIR and Raman spectroscopy. The HRTEM image shows the caps of MWCNTs are opened after modifying by microwave digestion method. The open-end and undamaged MWCNTs can provide a larger surface area for supporting more catalysts. Furthermore, the methanol electrocatalytic oxidation of microwave digestion treated Pt/MWCNTs electrode shows higher current density than pristine and nitric acid-treated MWCNTs from cyclic voltammograms. This can be an effective …
Effect Of Disorder On The Thermal Transport And Elastic Properties In Thermoelectric Zn4Sb3, S. Bhattacharya, R.P. Hermann, Veerle Keppens, T. M. Tritt, G. J. Snyder
Effect Of Disorder On The Thermal Transport And Elastic Properties In Thermoelectric Zn4Sb3, S. Bhattacharya, R.P. Hermann, Veerle Keppens, T. M. Tritt, G. J. Snyder
Veerle Keppens
Zn4Sb3 undergoes a phase transition from α to β phase at T1≈250 K. The high temperature β-Zn4Sb3 phase has been widely investigated as a potential state-of-the-art thermoelectric (TE) material, due to its remarkably low thermal conductivity. We have performed electronic and thermal transport measurements exploring the structural phase transition at 250 K. The α to β phase transition manifests itself by anomalies in the resistivity, thermopower, and specific heat at 250 K as well as by a reduction in the thermal conductivity as Zn4Sb3 changes phase from the ordered α to the disordered β-phase. Moreover, measurements of the elastic constants …
Direct Experimental Evidence For Atomic Tunneling Of Europium In Crystalline Eu8Ga16Ge30, Raphaël P. Hermann, Veerle Keppens, Pierre Bonville, George S. Nolas, Fernande Grandjean, Gary J. Long, Hans M. Christen, Bryan C. Chakoumakos, Brian C. Sales, David Mandrus
Direct Experimental Evidence For Atomic Tunneling Of Europium In Crystalline Eu8Ga16Ge30, Raphaël P. Hermann, Veerle Keppens, Pierre Bonville, George S. Nolas, Fernande Grandjean, Gary J. Long, Hans M. Christen, Bryan C. Chakoumakos, Brian C. Sales, David Mandrus
Veerle Keppens
Mössbauer-effect and microwave absorption experimental evidence unambiguously demonstrates the presence of slow, ∼450 MHz, tunneling of magnetic europium between four equivalent sites in Eu8Ga16Ge30, a stoichiometric clathrate. Remarkably, six of the eight europium atoms, or 11% of the constituents in this solid, tunnel between these four sites separated by 0.55 Å. The off centering of the atoms or ions in crystalline clathrates appears to be a promising route for producing Rabi oscillators in solid-state materials.
Study Of Chemical Surface Modifications Of Cnts As Cathode Electrode For Dmfc, Fang-Tzu Chuang
Study Of Chemical Surface Modifications Of Cnts As Cathode Electrode For Dmfc, Fang-Tzu Chuang
Fang-Tzu Chuang
In this study, multi-wall carbon nanotubes (MWNTs) are used as Pt catalyst support for cathode electrode in the direct methanol fuel cell (DMFC). Thus, a lot of well-align MWNTs are fabricated on carbon cloth directly. The method in the cathode electrode of DMFC is easy to constructed and sticking on the carbon cloth tightly. Then, MWNTs are modified by HNO3, H2SO4, and KOH at high temperature may produce different functional groups to attract more Pt ions nucleating uniformly and densely. Moreover, there are the other parameters, temperature, time, and concentration, in the function of chemical modification for MWNTs. In this …
Study Of Leading Factors In Formation Of Surface Wavy Structures On A Rubber Material, Fang-Tzu Chuang
Study Of Leading Factors In Formation Of Surface Wavy Structures On A Rubber Material, Fang-Tzu Chuang
Fang-Tzu Chuang
Wavy structures are often observed on the surface of a rubber material (polydimethylsiloxane, PDMS) covered with a thin metallic film. In this study we demonstrate that the orientation, periodicity, location of formation, and range of periodicity of the wavy structures can be regulated by three leading factors including the surface pattern, substrate hardness and the thickness of the metallic film. Results show the orientation of the wavy structures can be adjusted by the location, shape and size of the surface patterns. Enhancement of the substrate hardness can prevent forming random wavy structures. The thickness of surface metallic film significantly influenced …
Magnetic And Electronic Properties Of Eu4Sr4Ga16Ge30, G.T. Woods, J. Martin, M. Beekman, Raphaël P. Hermann, Fernande Grandjean, Veerle Keppens, O. Leupold, Gary J. Long, G.S. Nolas
Magnetic And Electronic Properties Of Eu4Sr4Ga16Ge30, G.T. Woods, J. Martin, M. Beekman, Raphaël P. Hermann, Fernande Grandjean, Veerle Keppens, O. Leupold, Gary J. Long, G.S. Nolas
Veerle Keppens
Magnetization, static and ac magnetic susceptibility, nuclear forward scattering, and electrical resistivity measurements have been performed on polycrystalline Eu4Sr4Ga16Ge30, a type I clathrate that has divalent strontium and europium ions encapsulated within a Ga-Ge framework. These data are compared with those of type I clathrates Eu8Ga16Ge30 and Eu6Sr2Ga16Ge30. The ferromagnetic ordering of these Eu-containing clathrates is substantially altered by the incorporation of strontium, as compared to Eu8Ga16Ge30. Ferromagnetism, accompanied by a relatively large negative magnetoresistance, is observed below 15 and 20 K in Eu4Sr4Ga16Ge30 and Eu6Sr2Ga16Ge30, respectively. An effective magnetic moment of 7.83 μB per Eu ion is observed above …
Theoretical Analysis Of Auto-Stability In Laser Resonator With Thermal Lenses Effect, Juan José Soto-Bernal, Adrian Bonilla-Petriciolet
Theoretical Analysis Of Auto-Stability In Laser Resonator With Thermal Lenses Effect, Juan José Soto-Bernal, Adrian Bonilla-Petriciolet
Adrian Bonilla-Petriciolet
In this work a numeric analysis is carried out to calculate the thermal lens effect in the stability of a barside-pumpedresonator at 808 nm. The active medium is a Nd:YVO4 crystal. It is demonstrated that the thermal effects produced by the radiative process, in certain conditions can take one of the planes to a non consistency, having as a consequence an oscillator that will work in intermittent form.
Characterization Of Cement And Concrete Exposed To Laser Radiation At 10.6 Um, María Del Rosario Moreno-Virgen, Juan José Soto-Bernal, Claudio Frausto-Reyes, Adrian Bonilla-Petriciolet
Characterization Of Cement And Concrete Exposed To Laser Radiation At 10.6 Um, María Del Rosario Moreno-Virgen, Juan José Soto-Bernal, Claudio Frausto-Reyes, Adrian Bonilla-Petriciolet
Adrian Bonilla-Petriciolet
In this paper, we report preliminary results of molecular structural changes in cement and concrete caused by laser radiation at 10.6 um. One of those structural changes is the generation of glazes. At low laser powers, the glazes are small and lined up while at high powers, the glazes are bigger and randomly distributed. In the not exposed to laser radiation concrete, the Raman spectrum presents weak peaks at 200 cm-1, 550 cm-1, 700 cm-1, 750 cm-1 and 1 150 cm-1. However, these peaks are amplified by laser exposure and other peaks appear at 800 cm-1 and 1 050 cm-1. …
The Synthesis Of Ultrafine And Nanocomposite Powders Based On Copper, Silver And Alumina, Zeljko J. Kamberovic
The Synthesis Of Ultrafine And Nanocomposite Powders Based On Copper, Silver And Alumina, Zeljko J. Kamberovic
Zeljko J Kamberovic
Contemporary materials with predetermined properties can be successfully synthesized by utilising the principles of hydrometallurgy and powder metallurgy. The results of developing a new procedure for the synthesis of ultrafine and nanocomposite powders based on copper, silver and alumina are presented in this paper. A two-component nanocomposite powder, Cu-Al2O3, was synthesized by a thermochemical procedure, by deposition from an aqueous solution of soluble metal salts, Cu(NO3)2 and Al(NO3)3. A three-component Cu-Ag-Al2O3 powder was produced by mechanically alloying nanocomposite Cu-Al2O3 powder and Cu-Ag powder, synthesized by the thermochemical procedure. The produced powders were characterized by determining the particle specific area, pouring …
Sulphated Almcm-41: Mesoporous Solid Brønsted Acid Catalyst For Dibenzoylation Of Biphenyl, Eng-Poh Ng, Hadi Nur, Mohd Nazlan Mohd Muhid, Halimaton Hamdan
Sulphated Almcm-41: Mesoporous Solid Brønsted Acid Catalyst For Dibenzoylation Of Biphenyl, Eng-Poh Ng, Hadi Nur, Mohd Nazlan Mohd Muhid, Halimaton Hamdan
Eng-Poh Ng
Sulphated mesoporous solid Brønsted acid catalyst (SO4-AlMCM-41) was prepared by impregnation of sulphuric acid on the surface of H-AlMCM-41. Characterization of SO4-AlMCM-41 by pyridine adsorption studies and 27Al MAS NMR showed that the presence of Brønsted acidity was correlated with octahedrally coordinated aluminium and solvent environment. Catalytic study demonstrated that the SO4-AlMCM-41 catalyst has a higher activity in the dibenzoylation of biphenyl with benzoyl chloride than sulphuric acid, H-AlMCM-41 and sulphated amorphous silica.