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Sample records for alloy anode catalysts

  1. Nickel Alloy Catalysts for the Anode of a High Temperature PEM Direct Propane Fuel Cell

    Directory of Open Access Journals (Sweden)

    Shadi Vafaeyan

    2014-01-01

    Full Text Available High temperature polymer electrode membrane fuel cells that use hydrocarbon as the fuel have many theoretical advantages over those that use hydrogen. For example, nonprecious metal catalysts can replace platinum. In this work, two of the four propane fuel cell reactions, propane dehydrogenation and water dissociation, were examined using nickel alloy catalysts. The adsorption energies of both propane and water decreased as the Fe content of Ni/Fe alloys increased. In contrast, they both increased as the Cu content of Ni/Cu alloys increased. The activation energy for the dehydrogenation of propane (a nonpolar molecule changed very little, even though the adsorption energy changed substantially as a function of alloy composition. In contrast, the activation energy for dissociation of water (a molecule that can be polarized decreased markedly as the energy of adsorption decreased. The different relationship between activation energy and adsorption energy for propane dehydrogenation and water dissociation alloys was attributed to propane being a nonpolar molecule and water being a molecule that can be polarized.

  2. A novel Pt-Co alloy hydrogen anode catalyst with superlative activity, CO-tolerance and robustness

    Science.gov (United States)

    Shi, G. Y.; Yano, H.; Tryk, D. A.; Watanabe, M.; Iiyama, A.; Uchida, H.

    2016-07-01

    PtCo nanoparticles, having two atomic layers of stabilized Pt skin, supported on carbon black (Pt2AL-PtCo/C), exhibited superlative mass activity for the CO-tolerant hydrogen oxidation reaction (HOR), together with high robustness with respect to air exposure, as a novel anode catalyst in reformate gas-based polymer electrolyte fuel cells. The high area-specific HOR activity and CO tolerance are consistent with DFT calculations.PtCo nanoparticles, having two atomic layers of stabilized Pt skin, supported on carbon black (Pt2AL-PtCo/C), exhibited superlative mass activity for the CO-tolerant hydrogen oxidation reaction (HOR), together with high robustness with respect to air exposure, as a novel anode catalyst in reformate gas-based polymer electrolyte fuel cells. The high area-specific HOR activity and CO tolerance are consistent with DFT calculations. Electronic supplementary information (ESI) available: Experimental details, TEM images and particle size distribution histograms of all catalysts, and details of the DFT calculations. See DOI: 10.1039/c6nr00778c

  3. Alloy catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel alloy catalyst material for use in the synthesis of hydrogen peroxide from oxygen and hydrogen, or from oxygen and water. The present invention also relates to a cathode and an electrochemical cell comprising the novel catalyst material, and the process use...

  4. Pt -based anode catalysts for direct ethanol fuel cells

    International Nuclear Information System (INIS)

    In this work it is studied the electro-catalytic behavior of pure platinum and platinum-based alloys with Ru, Sn, Ir, and Os supported on carbon to the ethanol electro-oxidation in aims to develop anodic catalysts for direct ethanol fuel cells, additionally, porous electrodes and membrane electrode assemblies were built for proton exchange membrane fuel cells in which the electrodes were tested. Catalysts characterization was made by cyclic voltammetry whereas the fuel cells behavior tests were made by current-potential polarization curves. in general, all alloys show a lower on-set reaction potential and a higher catalytic activity than pure platinum. However, in the high over potential zone, pure platinum has higher catalytic activity than the alloys. In agreement with these results, the alloys studied here could be useful in fuel cells operating on moderated and low current

  5. Galvanic aspects of aluminum sacrificial anode alloys in seawater.

    OpenAIRE

    Cummings, Jon Richard

    2012-01-01

    Galvanic aspects of aluminum sacrificial anode alloys in artificial seawater were investigated. Specifically, two mercury-bearing alloys and one tin-bearing alloy were studied. The polarization behavior of the aluminum sacrificial anode alloys coupled to HY-80 steel is discussed. Current versus time curves were obtained for aluminum/steel galvanic couples immersed in artificial seawater for specific intervals. Scanning elecron microscopy was used to characterize the anode dissolution patt...

  6. Nanotemplated platinum fuel cell catalysts and copper-tin lithium battery anode materials for microenergy devices

    Energy Technology Data Exchange (ETDEWEB)

    Rohan, J.F., E-mail: james.rohan@tyndall.ie [Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland); Hasan, M.; Holubowitch, N. [Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland)

    2011-11-01

    Highlights: > Anodic Aluminum oxide formation on Si substrate. > High density nanotemplated Pt catalyst on Si for integrated energy and electronics. > CuSn alloy deposition from a single, high efficiency methanesulfonate plating bath. > Nanotemplated CuSn Li anode electrodes with high capacity retention. - Abstract: Nanotemplated materials have significant potential for applications in energy conversion and storage devices due to their unique physical properties. Nanostructured materials provide additional electrode surface area beneficial for energy conversion or storage applications with short path lengths for electronic and ionic transport and thus the possibility of higher reaction rates. We report on the use of controlled growth of metal and alloy electrodeposited templated nanostructures for energy applications. Anodic aluminium oxide templates fabricated on Si for energy materials integration with electronic devices and their use for fuel cell and battery materials deposition is discussed. Nanostructured Pt anode catalysts for methanol fuel cells are shown. Templated CuSn alloy anodes that possess high capacity retention with cycling for lithium microbattery integration are also presented.

  7. New development of anodizing process of magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    BAI Li-qun; LI Di

    2004-01-01

    Magnesium alloy, a kind of environment-friendly material with promising and excellent properties, is a good choice for a number of applications. The research and development of anodizing on magnesium alloys and its application situation are reviewed, and the anodizing development trend on magnesium alloys is summarized.

  8. Vanadium-based anode catalysts for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Fu, X.Z.; Luo, J.L.; Chuang, K.T.; Sanger, A.R. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; Tu, H.Y. [Shanghai Jiao Tong Univ., Shanghai (China). Inst. of Fuel Cell, School of Mechanical Engineering; Yang, Q.M. [Vale-Inco Ltd., Mississauga, ON (Canada)

    2010-07-01

    Solid oxide fuel cells (SOFCs) are considered as important electricity generators because they convert carbon-containing fuels from fossil sources to electricity without generating pollution. Syngas is more available and less expensive than highly purified hydrogen. However, when exposed to syngas at SOFC operating temperatures, conventional nickel anode catalysts result in carbon deposition, which compromises their performance. Syngas derived from conversion of hydrocarbon or coal resources normally also contain hydrogen sulphide, which poisons nickel anode catalysts. In order to use syngas, it is necessary to either stringently clean the feed, which is a costly process, or develop catalysts that can operate using impure feed and are not prone to carbon deposition. This paper discussed the development of a vanadium-based material (VOx) which is an active anode catalyst for SOFCs, that is not prone to coking and is sulfur resistant. The VOx material was obtained by decomposition and reduction of ammonium metavanadate (NH{sub 4}VO{sub 3}) at high temperature. Coking and sulfur resistance of as-prepared VOx and nickel were compared in hydrogen sulphide-containing syngas environments at 900 degrees Celsius. It was concluded that the VOx material had much higher coking resistance and sulfur tolerance than nickel. The SOFC with VOx anode catalyst demonstrated excellent performance using hydrogen sulphide-containing syngas as fuel. 3 refs.

  9. In situ characterization of nanoscale catalysts during anodic redox processes

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Renu [National Institute of Standards and Technology; Crozier, Peter [Arizona State University; Adams, James [Arizona State University

    2013-09-19

    Controlling the structure and composition of the anode is critical to achieving high efficiency and good long-term performance. In addition to being a mixed electronic and ionic conductor, the ideal anode material should act as an efficient catalyst for oxidizing hydrogen, carbon monoxide and dry hydrocarbons without de-activating through either sintering or coking. It is also important to develop novel anode materials that can operate at lower temperatures to reduce costs and minimized materials failure associated with high temperature cycling. We proposed to synthesize and characterize novel anode cermets materials based on ceria doped with Pr and/or Gd together with either a Ni or Cu metallic components. Ceria is a good oxidation catalyst and is an ionic conductor at room temperature. Doping it with trivalent rare earths such as Pr or Gd retards sintering and makes it a mixed ion conductor (ionic and electronic). We have developed a fundamental scientific understanding of the behavior of the cermet material under reaction conditions by following the catalytic oxidation process at the atomic scale using a powerful Environmental Scanning Transmission Electron Microscope (ESTEM). The ESTEM allowed in situ monitoring of structural, chemical and morphological changes occurring at the cermet under conditions approximating that of typical fuel-cell operation. Density functional calculations were employed to determine the underlying mechanisms and reaction pathways during anode oxidation reactions. The dynamic behavior of nanoscale catalytic oxidation of hydrogen and methane were used to determine: ? Fundamental processes during anodic reactions in hydrogen and carbonaceous atmospheres ? Interfacial effects between metal particles and doped ceria ? Kinetics of redox reaction in the anode material

  10. Bifunctional Anode Catalysts for Direct Methanol Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Rossmeisl, Jan; Ferrin, Peter A.; Tritsaris, Georgios A.; Nilekar, Anand U.; Koh, Shirlaine; Bae, Sang Eun; Brankovic, Stanko R.; Strasser, Peter; Mavrikakis, Manos

    2012-06-13

    Using the binding energy of OH* and CO* on close-packed surfaces as reactivity descriptors, we screen bulk and surface alloy catalysts for methanol electro-oxidation activity. Using these two descriptors, we illustrate that a good methanol electro-oxidation catalyst must have three key properties: (1) the ability to activate methanol, (2) the ability to activate water, and (3) the ability to react off surface intermediates (such as CO* and OH*). Based on this analysis, an alloy catalyst made up of Cu and Pt should have a synergistic effect facilitating the activity towards methanol electro-oxidation. Using these two reactivity descriptors, a surface PtCu3 alloy is proposed to have the best catalytic properties of the Pt–Cu model catalysts tested, similar to those of a Pt–Ru bulk alloy. To validate the model, experiments on a Pt(111) surface modified with different amounts of Cu adatoms are performed. Adding Cu to a Pt(111) surface increases the methanol oxidation current by more than a factor of three, supporting our theoretical predictions for improved electrocatalysts.

  11. Bifunctional anode catalysts for direct methanol fuel cells

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Ferrin, Peter; Tritsaris, Georgios;

    2012-01-01

    Using the binding energy of OH* and CO* on close-packed surfaces as reactivity descriptors, we screen bulk and surface alloy catalysts for methanol electro-oxidation activity. Using these two descriptors, we illustrate that a good methanol electro-oxidation catalyst must have three key properties......: (1) the ability to activate methanol, (2) the ability to activate water, and (3) the ability to react off surface intermediates (such as CO* and OH*). Based on this analysis, an alloy catalyst made up of Cu and Pt should have a synergistic effect facilitating the activity towards methanol electro....... Adding Cu to a Pt(111) surface increases the methanol oxidation current by more than a factor of three, supporting our theoretical predictions for improved electrocatalysts....

  12. Effect of alloying elements Al and Ca on corrosion resistance of plasma anodized Mg alloys

    Science.gov (United States)

    Anawati, Asoh, Hidetaka; Ono, Sachiko

    2016-04-01

    Plasma anodizing is a surface treatment used to form a ceramic-type oxide film on Mg alloys by the application of a high anodic voltage to create intense plasma near the metal surface. With proper selection of the process parameters, the technique can produce high quality oxide with superior adhesion, corrosion resistance, micro-hardness, wear resistance and strength. The effect of alloying element Al on plasma anodizing process of Mg alloys was studied by comparing the anodizing curves of pure Mg, AZ31, and AZ61 alloys while the effect of Ca were studied on AZ61 alloys containing 0, 1, and 2 wt% Ca. Anodizing was performed in 0.5 M Na3PO4 solution at a constant current density of 200 Am-2 at 25°C. Anodic oxide films with lava-like structure having mix composition of amorphous and crystal were formed on all of the alloys. The main crystal form of the oxide was Mg3(PO4)2 as analyzed by XRD. Alloying elements Al and Ca played role in modifying the plasma lifetime during anodization. Al tended to extend the strong plasma lifetime and therefore accelerated the film thickening. The effect of Ca on anodizing process was still unclear. The anodic film thickness and chemical composition were altered by the presence of Ca in the alloys. Electrochemical corrosion test in 0.9% NaCl solution showed that the corrosion behavior of the anodized specimens depend on the behavior of the substrate. Increasing Al and Ca content in the alloys tended to increase the corrosion resistance of the specimens. The corrosion resistance of the anodized specimens improved significantly about two orders of magnitude relative to the bare substrate.

  13. ANODE CATALYST MATERIALS FOR USE IN FUEL CELLS

    DEFF Research Database (Denmark)

    2002-01-01

    Catalyst materials having a surface comprising a composition M¿x?/Pt¿3?/Sub; wherein M is selected from the group of elements Fe, Co, Rh and Ir; or wherein M represent two different elements selected from the group comprising Fe, CO, Rh, Ir, Ni, Pd, CU, Ag, Au and Sn; and wherein Sub represents a...... substrate material selected from Ru and Os; the respective components being present within specific ranges, display improved properties for use inanodes for low-temperature fuel cell anodes for PENFC fuel cells and direct methanol fuel cells....

  14. Impact of anode catalyst layer porosity on the performance of a direct formic acid fuel cell

    International Nuclear Information System (INIS)

    Highlights: ► Lithium carbonate is used as a pore-former to increase porosity of anode catalyst layer. ► Maximum power density increased by 25%. ► Onset potential for formic acid electro-oxidation reduced by 30 mV for anode catalyst layer with 17.5 wt% pore-former. ► Electrochemical impedance spectra confirm increased formic acid concentration inside the anode catalyst layer pores. - Abstract: Direct formic acid fuel cells (DFAFCs) have attracted much attention in the last few years for portable electronic devices, due to their potential of being high efficiency power sources. They have the potential to replace the state-of-the-art batteries in cell phones, PDAs, and laptop computers if their power density and durability can be improved. In the present investigation, the influence of increased anode catalyst layer porosity on DFAFC power density performance is studied. Lithium carbonate (Li2CO3) was used as a pore-former in this study because of its facile and complete removal after catalyst layer fabrication. The anode catalyst layers presented herein contained unsupported Pt/Ru catalyst and Li2CO3 (in the range of 0–50 wt%) bound with proton conducting ionomer. Higher DFAFC performance is obtained because of the increased porosity within the anode catalyst layer through enhanced reactant and product mass transport. The maximum power density of DFAFC increased by 25% when pore-former was added to the anode catalyst ink. The formic acid onset potential for the anode catalyst layer with 17.5 wt% pore-former was reduced by 30 mV. A constant phase element based equivalent-circuit model was used to investigate anode impedance spectra. Fitted values for the anode impedance spectra confirm the improvement in performance due to an increase in formic acid concentration inside the anode catalyst layer pores along with efficient transport of reactants and products.

  15. Highly efficient anode catalyst with a Ni@PdPt core–shell nanostructure for methanol electrooxidation in alkaline media

    Institute of Scientific and Technical Information of China (English)

    Pei-shu Yu; Chun-tao Liu; Bo Feng; Jia-feng Wan; Li Li; Chun-yu Du

    2015-01-01

    To enhance the electrocatalytic activity of anode catalysts used in alkaline-media direct methanol fuel cells (DMFCs), a Ni@PdPt electrocatalyst was successfully prepared using a three-phase-transfer method. The Ni@PdPt electrocatalyst was characterized by X-ray dif-fraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM) techniques. The experimental results indicate that the average particle size of the core–shell-structured Ni@PdPt electrocatalyst is approxi-mately 5.6 nm. The Ni@PdPt electrocatalyst exhibits a catalytic activity 3.36 times greater than that of PdPt alloys for methanol oxidation in alkaline media. The developed Ni@PdPt electrocatalyst offers a promising alternative as a highly electrocatalytically active anode catalyst for alkaline DMFCs.

  16. Solid solution lithium alloy cermet anodes

    Science.gov (United States)

    Richardson, Thomas J.

    2013-07-09

    A metal-ceramic composite ("cermet") has been produced by a chemical reaction between a lithium compound and another metal. The cermet has advantageous physical properties, high surface area relative to lithium metal or its alloys, and is easily formed into a desired shape. An example is the formation of a lithium-magnesium nitride cermet by reaction of lithium nitride with magnesium. The reaction results in magnesium nitride grains coated with a layer of lithium. The nitride is inert when used in a battery. It supports the metal in a high surface area form, while stabilizing the electrode with respect to dendrite formation. By using an excess of magnesium metal in the reaction process, a cermet of magnesium nitride is produced, coated with a lithium-magnesium alloy of any desired composition. This alloy inhibits dendrite formation by causing lithium deposited on its surface to diffuse under a chemical potential into the bulk of the alloy.

  17. Anodic behavior of alloy 22 in bicarbonate containing media: Effect of alloying

    International Nuclear Information System (INIS)

    Alloy 22 is one of the candidates for the manufacture of high level nuclear waste containers. These containers provide services in natural environments characterized by multi-ionic solutions.It is estimated they could suffer three types of deterioration: general corrosion, localized corrosion (specifically crevice corrosion) and stress corrosion cracking (SCC). It has been confirmed that the presence of bicarbonate and chloride ions is necessary to produce cracking, . It has also been determined that the susceptibility to SCC could be related to the occurrence of an anodic peak in the polarization curves in these media at potentials below transpassivity. The aim of this work is to study the effect of alloying elements on the anodic behavior of Alloy 22 in media containing bicarbonate and chloride ions at different concentrations and temperatures. Polarization curves were made on alloy 22 (Ni-22% Cr-13% Mo), Ni-Mo (Ni-28, 5% Mo) and Ni-Cr (Ni-20% Cr) in the following solutions: 1 mol/L NaCl at 90oC, and 1.148 mol/L NaHCO3; 1.148 mol/L NaHCO3 + 1 mol/L NaCl; 1.148 mol/L NaHCO3 + 0.1 mol/L NaCl, at 90oC, 75oC, 60oC and 25oC. It was found that alloy 22 has a anodic current density peak at potentials below transpassivity, only in the presence of bicarbonate ions. Curves performed in 1 mol/L NaCl did not show any anodic peak, in any of the tested alloys. The curves made on alloys Ni-Mo and Ni-Cr in the presence of bicarbonate ions, allowed to determine that Cr, is responsible for the appearance of the anodic peak in alloy 22. The curves of alloy Ni-Mo showed no anodic peak in the studied conditions. The potential at which the anodic peak appears in alloy 22 and Ni-Cr alloy, increases with decreasing temperature. The anodic peak was also affected by solution composition. When chloride ion is added to bicarbonate solutions, the anodic peak is shifted to higher potential and current densities, depending on the concentration of added chloride ions (author)

  18. Effects of sodium tartrate anodizing on fatigue life of TA15 titanium alloy

    Directory of Open Access Journals (Sweden)

    Fu Chunjuan

    2015-08-01

    Full Text Available Anodizing is always used as an effective surface modification method to improve the corrosion resistance and wear resistance of titanium alloy. The sodium tartrate anodizing is a new kind of environmental anodizing method. In this work, the effects of sodium tartrate anodizing on mechanical property were studied. The oxide film was performed on the TA15 titanium alloy using sodium tartrate as the film former. The effects of this anodizing and the traditional acid anodizing on the fatigue life of TA15 alloy were compared. The results show that the sodium tartrate anodizing just caused a slight increase of hydrogen content in the alloy, and had a slight effect on the fatigue life. While, the traditional acid anodizing caused a significant increase of hydrogen content in the substrate and reduced the fatigue life of the alloy significantly.

  19. Anodic behavior of nickel alloys in media containing bicarbonate ions

    International Nuclear Information System (INIS)

    Alloy 22 has been designed to resist corrosion in oxidizing and reducing conditions. Thanks to these properties it is considered a possible candidate for the fabrication of containers of high-level radioactive waste. Since the containers provide services in natural environments characterized by multi-ionic solutions, it is estimated they could suffer three types of deterioration: general corrosion, localized corrosion (specifically crevice corrosion) and stress corrosion cracking (SCC). It has been confirmed that the presence of bicarbonate and chloride ions is required in order to produce cracking. It has also been determined that the susceptibility to SCC could be related to the occurrence of an anodic peak in the polarization curves in these media potentials below trans-passivity. The aim of this work is to study the anodic behavior of Alloy 22 in different media containing bicarbonate and chloride ions in various concentrations and temperatures and compare the results with other alloys containing nickel, and relate them to the susceptibility to stress corrosion cracking in a future job. Polarization curves were made on alloy 22 (Ni-Cr-Mo), 600 (Ni- Cr-Fe), 800h (Ni-Fe- Cr) and 201 (Ni commercially pure) in the following environments: 1.148 mol/L NaHCO3, 1.148 mol/L NaHCO3 + 1 mol/L NaCl, 1.148 mol/L NaHCO3 + 0.1 mol/L NaCl. The tests were performed at the following temperatures: 90°C, 75°C, 60°C and 25°C. It was found that alloy 22 has a current peak in the anodic domain at potentials below trans-passivity between 200 and 300 m VECS, when the test temperature was 90°C. The potential, at which this peak occurred, increased with decreasing temperature. Also there was a variation of the peak with the composition of the solution. When bicarbonate ions were added to a solution containing chloride ions, the peak potential shifted to higher current densities, depending on the concentration of added chloride ions. It was found that diminishing the content of

  20. Mixed phase Pt-Ru catalyst for direct methanol fuel cell anode by flame aerosol synthesis

    DEFF Research Database (Denmark)

    Chakraborty, Debasish; Bischoff, H.; Chorkendorff, Ib;

    2005-01-01

    A spray-flame aerosol catalyzation technique was studied for producing Pt-Ru anode electrodes for the direct methanol fuel cell. Catalysts were produced as aerosol nanoparticles in a spray-flame reactor and deposited directly as a thin layer on the gas diffusion layer. The as-prepared catalyst was......Ru1/Vulcan carbon. The kinetics of methanol oxidation on the mixed phase catalyst was also explored by electrochemical impedance spectroscopy. (c) 2005 The Electrochemical Society....

  1. Anode properties of Zn 5 Al alloy alloyed by scandium, yttrium and erbium in NaCl medium

    International Nuclear Information System (INIS)

    Present work is devoted to anode properties of Zn 5 Al alloy alloyed by scandium, yttrium and erbium in NaCl medium. The results of studies of influence of scandium, yttrium and erbium additives on anode properties of zink-aluminium alloy Zn 5 Al intended as anode cover for corrosion protection of steel constructions are considered. The dependence of corrosion rate of zink-aluminium alloy Zn 5 Al on rare-earth metals content in NaCl medium is studied.

  2. Platinum-ruthenium-palladium alloys for use as a fuel cell catalyst

    Science.gov (United States)

    Gorer, Alexander

    2002-01-01

    A noble metal alloy composition for a fuel cell catalyst, a ternary alloy composition containing platinum, ruthenium and palladium. The alloy shows increased activity as compared to well-known catalysts.

  3. Influence of Metal Sulfides as Anode Catalysts on Performance of H2S SOFC

    Institute of Scientific and Technical Information of China (English)

    钟理; 刘曼; 韩国林; CHUANGKar

    2003-01-01

    Two anode catalysts with Pt, MoS2 and composite metal sulfides (MoS2+NiS), are investigated for electrochemical oxidation of hydrogen sulfide in solid oxide fuel cell (SOFC) at temperatures 750-850℃. The catalysts comprising MoS2 and MoS2+NiS exhibited good electrical conductivity and catalytic activity. MoS2 and composite catalysts were found to be more active than Pt, a widely used catalyst for high temperature H2S/O2 fuel cell at 750-850℃. However, MoS2 itself sublimes above 450℃. In contrast, composite catalysts containing both Mo and transition metal (Ni) are shown to be stable and effective in promoting the oxidation of H2S in SOFC up to 850℃. However, electric contact is poor between the platinum current collecting layer and the composite metal sulfide layer, so that the cell performance becomes worse. This problem is overcome by adding conductive Ag powder into the anode layer (forming MoS2+NiS+Ag anode material) to increase anode electrical conductance instead of applying a thin laver of platinum on the top of anode.

  4. The corrosion protection of several aluminum alloys by chromic acid and sulfuric acid anodizing

    Science.gov (United States)

    Danford, M. D.

    1994-01-01

    The corrosion protection afforded 7075-T6, 7075-T3, 6061-T6, and 2024-T3 aluminum alloys by chromic acid and sulfuric acid anodizing was examined using electrochemical techniques. From these studies, it is concluded that sulfuric acid anodizing provides superior corrosion protection compared to chromic acid anodizing.

  5. Band gap structure modification of amorphous anodic Al oxide film by Ti-alloying

    DEFF Research Database (Denmark)

    Canulescu, Stela; Rechendorff, K.; Borca, C. N.;

    2014-01-01

    The band structure of pure and Ti-alloyed anodic aluminum oxide has been examined as a function of Ti concentration varying from 2 to 20 at. %. The band gap energy of Ti-alloyed anodic Al oxide decreases with increasing Ti concentration. X-ray absorption spectroscopy reveals that Ti atoms are not...

  6. Palladium and Tin Alloyed Catalysts for the Ethanol Oxidation Reaction in an Alkaline Medium

    Energy Technology Data Exchange (ETDEWEB)

    Su D.; Du W.; Mackenzie K.E.; Milano D.F.; Deskins N.A.; Teng X.

    2012-02-01

    In this paper, we present a study of a series of carbon-supported Pd-Sn binary alloyed catalysts prepared through a modified Polyol method as anode electrocatalysts for direct ethanol fuel cell reactions in an alkaline medium. Transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and aberration-corrected scanning transmission electron microscopy equipped with electron energy loss spectroscopy were used to characterize the Pd-Sn/C catalysts, where homogeneous Pd-Sn alloys were determined to be present with the surface Sn being partially oxidized. Among various Pd-Sn catalysts, Pd{sub 86}Sn{sub 14}/C catalysts showed much enhanced current densities in cyclic voltammetric and chronoamperometric measurements, compared to commercial Pd/C (Johnson Matthey). The overall rate law of ethanol oxidation reaction for both Pd{sub 86}Sn{sub 14}/C and commercial Pd/C were also determined, which clearly showed that Pd{sub 86}Sn{sub 14}/C was more favorable in high ethanol concentration and/or high pH environment. Density functional theory calculations also confirmed Pd-Sn alloy structures would result in lower reaction energies for the dehydrogenation of ethanol, compared to the pure Pd crystal.

  7. Anode properties of alloy Zn 55 Al alloyed by calcium in the medium of NaCl

    International Nuclear Information System (INIS)

    The results of studies of influence of calcium additives on anode properties of zinc-aluminium alloy Zn 55 Al are given. Chemical composition and results of studies of corrosion-electrochemical properties of Zn 55 Al alloy alloyed by calcium are considered.

  8. Electrodeposited NiCu Alloy Catalysts for Glucose Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jieun; Park, Hansoo; Kim, Sookil [Chung-Ang Univ., Seoul (Korea, Republic of); Ahn, Sang Hyun; Jang, Jong Hyun [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2014-07-15

    NiCu alloys have been suggested as potential candidates for catalysts in glucose oxidation. In this study, NiCu alloys with different compositions were prepared on a glassy carbon substrate by changing the electrodeposition potential to examine the effect of Ni/Cu ratios in alloys on catalytic activity toward glucose oxidation. Cyclic voltammetry and chronoamperometry showed that NiCu alloys had higher catalytic activity than pure Ni and Cu catalysts. Especially, Ni{sub 59}Cu{sub 41} had superior catalytic activity, which was about twice that of Ni at a given oxidation potential. X-ray analyses showed that the oxidation state of Ni in NiCu alloys was increased with the content of Cu by lattice expansion. Ni components in alloys with higher oxidation state were more effective in the oxidation of glucose.

  9. Electrodeposited NiCu Alloy Catalysts for Glucose Oxidation

    International Nuclear Information System (INIS)

    NiCu alloys have been suggested as potential candidates for catalysts in glucose oxidation. In this study, NiCu alloys with different compositions were prepared on a glassy carbon substrate by changing the electrodeposition potential to examine the effect of Ni/Cu ratios in alloys on catalytic activity toward glucose oxidation. Cyclic voltammetry and chronoamperometry showed that NiCu alloys had higher catalytic activity than pure Ni and Cu catalysts. Especially, Ni59Cu41 had superior catalytic activity, which was about twice that of Ni at a given oxidation potential. X-ray analyses showed that the oxidation state of Ni in NiCu alloys was increased with the content of Cu by lattice expansion. Ni components in alloys with higher oxidation state were more effective in the oxidation of glucose

  10. An anodic alumina supported Ni-Pt bimetallic plate-type catalysts for multi-reforming of methane, kerosene and ethanol

    KAUST Repository

    Zhou, Lu

    2014-05-01

    An anodic alumina supported Ni-Pt bimetallic plate-type catalyst was prepared by a two-step impregnation method. The trace amount 0.08 wt% of Pt doping efficiently suppressed the nickel particle sintering and improved the nickel oxides reducibility. The prepared Ni-Pt catalyst showed excellent performance during steam reforming of methane, kerosene and ethanol under both 3000 h stationary and 500-time daily start-up and shut-down operation modes. Self-activation ability of this catalyst was evidenced, which was considered to be resulted from the hydrogen spillover effect over Ni-Pt alloy. In addition, an integrated combustion-reforming reactor was proposed in this study. However, the sintering of the alumina support is still a critical issue for the industrialization of Ni-Pt catalyst. Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  11. Anodic dissolution and corrosion of Cu30Ni alloys in chloride solutions

    International Nuclear Information System (INIS)

    Anodic and corrosion behaviour of Cu30Ni alloy in 3n. NaCl+0.01n. HCl solution is studied by radiometric method using 58Co gamma-isotopes (as an alien label for nickel) and 64Cu ones in combination with electrochemical measurements. It is ascertained that under stationary conditions both in the process of anodic dissolution and corrosion the alloy dissolves gradually. Partial anodic polarization dissolution curves of the alloy components are obtained. It is shown that kinetics of their dissolution differs from dissolution regularities of the corresponding pure metals. During the alloy corrosion in oxygen atmoshere the reverse precipitation of copper on the alloy surface is absent. The mentioned peculiarities in corrosion-electrochemical behaviour of the alloy in a concentrated chloride solution are explained by the presence of nickel on the surface of the dissolving alloy

  12. Microscopic observation of pattern attack by aggressive ions on finished surface of aluminium alloy sacrificial anode

    International Nuclear Information System (INIS)

    This paper presents the results of a microscopic observation on submerged finished surface of aluminium alloy sacrificial anode. Experimental tests were carried out on polished surface aluminium anode exposed to seawater containing aggressive ions in order to observe of pattern corrosion attack on corroding surface of anode. Results have shown, at least under the present testing condition, that surface of sacrificial anode were attack by an aggressive ion such as chloride along grain boundaries. In addition, results of microanalysis showed that the corrosion products on surface of aluminium alloy have Al, Zn and O element for all sample and within the pit was consists of Al, Zn, O and Cl element. (author)

  13. Surface nanotopography of an anodized Ti–6Al–7Nb alloy enhances cell growth

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Her-Hsiung [Department of Dentistry, National Yang-Ming University, Taipei 112, Taiwan (China); Graduate Institute of Basic Medical Science, China Medical University, Taichung 404, Taiwan (China); Department of Biomedical Informatics, Asia University, Taichung 413, Taiwan (China); Department of Stomatology, Taipei Veterans General Hospital, Taipei 112, Taiwan (China); Wu, Chia-Ping [Institute of Oral Biology, National Yang-Ming University, Taipei 112, Taiwan (China); Sun, Ying-Sui [Department of Dentistry, National Yang-Ming University, Taipei 112, Taiwan (China); Yang, Wei-En [Institute of Oral Biology, National Yang-Ming University, Taipei 112, Taiwan (China); Lee, Tzu-Hsin, E-mail: biomaterials@hotmail.com [School of Dentistry, Chung Shan Medical University, Taichung 402, Taiwan (China); Oral Medicine Center, Chung Shan Medical University Hospital, Taichung 402, Taiwan (China)

    2014-12-05

    Highlights: • An electrochemical anodization was applied to α/β-type Ti–6Al–7Nb alloy surface. • Anodized surface had a nontoxic nanoporous topography. • Anodized surface increased proteins adsorption due to nanotopography. • Anodized surface enhanced cell growth due to nanotopography. • Electrochemical anodization has potential as implant surface treatment. - Abstract: The α/β-type Ti–6Al–7Nb alloy is a potential replacement for α/β-type Ti–6Al–4V alloy, which is widely used in biomedical implant applications. The biological response to implant material is dependent on the surface characteristics of the material. In the present study, a simple and fast process was developed to perform an electrochemical anodization treatment on Ti–6Al–7Nb alloy. The proposed process yielded a thin surface nanotopography, which enhanced cell growth on the Ti–6Al–7Nb alloy. The surface characteristics, including the morphology, wettability, and protein adsorption, were investigated, and the cytotoxicity was evaluated according to International Organization for Standardization 10993-5 specifications. Cell adhesion of human bone marrow mesenchymal stem cells on the test specimens was observed via fluorescence microscopy and scanning electron microscopy. The anodization process produced a surface nanotopography (pore size <100 nm) on anodized Ti–6Al–7Nb alloy, which enhanced the wettability, protein adsorption, cell adhesion, cell migration, and cell mineralization. The results showed that the surface nanotopography produced using the proposed electrochemical anodization process enhanced cell growth on anodized Ti–6Al–7Nb alloy for implant applications.

  14. Surface nanotopography of an anodized Ti–6Al–7Nb alloy enhances cell growth

    International Nuclear Information System (INIS)

    Highlights: • An electrochemical anodization was applied to α/β-type Ti–6Al–7Nb alloy surface. • Anodized surface had a nontoxic nanoporous topography. • Anodized surface increased proteins adsorption due to nanotopography. • Anodized surface enhanced cell growth due to nanotopography. • Electrochemical anodization has potential as implant surface treatment. - Abstract: The α/β-type Ti–6Al–7Nb alloy is a potential replacement for α/β-type Ti–6Al–4V alloy, which is widely used in biomedical implant applications. The biological response to implant material is dependent on the surface characteristics of the material. In the present study, a simple and fast process was developed to perform an electrochemical anodization treatment on Ti–6Al–7Nb alloy. The proposed process yielded a thin surface nanotopography, which enhanced cell growth on the Ti–6Al–7Nb alloy. The surface characteristics, including the morphology, wettability, and protein adsorption, were investigated, and the cytotoxicity was evaluated according to International Organization for Standardization 10993-5 specifications. Cell adhesion of human bone marrow mesenchymal stem cells on the test specimens was observed via fluorescence microscopy and scanning electron microscopy. The anodization process produced a surface nanotopography (pore size <100 nm) on anodized Ti–6Al–7Nb alloy, which enhanced the wettability, protein adsorption, cell adhesion, cell migration, and cell mineralization. The results showed that the surface nanotopography produced using the proposed electrochemical anodization process enhanced cell growth on anodized Ti–6Al–7Nb alloy for implant applications

  15. Modelling of binary alloy (Al–Mg) anode evaporation in arc welding

    International Nuclear Information System (INIS)

    A simple analytical model of binary alloy anode evaporation in gas–tungsten arc and gas–metal arc welding is proposed. The model comprises the model of evaporation in convective and diffusive regimes, model of anode processes and allows one to calculate basic physical properties of multicomponent arc plasma near the anode surface as functions of the anode surface temperature, anode chemical composition, electron temperature and electric current density at the anode surface. Evaporation of binary Al–Mg alloys with different magnesium mass fraction into argon plasma is considered on the basis of the proposed model. The dependences of the alloy boiling temperature on the magnesium mass fraction and electron temperature are presented. Several physical parameters, which are important from the technological point of view (magnesium mass flux, heat loss due to evaporation, anode potential drop, anode heat flux), are calculated for a wide range of anode surface temperature and different values of the magnesium mass fraction. In addition, the influence of heat loss due to evaporation on the total heat flux coming to the anode surface is demonstrated. (paper)

  16. Transient behavior of CO poisoning of the anode catalyst layer of a PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Chu, H.S.; Wang, C.P.; Liao, W.C. [Department of Mechanical Engineering, National Chiao Tung University, Hsinchu, Taiwan 300 (ROC); Yan, W.M. [Department of Mechatronic Engineering, Huafan University, Shih Ting, Taipei, Taiwan 223 (ROC)

    2006-09-22

    A one-dimensional transient mathematical model is applied to simulate the carbon monoxide poisoning effect on the performance of a PEM fuel cell. Based on the CO kinetic model developed by Springer et al. [T.E. Springer, T. Rockward, T.A. Zawodzinski, S. Gottesfeld, J. Electrochem. Soc. 148 (2001) A11-A23], the transient behaviors of the CO poisoning process across the anode catalyst layer is investigated. The results show that the hydrogen coverage, {theta}{sub H}, decreases with the time due to CO adsorption on the catalyst sites. A higher CO concentration results in fewer available catalyst sites for hydrogen electro-oxidation and a significant decrease in the response time to reach steady state, t{sub ss}. Increasing the anode overpotential and the gas porosity would result in an increase in the current density, especially at low levels of CO concentration. (author)

  17. Properties of thin anodic oxide films on zirconium alloys

    International Nuclear Information System (INIS)

    Thin (0.1-0.2 μm) anodic oxide films were formed on zirconium, Zircaloy-2 and Zr-2.5 wt% Nb alloy specimens and examined by AC impedance spectroscopy (using both metal and aqueous electrolyte contacts), UV/VIS interferometry, and scanning electron microscopy (SEM). The SEM studies showed that the extent of oxide cracking was a function of the particular alloy and the electrolyte in which the oxide was formed. AC impedance spectroscopy showed that with metallic contacts a Young impedance behaviour was observed as a result of local conduction paths in the oxide film, probably resulting from second phase particles. The extent of cracking in the oxide was identified best from SEM and AC impedance measurements in aqueous electrolytes, and did not appear to contribute to the results obtained with metallic contacts. Large discrepancies between the apparent oxide thicknesses measured from AC impedance data obtained from measurements with aqueous electrolyte and liquid metal contacts, respectively, were shown to result from surface roughness and inadequate wetting by the liquid metals. These discrepancies could be eliminated by using evaporated platinum contacts, which also showed evidence for local conduction in the oxides. UV/VIS interferometry results for the oxide refractive indices and oxide thicknesses gave much scatter because of the small number of fringes available for the analysis and the difficulties in establishing the positions of interference minima with the same accuracy as was possible for interference maxima. The use of this combination of techniques still appears to be the best method for investigating the presence of conducting paths in thick porous oxide films on these alloys. Preference should be given to using evaporated rather than liquid metal contacts when studying such oxides. The advantages of easy removal for the liquid metal contacts often, however, outweigh the errors introduced by surface roughness when using them for repetitive measurements

  18. Ruthenium behaviour during anodic dissolution of ruthenium alloys with nickel in sulfuric acid solutions

    International Nuclear Information System (INIS)

    Investigated are the forms of being of ruthenium in sulfuric acid electrolytes and ruthenium distribution between the solution and slime after anodic dissolution of the nickel-ruthenium alloys (1.5 and 10 mass.% Ru) at 65+-1 deg in the conditions imitating processes of secondary electrolysis. The oxidation state and the forms of being of ruthenium in anolytes were established by the spectrophotometric method. The anodic polarization curves of the Ni-Ru alloy are presented. It is shown that in the process under investigation ruthenium in anolytes is in the oxidation degree (4) in the form of a mixture of labile anionic and neutral oxoaquohydroxosulfate complexes independing of the alloy content, anodic potential and type of an electrolytic cell. Slime formed in the process of electrolysis is a fine dispersed product, consisting of amorphous metallic Ru and its oxides. The Ru transition into anolyte is determined by the value of anodic potential and Ru content in the alloy

  19. Lithium alloys and metal oxides as high-capacity anode materials for lithium-ion batteries

    International Nuclear Information System (INIS)

    Highlights: •Progress in lithium alloys and metal oxides as anode materials for lithium-ion batteries is reviewed. •Electrochemical characteristics and lithium storage mechanisms of lithium alloys and metal oxides are summarized. •Strategies for improving electrochemical lithium storage properties of lithium alloys and metal oxides are discussed. •Challenges in developing lithium alloys and metal oxides as commercial anodes for lithium-ion batteries are pointed out. -- Abstract: Lithium alloys and metal oxides have been widely recognized as the next-generation anode materials for lithium-ion batteries with high energy density and high power density. A variety of lithium alloys and metal oxides have been explored as alternatives to the commercial carbonaceous anodes. The electrochemical characteristics of silicon, tin, tin oxide, iron oxides, cobalt oxides, copper oxides, and so on are systematically summarized. In this review, it is not the scope to retrace the overall studies, but rather to highlight the electrochemical performances, the lithium storage mechanism and the strategies in improving the electrochemical properties of lithium alloys and metal oxides. The challenges and new directions in developing lithium alloys and metal oxides as commercial anodes for the next-generation lithium-ion batteries are also discussed

  20. The Electrical and Mechanical Properties of Porous Anodic 6061-T6 Aluminum Alloy Oxide Film

    OpenAIRE

    Tsung-Chieh Cheng; Chu-Chiang Chou

    2015-01-01

    The properties of the growth of the 6061-T6 aluminum alloy oxide were studied using sulfuric acid anodization. The parameters for the manufacturing process include electrolyte categories, electrolyte concentration, and operating voltages. The results showed that the aluminum oxides obtained by anodization process are mainly amorphous structure and the anodic current density is an important factor affecting the rate of response for oxygen and aluminum ions in barrier. In this experiment, polis...

  1. Design of a surface alloy catalyst for steam reforming

    DEFF Research Database (Denmark)

    Besenbacher, F.; Chorkendorff, Ib; Clausen, B.S.;

    1998-01-01

    Detailed studies of elementary chemical processes on well-characterized single crystal surfaces have contributed substantially to the understanding of heterogeneous catalysis. insight into the structure of surface alloys combined with an understanding of the relation between the surface composition...... and reactivity is shown to lead directly to new ideas for catalyst design, The feasibility of such an approach is illustrated by the synthesis, characterization, and tests of a high-surface area gold-nickel catalyst for steam reforming....

  2. Ultrasmall PdmMn1-mOx binary alloyed nanoparticles on graphene catalysts for ethanol oxidation in alkaline media

    Science.gov (United States)

    Ahmed, Mohammad Shamsuddin; Park, Dongchul; Jeon, Seungwon

    2016-03-01

    A rare combination of graphene (G)-supported palladium and manganese in mixed-oxides binary alloyed catalysts (BACs) have been synthesized with the addition of Pd and Mn metals in various ratios (G/PdmMn1-mOx) through a facile wet-chemical method and employed as an efficient anode catalyst for ethanol oxidation reaction (EOR) in alkaline fuel cells. The as prepared G/PdmMn1-mOx BACs have been characterized by several instrumental techniques; the transmission electron microscopy images show that the ultrafine alloyed nanoparticles (NPs) are excellently monodispersed onto the G. The Pd and Mn in G/PdmMn1-mOx BACs have been alloyed homogeneously, and Mn presents in mixed-oxidized form that resulted by X-ray diffraction. The electrochemical performances, kinetics and stability of these catalysts toward EOR have been evaluated using cyclic voltammetry in 1 M KOH electrolyte. Among all G/PdmMn1-mOx BACs, the G/Pd0.5Mn0.5Ox catalyst has shown much superior mass activity and incredible stability than that of pure Pd catalysts (G/Pd1Mn0Ox, Pd/C and Pt/C). The well dispersion, ultrafine size of NPs and higher degree of alloying are the key factor for enhanced and stable EOR electrocatalysis on G/Pd0.5Mn0.5Ox.

  3. Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

    Science.gov (United States)

    Li, Song-mei; Li, Ying-dong; Zhang, You; Liu, Jian-hua; Yu, Mei

    2015-02-01

    Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered intermetallic particles were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after pretreatment. The anodic film was investigated by transmission electron microscopy (TEM), and its corrosion resistance was analyzed by electrochemical impedance spectroscopy (EIS) and Tafel polarization in NaCl solution. The results show that the size of Al-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the anodic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

  4. SURFACE CHARACTERIZATION OF ANODICALLY TREATED β TITANIUM ALLOY FOR BIOMEDICAL APPLICATIONS

    OpenAIRE

    Bhola, R.; Bhola, S.; Mishra, B.; Ayers, R.; Olson, D; Ohno, T

    2011-01-01

    The cellular response of anodically treated titanium alloys was investigated using cell attachment, morphological and surface analytical techniques. The behavior of a β Ti15Mo alloy has been compared with the conventional mixed alloy, Ti6Al4V and the a alloy, Ti2. Ti15Mo β alloy demonstrated a higher cell count and a thicker oxide on its surface. The presence of Ca and P was detected in all the alloys after the invitro cell culture test. TiO 2 was present as the dominant oxide in all three al...

  5. The Microstructure and Capacitance Characterizations of Anodic Titanium Based Alloy Oxide Nanotube

    OpenAIRE

    Po Chun Chen; Sheng Jen Hsieh; Chien Chon Chen; Jun Zou

    2013-01-01

    This paper presents a simple anodization process to fabricate ordered nanotubes (NTs) of titanium and its alloys (Ti-Mo and Ti-Ta). TiO2, MoO3, and Ta2O5 are high dielectric constant materials for ultracapacitor application. The anodic titanium oxide contains a compact layer on the NT film and a barrier layer under the NT film. However, the microstructure of oxide films formed by anodic Ti-Mo and Ti-Ta alloys contains six layers, including a continuous compact layer, a continuous partial poro...

  6. Characterization and Tribological Properties of Hard Anodized and Micro Arc Oxidized 5754 Quality Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    M. Ovundur

    2015-03-01

    Full Text Available This study was initiated to compare the tribological performances of a 5754 quality aluminum alloy after hard anodic oxidation and micro arc oxidation processes. The structural analyses of the coatings were performed using XRD and SEM techniques. The hardness of the coatings was determined using a Vickers micro-indentation tester. Tribological performances of the hard anodized and micro arc oxidized samples were compared on a reciprocating wear tester under dry sliding conditions. The dry sliding wear tests showed that the wear resistance of the oxide coating generated by micro arc oxidation is remarkably higher than that of the hard anodized alloy.

  7. Corrosion resistance of plasma-anodized AZ91D magnesium alloy by electrochemical methods

    Energy Technology Data Exchange (ETDEWEB)

    Barchiche, C.-E. [Nancy Universite, Universite Henri Poincare, Laboratoire de Chimie du Solide Mineral, UMR CNRS 7555, BP 239, Vandoeuvre-Les-Nancy 54506 (France); Rocca, E. [Nancy Universite, Universite Henri Poincare, Laboratoire de Chimie du Solide Mineral, UMR CNRS 7555, BP 239, Vandoeuvre-Les-Nancy 54506 (France)], E-mail: emmanuel.rocca@lcsm.uhp-nancy.fr; Juers, C.; Hazan, J.; Steinmetz, J. [Nancy Universite, Universite Henri Poincare, Laboratoire de Chimie du Solide Mineral, UMR CNRS 7555, BP 239, Vandoeuvre-Les-Nancy 54506 (France)

    2007-12-01

    Anodic coatings formed on magnesium alloys by plasma anodization process are mainly used as protective coatings against corrosion. The effects of KOH concentration, anodization time and current density on properties of anodic layers formed on AZ91D magnesium alloy were investigated to obtain coatings with improved corrosion behaviour. The coatings were characterized by scanning electron microscopy (SEM), electron dispersion X-ray spectroscopy (EDX), X-ray diffraction (XRD) and micro-Raman spectroscopy. The film is porous and cracked, mainly composed of magnesium oxide (MgO), but contains all the elements present in the electrolyte and alloy. The corrosion behaviour of anodized Mg alloy was examined by using stationary and dynamic electrochemical techniques in corrosive water. The best corrosion resistance measured by electrochemical methods is obtained in the more concentrated electrolyte 3 M KOH + 0.5 M KF + 0.25 M Na{sub 3}PO{sub 4}.12 H{sub 2}O, with a long anodization time and a low current density. A double electrochemical effects of the anodized layer on the magnesium corrosion is observed: a large inhibition of the cathodic process and a stabilization of a large passivation plateau.

  8. Corrosion resistance of plasma-anodized AZ91D magnesium alloy by electrochemical methods

    International Nuclear Information System (INIS)

    Anodic coatings formed on magnesium alloys by plasma anodization process are mainly used as protective coatings against corrosion. The effects of KOH concentration, anodization time and current density on properties of anodic layers formed on AZ91D magnesium alloy were investigated to obtain coatings with improved corrosion behaviour. The coatings were characterized by scanning electron microscopy (SEM), electron dispersion X-ray spectroscopy (EDX), X-ray diffraction (XRD) and micro-Raman spectroscopy. The film is porous and cracked, mainly composed of magnesium oxide (MgO), but contains all the elements present in the electrolyte and alloy. The corrosion behaviour of anodized Mg alloy was examined by using stationary and dynamic electrochemical techniques in corrosive water. The best corrosion resistance measured by electrochemical methods is obtained in the more concentrated electrolyte 3 M KOH + 0.5 M KF + 0.25 M Na3PO4.12 H2O, with a long anodization time and a low current density. A double electrochemical effects of the anodized layer on the magnesium corrosion is observed: a large inhibition of the cathodic process and a stabilization of a large passivation plateau

  9. Reactivity descriptors for direct methanol fuel cell anode catalysts

    DEFF Research Database (Denmark)

    Ferrin, Peter; Nilekar, Anand Udaykumar; Greeley, Jeff;

    2008-01-01

    We have investigated the anode reaction in direct methanol fuel cells using a database of adsorption free energies for 16 intermediates on 12 close-packed transition metal surfaces calculated with periodic, self-consistent, density functional theory (DFT-GGA). This database, combined with a simple...... electrokinetic model of the methanol electrooxidation reaction, yields mechanistic insights that are consistent with previous experimental and theoretical studies on Pt, and extends these insights to a broad spectrum of other transition metals. In addition, by using linear scaling relations between the...... adsorption free energies of various intermediates in the reaction network, we find that the results determined with the full database of adsorption energies can be estimated by knowing only two key descriptors for each metal surface: the free energies of OH and CO on the surface. Two mechanisms for methanol...

  10. Corrosion resistance of anodized AZ31 Mg alloy in borate solution containing titania sol

    Energy Technology Data Exchange (ETDEWEB)

    Guo Yan; Wang Guixiang [Key Laboratory of Superlight Material and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Dong Guojun [Key Laboratory of Superlight Material and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)], E-mail: dgj1129@163.com; Gong Fan; Zhang Lili; Zhang Milin [Key Laboratory of Superlight Material and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)

    2008-09-08

    Anodic films were prepared on the AZ31 magnesium alloy in alkaline borate solution with or without addition of titania sol under the constant potential of 50 V (dc) for 10 min at room temperature. The morphology of the anodic films was observed by scanning electron microscope (SEM). The corrosion resistance of the anodic films was evaluated in 3.5% NaCl solution using fast anti-acid test, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The anodic film formed in borate solution with addition of 4% titania sol has superior uniform surface and higher corrosion resistance than in other conditions.

  11. Anodization of AZ91 magnesium alloy in alkaline solution containing silicate and corrosion properties of anodized films

    Institute of Scientific and Technical Information of China (English)

    LI Ling-ling; CHENG Ying-liang; WANG Hui-min; ZHANG Zhao

    2008-01-01

    The anodization of AZ91 magnesium alloy in an alkaline electrolyte of 100g/L NaOH+20g/L Na2B4O7·10H2O+50g/L C6H5Na3O7·2H2O+60g/L Na2SiO3·9H2O was studied.The corrosion resistance of the anodized films was studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques.The microstructure of the films was examined with scanning electronic microscope (SEM) and X-ray diffractometer (XRD).The results show that,under the experimental conditions,the optimum anodizing time and the optimum anodizing current density are 40min and 20mA/cm2 respectively for obtaining the anodic film with high corrosion resistance.The XRD pattern shows that the components of the anodized film consist of MgO and Mg2 (SiO4).

  12. Genetic Algorithm Procreation Operators for Alloy Nanoparticle Catalysts

    DEFF Research Database (Denmark)

    Lysgaard, Steen; Landis, David Dominic; Bligaard, Thomas;

    2014-01-01

    The long-term stability of binary nanoparticles and clusters is one of the main challenges in the development of novel (electro-)catalysts for e.g. CO2 reduction. Here, we present a method for predicting the optimal composition and structure of alloy nanoparticles and clusters, with particular...

  13. Manganese Detection with a Metal Catalyst Free Carbon Nanotube Electrode: Anodic versus Cathodic Stripping Voltammetry

    OpenAIRE

    Yue, Wei; Bange, Adam; Riehl, Bill L.; Riehl, Bonnie D.; Johnson, Jay M.; Papautsky, Ian; Heineman, William R.

    2012-01-01

    Anodic stripping voltammetry (ASV) and cathodic stripping voltammetry (CSV) were used to determine Mn concentration using metal catalyst free carbon nanotube (MCFCNT) electrodes and square wave stripping voltammetry (SWSV). The MCFCNTs are synthesized using a Carbo Thermal Carbide Conversion method which results in a material that does not contain residual transition metals. Detection limits of 120 nM and 93 nM were achieved for ASV and CSV, respectively, with a deposition time of 60 s. CSV w...

  14. Application of carbon supported NiMo carburized catalyst to fuel cell anode electrocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Izhar, S.; Otsuka, S.; Nagai, M. [Tokyo Univ. of Agriculture and Technology, Tokyo (Japan). Graduate School of Bio-applications and Systems Engineering

    2008-01-15

    The fabrication of polymer electrolyte fuel cells using platinum (Pt) base catalysts is a challenge due to the high cost of Pt and the potential for carbon monoxide poisoning. Transition metal carbides are highly regarded as a material substitute because of their high conductivity, high activity in hydrogenolysis reactions and high resistance to poisoning of the catalyst. A study was conducted in which nickel (Ni) molybdenum (Mo)/Ketjen carbon (KC) carbides were prepared with various Ni compositions and carburization temperatures. XRD, temperature programmed reduction and the cyclic voltammetric method were used to evaluate these catalysts through comparative evaluations with a Pt/C catalyst. The Ni-Mo/KC catalysts were evaluated for their electrocatalytic activity using a H{sub 2}O{sub 2} single stack cell and a 3-electrode cell in order to identify the active species. Cyclic voltammetry measurements indicated that the Ni-Mo/KC carbide catalysts have a high activity towards the anodic electrooxidation of hydrogen. The activity was attributed to the amorphous Ni-Mo carbide measured by XRD and temperature programmed reduction techniques. It was concluded that bimetallic carbides can reduce the manufacturing cost of fuel cells and are therefore a suitable material for Pt/C catalysts. 17 refs., 3 tabs., 7 figs.

  15. Fabrication of the superhydrophobic surface on aluminum alloy by anodizing and polymeric coating

    Science.gov (United States)

    Liu, Wenyong; Luo, Yuting; Sun, Linyu; Wu, Ruomei; Jiang, Haiyun; Liu, Yuejun

    2013-01-01

    We reported the preparation of the superhydrophobic surface on aluminum alloy via anodizing and polymeric coating. Both the different anodizing processes and different polymeric coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. The results showed that a good superhydrophobic surface was facilely fabricated by polypropylene (PP) coating after anodizing. The optimum conditions for anodizing were determined by orthogonal experiments. When the concentration of oxalic acid was 10 g/L, the concentration of NaCl was 1.25 g/L, anodization time was 40 min, and anodization current was 0.4 A, the best superhydrophobic surface on aluminum alloy with the contact angle (CA) of 162° and the sliding angle of 2° was obtained. On the other hand, the different polymeric coatings, such as polystyrene (PS), polypropylene (PP) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after anodizing. The results showed that the superhydrophobicity was most excellent by coating PP, while the duration of the hydrophobic surface was poor. By modifying the surface with the silane coupling agent before PP coating, the duration of the superhydrophobic surface was improved. The morphologies of the superhydrophobic surface were further confirmed by optical microscope (OM) and scanning electron microscope (SEM). Combined with the material of PP with the low surface free energy, the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.

  16. Furfural Hydrogenation on Alloyed Copper Catalysts With Additives of Ferrosilicium

    Directory of Open Access Journals (Sweden)

    T. K. Akilov

    2015-12-01

    Full Text Available The present work is dedicated to the study of influence of ferrosilicium additives [FA*-ferroalloy containing (% mass: 46.8 Si, ~53,0 Fe, other are (C, P, S impurities] on the activity of alloyed Gu-Al = 50-50 catalyst in the reaction of furfural hydrogenation under hydrogen pressure. Components content varied (% mass: Cu- 40...49, aluminum- 50, FA* -1.0...10.0. The catalysts were prepared from 1g alloys by leaching it with 20% of aqueous solution of caustic soda in boiling water-bath during 1 hour. The phase composition and structure of alloys were investigated by means of roentgenographic and X-ray spectrum methods.

  17. A study of the anodic behaviour of aluminium alloys in alkaline electrolytes

    OpenAIRE

    Walters, B N

    1988-01-01

    Recent studies an the discharge performance of aluminium alloys in alkaline media have led to improved alloys with significantly lower corrosion rates and more anodic potentials. Performance, of various alkaline electrolytes have also been examined and considerable progress has been made in this area. A review of the available literature reveals a list of several elements which are suitable for alloying with aluminium as regards reducing corrosion and overpotential. Previous work at the Chemi...

  18. Fabrication of the superhydrophobic surface on aluminum alloy by anodizing and polymeric coating

    International Nuclear Information System (INIS)

    Graphical abstract: The hydrophobic surface on aluminum alloy fabricated by anodizing and polymeric coating. Highlights: ► Anodizing and polymeric coating were used to prepare a superhydrophobic surface on aluminum alloy. ► Superhydrophobic surfaces with a high water contact angle of 162° and a low rolling angle of 2° were obtained. ► The method is facile, and the materials are inexpensive, and is expected to be used widely. - Abstract: We reported the preparation of the superhydrophobic surface on aluminum alloy via anodizing and polymeric coating. Both the different anodizing processes and different polymeric coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. The results showed that a good superhydrophobic surface was facilely fabricated by polypropylene (PP) coating after anodizing. The optimum conditions for anodizing were determined by orthogonal experiments. When the concentration of oxalic acid was 10 g/L, the concentration of NaCl was 1.25 g/L, anodization time was 40 min, and anodization current was 0.4 A, the best superhydrophobic surface on aluminum alloy with the contact angle (CA) of 162° and the sliding angle of 2° was obtained. On the other hand, the different polymeric coatings, such as polystyrene (PS), polypropylene (PP) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after anodizing. The results showed that the superhydrophobicity was most excellent by coating PP, while the duration of the hydrophobic surface was poor. By modifying the surface with the silane coupling agent before PP coating, the duration of the superhydrophobic surface was improved. The morphologies of the superhydrophobic surface were further confirmed by optical microscope (OM) and scanning electron microscope (SEM). Combined with the material of PP with the low

  19. Fabrication of the superhydrophobic surface on aluminum alloy by anodizing and polymeric coating

    Energy Technology Data Exchange (ETDEWEB)

    Liu Wenyong, E-mail: lwy@iccas.ac.cn [Key Laboratory of Advanced Materials and Technology for Packaging, Hunan University of Technology, Zhuzhou 412007 (China); College of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007 (China); Luo Yuting; Sun Linyu [College of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007 (China); Wu Ruomei, E-mail: cailiaodian2004@126.com [College of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007 (China); Jiang Haiyun [College of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007 (China); Liu Yuejun [Key Laboratory of Advanced Materials and Technology for Packaging, Hunan University of Technology, Zhuzhou 412007 (China); College of Packaging and Materials Engineering, Hunan University of Technology, Zhuzhou 412007 (China)

    2013-01-01

    Graphical abstract: The hydrophobic surface on aluminum alloy fabricated by anodizing and polymeric coating. Highlights: Black-Right-Pointing-Pointer Anodizing and polymeric coating were used to prepare a superhydrophobic surface on aluminum alloy. Black-Right-Pointing-Pointer Superhydrophobic surfaces with a high water contact angle of 162 Degree-Sign and a low rolling angle of 2 Degree-Sign were obtained. Black-Right-Pointing-Pointer The method is facile, and the materials are inexpensive, and is expected to be used widely. - Abstract: We reported the preparation of the superhydrophobic surface on aluminum alloy via anodizing and polymeric coating. Both the different anodizing processes and different polymeric coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. The results showed that a good superhydrophobic surface was facilely fabricated by polypropylene (PP) coating after anodizing. The optimum conditions for anodizing were determined by orthogonal experiments. When the concentration of oxalic acid was 10 g/L, the concentration of NaCl was 1.25 g/L, anodization time was 40 min, and anodization current was 0.4 A, the best superhydrophobic surface on aluminum alloy with the contact angle (CA) of 162 Degree-Sign and the sliding angle of 2 Degree-Sign was obtained. On the other hand, the different polymeric coatings, such as polystyrene (PS), polypropylene (PP) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after anodizing. The results showed that the superhydrophobicity was most excellent by coating PP, while the duration of the hydrophobic surface was poor. By modifying the surface with the silane coupling agent before PP coating, the duration of the superhydrophobic surface was improved. The morphologies of the superhydrophobic surface were further confirmed

  20. The influence of Ti and Sr alloying elements on electrochemical properties of aluminum sacrificial anodes

    Energy Technology Data Exchange (ETDEWEB)

    Saremi, M.; Sina, H.; Keyvani, A.; Emamy, M. [Metallurgy and Materials Department, University of Tehran, P.O. Box 11365/4563, Tehran (Iran)

    2004-07-01

    Aluminum sacrificial anodes are widely used in cathodic protection of alloys in seawater. The interesting properties due to low specific weight, low electrode potential and high current capacity are often hindered by the presence of a passive oxide film which causes several difficulties in their practical application. In this investigation, the electrochemical behavior of Al- 5Zn-0.02In sacrificial anode is studied in 3 wt. % sodium chloride solution. The experiments focused on the influence of Ti and Sr as alloying elements on electrochemical behavior of aluminum sacrificial anode. Ti and Sr are used in different concentrations from 0.03 to 0.1 wt.% 0.01 to 0.05 wt.%, respectively. NACE efficiency and polarization tests are used in this case. It is shown that by using 0.03 wt.% Ti and 0.01 wt.% Sr as the alloying elements to investigate the anodic behavior of the anodes, homogeneous microstructures are obtained which results in improvement of electrochemical properties of aluminum sacrificial anode such as current capacity and anode efficiency. (authors)

  1. Effects of Tin Content and Heat Treatment on the Anodic Characteristics of Al-Sn Alloy

    International Nuclear Information System (INIS)

    Anodic characteristics of specifically prepared laboratory Al-Sn binary alloys in 3% NaCl aqueous solution have been studied to clarify the effect of Sn addition to Al sacrificial anode. Five nine grade pure Al and reagent grade Sn were melted in a high purity graphite crucible in a glove box under Ar atmosphere. The amount of Sn addition to Al was varied in the range of 0.05 to 0.8% by weight. Alloys thus prepared were fashioned into electrode specimens as cast or after different heat-treatments. Distribution of Sn in alloy specimens was examined by EPMA method, which revealed that only the alloy specimens containing less than 0.2% w/o Sn maintain the Al-Sn solid solution after homogenizing heat-treatment at 620 .deg. C for 18 hrs. Segregation of Sn at grain boundaries and even within grains occurs in other specimens. Only the Sn dissolved within aluminum grains appeared to have a major effect on the anodic characteristics of alloy. Most Al-Sn alloy containing more than 0.05 w/o Sn exhibited very low corrosion potential of -1450 ± 20mV vs. SCE except those heat-treated at 500 .deg. C. In potentiostatic anodic polarization measurements for alloy specimens, the largest polarized currents at each set potentials were observed in the alloy specimen which contains 0.2 w/o Sn and homogenized at 620 .deg. C as well. Galvanic couples of the latter alloy specimen coupled to mild steel cathode with the apparent area ratio of anode to cathode 1:63 gave steady state galvanic current of 17 mA and exhibited electrode potential of -1190 mV vs. SCE in 3% NaCl solution, completely protecting the steel cathode even after 72 hours passed

  2. Adsorption orientation of sodium of polyaspartic acid effect on anodic films formed on magnesium alloy

    Science.gov (United States)

    Liu, YuPing; Zhang, Dingfei; Chen, Changguo; Zhang, Jiangang; Cui, libo

    2011-06-01

    We previously reported organic addition agent in improving the performance of anodic film formed on magnesium alloy. Here we report that the environment-friendly electrolyte with sodium of polyaspartic acid (PASP) affects the anodizing process including the microstructure, phase constituents and corrosion performance. We have used SEM, XRD, XPS and polarization curve to study in detail the electrolyte impact. Our results show that the anodic film in electrolyte with 19.2-28.8 g/L PASP is compact, smooth and high corrosion resistant. And also, increasing the PASP concentration ranging from 9.6 to 28.8 g/L results in enhancing the cell voltage, thickness and the content of compound including MgO and Mg 2SiO 4 in anodic film. Interestingly, the anodic film is non-stoichiometric oxide. Comparing with Tafel curves of the anodic film to the addition of PASP or not to, the corrosion current density is 1-2 magnitudes less than the later. Furthermore, a plausible model we propose that the anodizing process is regulated by two main plausible adsorption orientations of PASP at the surface anode. With the increasing of PASP content, the adsorption orientation may transit from "end-on" to "flat-on". This research using organic addition agent PASP may further broaden applications of organic additive in the anti-corrosion engineering and electrochemical surface treatment of magnesium alloy.

  3. Highly Dispersed Alloy Catalyst for Durability

    Energy Technology Data Exchange (ETDEWEB)

    Murthi, Vivek S.; Izzo, Elise; Bi, Wu; Guerrero, Sandra; Protsailo, Lesia

    2013-01-08

    Achieving DOE's stated 5000-hr durability goal for light-duty vehicles by 2015 will require MEAs with characteristics that are beyond the current state of the art. Significant effort was placed on developing advanced durable cathode catalysts to arrive at the best possible electrode for high performance and durability, as well as developing manufacturing processes that yield significant cost benefit. Accordingly, the overall goal of this project was to develop and construct advanced MEAs that will improve performance and durability while reducing the cost of PEMFC stacks. The project, led by UTC Power, focused on developing new catalysts/supports and integrating them with existing materials (membranes and gas diffusion layers (GDLs)) using state-of-the-art fabrication methods capable of meeting the durability requirements essential for automotive applications. Specifically, the project work aimed to lower platinum group metals (PGM) loading while increasing performance and durability. Appropriate catalysts and MEA configuration were down-selected that protects the membrane, and the layers were tailored to optimize the movements of reactants and product water through the cell to maximize performance while maintaining durability.

  4. The effect of different aluminum alloy surface compositions on barrier anodic film formation

    International Nuclear Information System (INIS)

    The authors have grown barrier anodic coatings on samples of aluminum alloy with different elemental surface compositions. In one series of experiments, they characterized the surface composition present on 6061 aluminum alloy samples after different chemical treatments including a detergent-water and methyl-ethyl ketone solvent clean, a 50% nitric acid-water etch, and a concentrated nitric acid-ammonium bifluoride etch. They anodized samples which were prepared similarly to those analyzed to evaluate the practical effects of the three different surface compositions. The anodization voltage rise time to 950V at constant current was used as a figure of merit. The solvent cleaned and the 50% nitric acid etched samples required, respectively, 113% and 41% more time to reach 950V than the concentrated nitric acidammonium bifloride etched samples. In a second series of experiments, they alternately anodized groups of either 6061 or 1100 (commercially pure) aluminum alloy, observed rise times to 950V, and measured chloride ion concentrations in the electrolyte. Longer rise times and higher chloride ion concentrations were observed for the 1100 samples. It was observed that the chloride ion concentration fell from initially high levels when 6061 samples were anodized. The results of both series of experiments augment the results of other investigators, who report that the surface species initially present on aluminum have a significant effect on anodic film formation

  5. Cracking associated with micrometeoroid impact craters in anodized aluminum alloy clamps on LDEF

    Science.gov (United States)

    Murr, Lawrence E.; Niou, Chorng S.; Quinones, Stella; Murr, Kyle S.

    1992-01-01

    The Long Duration Exposure Facility (LDEF) is a reusable hollow-cylindrical satellite sustaining a total of 57 different experiments. The 130 sq m of spacecraft surface area included anodized 6061-T6 Al alloy bay frames and clamps for holding experiment trays in the bay areas. Attention is presently given to the micrometeoroid impact crater features observed on two tray clamps recovered from the LDEF leading-edge locations. It is found that even very subtle surface modifications in structural alloy anodizing can influence micrometeoroid impact crater cracking, notable radial cracking due to the ejecta-rim of the impact craters.

  6. Spark anodizing of β-Ti alloy for wear-resistant coating

    OpenAIRE

    Habazaki, H.; Onodera, T.; Fushimi, K; Konno, H.; Toyotake, K.

    2007-01-01

    Spark anodizing of a bcc solid solution Ti–15% V–3% Al–3% Cr–3% Sn alloy has been performed in an alkaline electrolyte containing aluminate and phosphate using dc-biased ac anodizing to form a wear-resistant coating on the alloy. The coating consists mainly of Al2TiO5, with rutile and γ-Al2O3 being present as minor oxide phases. Depth profiles of the coating, examined by glow discharge optical emission spectroscopy, have revealed that aluminium species, highly enriched in the coating, distrib...

  7. XPS study of cerium conversion coating on the anodized 2024 aluminum alloy

    International Nuclear Information System (INIS)

    Cerium-rich conversion coating was deposited on anodized aluminum alloy 2024 in a solution containing Ce(NO3)3. X-ray photoelectron spectroscopy (XPS) was used as the analysis method. The composition of the Ce conversion coating deposited on the anodized 2024 alloy was investigated using this method. It was revealed that the coating predominately consisted of three-valent state cerium compound. Some of the CeIII was oxidized to CeIV in the outer layer coating

  8. Influence of magnesium additives on anode properties of Zn 55 Al alloy in the medium of NaCl electrolyte

    International Nuclear Information System (INIS)

    Present article is devoted to influence of magnesium additives on anode properties of Zn 55 Al alloy in the medium of NaCl electrolyte. Thus, the results of studies of influence of magnesium additives on anode properties of zink-aluminium alloy Zn 55 Al intended as anode cover for corrosion protection of steel constructions are considered. Chemical composition and studies results of corrosion-electrochemical properties of Zn 55 Al alloy alloyed by magnesium are presented. Corrosion-electrochemical properties of zink-aluminium covers Zn 55 Al alloyed by magnesium in the medium of NaCl electrolyte are considered as well. Dependence of pitting potential of Zn 55 Al alloy alloyed by magnesium on concentration of NaCl electrolyte is studied. Dependence of corrosion rate of Zn 55 al alloy on magnesium content in the medium of NaCl electrolyte is studied as well.

  9. Influence of Mg and Ti on the microstructure and electrochemical performance of aluminum alloy sacrificial anodes

    Institute of Scientific and Technical Information of China (English)

    MA Jingling; WEN Jiuba; LI Xudong; ZHAO Shengli; YAN Yanfu

    2009-01-01

    The experiments focused on the influence of magnesium and titanium as additional alloying elements on the microstructure and electro-chemical behavior of Al-Zn-ln sacrificial anodes. The electrochemical behavior of the aluminum sacrificial anode with 3 wt.% sodium chlo-fide solution was studied by electrochemical impedance spectroscopy (EIS) tests. It was found that a microstructure with few precipitates and refined grains could be achieved by adding 1 wt.% Mg and 0.05 wt.% Ti to the Al-Zn-In alloy, resulting in the improved current capacity and efficiency of the alloy. The equivalent circuit based on the EIS experimental data revealed less corrosion and lower adsorbed corrosion pro-duction on the surface of the aluminum alloy with a combination of 1 wt.% Mg and 0.05 wt.% Ti, which suggested that the corrosion behav-ior seemed to be strongly related to the presence of precipitate particles in the aluminum alloy, and moderate amounts of precipitate particles could be beneficial to the electrochemical performance of the aluminum alloy sacrificial anode.

  10. Dissolution of Plutonium Scrub Alloy and Anode Heel Materials in H-Canyon

    International Nuclear Information System (INIS)

    H-Canyon has a ''gap'' in dissolver operations during the last three months of FY03. One group of material to be processed during the gap is pre-existing scrub alloy material. There are 14 cans of material containing approximately 3.8 kilograms of plutonium. Of the 14 cans, it was anticipated that four cans contain salts, two cans contain anode heel materials, and eight cans contain scrub alloy buttons. H-Canyon desires to process the materials using a flowsheet similar to the SS and C (sand, slag and crucible) dissolution flowsheet used in F-Canyon. The materials will be loaded into carbon steel cans and then placed into aluminum metal charging bundles. Samples were sent to Savannah River Technology Center (SRTC) for characterization and flowsheet testing -- four MSE salts, two anode heels, and seven scrub alloy buttons. SRTC dissolved and characterized each of the samples. Two of them, originally thought to be MSE salts, were found to be graphite mold materials and were unsuitable for processing in H-Canyon. Characterization studies confirmed that the identification of the remaining items as MSE salts, scrub alloy buttons, and anode heel materials was correct. The MSE salts and anode heels solids are comprised primarily of plutonium, potassium, sodium and chloride. Both the MSE salts and anode heels left behind small amounts of residual solids. The scrub alloy buttons are comprised primarily of plutonium and aluminum. The solids dissolve readily with light, effervescent gas generation at the material surface and only trace amounts of NOx generation. Of the seven button samples, four dissolved completely. Two button samples contained small amounts of tantalum that did not dissolve. The last of the seven scrub alloy samples left a trace amount of residual plutonium solids. It is anticipated that the presence of undissolved fissile material is a function of where the sample was located relative to the button surface

  11. FeCrO Nanoparticles as Anode Catalyst for Ethane Proton Conducting Fuel Cell Reactors to Coproduce Ethylene and Electricity

    Directory of Open Access Journals (Sweden)

    Jian-Hui Li

    2011-01-01

    Full Text Available Ethylene and electrical power are cogenerated in fuel cell reactors with FeCr2O4 nanoparticles as anode catalyst, La0.7Sr0.3FeO3- (LSF as cathode material, and BaCe0.7Zr0.1Y0.2O3- (BCZY perovskite oxide as proton-conducting ceramic electrolyte. FeCr2O4, BCZY and LSF are synthesized by a sol-gel combustion method. The power density increases from 70 to 240 mW cm−2, and the ethylene yield increases from about 14.1% to 39.7% when the operating temperature of the proton-conducting fuel cell reactor increases from 650∘C to 750∘C. The FeCr2O4 anode catalyst exhibits better catalytic performance than nanosized Cr2O3 anode catalyst.

  12. PEO of pre-anodized Al–Si alloys: Corrosion properties and influence of sealings

    Energy Technology Data Exchange (ETDEWEB)

    Mohedano, M., E-mail: marta.mohedano@hzg.de [Helmholtz Zentrum Geesthacht, Magnesium Innovation Centre, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Matykina, E.; Arrabal, R.; Mingo, B.; Pardo, A. [Departamento de Ciencia de Materiales, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid (Spain)

    2015-08-15

    Highlights: • A356 gravity-cast and rheocast pre-anodized aluminium alloys were coated by PEO. • Different sealing techniques were applied after the coating process. • Iron-rich constituents of the substrate occlude the continuity of the porous anodic film. • PEO coatings consisted of a mixture of α-Al{sub 2}O{sub 3}, γ-Al{sub 2}O{sub 3} and mullite. • Post-treatments improved both hydrophobic and corrosion properties. - Abstract: Voltage-controlled PEO coatings were developed on A356 aluminum alloys (gravity-cast and rheocast) with a pre-anodized layer. The influence of the alloy manufacturing process and the effect of Si-rich phase on the structure and composition of the oxide layers were evaluated using SEM, EDS and XRD. The pre-anodized oxide layer preserves the microstructure of the substrate due to the presence of secondary phases that have a different behavior relative to the matrix during anodizing. PEO coatings consisted of a mixture of α-Al{sub 2}O{sub 3}, γ-Al{sub 2}O{sub 3} and mullite. The corrosion behavior and the effectiveness of different sealing techniques based on salts of nickel, cobalt, cerium and phosphonic acid were also studied. Post-treatments improved the hydrophobic properties of the coatings and showed a beneficial effect, significantly increasing the coating impedance and thereby reducing the susceptibility to corrosion.

  13. Anodic behaviour of oxidised Ni-Fe alloys in cryolite-alumina melts

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, Vivien, E-mail: v.singleton@student.unsw.edu.a [Centre for Electrochemical and Mineral Processing, School of Chemical Engineering, University of New South Wales, Sydney 2052 (Australia); Welch, Barry J. [Welbank Consulting Ltd., PO Box 207, Whitianga 3542 (New Zealand); Skyllas-Kazacos, Maria [Centre for Electrochemical and Mineral Processing, School of Chemical Engineering, University of New South Wales, Sydney 2052 (Australia)

    2011-01-01

    Nickel-iron alloys have been identified as promising inert anode candidates for the Hall-Heroult process. In this study, binary Ni-Fe alloys of various compositions were subjected to short-term galvanostatic electrolysis in a cryolite-alumina bath at 960 {sup o}C. Prior to electrolysis, the anodes were oxidised at 800 {sup o}C for 48 h, forming a protective scale. Fe{sub 2}O{sub 3}, Ni{sub x}Fe{sub 3-x}O{sub 4} and Ni{sub x}Fe{sub 1-x}O were identified as the major scale components using a combination of X-ray diffraction (XRD) analysis and energy dispersive X-ray spectroscopy (EDX). Anodes having Ni content of 50-65 wt% performed adequately during short-term electrolysis, operating at a steady potential of 3-3.5 V vs. AlF{sub 3}/Al. Overall, it was found that the pre-formed oxide scale was effective in reducing anode wear and fluoridation. In the absence of a pre-formed scale, anodes were shown to undergo appreciable internal corrosion and/or passivation due to metal fluoride formation. Analysis of the anodes following electrolysis was performed using XRD and electron microprobe analysis (EPMA).

  14. Anodic behaviour of oxidised Ni-Fe alloys in cryolite-alumina melts

    International Nuclear Information System (INIS)

    Nickel-iron alloys have been identified as promising inert anode candidates for the Hall-Heroult process. In this study, binary Ni-Fe alloys of various compositions were subjected to short-term galvanostatic electrolysis in a cryolite-alumina bath at 960 oC. Prior to electrolysis, the anodes were oxidised at 800 oC for 48 h, forming a protective scale. Fe2O3, NixFe3-xO4 and NixFe1-xO were identified as the major scale components using a combination of X-ray diffraction (XRD) analysis and energy dispersive X-ray spectroscopy (EDX). Anodes having Ni content of 50-65 wt% performed adequately during short-term electrolysis, operating at a steady potential of 3-3.5 V vs. AlF3/Al. Overall, it was found that the pre-formed oxide scale was effective in reducing anode wear and fluoridation. In the absence of a pre-formed scale, anodes were shown to undergo appreciable internal corrosion and/or passivation due to metal fluoride formation. Analysis of the anodes following electrolysis was performed using XRD and electron microprobe analysis (EPMA).

  15. Electrochemical machining of hard tungsten carbide base alloys in neutral solutions using anodal pulses imposition

    Energy Technology Data Exchange (ETDEWEB)

    Davydov, A.D.; Klepikov, R.P.; Moroz, I.I.

    1981-01-01

    The experiments carried out show that activating pulses of higher amplitude imposition on constant comparatively low voltage extends the possibility of anodic dissolution process control. It proves to be possible to select pulse and constant voltage parameters, allowing to decrease the passivation effect and conduct the process of electrochemical machining of hard tungsten carbide base alloys in neutral water solutions.

  16. Electrochemical machining of hard tungsten carbide base alloys in neutral solutions using anodal pulses imposition

    International Nuclear Information System (INIS)

    The experiments carried out show that activating pulses of higher amplitude imposition on constant comparatively low voltage extends the possibility of anodic dissolution process control. It proves to be possible to select pulse and constant voltage parameters, allowing to decrease the passivation effect and conduct the process of electrochemical machining of hard tungsten carbide base alloys in neutral water solutions

  17. PEO of pre-anodized Al-Si alloys: Corrosion properties and influence of sealings

    Science.gov (United States)

    Mohedano, M.; Matykina, E.; Arrabal, R.; Mingo, B.; Pardo, A.

    2015-08-01

    Voltage-controlled PEO coatings were developed on A356 aluminum alloys (gravity-cast and rheocast) with a pre-anodized layer. The influence of the alloy manufacturing process and the effect of Si-rich phase on the structure and composition of the oxide layers were evaluated using SEM, EDS and XRD. The pre-anodized oxide layer preserves the microstructure of the substrate due to the presence of secondary phases that have a different behavior relative to the matrix during anodizing. PEO coatings consisted of a mixture of α-Al2O3, γ-Al2O3 and mullite. The corrosion behavior and the effectiveness of different sealing techniques based on salts of nickel, cobalt, cerium and phosphonic acid were also studied. Post-treatments improved the hydrophobic properties of the coatings and showed a beneficial effect, significantly increasing the coating impedance and thereby reducing the susceptibility to corrosion.

  18. Investigation of platinum and palladium as potential anodic catalysts for direct borohydride and ammonia borane fuel cells

    Science.gov (United States)

    Olu, Pierre-Yves; Deschamps, Fabien; Caldarella, Giuseppe; Chatenet, Marian; Job, Nathalie

    2015-11-01

    Platinum and palladium are investigated as anodic catalysts for direct borohydride and direct ammonia borane fuel cells (DBFC and DABFC). Half-cell characterizations performed at 25 °C using NH3BH3 or NaBH4 alkaline electrolytes demonstrate the lowest open-circuit potential and highest electrocatalytic activity for the NH3BH3 alkaline electrolyte for Pd and Pt rotating disk electrodes, respectively. Voltammograms performed in fuel cell configuration at 25 °C confirm this trend: the highest open circuit voltage (1.05 V) and peak power density (181 mW·cm-2) are monitored for DABFC using Pd/C and Pt/C anodes, respectively. Increasing the temperature heightens the peak power density (that reaches 420 mW·cm-2 at 60 °C for DBFC using Pt/C anodes), but strongly generates gas from the fuel hydrolysis, hindering the overall fuel cells performances. The anode texture strongly influences the fuel cell performances, highlighting: (i) that an open anode texture is required to efficiently circulate the anolyte and (ii) the difficulty to compare potential anodic catalysts characterized using different fuel cell setups within the literature. Furthermore, TEM imaging of Pt/C and Pd/C catalysts prior/post DBFC and DABFC operation shows fast degradation of the carbon-supported nanoparticles.

  19. Nanoporous carbon supported platinum-copper nanocomposites as anode catalysts for direct borohydride-hydrogen peroxide fuel cell

    International Nuclear Information System (INIS)

    Highlights: • NPC supported Pt-Cu nanocomposites are used firstly as anode catalysts for DBHFC. • The average size of the Pt-Cu nanocrystals is around 2.3 nm. • The DBHFC with Pt2Cu/NPC anode shows the maximum power density of 89 mW cm−2. -- Abstract: Nanoporous carbon (NPC) supported Pt-Cu nanocomposites (PtxCu/NPC) with different Pt/Cu molar ratios have been successfully synthesized via NaBH4 reduction method and used as anode catalysts for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The as-synthesized PtxCu/NPC electrocatalysts are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), cyclic voltammetry (CV), chronoamperometry (CA), rotating disc electrode (RDE) and fuel cell test. It has been found that the PtCu nanoparticles are uniformly dispersed on the surface of the NPC support with average size of about 2.3 nm. Besides, the PtxCu/NPC catalysts show higher activities for borohydride oxidation than that of monometallic Pt/NPC and Vulcan XC-72 carbon supported Pt2Cu (Pt2Cu/XC-72) catalysts. Especially, the DBHFC equipped with Pt2Cu/NPC as anode catalyst shows the maximum power density of 89 mW cm−2 at 25 °C

  20. Fabrication of the micro/nano-structure superhydrophobic surface on aluminum alloy by sulfuric acid anodizing and polypropylene coating.

    Science.gov (United States)

    Wu, Ruomei; Liang, Shuquan; Liu, Jun; Pan, Anqiang; Yu, Y; Tang, Yan

    2013-03-01

    The preparation of the superhydrophobic surface on aluminum alloy by anodizing and polypropylene (PP) coating was reported. Both the different anodizing process and different PP coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. By PP coating after anodizing, a good superhydrophobic surface was facilely fabricated. The optimum conditions for anodizing were determined by orthogonal experiments. After the aluminium-alloy was grinded with 600# sandpaper, pretreated by 73 g/L hydrochloric acid solution at 1 min, when the concentration of sulfuric acid was 180 g/L, the concentration of oxalic acid was 5 g/L, the concentration of potassium dichromate was 10 g/L, the concentration of chloride sodium was 50 g/L and 63 g/L of glycerol, anodization time was 20 min, and anodization current was 1.2 A/dm2, anodization temperature was 30-35 degrees C, the best micro-nanostructure aluminum alloy films was obtained. On the other hand, the PP with different concentrations was used to the PP with different concentrations was used to coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was achieved by coating PP, and the duration of the superhydrophobic surface was improved by modifying the coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was surface with high concentration PP. The morphologies of micro/nano-structure superhydrophobic surface were further confirmed by scanning electron microscope (SEM). The material of PP with the low surface free energy combined with the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface. PMID:23755692

  1. Evaluation of Pt-Ru-Ni and Pt-Sn-Ni catalysts as anodes in direct ethanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Ribadeneira, Esteban; Hoyos, Bibian A. [Escuela de Procesos y Energia, Facultad de Minas, Universidad Nacional de Colombia, Medellin (Colombia)

    2008-05-15

    In this study, the electrooxidation of ethanol on carbon supported Pt-Ru-Ni and Pt-Sn-Ni catalysts is electrochemically studied through cyclic voltammetry at 50 C in direct ethanol fuel cells. All electrocatalysts are prepared using the ethylene glycol-reduction process and are chemically characterized by energy-dispersive X-ray analysis (EDX). For fuel cell evaluation, electrodes are prepared by the transfer-decal method. Nickel addition to the anode improves DEFC performance. When Pt{sub 75}Ru{sub 15}Ni{sub 10}/C is used as an anode catalyst, the current density obtained in the fuel cell is greater than that of all other investigated catalysts. Tri-metallic catalytic mixtures have a higher performance relative to bi-metallic catalysts. These results are in agreement with CV results that display greater activity for PtRuNi at higher potentials. (author)

  2. Advances in chemical synthesis and application of metal-metalloid amorphous alloy nanoparticulate catalysts

    Institute of Scientific and Technical Information of China (English)

    WU Zhijie; LI Wei; ZHANG Minghui; TAO Keyi

    2007-01-01

    This paper reviews the advances in the chemical synthesis and application of metal-metalloid amorphous alloy nanoparticles consisting of transition metal (M) and metalloid elements (B,P).After a brief introduction on the history of amorphous alloy catalysts,the paper focuses on the properties and characterization of amorphous alloy catalysts,and recent developments in the solution-phase synthesis of amorphous alloy nanoparticles.This paper further outlines the applications of amorphous alloys,with special emphasis on the problems and strategies for the application of amorphous alloy nanoparticles in catalytic reactions.

  3. Effect of temperature on the anodizing process of aluminum alloy AA 5052

    Science.gov (United States)

    Theohari, S.; Kontogeorgou, Ch.

    2013-11-01

    The effect of temperature (10-40 °C) during the anodizing process of AA 5052 for 40 min in 175 g/L sulfuric acid solution at constant voltage (15 V) was studied in comparison with pure aluminum. The incorporated magnesium species in the barrier layer result in the further increase of the minimum current density passed during anodizing, as the temperature increases, by about 42% up to 30 °C and then by 12% up to 40 °C. Then during the anodizing process for 40 min a blocking effect on oxide film growth was gradually observed as the temperature increased until 30 °C. The results of EDAX analysis on thick films reveal that the mean amount of the magnesium species inside the film is about 50-70% less than that in the bulk alloy, while it is higher at certain locations adjacent to the film surface at 30 °C. The increase of anodizing temperature does not influence the porosity of thin films (formed for short times) on pure aluminum, while it reduces it on the alloy. At 40 °C the above mentioned blocking effects disappear. It means that the presence of magnesium species causes an impediment to the effect of temperature on iss, on the film thickness and on the porosity of thin films, only under conditions where film growth takes place without significant loss of the anodizing charge to side reactions.

  4. Improvements in the corrosion resistance and biocompatibility of biomedical Ti–6Al–7Nb alloy using an electrochemical anodization treatment

    International Nuclear Information System (INIS)

    The biocompatibility of an implant material is determined by its surface characteristics. This study investigated the application of an electrochemical anodization surface treatment to improve both the corrosion resistance and biocompatibility of Ti–6Al–7Nb alloy for implant applications. The electrochemical anodization treatment produced an Al-free oxide layer with nanoscale porosity on the Ti–6Al–7Nb alloy surface. The surface topography and microstructure of Ti–6Al–7Nb alloy were analyzed. The corrosion resistance was investigated using potentiodynamic polarization curve measurements in simulated blood plasma (SBP). The adhesion and proliferation of human bone marrow mesenchymal stem cells to test specimens were evaluated using various biological analysis techniques. The results showed that the presence of a nanoporous oxide layer on the anodized Ti–6Al–7Nb alloy increased the corrosion resistance (i.e., increased the corrosion potential and decreased both the corrosion rate and the passive current) in SBP compared with the untreated Ti–6Al–7Nb alloy. Changes in the nanotopography also improved the cell adhesion and proliferation on the anodized Ti–6Al–7Nb alloy. We conclude that a fast and simple electrochemical anodization surface treatment improves the corrosion resistance and biocompatibility of Ti–6Al–7Nb alloy for biomedical implant applications. - Highlights: ► Simple/fast electrochemical anodization was applied to biomedical Ti–6Al–7Nb surface. ► Anodized surface had nano-porous topography and contained Al-free oxide layer. ► Anodized surface raised corrosion resistance in three simulated biological solutions. ► Anodized surface enhanced cell adhesion and cell proliferation. ► Electrochemical anodization has potential as biomedical implant surface treatment

  5. Enhanced corrosion resistance and biocompatibility of β-type Ti–25Nb–25Zr alloy by electrochemical anodization

    International Nuclear Information System (INIS)

    The biocompatibility of implants is largely determined by their surface characteristics. This study presents a novel method for performing electrochemical anodization on β-type Ti–25Nb–25Zr alloy with a low elastic modulus (approximately 70 GPa). This method results in a thin hybrid layer capable of enhancing the surface characteristics of the implants. We investigated the surface topography and microstructure of the resulting Ti–25Nb–25Zr alloy. The corrosion resistance was evaluated using potentiodynamic polarization curve measurements in simulated body fluid. The cytotoxicity was evaluated according to International Organization for Standardization 10993–5 specification. Cell adhesion of human bone marrow mesenchymal stem cells on the test specimens was observed using scanning electron microscopy and fluorescence microscopy. The anodization produced a thin (approximately 40 nm-thick) hybrid oxide layer with a nanoporous outer sublayer (pore size < 15 nm) and a dense inner layer. The thin hybrid oxide layer increased the corrosion resistance of the Ti–25Nb–25Zr alloy by increasing the corrosion potential and decreasing both the corrosion rate and passive current. Ti–25Nb–25Zr alloys with and without anodization treatment were non-toxic. Surface nanotopography on the anodized Ti–25Nb–25Zr alloy enhanced protein adsorption and cell adhesion. Our results demonstrate that electrochemical anodization increases the corrosion resistance and cell adhesion of β-type Ti–25Nb–25Zr alloy while providing a lower elastic modulus suitable for implant applications. - Highlights: • An electrochemical anodization was applied to β-type Ti–25Nb–25Zr alloy surface. • Anodized surface had nanoscale hybrid oxide layer. • Anodized surface increased corrosion resistance due to dense inner sublayer. • Anodized surface enhanced cell adhesion due to nanoporous outer sublayer. • Electrochemical anodization has potential as implant surface treatment

  6. Novel Carbon Nanotubes-supported NiB Amorphors Alloy Catalyst for Benzene Hydrogenation

    Institute of Scientific and Technical Information of China (English)

    Mei Hua YANG; Rong Bin ZHANG; Feng Yi LI

    2004-01-01

    The NiB amorphous alloy catalysts supported on CNTs and alumina were prepared by impregnation and chemical reduction. The gas-phase benzene hydrogenation was used as a probe reaction to evaluate the catalytic activity. The result showed that the NiB amorphous alloy catalyst supported on carbon nanotubes exhibited higher activity than that supported on alumina.

  7. Nanostructured surface changes of Ti-35Ta-xZr alloys with changes in anodization factors

    International Nuclear Information System (INIS)

    The purpose of this study was to investigate the changes of the nanostructured surface of Ti-35Ta-xZr alloys for dental application resulting from changes in anodization factors. TiO2 nanotubes were formed on Ti-35Ta-xZr alloys by anodization in H3PO4-containing NaF solutions. Anodization was carried out using a scanning potentiostat. Microstructures of the alloys were examined by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). Microstructures of the Ti-35Ta-xZr alloys were changed from α'' phase to β phase, and morphologies changed from a needle-like to an equiaxed structure, with increasing Zr content. As the Zr content increased from 3 to 7 to 15 wt.%, the average thickness of the TiO2 nanotubes increased from 4.5 μm to 6.1 μm to 9.0 μm. When the anodizing potential was increased from 3 V to 10 V, the thickness of the nanotube layers increased from about 0.5 μm to 9.5 μm. As the anodization time increased from 30 min to 180 min at 10 V, the nanotube thickness increased from 4 μm to 9.5 μm. The amorphous oxide phase in the nanotubes transformed to anatase and rutile phases of TiO2 by heat treatment above 300 oC.

  8. Wear Resistance of Anodic Titanium Dioxide Films Produced on Ti-6Al-4V Alloy

    OpenAIRE

    María Laura Vera; Mario Roberto Rosenberger; Carlos Enrique Schvezov; Alicia Esther Ares

    2015-01-01

    Ti-6Al-4V alloy with TiO2 coating is the most commonly selected material to construct an aortic heart valve. Wear resistance is the main mechanical property to be evaluated for this purpose. In this paper, the wear resistance of TiO2 thin films obtained by anodic oxidation of Ti-6Al-4V is evaluated. Anodic oxidation was performed at 20 V to 70 V with a H2SO4 1 M electrolyte. The samples were thermally treated at 500°C for 1 h, and crystalline phases of TiO2 were obtained. The wear was perform...

  9. Fabrication of Sn-Ni alloy film anode for Li-ion batteries by electrochemical deposition

    Institute of Scientific and Technical Information of China (English)

    ZHANG Da-wei; YANG Chen-ge; DAI Jun; WEN Jian-wu; WANG Long; CHEN Chun-hua

    2009-01-01

    Sn-Ni alloy films for Li-ion batteries were fabricated by electrochemical deposition with rough copper foils as current collectors.The influence of electrochemical-deposition temperature and heat treatment were also investigated.By galvanostatic cell cycling the film anodes can deliver a steady specific capacity.The morphological changes cause the differences in capacity retention.After farther heat treatment,the film anodes present a better cycle performance,with a specific capacity of 314 mA-h/g after 100 cycles.This high capacity retention can be due to its smooth,compact surface formed in the heat treatment process.

  10. Fe-30Ni-5NiO alloy as inert anode for low-temperature aluminum electrolysis

    Science.gov (United States)

    Zhu, Yuping; He, Yedong; Wang, Deren

    2011-05-01

    Fe-30Ni-5NiO alloy anodes were prepared by a spark plasma sintering process for aluminum electrolysis. NiO nano-particles with the size of ˜20 nm were dispersed in the anodes. The oxidation behaviors of the anodes were investigated at 800°C and 850°C, respectively. The electrolysis corrosion behaviors were tested in a cryolite-alumina electrolyte at a low temperature of 800°C with anodic current densities of ˜0.5 A/cm2. The results indicated that the oxidation kinetic of the anodes followed a parabolic law. A continuous Fe2O3 film selectively formed on the surface of the anode during the electrolysis process. A semi-continuous Al2O3 layer was observed at oxide film/alloy interface, probably caused by an in-situ chemical dissolution process.

  11. Carbon supported Cu-Pd nanoparticles as anode catalyst for direct borohydride-hydrogen peroxide fuel cells

    International Nuclear Information System (INIS)

    Carbon supported Cu-Pd bimetallic nanoparticles were prepared by a successive reduction method in aqueous solution and used as anode electrocatalyst for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), chronopotentiometry (CP), linear sweep voltammetry (LSV) and fuel cell test. The results show that the size of the crystallite is around 12.5 nm, the Cu1Pd1/C catalyst presents the highest catalytic activity among all the resultant catalysts, and the DBHFC using Cu1Pd1/C as anode catalyst and Pt mesh (1 cm × 1 cm) as cathode electrode obtains the maximum power density as high as 39.8 mW cm-2 at a discharge current density of 80.1 mA cm-2 at 20 °C

  12. Metamorphosis of the mixed phase PtRu anode catalyst for direct methanol fuel cells after exposure of methanol: In situ and ex situ characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Debasish [Center for Individual Nanoparticle Functionality (CINF), Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Aerosol Laboratory, Nano.DTU, Department of Chemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Chorkendorff, Ib [Center for Individual Nanoparticle Functionality (CINF), Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Johannessen, Tue [Aerosol Laboratory, Nano.DTU, Department of Chemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2007-11-08

    The change in the mixed phase heavily oxidized PtRu anode with the exposure of methanol in a direct methanol fuel cell (DMFC) has been investigated by electrochemical impedance spectroscopy (EIS) and X-ray diffraction (XRD). The investigation had two major objectives: (i) to explore the original state of the active catalyst and (ii) to understand if alloying of Pt and Ru is a requirement for higher methanol oxidation activity. It was found that the methanol oxidation activity gradually improved for {proportional_to}2 h of exposure. The impedance spectra were taken at different times within this time of improvement of activity. The impedance spectra were deconvoluted in different contributions like membrane resistance (R{sub m}), charge transfer resistance (R{sub Ct}), adsorption resistance (R{sub ad}), and oxidation resistance (R{sub ox}). The improvement of the activity was explained in terms of the effect of the pretreatment on different contributions. XRD was done on the virgin and methanol exposed sample as a possible mean to identify the difference. It was postulated that the reduction of the as prepared PtRu after exposure was responsible for the activity improvement. Also, it was shown that bulk alloy formation is not a necessary condition for higher methanol activity of PtRu catalysts. (author)

  13. Cermet anode compositions with high content alloy phase

    Science.gov (United States)

    Marschman, Steven C.; Davis, Norman C.

    1989-01-01

    Cermet electrode compositions comprising NiO-NiFe.sub.2 O.sub.4 -Cu-Ni, and methods for making, are disclosed. Addition of nickel metal prior to formation and densification of a base mixture into the cermet allows for an increase in the total amount of copper and nickel that can be contained in the NiO-NiFe.sub.2 O.sub.4 oxide system. Nickel is present in a base mixture weight concentration of from 0.1% to 10%. Copper is present in the alloy phase in a weight concentration of from 10% to 30% of the densified composition. Such cermet electrodes can be formed to have electrical conductivities well in excess of 100 ohm.sup.-1 cm.sup.-1. Other alloy and oxide system cermets having high content metal phases are also expected to be manufacturable in accordance with the invention.

  14. A potentiostatic study of the corrosion behavior of anodized and nonanodized aluminum alloy.

    Science.gov (United States)

    White, K C; Svare, C W; Taylor, T D

    1985-06-01

    The clinical implication of this study is that some improvement in the corrosion resistance of denture bases made with aluminum alloy D-214 may be obtained by anodization. However, since this study does not exactly duplicate an oral environment or take into consideration the variation in oral environments, it cannot be assumed that the additional corrosion resistance would be discernible in a particular patient. PMID:3859652

  15. Anodic Layer of Pb-Ca-Sn-Ce Alloy for Maintenance-Free Lead/Acid Batteries

    Institute of Scientific and Technical Information of China (English)

    Li Dangguo; Zhou Genshu; Lin Guanfa; Zheng Maosheng

    2005-01-01

    The anodic films of novel Pb-Ca-Sn-Ce alloy, traditional Pb-Ca-Sn and Pb-Sb alloys formed in sulfuric solution at anodic +0.9 V potential corrosion for 6 h were investigated by means of XPS, XRD methods and AC impedance measurement. The results show that the growth of Pb(Ⅱ) oxide on the new Pb-Ca-Sn-Ce alloy surface is inhibited. The AC impedance measurement shows that resistance of the corrosion layer of novel Pb-Ca-Sn-Ce alloy decreases. It is found that the novel Pb-Ca-Sn-Ce alloy can encourage the development of PbO2 in the scale, and enhance the conductivity of the anodic scale. Hence the deep recycling properties of the battery can be expected better.

  16. Formation of self-repairing anodized film on ACM522 magnesium alloy by plasma electrolytic oxidation

    International Nuclear Information System (INIS)

    Highlights: •We studied plasma electrolytic oxidation (PEO) for a magnesium alloy, ACM522. •Amorphous film was obtained from silicate solution, while crystalline film was deposited from phosphate solution. •Both anodized films using silicate and phosphate solutions indicated a self-repairing behavior. •The addition of Na2B4O7 to the phosphate solution reduced the cracks on a self-repaired film. -- Abstract: Plasma electrolytic oxidation (PEO) on a die-casting ACM522 Mg alloy was conducted in aqueous silicate and phosphate solutions. The corrosion behavior of the anodized ACM522 Mg alloy was investigated in detail. During the investigation, the self-repairing behavior of the anodized films was evaluated by a salt spray test for 168 h, and the mechanism of this self-repairing was discussed in terms of thermodynamic equilibrium constants. Furthermore, the effects of additives to the phosphate solution on the self-repairing behavior were examined, and the addition of Na2B4O7 was found to effectively reduce cracks on a self-repaired film

  17. Pd-Au/C catalysts with different alloying degrees for ethanol oxidation in alkaline media

    International Nuclear Information System (INIS)

    High alloyed Pd-Au/C catalyst is prepared through a rate-limiting strategy in water/ethylene glycol solution. Pd/C and low alloyed Pd-Au/C catalysts are prepared with trisodium citrate and sodium borohydride as stabilizing and reducing agents, respectively. Transmission electron microscopy (TEM) shows that the synthesized Pd(Au) particles are well dispersed on the catalysts. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) show that the high alloyed Pd-Au/C catalyst presents a relatively homogenous structure while the low alloyed Pd-Au/C catalyst presents a Pd-rich shell/Au-rich core structure. Electrochemical characterization shows that the low alloyed Pd-Au/C catalyst exhibits the best catalytic activity for ethanol oxidation reaction (EOR) in alkaline media, which could be attributed to its relatively large exposed Pd surface area as compared with the high alloyed Pd-Au/C catalyst due to its Pd-rich shell structure and its enhanced adsorption of OHads as compared with Pd/C catalyst due to its core-shell structure

  18. Formation of titanium dioxide nanotubes on Ti–30Nb–xTa alloys by anodizing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun-Sil [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Jeong, Yong-Hoon [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Biomechanics and Tissue Engineering Laboratory, Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Brantley, William A. [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State University, Columbus, OH (United States)

    2013-12-31

    The goal of this study was to investigate the formation of titanium dioxide nanotubes on the surface of cast Ti–30Nb–xTa alloys by anodizing. The anodization technique for creating the nanotubes utilized a potentiostat and an electrolyte containing 1 M H{sub 3}PO{sub 4} with 0.8 wt.% NaF. The grain size of the Ti–30Nb–xTa alloys increased as the Ta content increased. Using X-ray diffraction, for the Ti–30Nb alloy the main peaks were identified as α″ martensite with strong peaks of β phase. The phases in the Ti–30Nb–xTa alloys changed from a duplex (α″ + β) microstructure to solely β phase with increasing Ta content. The nanotubes that formed on the surface of the Ti–30Nb–xTa alloys were amorphous TiO{sub 2} without an evidence of the crystalline anatase or rutile forms of TiO{sub 2}. Scanning electron microscopy revealed that the average diameters of the small and large nanotubes on the Ti–30Nb alloy not containing Ta were approximately 100 nm and 400 nm, respectively, whereas the small and large nanotubes on the alloy had diameters of approximately 85 nm and 300 nm, respectively. As the Ta content increased from 0 to 15 wt.%, the average lengths of the nanotubes increased from 2 μm to 3.5 μm. Energy-dispersive X-ray spectroscopy indicated that the nanotubes were principally composed of Ti, Nb, Ta, O and F. Contact angle measurements showed that the nanotube surface had good wettability by water droplets. - Highlights: • TiO{sub 2} nanotube layers on anodized Ti-30Nb-xTa alloys have been investigated. • Nanotube surface had an amorphous structure without heat treatment. • Nanotube diameter of Ti-30Nb-xTa decreased, whereas tube layer increased with Ta content. • The nanotube surface exhibited the low contact angle and good wettability.

  19. Formation of titanium dioxide nanotubes on Ti–30Nb–xTa alloys by anodizing

    International Nuclear Information System (INIS)

    The goal of this study was to investigate the formation of titanium dioxide nanotubes on the surface of cast Ti–30Nb–xTa alloys by anodizing. The anodization technique for creating the nanotubes utilized a potentiostat and an electrolyte containing 1 M H3PO4 with 0.8 wt.% NaF. The grain size of the Ti–30Nb–xTa alloys increased as the Ta content increased. Using X-ray diffraction, for the Ti–30Nb alloy the main peaks were identified as α″ martensite with strong peaks of β phase. The phases in the Ti–30Nb–xTa alloys changed from a duplex (α″ + β) microstructure to solely β phase with increasing Ta content. The nanotubes that formed on the surface of the Ti–30Nb–xTa alloys were amorphous TiO2 without an evidence of the crystalline anatase or rutile forms of TiO2. Scanning electron microscopy revealed that the average diameters of the small and large nanotubes on the Ti–30Nb alloy not containing Ta were approximately 100 nm and 400 nm, respectively, whereas the small and large nanotubes on the alloy had diameters of approximately 85 nm and 300 nm, respectively. As the Ta content increased from 0 to 15 wt.%, the average lengths of the nanotubes increased from 2 μm to 3.5 μm. Energy-dispersive X-ray spectroscopy indicated that the nanotubes were principally composed of Ti, Nb, Ta, O and F. Contact angle measurements showed that the nanotube surface had good wettability by water droplets. - Highlights: • TiO2 nanotube layers on anodized Ti-30Nb-xTa alloys have been investigated. • Nanotube surface had an amorphous structure without heat treatment. • Nanotube diameter of Ti-30Nb-xTa decreased, whereas tube layer increased with Ta content. • The nanotube surface exhibited the low contact angle and good wettability

  20. Effect of Annealing on the Pitting Corrosion Resistance of Anodized Aluminum-Magnesium Alloy Processed by Equal Channel Angular Pressing

    Energy Technology Data Exchange (ETDEWEB)

    Son, In Joon; Nakano, Hiroaki; Oue, Satoshi; Fukushima, Hisaaki; Horita, Zenji [Kyushu University, Fukuoka (Japan); Kobayashi, Shigeo [Kyushu Sangyo University, Fukuoka (Japan)

    2007-12-15

    The effect of annealing on the pitting corrosion resistance of anodized Al-Mg alloy (AA5052) processed by equal-channel angular pressing (ECAP) was investigated by electrochemical techniques in a solution containing 0.2 mol/L of AlCl{sub 3} and also by surface analysis. The Al-Mg alloy was annealed at a fixed temperature between 473 and 573 K for 120 min in air after ECAP. Anodizing was conducted for 40 min at 100-400 A/m{sup 2} at 293 K in a solution containing 1.53 mol/L of H{sub 2}SO{sub 4} and 0.0185 mol/L of Al{sub 2}(SO{sub 4}){sub 3}. The internal stress generated in anodic oxide films during anodization was measured with a strain gauge to clarify the effect of ECAP on the pitting corrosion resistance of anodized Al-Mg alloy. The time required to initiate the pitting corrosion of anodized Al-Mg alloy was shorter in samples subjected to ECAP, indicating that ECAP decreased the pitting corrosion resistance. however, the pitting corrosion resistance was greatly improved by annealing after ECAP. The time required to initiate pitting corrosion increased with increasing annealing temperature. The strain gauge attached to Al-Mg alloy revealed that the internal stress present in the anodic oxide films was compressive stress, and that the stress was larger with ECAP than without. The compressive internal stress gradually decreased with increasing annealing temperature. Scanning electron microscopy showed that cracks occurred in the anodic oxide film on Al-Mg alloy during initial corrosion and that the cracks were larger with ECAP than without. The ECAP process of severe plastic deformation produces large internal stresses in the Al-Mg alloy: the stresses remain in the anodic oxide films, increasing the likelihood of cracks. it is assumed that the pitting corrosion is promoted by these cracks as a result of the higher internal stress resulting from ECAP. The improvement in the pitting corrosion resistance of anodized AlMg alloy as a result of annealing appears to be

  1. Effect of Annealing on the Pitting Corrosion Resistance of Anodized Aluminum-Magnesium Alloy Processed by Equal Channel Angular Pressing

    International Nuclear Information System (INIS)

    The effect of annealing on the pitting corrosion resistance of anodized Al-Mg alloy (AA5052) processed by equal-channel angular pressing (ECAP) was investigated by electrochemical techniques in a solution containing 0.2 mol/L of AlCl3 and also by surface analysis. The Al-Mg alloy was annealed at a fixed temperature between 473 and 573 K for 120 min in air after ECAP. Anodizing was conducted for 40 min at 100-400 A/m2 at 293 K in a solution containing 1.53 mol/L of H2SO4 and 0.0185 mol/L of Al2(SO4)3. The internal stress generated in anodic oxide films during anodization was measured with a strain gauge to clarify the effect of ECAP on the pitting corrosion resistance of anodized Al-Mg alloy. The time required to initiate the pitting corrosion of anodized Al-Mg alloy was shorter in samples subjected to ECAP, indicating that ECAP decreased the pitting corrosion resistance. however, the pitting corrosion resistance was greatly improved by annealing after ECAP. The time required to initiate pitting corrosion increased with increasing annealing temperature. The strain gauge attached to Al-Mg alloy revealed that the internal stress present in the anodic oxide films was compressive stress, and that the stress was larger with ECAP than without. The compressive internal stress gradually decreased with increasing annealing temperature. Scanning electron microscopy showed that cracks occurred in the anodic oxide film on Al-Mg alloy during initial corrosion and that the cracks were larger with ECAP than without. The ECAP process of severe plastic deformation produces large internal stresses in the Al-Mg alloy: the stresses remain in the anodic oxide films, increasing the likelihood of cracks. it is assumed that the pitting corrosion is promoted by these cracks as a result of the higher internal stress resulting from ECAP. The improvement in the pitting corrosion resistance of anodized AlMg alloy as a result of annealing appears to be attributable to a decrease in the internal

  2. Nanoporous alumina formed by self-organized two-step anodization of Ni3Al intermetallic alloy in citric acid

    International Nuclear Information System (INIS)

    Highlights: ► Anodic porous alumina was formed by Ni3Al intermetallic alloy anodization. ► The anodizations were conducted in 0.3 M citric acid. ► Nanopores geometry depends on anodizing voltage. ► No barrier layer was formed during anodization. - Abstract: Formation of the nanoporous alumina on the surface of Ni3Al intermetallic alloy has been studied in details and compared with anodization of aluminum. Successful self-organized anodization of this alloy was performed in 0.3 M citric acid at voltages ranging from 2.0 to 12.0 V using a typical two-electrode cell. Current density records revealed different mechanism of the porous oxide growth when compared to the mechanism pertinent for the anodization of aluminum. Electrochemical impedance spectroscopy experiments confirmed the differences in anodic oxide growth. Surface and cross-sections of the Ni3Al intermetallic alloy with anodic oxide were observed with field-emission scanning electron microscope and characterized with appropriate software. Nanoporous oxide growth rate was estimated from cross-sectional FE-SEM images. The lowest growth rate of 0.14 μm/h was found for the anodization at 0 °C and 2.0 V. The highest one – 2.29 μm/h – was noticed for 10.0 V and 30 °C. Pore diameter was ranging from 18.9 nm (2.0 V, 0 °C) to 32.0 nm (12.0 V, 0 °C). Interpore distance of the nanoporous alumina was ranging from 56.6 nm (2.0 V, 0 °C) to 177.9 nm (12.0 V, 30 °C). Pore density (number of pore occupying given area) was decreasing with anodizing voltage increase from 394.5 pores/μm2 (2.0 V, 0 °C) to 94.9 pores/μm2 (12.0 V, 0 °C). All the geometrical features of the anodic alumina formed by two-step self-organized anodization of Ni3Al intermetallic alloy are depending on the operating conditions.

  3. Tackling CO Poisoning with Single-Atom Alloy Catalysts.

    Science.gov (United States)

    Liu, Jilei; Lucci, Felicia R; Yang, Ming; Lee, Sungsik; Marcinkowski, Matthew D; Therrien, Andrew J; Williams, Christopher T; Sykes, E Charles H; Flytzani-Stephanopoulos, Maria

    2016-05-25

    Platinum catalysts are extensively used in the chemical industry and as electrocatalysts in fuel cells. Pt is notorious for its sensitivity to poisoning by strong CO adsorption. Here we demonstrate that the single-atom alloy (SAA) strategy applied to Pt reduces the binding strength of CO while maintaining catalytic performance. By using surface sensitive studies, we determined the binding strength of CO to different Pt ensembles, and this in turn guided the preparation of PtCu alloy nanoparticles (NPs). The atomic ratio Pt:Cu = 1:125 yielded a SAA which exhibited excellent CO tolerance in H2 activation, the key elementary step for hydrogenation and hydrogen electro-oxidation. As a probe reaction, the selective hydrogenation of acetylene to ethene was performed under flow conditions on the SAA NPs supported on alumina without activity loss in the presence of CO. The ability to maintain reactivity in the presence of CO is vital to other industrial reaction systems, such as hydrocarbon oxidation, electrochemical methanol oxidation, and hydrogen fuel cells. PMID:27167705

  4. Behaviour of ruthenium during anodic dissolution of ternary ruthenium alloys with nickel and iron in sulfuric acid solutions

    International Nuclear Information System (INIS)

    The effect is studied of iron on the rate of ruthenium transport to the solution and Ru distribution among the electrolysis products during electrochemical dissolution of the Ni-Fe-Ru alloys in sulfuric acid solutions of the 0.5MNa2SO4-1MH2SO4 composition at 65 deg C. It has been found that the iron addition to the nickel-ruthenium alloys leads to higher rates of ruthenium transport to the sulfuric acid anolytes in the course of anodic dissolution of the alloys as compared with the binary nickel-ruthenium anodes. The dissolution of Ni-Fe-Ru alloys in sulfuric acid electrolytes with the purpose of ruthenium concentration in slurriers should be carried out at low potentials of anodic dissolution (phisub(a) 4

  5. Anodic Behavior of Alloy 22 in Calcium Chloride and in Calcium Chloride Plus Calcium Nitrate Brines

    Energy Technology Data Exchange (ETDEWEB)

    Evans, K J; Day, S D; Ilevbare, G O; Whalen, M T; King, K J; Hust, G A; Wong, L L; Estill, J C; Rebak, R B

    2003-05-13

    Alloy 22 (UNS N60622) is a nickel-based alloy, which is extensively used in aggressive industrial applications, especially due to its resistance to localized corrosion and stress corrosion cracking in high chloride environments. The purpose of this work was to characterize the anodic behavior of Alloy 22 in concentrated calcium chloride (CaCl{sub 2}) brines and to evaluate the inhibitive effect of nitrate, especially to localized corrosion. Standard electrochemical tests such as polarization resistance and cyclic polarization were used. Results show that the corrosion potential of Alloy 22 was approximately -360 mV in the silver-silver chloride (SSC) scale and independent of the tested temperature. Cyclic polarization tests showed that Alloy 22 was mainly susceptible to localized attack in 5 M CaCl{sub 2} at 75 C and higher temperatures. The addition of nitrate in a molar ratio of chloride to nitrate equal to 10 increased the onset of localized corrosion to approximately 105 C. The addition of nitrate to the solution also decreased the uniform corrosion rate and the passive current of the alloy.

  6. A comparative study of enhanced electrochemical stability of tin–nickel alloy anode for high-performance lithium ion battery

    International Nuclear Information System (INIS)

    Highlights: • Sn and Sn–Ni alloy nanoparticles are synthesized by chemical co-precipitation method. • Sn–Ni alloy particles show different phase structure and morphology from Sn particles. • Cyclic voltammetry reveals distinct redox reaction behaviors at Sn and alloy anodes. • Impedance analyses show better stability of alloy electrodes over prolonged cycling. - Abstract: Sn and Sn–Ni alloy nanoparticles are synthesized readily by co-precipitation method for their applications in Li-ion batteries. It is found that nickel not only affects the phase structure and morphology of the alloy, but also impacts Li–Sn alloying and dealloying behaviors. In Li-ion batteries, the alloy electrodes deliver stronger cycling stability than the pure Sn anode. In tests the former exhibits a final capacity of 228.5 mA h g−1 over 50 cycles, while the latter displays 14.3 mA h g−1. Smaller current for battery cycles increases capacities of the alloys beyond 408.4 mA h g−1. The mechanism of enhanced stability of Sn–Ni alloys is examined. Redox reaction characteristics and Li-ion transfer kinetics at these anodes after different cycles are investigated by cyclic voltammetry and electrochemical impedance spectroscopy, which are considered to associate with buffering effects of nickel and structural integrity of electrodes. Li–Sn alloying and dealloying reactions cause volume changes and induce stress that releases in the formation of tiny cracks within the particles. The cracks accelerate side reactions and decelerate charge transport, detrimental to the electrode stability. Nickel cushions the volume variations and reduces the stress and cracks at Sn–Ni alloy anodes to allow them to maintain better electrode integrity and smaller charge resistance, thus yielding their improved Li-ion intercalation stability during long-term cycling

  7. A comparative study of enhanced electrochemical stability of tin–nickel alloy anode for high-performance lithium ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Dongsheng; Li, Jianyang; Gao, Xianfeng; Yuan, Chris, E-mail: cyuan@uwm.edu

    2014-12-25

    Highlights: • Sn and Sn–Ni alloy nanoparticles are synthesized by chemical co-precipitation method. • Sn–Ni alloy particles show different phase structure and morphology from Sn particles. • Cyclic voltammetry reveals distinct redox reaction behaviors at Sn and alloy anodes. • Impedance analyses show better stability of alloy electrodes over prolonged cycling. - Abstract: Sn and Sn–Ni alloy nanoparticles are synthesized readily by co-precipitation method for their applications in Li-ion batteries. It is found that nickel not only affects the phase structure and morphology of the alloy, but also impacts Li–Sn alloying and dealloying behaviors. In Li-ion batteries, the alloy electrodes deliver stronger cycling stability than the pure Sn anode. In tests the former exhibits a final capacity of 228.5 mA h g{sup −1} over 50 cycles, while the latter displays 14.3 mA h g{sup −1}. Smaller current for battery cycles increases capacities of the alloys beyond 408.4 mA h g{sup −1}. The mechanism of enhanced stability of Sn–Ni alloys is examined. Redox reaction characteristics and Li-ion transfer kinetics at these anodes after different cycles are investigated by cyclic voltammetry and electrochemical impedance spectroscopy, which are considered to associate with buffering effects of nickel and structural integrity of electrodes. Li–Sn alloying and dealloying reactions cause volume changes and induce stress that releases in the formation of tiny cracks within the particles. The cracks accelerate side reactions and decelerate charge transport, detrimental to the electrode stability. Nickel cushions the volume variations and reduces the stress and cracks at Sn–Ni alloy anodes to allow them to maintain better electrode integrity and smaller charge resistance, thus yielding their improved Li-ion intercalation stability during long-term cycling.

  8. Electrochemical Random Signal Analysis during Localized Corrosion of Anodized 1100 Aluminum Alloy in Chloride Environments

    Energy Technology Data Exchange (ETDEWEB)

    Sakairi, M.; Shimoyama, Y. [Hokkaido University, Sapporo (Korea, Republic of); Nagasawa, D. [Nippon light metal co., Shizuoka-ken (Japan)

    2008-06-15

    A new type of electrochemical random signal (electrochemical noise) analysis technique was applied to localized corrosion of anodic oxide film formed 1100 aluminum alloy in 0.5 kmol/m{sup 3} H{sub 3}BO{sub 4}/0.05 kmol/m{sup 3} Na{sub 2}B{sub 4}O{sub 7} with 0.01 kmol/m{sup 3} NaCl. The effect of anodic oxide film structure, barrier type, porous type, and composite type on galvanic corrosion resistance was also examined. Before localized corrosion started, incubation period for pitting corrosion, both current and potential slightly change as initial value with time. The incubation period of porous type anodic oxide specimens are longer than that of barrier type anodic oxide specimens. While pitting corrosion, the current and potential were changed with fluctuations and the potential and the current fluctuations show a good correlation. The records of the current and potential were processed by calculating the power spectrum density (PSD) by the Fast Fourier Transform (FFT) method. The potential and current PSD decrease with increasing frequency, and the slopes are steeper than or equal to minus one (-1). This technique allows observation of electrochemical impedance changes during localized corrosion.

  9. Electrochemical Random Signal Analysis during Localized Corrosion of Anodized 1100 Aluminum Alloy in Chloride Environments

    International Nuclear Information System (INIS)

    A new type of electrochemical random signal (electrochemical noise) analysis technique was applied to localized corrosion of anodic oxide film formed 1100 aluminum alloy in 0.5 kmol/m3 H3BO4/0.05 kmol/m3 Na2B4O7 with 0.01 kmol/m3 NaCl. The effect of anodic oxide film structure, barrier type, porous type, and composite type on galvanic corrosion resistance was also examined. Before localized corrosion started, incubation period for pitting corrosion, both current and potential slightly change as initial value with time. The incubation period of porous type anodic oxide specimens are longer than that of barrier type anodic oxide specimens. While pitting corrosion, the current and potential were changed with fluctuations and the potential and the current fluctuations show a good correlation. The records of the current and potential were processed by calculating the power spectrum density (PSD) by the Fast Fourier Transform (FFT) method. The potential and current PSD decrease with increasing frequency, and the slopes are steeper than or equal to minus one (-1). This technique allows observation of electrochemical impedance changes during localized corrosion

  10. Ni-Mo-W catalysts synthesized by mechanical alloying for HDS of dibenzothiophene

    International Nuclear Information System (INIS)

    In this work we reported new trimetallic Ni-Mo-W catalysts synthesized by leaching an Ni-Mo-W-Al alloy produced by mechanical alloying. The materials were tested in the hydrodesulphurization of dibenzothiophene and characterized by scanning electron microscopy, trasmission electron microscopy, X-ray diffraction and specific surface area measurements by using the BET method. This kind of catalysts shows a moderate catalytic activity, due to the synergized effect of small particle and crystal size, and presence of porosity

  11. New composite DMFC anode with PEDOT as a mixed conductor and catalyst support

    Energy Technology Data Exchange (ETDEWEB)

    Drillet, J.F.; Dittmeyer, R.; Juettner, K.; Li, L.; Mangold, K.M. [DECHEMA e.V., Karl-Winnacker-Institut, Theodor-Heuss-Allee 25, 60486 Frankfurt a. M. (Germany)

    2006-12-15

    The conducting polymer PEDOT is tested as a carbon substitute material for the DMFC anode. Electrochemical experiments are carried out in a three-electrode half-cell at room temperature. The first part of this paper focuses on the characterization of PEDOT and PEDOT-PSS as a diffusion layer material. PEDOT/C cyclic voltammograms are recorded in 1 M H{sub 2}SO{sub 4} in the range between the hydrogen evolution and polymer over-oxidation potentials. The incorporation of the PSS counter-ion into the polymer matrix leads to higher impedance values compared to PEDOT without PSS. The second part deals with the study of PEDOT as a Pt catalyst support. It is found that the partial over-oxidation of PEDOT enhances the activity of Pt for methanol oxidation. This can be explained by a change in the morphology of PEDOT that probably improves methanol diffusion within the reaction layer. The degradation of the conducting polymer is confirmed by SEM, EDX, and FTIR measurements. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  12. Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers for Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Michael D. Blanton

    2012-09-01

    Full Text Available Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed as Mg-rich primers as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

  13. Anodic oxidation of Ti–13Nb–13Zr alloy in silicate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Simka, Wojciech, E-mail: wojciech.simka@polsl.pl [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Socha, Robert P. [Institute of Catalysis and Surface Chemistry PAS, Niezapominajek Street 8, 30-239 Krakow (Poland); Dercz, Grzegorz [Institute of Materials Science, University of Silesia, 75 Pułku Piechoty Street 1A, 41-500 Chorzów (Poland); Michalska, Joanna [Faculty of Materials Science and Metallurgy, Silesian University of Technology, Krasińskiego Street 8, 40-019 Katowice (Poland); Maciej, Artur; Krząkała, Agnieszka [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland)

    2013-08-15

    Investigations on the surface modification of Ti–13Nb–13Zr alloy by anodic oxidation are reported here. The oxidation process was carried out in a solution containing K{sub 2}SiO{sub 3} and KOH. The anodising was conducted at voltages of 100, 200 and 400 V. The morphology, chemical composition, and phase composition of the treated Ti–13Nb–13Zr alloy were investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It was found that the morphology of the samples surface did not change during the alloy oxidation at 100 and 200 V. It was observed that during the anodic process under sparking discharge conditions, the simultaneous incorporation of silicon in the forming oxide layer occurs. An application of 400 V led to the incorporation of silicon into the formed oxide layer and significant modification of the surface morphology. The formed coatings are typical of the plasma electrolytic oxidation process, and they include a considerable amount of incorporated silicon, which is present as SiO{sub 2}.

  14. Anodic behaviours, dissolution and passivation of iron-nickel alloys in sulphuric environment. Influence of friction

    International Nuclear Information System (INIS)

    This research thesis reports the study of anodic dissolution and passivation of iron-nickel alloys (10, 20 and 31 pc nickel) in a sulphuric environment, with or without friction, by using anodic polarization curves. Without friction, the three alloys have a similar behaviour as pure iron. The analysis reveals different dissolution and passivation mechanisms with pure iron, and highlights the influence of nickel content on corresponding kinetics. The influence of cyclic plane-on-plane friction has been studied for the 31 pc nickel alloy which has an unsteady austenitic structure. Fretting results in some modifications of polarization curves. These modifications are analysed with respect to fretting parameters (relative speed of antagonist surfaces, contact pressure). They reveal the specific influence of the following phenomena: material strain hardening, martensitic transformation induced by strain hardening, partial destruction of adsorbates and/or of the passive film. Modifications of polarization curves give also information on the evolution of friction characteristics with respect to speed (a phenomenon of lubrication by the electrolyte occurs)

  15. Effect of different ions on the anodic behaviour of alloy 800 chloride solutions at high temperature

    International Nuclear Information System (INIS)

    The anodic behaviour and passivity breakdown of alloy 800 in sodium bicarbonate and sodium phosphate aqueous solutions were studied in the temperature range from 100 degrees C to 280 degrees C by means of electrochemical techniques. The effect of phosphate or bicarbonate additions on the pitting susceptibility and pitting morphology of the alloy in chloride solutions was also examined. Experiments were performed in the following solutions: 0.1M NaHCO3, at 100 degrees C, 200 degrees C, 280 degrees C; 0.06M NaH2PO4 + 0.04M Na2HPO4, at 100 degrees C, 200 degrees C and 280 degrees C, and 0.1M NaCl with different additions of bicarbonate ion (0.02M, 0.05M and 0.1M) and phosphate ion (0.01M, 0.05M and 0.1M) at 100 degrees C and 280 degrees C. The anodic polarization curves of alloy 800 in deaerated 0.1M NaHCO3 and 0.06M NaH2PO4 + 0.04M Na2HPO4 solutions exhibited a similar shape at all the tested temperatures. No localized or generalized corrosion was detected on the metallic surface after polarization. The results obtained in chloride plus bicarbonate and chloride plus phosphate mixtures showed that the pitting potential of alloy 800 in chloride solutions was increased by the presence of bicarbonate or phosphate ions. In those solutions where the inhibitor concentration in the mixture is equal or higher than the chloride concentration , the behaviour of the alloy is similar to the one observed in the absence of chlorides. Changes in pitting morphology were found in phosphate containing solutions, while the pits found in bicarbonate containing solutions were similar to those formed in pure chloride solutions. (author). 3 refs., 4 figs

  16. Mechanisms of oxygen reduction reactions for carbon alloy catalysts via first principles molecular dynamics

    International Nuclear Information System (INIS)

    Carbon alloy catalysts (CACs) are one of promising candidates for platinum-substitute cathode catalysts for polymer electrolyte fuel cells. We have investigated possible mechanisms of oxygen reduction reactions (ORRs) for CACs via first-principles-based molecular dynamics simulations. In this contribution, we review possible ORRs at likely catalytic sites of CACs suggested from our simulations. (author)

  17. TiO{sub 2} nanotubes promoted PT-NI/C catalyst with low PT content as anode catalyst for direct ethanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Shen, L.; Jiang, Q.Z.; Gan, T.G.; Ma, Z.F. [Shanghai Jiao Tong Univ., Shanghai (China). Dept. of Chemical Engineering; Shen, M. [Oklahoma Univ., Norman, OK (United States). School of Chemical, Biological and Materials Engineering, Sarkeys Energy Center; Rodriguez Varela, F.J. [Cinvestav Unidad Saltillo, Coahuila (Mexico). Grupo de Recursos Naturales y Energeticos; Ocampo, A.L. [Univ. Nacional Autonoma, Mexico City (Mexico). Dept. de Quimica Analitica

    2010-07-15

    Although direct ethanol fuel cells (DEFC) have more energy density than direct methanol fuel cells (DMFC), their widespread use has been hampered by the fact that metallic platinum (Pt) catalysts are readily poisoned by strongly absorbed reaction intermediates such as CO{sub ads} at low operating temperatures. The addition of a second transition metal or a metal oxide component has been considered as a means to improve performance of DEFCs by forming a binary anode based on Pt. In this study, titanium oxide (TiO{sub 2}) nanotubes (TiO{sub 2}NTs) were added into a low-platinum content Pt-Ni/C catalyst to improve its catalytic activity for the ethanol oxidation reaction (EOR). The promotion effect of TiO{sub 2}NTs on Pt-Ni/C catalyst was examined. Cyclic voltametry (CV) and chronoamperometry showed that TiO{sub 2}NTs can improve the catalytic activity of the Pt-Ni/C catalyst considerably. Compared to a commercial Pt-Ru/C catalyst, the Pt-Ni-TiO{sub 2}NT/C catalyst has a larger electrochemical active surface (EAS) and has lower onset potential for the EOR. The elemental composition and electronic structure of the catalyst were characterized by X-ray photoelectron spectroscopy, energy dispersive X-ray spectrometry, inductively coupled plasma-optical emission spectrometry and X-ray diffraction. High resolution transmission electron microscopy was used to characterize the morphological properties of these catalysts. The study showed that onset oxidation potential can be lowered by the presence of TiO{sub 2}NTs because they retain more of the Pt metallic species and provide more hydroxides groups. 35 refs., 2 tabs., 10 figs.

  18. Corrosion Behavior of the Rare Earth Sealing Anodized Coating on Aluminum Alloy LY12

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Technological process of rare earth sealing anodized LY12 (2024) alloy is introduced. Corrosion behavior of the filmwas studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that thecoating remained passivity at the potential range from the open circuit potential (-780 mV) to -250 mV in NaClsolution. When the potential exceeded -200 mV, corrosion reaction happened on the coating. the results of ElSanalysis was consistent with the results of polarization curves.

  19. Corrosion study of Ti6Al7Nb alloy after thermal, anodic and alkali surface treatments

    OpenAIRE

    W. Chrzanowski

    2008-01-01

    Purpose: The aim of the work was to work out methods to improve biocompatibility of the Ti6Al7Nb alloy by creating thick, porous layer which ensure corrosion resistance and which could be a base for biological reactions leading to improvements in the tissue bond with the implant.Design/methodology/approach: Surface were prepared using electropolishing, thermal oxidation, thermal oxidation in TiO2 powder, anodic oxidation in NaH2PO4, in NaOH and spark oxidation in H2SO4+H3PO4. The roughness wa...

  20. Structured Ni catalysts on porous anodic alumina membranes for methane dry reforming: NiAl 2 O 4 formation and characterization

    KAUST Repository

    Zhou, Lu

    2015-06-29

    This communication presents the successful design of a structured catalyst based on porous anodic alumina membranes for methane dry reforming. The catalyst with a strong Ni-NiAl2O4 interaction shows both excellent activity and stability. This journal is © The Royal Society of Chemistry.

  1. Sol-gel synthesis of Pt-Ru-Os-Ir based anode electro-catalysts for direct methanol fuel cells

    International Nuclear Information System (INIS)

    Research highlights: → Complex sol-gel synthesis (CSG) of high specific surface area Pt-Ru-Os-Ir catalysts. → Catalysts exhibit specific surface area of ∼95 m2/g. → Electrocatalytic activity is 35-40% higher than CSG derived Pt0.5Ru0.5 and commercially obtained JM catalyst. - Abstract: A high specific surface area (∼95 m2/g) Pt44Ru41Os10Ir5 based anode electro-catalysts for direct methanol fuel cell, synthesized by a novel complexed sol-gel (CSG) process, shows better catalytic activity in comparison to pure equi-atomic compositions of Pt-50 at.% Ru anode catalysts synthesized by similar sol-gel processes. A homogeneous amorphous gel was successfully synthesized by complexing platinum(II) acetylacetonate, ruthenium(III) acetylacetonate, iridium(III) acetylacetonate and osmium(III) chloride with tetramethylammonium hydroxide (TMAH) used as a complexing agent. Phase-pure Pt(Ru,Os,Ir) and Pt(Ru) solid solutions possessing high specific surface area (SSA) (∼90-120 m2/g) were successfully synthesized by thermal decomposition of the amorphous gel followed by controlled removal of carbonaceous species present in the thermally treated powders. The controlled removal of carbon, present in the thermally treated Pt-Ru-Os-Ir powder, has been successfully achieved by conducting precise thermal treatments of the thermally treated powders using controlled oxidizing atmospheres. Results indicate that the nano-crystalline pure Pt(Ru,Os,Ir) solid solution of nominal composition Pt-41 at.%Ru-10 at.%Os-5 at.% Ir possessing good chemical homogeneity exhibit excellent catalytic activity, demonstrating the potential of the novel complexed sol-gel process for synthesizing high-performance Pt-Ru-Os-Ir based catalysts for direct methanol fuel cells.

  2. Sol-gel synthesis of Pt-Ru-Os-Ir based anode electro-catalysts for direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Alyousef, Yousef M. [Energy Research Institute, King Abdulaziz City for Science and Technology, Riyadh 11442 (Saudi Arabia); Datta, Moni Kanchan [Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Kadakia, Karan [Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Yao, S.C. [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Kumta, Prashant N., E-mail: pkumta@pitt.ed [Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Mechanical Engineering and Materials Science, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States)

    2010-09-17

    Research highlights: {yields} Complex sol-gel synthesis (CSG) of high specific surface area Pt-Ru-Os-Ir catalysts. {yields} Catalysts exhibit specific surface area of {approx}95 m{sup 2}/g. {yields} Electrocatalytic activity is 35-40% higher than CSG derived Pt{sub 0.5}Ru{sub 0.5} and commercially obtained JM catalyst. - Abstract: A high specific surface area ({approx}95 m{sup 2}/g) Pt{sub 44}Ru{sub 41}Os{sub 10}Ir{sub 5} based anode electro-catalysts for direct methanol fuel cell, synthesized by a novel complexed sol-gel (CSG) process, shows better catalytic activity in comparison to pure equi-atomic compositions of Pt-50 at.% Ru anode catalysts synthesized by similar sol-gel processes. A homogeneous amorphous gel was successfully synthesized by complexing platinum(II) acetylacetonate, ruthenium(III) acetylacetonate, iridium(III) acetylacetonate and osmium(III) chloride with tetramethylammonium hydroxide (TMAH) used as a complexing agent. Phase-pure Pt(Ru,Os,Ir) and Pt(Ru) solid solutions possessing high specific surface area (SSA) ({approx}90-120 m{sup 2}/g) were successfully synthesized by thermal decomposition of the amorphous gel followed by controlled removal of carbonaceous species present in the thermally treated powders. The controlled removal of carbon, present in the thermally treated Pt-Ru-Os-Ir powder, has been successfully achieved by conducting precise thermal treatments of the thermally treated powders using controlled oxidizing atmospheres. Results indicate that the nano-crystalline pure Pt(Ru,Os,Ir) solid solution of nominal composition Pt-41 at.%Ru-10 at.%Os-5 at.% Ir possessing good chemical homogeneity exhibit excellent catalytic activity, demonstrating the potential of the novel complexed sol-gel process for synthesizing high-performance Pt-Ru-Os-Ir based catalysts for direct methanol fuel cells.

  3. Dead lithium phase investigation of Sn-Zn alloy as anode materials for lithium ion battery

    Institute of Scientific and Technical Information of China (English)

    HUANG ZhaoWen; HU SheJun; HOU XianHua; RU Qiang; YU HongWen; ZHAO LingZhi; LI WeiShan

    2009-01-01

    In this work, based on First-principle plane wave pseudo-potential method, we have carried out an in-depth study on the possible dead lithium phase of Sn-Zn alloy as anode materials for lithium ion batteries. Through investigation, we found that the phases LixSn4Zn4(x = 2, 4, 6, 8) contributed to reversible capacity, while the phases LixSn4Zns-(x-4)(x = 4.74, 7.72) led to capacity loss due to high formation energy, namely, they were the dead lithium phases during the charge/discharge process. And we come up with a new idea that stable lithium alloy phase with high lithiation formation energy (dead lithium phase) can also result in high loss of active lithium ion, besides the traditional expression that the formation of solid electrolyte interface film leads to high capacity loss.

  4. Characterization of thin anodic oxides of Ti–Nb alloys by electrochemical impedance spectroscopy

    International Nuclear Information System (INIS)

    Highlights: ► passivity of mixed α/β-phase NbTi alloys with 10 or 20 wt% Nb was studied. ► EBSD proved the α/β dual phase structure with complex subgrain crystallography. ► Voltammetry, EIS and Mott–Schottky analysis were performed. ► k, DK and EFlatband are similar, but donor density is doubled. ► Both alloys showed excellent passivity with stable and passive grain boundaries. - Abstract: Electrochemical impedance spectroscopy was used to study the interface between the anodic oxide formed on Ti–Nb alloys with specific compositions of Ti–10 wt.% Nb and Ti–20 wt.% Nb and the electrolyte. The anodic oxides were grown in an acetate buffer of pH 6.0 by using cyclic voltammetry electrochemical technique in which the potential is scanned at a rate of 100 mV s−1. The potential applied starts from 0 V and increasing at steps of 1 V till 8 V which allows to study the mechanism and the kinetics involved during the oxide growth. The electrochemical impedance measurements were started prior to applying any potential so that the electronic properties of the native oxide on the Ti–Nb alloys can be determined. The electrochemical measurements were then carried out after each oxide growth so that the electronic properties of the previously grown oxide can also be determined. The variation of the capacitance of the respective oxides determined from the impedance measurements with the applied potential enables the calculation of the relative permittivity of the respective oxides on the two alloys. Moreover the semiconducting properties of the oxides were determined by using Mott–Schottky analysis. The Mott–Schottky analysis involves electrochemical impedance measurements at fixed frequency with increasing applied bias potential so that the variation of the capacitance of the space charge region with the applied potential can be followed. The oxides from both alloys showed an n-type semiconducting property with 7.5 × 1018 cm−3 and 2.4 × 1019 cm−3

  5. Nanosized IrOx–Ir Catalyst with Relevant Activity for Anodes of Proton Exchange Membrane Electrolysis Produced by a Cost-Effective Procedure

    OpenAIRE

    Lettenmeier, Philipp; Wang, Li; Golla-Schindler, Ute; Gazdzicki, Pawel; Cañas, Natalia A.; Handl, Michael; Hiesgen, Renate; Hosseiny, S.S.; Gago, Aldo; Friedrich, K. Andreas

    2015-01-01

    We have developed a highly active nanostructured iridium catalyst for anodes of proton exchange membrane (PEM) electrolysis. Clusters of nanosized crystallites are obtained by reducing surfactant-stabilized IrCl3 in water-free conditions. The catalyst shows a five-fold higher activity towards oxygen evolution reaction (OER) than commercial Ir-black. The improved kinetics of the catalyst are reflected in the high performance of the PEM electrolyzer (1 mgIr cm−2), showing an unparalleled low ov...

  6. Improvement of corrosion resistance of AZ31 Mg alloy by anodizing with co-precipitation of cerium oxide

    Institute of Scientific and Technical Information of China (English)

    Salah Abdelghany SALMAN; Ryoichi ICHINO; Masazumi OKIDO

    2009-01-01

    Anodizing of AZ31 Mg alloy in NaOH solution by co-precipitation of cerium oxide was investigated. The chemical composition and phase structure of the coating film were determined via optical microscopy, SEM and XRD. The corrosion properties of the anodic film were characterized by using potentiodynamic polarization curves in 17 mmol/L NaCl and 0.1 mol/L Na2SO4 solution at 298 K. The corrosion resistance of AZ31 magnesium alloy is significantly improved by adding cerium oxide to alkaline solution. In addition, the surface properties are enhanced and the film contains no crack.

  7. Cermet anode with continuously dispersed alloy phase and process for making

    Science.gov (United States)

    Marschman, Steven C.; Davis, Norman C.

    1989-01-01

    Cermet electrode compositions and methods for making are disclosed which comprise NiO--NiFe.sub.2 O.sub.4 --Cu--Ni. Addition of an effective amount of a metallic catalyst/reactant to a composition of a nickel/iron/oxide, NiO, copper, and nickel produces a stable electrode having significantly increased electrical conductivity. The metallic catalyst functions to disperse the copper and nickel as an alloy continuously throughout the oxide phase of the cermet to render the electrode compositon more highly electrically conductive than were the third metal not present in the base composition. The third metal is preferably added to the base composition as elemental metal and includes aluminum, magnesium, sodium and gallium. The elemental metal is converted to a metal oxide during the sintering process.

  8. Evolution of insoluble eutectic Si particles in anodic oxidation films during adipic-sulfuric acid anodizing processes of ZL114A aluminum alloys

    Science.gov (United States)

    Hua, Lei; Liu, Jian-hua; Li, Song-mei; Yu, Mei; Wang, Lei; Cui, Yong-xin

    2015-03-01

    The effects of insoluble eutectic Si particles on the growth of anodic oxide films on ZL114A aluminum alloy substrates were investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The anodic oxidation was performed at 25°C and a constant voltage of 15 V in a solution containing 50 g/L sulfuric acid and 10 g/L adipic acid. The thickness of the formed anodic oxidation film was approximately 7.13 μm. The interpore distance and the diameters of the major pores in the porous layer of the film were within the approximate ranges of 10-20 nm and 5-10 nm, respectively. Insoluble eutectic Si particles strongly influenced the morphology of the anodic oxidation films. The anodic oxidation films exhibited minimal defects and a uniform thickness on the ZL114A substrates; in contrast, when the front of the oxide oxidation films encountered eutectic Si particles, defects such as pits and non-uniform thickness were observed, and pits were observed in the films.

  9. Advances in aluminum anodizing

    Science.gov (United States)

    Dale, K. H.

    1969-01-01

    White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.

  10. Tin-alloy heterostructures encapsulated in amorphous carbon nanotubes as hybrid anodes in rechargeable lithium ion batteries

    International Nuclear Information System (INIS)

    Sn anode in rechargeable lithium ion batteries (LIBs) is currently being intensely investigated due to high reversible capacity and energy density as compared to the commercialized graphite anode. However, large volume change upon cycling causes poor cyclic performance, which prevents the practical application of Sn anode in LIBs. In this study, the nanosized MxSn (M = Ni, Fe, and Cr) alloys were encapsulated in amorphous carbon nanotubes (ACNTs) creating hybrid anode heterostructures. The structure of the hybrid anodes was confirmed by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and high angle dark field scanning transmission electron microscope (HAADF-STEM), and demonstrated that Ni3Sn4, FeSn2, and Cr2Sn3 alloys exist in the hybrid anodes as both nanowires and nanoparticles. The galvanostatic cycling originating from over 330 charge–discharge cycles indicated that encapsulation of Ni3Sn4, FeSn2, and Cr2Sn3 into ACNTs results in surprisingly excellent cycling performance, high rate capability, and increased initial coulombic efficiency (81.4%). Ex situ HAADF-STEM images of anodes after cycles showed that one-dimensional ACNTs as well as electrochemically inactive phase M (Ni, Fe, and Cr) in MxSn function as good matrices, offering “buffer zone” to effectively accommodate the mechanical stress induced by Sn anode expansion and shrinkage. Importantly, ACNTs enable electrical contact of Sn nanoparticles with the current collectors. Therefore, our design can significantly overcome electrochemical degradation of anodes with large volume change, resulting in increased LIB performance

  11. Influence of 8-hydroxyquinoline on properties of anodic coatings obtained by micro arc oxidation on AZ91 magnesium alloys

    International Nuclear Information System (INIS)

    Highlights: ► 8-HQ can promote the coating formation and change the coating color. ► 8-HQ can increase the coating thickness and decrease the pore size. ► Insoluble Mg(HQ)2 is formed in anodic coatings in an alkaline solution with 8-HQ. ► 8-HQ improves the corrosion resistance of the anodized magnesium alloys. - Abstract: The influence of 8-hydroxyquinoline (8-HQ) on formation and properties of anodic coatings obtained by micro arc oxidation (MAO) on AZ91 magnesium alloys was studied by scanning electron microscope (SEM), energy dispersive spectrometry (EDS), Fourier transform infrared (FT-IR) spectroscopy and potentiodynamic polarization tests. The results demonstrate that 8-HQ can decrease the solution conductivity, take part in the coating formation and change the coating color. By developing anodic coatings with increasing thickness, insoluble Mg(HQ)2 and small pore size, 8-HQ improves the corrosion resistance of the anodized magnesium alloys. The coating shows the best corrosion resistance in the solution of 10 g/L NaOH and 18 g/L Na2SiO3 with 2 g/L 8-HQ.

  12. Influence of 8-hydroxyquinoline on properties of anodic coatings obtained by micro arc oxidation on AZ91 magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, R.F. [Jiangxi Key Laboratory of Surface Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); School of Material Science and Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); Zhang, S.F., E-mail: zhangshufang790314@sina.com [Jiangxi Key Laboratory of Surface Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); School of Material Science and Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); Yang, N.; Yao, L.J.; He, F.X.; Zhou, Y.P.; Xu, X.; Chang, L.; Bai, S.J. [School of Material Science and Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China)

    2012-10-25

    Highlights: Black-Right-Pointing-Pointer 8-HQ can promote the coating formation and change the coating color. Black-Right-Pointing-Pointer 8-HQ can increase the coating thickness and decrease the pore size. Black-Right-Pointing-Pointer Insoluble Mg(HQ){sub 2} is formed in anodic coatings in an alkaline solution with 8-HQ. Black-Right-Pointing-Pointer 8-HQ improves the corrosion resistance of the anodized magnesium alloys. - Abstract: The influence of 8-hydroxyquinoline (8-HQ) on formation and properties of anodic coatings obtained by micro arc oxidation (MAO) on AZ91 magnesium alloys was studied by scanning electron microscope (SEM), energy dispersive spectrometry (EDS), Fourier transform infrared (FT-IR) spectroscopy and potentiodynamic polarization tests. The results demonstrate that 8-HQ can decrease the solution conductivity, take part in the coating formation and change the coating color. By developing anodic coatings with increasing thickness, insoluble Mg(HQ){sub 2} and small pore size, 8-HQ improves the corrosion resistance of the anodized magnesium alloys. The coating shows the best corrosion resistance in the solution of 10 g/L NaOH and 18 g/L Na{sub 2}SiO{sub 3} with 2 g/L 8-HQ.

  13. Miniature fuel cell with monolithically fabricated Si electrodes - Alloy catalyst formation -

    Science.gov (United States)

    Ogura, Daiki; Suzuki, Takahiro; Katayama, Noboru; Dowaki, Kiyoshi; Hayase, Masanori

    2013-12-01

    A novel Pd-Pt catalyst formation process was proposed for reduction of Pt usage. In our miniature fuel cells, porous Pt was used as the catalyst, and the Pt usage was quite high. To reduce the Pt usage, we have attempted to deposit Pt on porous Pd by galvanic replacement, and relatively large output was demonstrated. In this study, in order to reduce more Pt usage and explore the alloy catalyst formation process, atomic layer deposition by UPD-SLRR (Under Potential Deposition - Surface Limited Redox Replacement) was applied to the Pd-Pt catalyst formation. The new process was verified at each process steps by EDS elemental analysis, and the expected spectra were obtained. Prototype cells were constructed by the new process, and cell output was raised to 420mW/cm2 by the Pd-Pt catalyst from 125mW/cm2 with Pd catalyst.

  14. Miniature fuel cell with monolithically fabricated Si electrodes – Alloy catalyst formation –

    International Nuclear Information System (INIS)

    A novel Pd-Pt catalyst formation process was proposed for reduction of Pt usage. In our miniature fuel cells, porous Pt was used as the catalyst, and the Pt usage was quite high. To reduce the Pt usage, we have attempted to deposit Pt on porous Pd by galvanic replacement, and relatively large output was demonstrated. In this study, in order to reduce more Pt usage and explore the alloy catalyst formation process, atomic layer deposition by UPD-SLRR (Under Potential Deposition – Surface Limited Redox Replacement) was applied to the Pd-Pt catalyst formation. The new process was verified at each process steps by EDS elemental analysis, and the expected spectra were obtained. Prototype cells were constructed by the new process, and cell output was raised to 420mW/cm2 by the Pd-Pt catalyst from 125mW/cm2 with Pd catalyst

  15. Structure, activity, and stability of platinum alloys as catalysts for the oxygen reduction reaction

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg

    essential for wide-spread use of this technology. platinum alloys have shown great promise as more active catalysts, which are still stable under reaction conditions. We have investigated these systems on multiple scales, using either Density Functional Theory (DFT) or Effective Medium Theory (EMT......In this thesis I present our work on theoretical modelling of platinum alloys as catalysts for the Oxygen Reduction Reaction (ORR). The losses associated with the kinetics of the ORR is the main bottleneck in low-temperature fuel cells for transport applications, and more active catalysts are...... increased activity that has been seen experimentally. We show how the platinum-platinum distance at the surface is decreased for a variety of alloy phases in the core, with greater compression of the overlayer for core phases with lattice parameters which are either much smaller or much larger than pure...

  16. Synthesis and characterization of highly dispersed Pt–TiO2|WC/BC as anode catalyst for methanol oxidation

    International Nuclear Information System (INIS)

    Highlights: • WC could enhance the electron transfer between the catalyst and support and accelerate the oxidation of residual carbon species. • TiO2 could absorb methanol and accelerate the breakage of O–H bond. • An enduring, versatile and renewable materials, bamboo charcoals, which have tremendous mesoporous structure were used as the support. - Abstract: To search the active anode electrocatalyst in direct methanol fuel cells, bamboo charcoals (BC)—supported titanium oxide|tungsten carbide system (TiO2|WC/BC) was constructed with a well defined structure in a designed process. Platinum was homogeneously dispersed on TiO2|WC/BC with an average particle size of 3.75 nm by microwave-assisted ethylene glycol process. The electro-catalytic performance of the catalyst Pt–TiO2|WC/BC toward methanol oxidation reaction (MOR) was studied by cyclic voltammetry (CV), chronoamperometry and CO stripping experiments. Results showed that the new electro-catalyst had a higher activity towards MOR compared with that of Pt–WC/BC and commercial Pt/C. The components in the complex were proved to play different roles in MOR where BC offered the larger surface areas and higher conductivity, the TiO2 could absorb methanol and accelerate the breakage of O–H bond, meanwhile WC may enhance the electron transfer between the catalyst and support and accelerate the oxidation of residual carbon species

  17. Elaboration, physical and electrochemical characterizations of CO tolerant PEMFC anode materials. Study of platinum-molybdenum and platinum-tungsten alloys and composites; Elaborations et caracterisations electrochimiques et physiques de materiaux d'anode de PEMFC peu sensibles a l'empoisonnement par CO: etude d'alliages et de composites a base de platine-molybdene et de platine-tungstene

    Energy Technology Data Exchange (ETDEWEB)

    Peyrelade, E.

    2005-06-15

    PEMFC development is hindered by the CO poisoning ability of the anode platinum catalyst. It has been previously shown that the oxidation potential of carbon monoxide adsorbed on the platinum atoms can be lowered using specific Pt based catalysts, either metallic alloys or composites. The objective is then to realize a catalyst for which the CO oxidation is compatible with the working potential of a PEMFC anode. In our approach, to enhance the CO tolerance of platinum based catalyst supported on carbon, we studied platinum-tungsten and platinum-molybdenum alloys and platinum-metal oxide materials (Pt-WO{sub x} and Pt-MoO{sub x}). The platinum based alloys demonstrate a small effect of the second metal towards the oxidation of carbon monoxide. The platinum composites show a better tolerance to carbon monoxide. Electrochemical studies on both Pt-MoO{sub x} and Pt-WO{sub x} demonstrate the ability of the metal-oxides to promote the ability of Pt to oxidize CO at low potentials. However, chrono-amperometric tests reveal a bigger influence of the tungsten oxide. Complex chemistry reactions on the molybdenum oxide surface make it more difficult to observe. (author)

  18. Formation of barrier-type anodic films on ZE41 magnesium alloy in a fluoride/glycerol electrolyte

    International Nuclear Information System (INIS)

    Highlights: • Barrier anodic films formed on ZE41 Mg alloy in glycerol/fluoride electrolyte. • Films contain oxygen and fluorine species; formation ratio ∼1.3 nm V−1. • Nanocrystalline film structure, with MgO and MgF2. • Zinc enrichment in alloy beneath anodic film. • Modified film formed above Mg-Zn-RE second phase. - Abstract: Barrier-type, nanocrystalline anodic films have been formed on a ZE41 magnesium alloy under a constant current density of 5 mA cm−2 in a glycerol/fluoride electrolyte, containing 5 vol.% of added water, at 293 K. The films contain magnesium, fluorine and oxygen as the major species, and lower amounts of alloying element species. The films grow at an efficiency of ∼0.8 to 0.9, with a formation ratio in the range of ∼1.2 to 1.4 nm V−1 at the matrix regions and with a ratio of ∼1.8 nm V−1 at Mg-Zn-RE second phase. At the former regions, rare earth species are enriched at the film surface and zinc is enriched in the alloy. A carbon- and oxygen-rich band within the film suggests that the films grow at the metal/film and film/electrolyte interfaces

  19. Anodic-spark layers on aluminium and titanium alloys in electrolytes with sodium tungstophosphate

    International Nuclear Information System (INIS)

    Influence of pH value of Na2H[PW12O40] aqueous 0.0083 M solution on the composition and morphology of anodic coatings on aluminium and titanium alloys formed galvanostatically under sparkling and breakdown voltage was studied using data of electron microscopy, elementary and X-ray phase analyses. It was ascertained that in low-acid, neutral and low-alkaline electrolytes multilayer coatings are formed, which contain in their outer layer oxides of elements making up the ligand sphere of heteropolyanions. In solutions featuring higher acidity and alkalinity the content of heteropolyanion components in the coatings decreases. By and large, the coating composition reflects the dependence of heteropolyanions composition in aqueous solution on pH value

  20. Corrosion protection of AZ91 magnesium alloy by anodizing in niobium and zirconium-containing electrolytes

    International Nuclear Information System (INIS)

    A new Nb + Zr-based anodized coating was designed for the corrosion protection of AZ91 magnesium alloy. Polarization curves and electrochemical impedance diagrams plotted in Na2SO4 electrolyte showed its high protective effect. Analysis of the chemical composition by X-ray photoelectron spectroscopy indicated that the coating mainly consisted of (i) magnesium metaborate and metaphosphate, (ii) MgF2 and ZrF4, and (iii) Nb2O5, ZrO2 and MgO. A higher concentration of fluorine at both interfaces and an enrichment in Zr compared to Nb were revealed by SEM and EDS analyses. Thus, Zr-based compounds and MgF2 play a key role in the anti-corrosion ability of the coating.

  1. Wear Resistance of Anodic Titanium Dioxide Films Produced on Ti-6Al-4V Alloy

    Directory of Open Access Journals (Sweden)

    María Laura Vera

    2015-03-01

    Full Text Available Ti-6Al-4V alloy with TiO2 coating is the most commonly selected material to construct an aortic heart valve. Wear resistance is the main mechanical property to be evaluated for this purpose. In this paper, the wear resistance of TiO2 thin films obtained by anodic oxidation of Ti-6Al-4V is evaluated. Anodic oxidation was performed at 20 V to 70 V with a H2SO4 1 M electrolyte. The samples were thermally treated at 500°C for 1 h, and crystalline phases of TiO2 were obtained. The wear was performed in a ball-on-flat recip‐ rocating machine with a range of loads from 1 gf to 4 gf and times between 60 s and 1200 s, using a diamond sphere as counterface. The counterface oscillates at 0.5 Hz and 4 mm in amplitude. The wear is measured using a profilometer and is calculated as the worn volume. The wear resistance of the coated samples is larger than the substrate, and increases with thickness and with crystalline coating.

  2. A novel tin-bismuth alloy electrode for anodic stripping voltammetric determination of zinc

    International Nuclear Information System (INIS)

    We report on a novel tin-bismuth alloy electrode (SnBiE) for the determination of trace concentrations of zinc ions by square-wave anodic stripping voltammetry without deoxygenation. The SnBiE has the advantages of easy fabrication and low cost, and does not require a pre-treatment (in terms of modification) prior to measurements. A study on the potential window of the electrode revealed a high hydrogen overvoltage though a limited anodic range due to the oxidation of tin. The effects of pH value, accumulation potential, and accumulation time were optimized with respect to the determination of trace zinc(II) at pH 5. 0. The response of the SnBiE to zinc(II) ion is linear in the 0.5-25 μM concentration range. The detection limit is 50 nM (after 60 s of accumulation). The SnBiE was applied to the determination of zinc(II) in wines and honeys, and the results were consistent with those of AAS. (author)

  3. Effect of bending on anodized Ti6Al4V alloy: I. Surface layers characteristics

    Directory of Open Access Journals (Sweden)

    A. Kierzkowska

    2006-08-01

    Full Text Available Purpose: The plastic deformation behaviour of the anodized binary titanium alloy Ti6Al4V was characterizedin mechanical and electrochemical tests.Design/methodology/approach: The effect of tensile and compressive stresses on properties of differentclinically relevant surfaces of the deformed by bending implant rods was investigated. The deformationbehaviour was characterized by FEM analysis. Relevant surfaces in tensile and compressive zones werecharacteristics by microhardness and roughness measurements, and electrochemical testing (Ecor, anodicpolarization, EIS in oxygen-saturated Ringer’s solution.Findings: It was concluded that bending influenced mostly the properties of material in the tensile zone of thespecimen, whereas the properties of surface layer in the compressive zone and the properties of surface layer intensile zone after rebending are comparable and not so severe.Research limitations/implications: Studies were performed in static conditions, fatique studies are planned inthe future.Practical implications: Results are of great importance in for surgical practice in the in the evaluation of theinfluence of shaping process applied during pre-operative procedures on the performance of spinal implantsystems.Originality/value: In the paper a typical pre-operative procedure of shaping was applied to anodized titaniumimplants in order to evaluate its influence on the characteristics of the surface layer. Studies were focused onthe safety their application in vivo.

  4. Effect of nitrogen post-doping on a commercial platinum-ruthenium/carbon anode catalyst

    Science.gov (United States)

    Corpuz, April R.; Wood, Kevin N.; Pylypenko, Svitlana; Dameron, Arrelaine A.; Joghee, Prabhuram; Olson, Tim S.; Bender, Guido; Dinh, Huyen N.; Gennett, Thomas; Richards, Ryan M.; O'Hayre, Ryan

    2014-02-01

    This work investigates the effects of after-the-fact chemical modification of a state-of-the-art commercial carbon-supported PtRu catalyst for direct methanol fuel cells (DMFCs). A commercial PtRu/C (JM HiSPEC-10000) catalyst is post-doped with nitrogen by ion-implantation, where "post-doped" denotes nitrogen doping after metal is carbon-supported. Composition and performance of the PtRu/C catalyst post-modified with nitrogen at several dosages are evaluated using X-ray photoelectron spectroscopy (XPS), rotating disk electrode (RDE), and membrane electrode assemblies (MEAs) for DMFC. Overall, implantation at high dosage results in 16% higher electrochemical surface area and enhances performance, specifically in the mass transfer region. Rotating disk electrode (RDE) results show that after 5000 cycles of accelerated durability testing to high potential, the modified catalyst retains 34% more electrochemical surface area (ECSA) than the unmodified catalyst. The benefits of nitrogen post-doping are further substantiated by DMFC durability studies (carried out for 425 h), where the MEA with the modified catalyst exhibits higher surface area and performance stability in comparison to the MEA with unmodified catalyst. These results demonstrate that post-doping of nitrogen in a commercial PtRu/C catalyst is an effective approach, capable of improving the performance of available best-in-class commercial catalysts.

  5. SURFACE STRUCTURE AND COMPOSITION CHANGES ON PLATINUM - RHODIUM ALLOY CATALYSTS

    OpenAIRE

    McCabe, A.; Smith, G.

    1984-01-01

    Platinum-rhodium gauze catalysts used in the manufacture of nitric acid undergo an extensive surface reconstruction process. This has been investigated using a miniature catalytic reactor, FIM atom probe, electron microscopy and X-ray techniques. A mechanism involving vapour transport is proposed to explain the main features of the variation in catalyst behaviour with operating conditions.

  6. Effects of benzotriazole on anodized film formed on AZ31B magnesium alloy in environmental-friendly electrolyte

    International Nuclear Information System (INIS)

    An environmental-friendly electrolyte of silicate and borate, which contained an addition agent of 1H-benzotriazole (BTA) with low toxicity (LD50 of 965 mg/kg), was used to prepare an anodized film on AZ31B magnesium alloy under the constant current density of 1.5 A/dm2 at room temperature. Effects of BTA on the properties of the anodized film were studied by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), loss weight measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), respectively. The results demonstrated that anodized growth process, surface morphology, thickness, phase structure and corrosion resistance of the anodized film were strongly dependant on the BTA concentration, which might be attributed to the formation of an BTA adsorption layer on magnesium substrate surface. When the BTA concentration was 5 g/L in the electrolyte, a compact and thick anodized film could provide excellent corrosion resistance for AZ31B magnesium alloy.

  7. Ethanol electro-oxidation on partially alloyed Pt-Sn-Rh/C catalysts

    International Nuclear Information System (INIS)

    Ternary Pt-Sn-Rh/C catalysts of Pt:Sn:Rh = 1:0.8:0.2 and 1:1:0.33 atomic ratios were synthesized using the formic acid method and their electrochemical activities were compared for ethanol oxidation with that of binary Pt-Sn/C (1:1) and Pt-Rh/C (1:0.11) catalysts. XRD analysis indicated the presence of Sn in both alloyed and oxide form and suggested the formation of a ternary Pt-Sn-Rh alloy in both catalysts. The particle size by TEM was around 3.5 nm for all catalysts. The efficiency for Pt utilization increased with Rh content. Pt-Sn-Rh/C catalysts exhibited higher catalytic activity for ethanol oxidation than Pt-Rh/C, but lower than Pt-Sn/C. Among ternary catalysts, Pt-Sn-Rh/C (1:0.8:0.2) was the most active. In situ IRRAS showed Rh plays a dual counteracting role during ethanol electro-oxidation on Pt-Sn-Rh/C catalysts, once it promotes C-C bond breaking, thus favouring CO2 formation, but hinders adsorption of ethanol, decreasing the production of acetic acid

  8. Corrosion study of Ti6Al7Nb alloy after thermal, anodic and alkali surface treatments

    Directory of Open Access Journals (Sweden)

    W. Chrzanowski

    2008-12-01

    Full Text Available Purpose: The aim of the work was to work out methods to improve biocompatibility of the Ti6Al7Nb alloy by creating thick, porous layer which ensure corrosion resistance and which could be a base for biological reactions leading to improvements in the tissue bond with the implant.Design/methodology/approach: Surface were prepared using electropolishing, thermal oxidation, thermal oxidation in TiO2 powder, anodic oxidation in NaH2PO4, in NaOH and spark oxidation in H2SO4+H3PO4. The roughness was examined using MSP and LPM. Corrosion resistance tests were carried out in SBF with pH values characterized for neutral, inflammatory and stagnation state. Topographical features were determined using confocal microscope.Findings: The surface treatments guarantee a smooth surface (low value of Ra and RZDIN or porous surface structure and high corrosion resistance. Topographical parameters of the layer can be altered according to the duration of that process. The corrosion resistance of the specimens anodically oxidized in NaOH and spark oxidized possessed high corrosion resistance in SBF also in SBF with low and high pH value.Research limitations/implications: For the layers, further mechanical, chemical, biological and composition examinations are planed.Practical implications: The paper presents different surface treatments and their influence on corrosion and topographical properties and it could be useful for implant producers to take into consideration one of these methods. Anodic oxidation is a very simple method to ensure high corrosion resistance of implants.Originality/value: The paper presented new approaches to the surface preparation by spark oxidation in the acids and anodic oxidation in NaH2PO4 and NaOH at different parameters which haven’t previously been used. There were proposed thermal oxidation in TiO2 powder that was not presented before. The paper compares corrosion resistance and topographical features of the Ti6Al7Nb modified by

  9. Sacrificial anode stability and polarization potential variation in a ternary Al-xZn-xMg alloy in a seawater-marine environment

    Science.gov (United States)

    Muazu, Abubakar; Aliyu, Yaro Shehu; Abdulwahab, Malik; Idowu Popoola, Abimbola Patricia

    2016-06-01

    In this paper, the effects of zinc (Zn) and magnesium (Mg) addition on the performance of an aluminum-based sacrificial anode in seawater were investigated using a potential measurement method. Anodic efficiency, protection efficiency, and polarized potential were the parameters used. The percentages of Zn and Mg in the anodes were varied from 2% to 8% Zn and 1% to 4% Mg. The alloys produced were tested as sacrificial anodes for the protection of mild steel in seawater at room temperature. Current efficiency as high as 88.36% was obtained in alloys containing 6% Zn and 1% Mg. The polarized potentials obtained for the coupled (steel/Al-based alloys) are as given in the Pourbaix diagrams, with steel lying within the immunity region/cathodic region and the sacrificial anodes within the anodic region. The protection offered by the sacrificial anodes to the steel after the 7th and 8th week was measured and protection efficiency values as high as 99.66% and 99.47% were achieved for the Al-6%Zn-1%Mg cast anode. The microstructures of the cast anodes comprise of intermetallic structures of hexagonal Mg3Zn2 and body-centered cubic Al2Mg3Zn3. These are probably responsible for the breakdown of the passive alumina film, thus enhancing the anode efficiency.

  10. Porous anodic film formation on an Al-3.5 wt % Cu alloy

    Directory of Open Access Journals (Sweden)

    Páez, M. A.

    2003-12-01

    Full Text Available The morphological development of porous anodic films in the initial stages is examined during anodizing an Al-3.5 wt % Cu alloy in phosphoric acid. Using transmission electron microscopy a sequence of ultramicrotomed anodic sections reveals the dynamic evolution of numerous features in the thickening film in the initial stages of anodizing. The morphological changes in the anodic oxide in the initial stages of its formation appears related to the formation of bubbles during film growth. From Rutherford backscattering spectroscopy (RBS analysis of the film, the formation of the bubbles is associated with the enrichment of copper in the alloy due to growth of the anodic oxide. On the other hand, during constant current anodizing of Al-Cu in phosphoric acid, the current efficiency is considerably less than that for anodizing superpure aluminium under similar conditions. From the contrasting results between the charge consumed calculated from RBS and the real charge consumed during anodizing, oxygen gas bubbles generation and copper oxidation seem to be of less importance on the low efficiency for film formation. It is apparent that the main cause of losing efficiency for film growth on Al-Cu is associated with generation of oxygen at residual second phase, with the development of stresses in the film and, the consequence of these effects on film cracking during film growth.

    En este trabajo se examinó el desarrollo morfológico de películas anódicas porosas en los estados iniciales de la anodización de una aleación de aluminio Al-3,5 % p/p Cu. La observación de una secuencia de secciones ultramicrotomadas del metal y su película anódica, por microscopía electrónica de transmisión, revela la evolución dinámica de numerosos detalles morfológicos durante los inicios del crecimiento de la película anódica. Los cambios morfológicos en el óxido anódico, en los inicios de su formación, aparecen relacionados a la formación de

  11. Effect of sandblasting and shot-peening on the corrosion behavior of Pb-Ag alloy anodes in acid zinc sulfate electrolyte at 38oC

    International Nuclear Information System (INIS)

    The surface treatment of Pb-Ag alloy anodes is a measure used in zinc electrowinning industry to stabilize the anode surface and decrease the lead contamination of the zinc cathode. In this work, the effect of sandblasting and shot-peening treatments on the corrosion behavior of the Pb-Ag alloy anodes in zinc electrolyte was studied using electrochemical methods. The results showed that the sandblasting treatment slightly decreased the corrosion rate of the anode in acid zinc sulfate solution without manganese addition, while the shot-peening treatment remarkably decreased the corrosion rate of the anode when it was immersed in the same electrolyte. In zinc electrolyte containing Mn2+ and MnO4-, the corrosion potentials of the untreated and sandblasted anodes were ca. 750 mV higher than that those observed in the zinc electrolyte without manganese. As a result the corrosion rates were greatly decreased. The presence of Mn2+ and MnO4- in the zinc electrolyte shifted the corrosion potential of the shot-peened anode in the positive direction by 400 mV, but did not influence its corrosion rate. The sandblasting and shot-peening treatments made the MnO2-PbO2 layer formed on the anodes during the electrolysis more compact and slightly increased the overpotential of the anodic reaction during five hours of electrolysis. One hour after the electrolysis, the corrosion rates for the three anodes were: shot-peened anode > sandblasted anode > untreated anode. Five hours after the electrolysis, the order of the corrosion rates changed to: sandblasted anode > untreated anode > shot-peened anode. (author)

  12. Electrodeposition, Characterization, and Corrosion Stability of Nanostructured Anodic Oxides on New Ti-15Zr-5Nb Alloy Surface

    Directory of Open Access Journals (Sweden)

    Jose M. Calderon Moreno

    2013-01-01

    Full Text Available A new Ti-15Zr-5Nb alloy with suitable microstructure and mechanical properties was processed by galvanostatic anodization in 0.3 M H3PO4 solution and a continuous nanostructured layer of protective TiO2 oxide was electrodeposited. The obtained anatase oxide layer has a nanotubes-like porosity (SEM observations and contains significant amount of phosphorus in phosphotitanate compound embedded in the oxide lattice (Raman, FT-IR, SEM, and EDX analysis. This layer composition can stimulate the formation of the bone and its porosity can offer a good scaffold for bone cell adhesion. The electrochemical behaviour, corrosion stability, and variations of the open circuit potentials, Eoc, and corresponding open circuit potential gradients, ΔEoc, for 1500 soaking hours in Ringer solutions of 3.21, 7.58, and 8.91 pH values were studied. The anodized layer was more resistant, stable (from EIS spectra, and was formed from an inner barrier insulating layer that assures the very good alloy corrosion resistance and an outer porous layer that provides the good conditions for cell development. The nanostructured alloy has higher corrosion stability, namely, a more reduced quantity of ions released and a lower toxicity than that of the bare one. The monitoring of Eoc and ΔEoc showed the enhancement and stabilizing of the long-term passive state of the anodized alloy and, respectively, no possibility at galvanic corrosion.

  13. Effect of anodizing on pulsed Nd:YAG laser joining of polyethylene terephthalate (PET) and aluminium alloy (A5052)

    International Nuclear Information System (INIS)

    Highlights: ► Anodizing could improve the effectiveness of the laser joining process. ► Depth of molten pool will increase shear strength. ► Formation of bubbles will influence the shear strength. ► Shear strength is increased with increasing of heat input and pulse duration. -- Abstract: A series of laser joining experiments between polyethylene terephthalate (PET) and aluminium alloy (A5052) were conducted to investigate the effect of anodizing on A5052 surface on dissimilar materials used in joining. In this study, PET/A5052 joints with anodized A5052 surface exhibited greater shear strength compared to PET/A5052 joints without anodizing. The shear strength of the joints was increased with increasing of heat input and pulse duration. This indicates that the anodizing process could improve shear strength of the laser joining specimens. Significant molten pools were formed in both PET/A5052 (anodized) and PET/A5052 (as-received) joints except for PET/A5052 (as-received) sample joined at the lowest heat input and pulse duration. For the test results from laser joining under different pulse duration at the constant heat input, it was shown that joining behaviour was dominantly controlled by heat input and not by pulse duration.

  14. Structure-activity relationship of surfactant for preparing DMFC anodic catalyst

    International Nuclear Information System (INIS)

    Three kinds of surfactants as stabilizer were applied to the preparation of electrocatalysts for direct methanol fuel cell (DMFC). The catalysts have been characterized by examining their catalytic activities, morphologies and particle sizes by means of cyclic voltammetry, chronoamperometry, X-ray diffraction and transmission electron microscopy (TEM). It is found that the surfactants with different structures have a significantly influence on the catalyst shape and activity. The catalysts prepared with non-ionic surfactants as the stabilizer show higher activity for direct oxidation of methanol. The structure-activity relationship (SAR) analysis has been explored and the effect of hydrophile-lipophile balance (HLB value) has also been discussed

  15. Skeletal Amorphous Nickel Based Alloy Catalysts and Magnetically Stabilized Bed Hydrogenation Technology

    Institute of Scientific and Technical Information of China (English)

    Min Enze

    2004-01-01

    Looking toward 21 century, smaller, cleaner and more energy-efficient technology will be an important trend in the development of chemical industry. In light of the new process requirements,a number of technology breakthroughs have occurred. One of these discoveries, the magnetically stabilized bed (MSB), has been proven a powerful process for intensification. Since its initial research in the late 1980's at Research Institute of Petroleum Processing (RIPP), the MSB technology and related catalytic material have matured rapidly through an intensive research and engineering program, primarily focused on its scaling-up.In this paper, we report the discovery of a novel skeletal amorphous nickel-based alloy and its use in magnetically stabilized bed (MSB). Amorphous alloys are new kinds of catalytic materials with short-range order but long-range disorder structure. In comparison with Raney Ni, the skeletal amorphous nickel-based alloy has an increasingly higher activity in the hydrogenation of reactive groups and compounds including nitro, nitrile, olefin, acetylene, aromatics, etc. Up to now, the amorphous nickel based alloy catalysts, SRNA series catalyst, one with high Ni ratio have been commercially manufactured more than four year. The new SRNA catalyst has been successfully implemented for hydrogenation applications in slurry reactor at Balin Petrochemical, SINOPEC.SRNA catalyst with further improvement in catalytic activity and stability raise its relative stability to 2~4 times of that of conventional catalyst. In the course of the long-cycle operation of SRNA-4 the excellent catalyst activity and stability can bring about such advantage as low reaction temperature, good selectivity and low catalyst resumption.Magnetically stabilized bed (MSB), a fluidized bed of magnetizable particles by applying a spatially uniform and time-invariant magnetic field oriented axially relative to the fluidizing fluid flow, had many advantages such as the low pressure drop and

  16. Highly redox-resistant solid oxide fuel cell anode materials based on La-doped SrTiO3 by catalyst impregnation strategy

    Science.gov (United States)

    Shen, X.; Sasaki, K.

    2016-07-01

    An anode backbone using 40 wt% (ZrO2)0.89(Sc2O3)0.1(CeO2)0.01 (SSZ)-Sr0.9La0.1TiO3 (SLT) cermet was prepared for SSZ electrolyte-supported SOFC single cells. 15 mgcm-2 Ce0.9Gd0.1O2 (GDC) was impregnated to totally cover the SSZ-SLT anode backbone surface acting as a catalyst, and the cell voltage achieved 0.865 V at 200 mAcm-2 using (La0.75Sr0.25)0.98MnO3 (LSM)-SSZ cathode in 3%-humidified hydrogen fuel at 800 °C. Cell performance was substantially improved from 0.865 V to >0.97 V when 0.03 mgcm-2 Pd or Ni was further incorporated as a secondary catalyst into the anode layer. 50 redox cycles were performed to investigate redox stability of this high performance anode. It was found that even after the 50 redox cycle long-term degradation test, cell voltage at 200 mAcm-2 was retained around 0.94 V, higher than the cell performance using the conventional Ni-SSZ cermet anode. The catalytically-active reaction sites at ceria-Pd or ceria-Ni may account for the excellent performance, and the extremely low metal catalyst concentration prevent serious metal aggregation in achieving excellent redox stability.

  17. The Effect of Silane on the Microstructure, Corrosion, and Abrasion Resistances of the Anodic Films on Ti Alloy

    Science.gov (United States)

    Wang, Jinwei; Chen, Jiali

    2016-04-01

    Anodic oxide films on Ti-6Al-4V alloy are prepared using sodium hydroxide as the base electrolyte containing aminopropyl trimethoxysilane (APS) as an additive. Some APS undergo hydrolysis, adsorption, and chemical reaction with the TiO x to form Ti-O-Si bond as confirmed by ATR-FTIR and XPS spectra, and in turn their surface appearance and roughness are greatly changed with the addition of APS as observed by their SEM images. These amino anodic films possess much higher corrosive resistances since the formation of Ti-O-Si complex enhances the compactness of the anodic films and the existence of aminopropyl groups inside the pores provides additional blocking effects. Besides, their improvement in anti-abrasive capability is attributed to the toughening effect of the chemically bonded silanes and the lubrication functions from both the chemically bonded and physically absorbed silanes between the touched interfaces.

  18. Growth characterization of anodic film on AZ91D magnesium alloy in an electrolyte of Na2SiO3 and KF

    Institute of Scientific and Technical Information of China (English)

    Weiping Li; Liqun Zhu; Yihong Li; Bo Zhao

    2006-01-01

    Anodization of AZ91D magnesium alloy in the electrolyte solution of 0.5 mol/L of sodium silicate and 1.0 mol/L of potassium fluoride was investigated. The anodic films were characterized using optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The corrosion resistance of the various anodized alloys was evaluated by a fast corrosion test using the solution of hydrochloric acid and potassium dichromate. The results showed that the addition of KF resulted in the presence of NaF in the anodic film. The thickness of the anodic film formed under a constant current density of 20 mA/cm2 for 16 min at 60℃ exceeded 100 μm. The growth of the anodic film could be divided into three stages based on the anodizing time; the growth rate was much faster during stage Ⅱ than in stages Ⅰ and Ⅲ. The anodic film exhibited the highest corrosion resistance for the AZ91 alloy,which is attributed to the fact that the anodization was maintained until the end of stage Ⅱ.

  19. Regularities of anodic oxidation and properties of oxidized surface of titanium ruthenium alloys in neutral sulfate solutions

    International Nuclear Information System (INIS)

    Anodic behaviour of the alloys Ti-Ru (0.1-20 weight % of Ru) in pure solUtion 1NNa2So4 (pH 5.6) and in solution containing the syste Fe(CN)64- Fe(CN)63- has been studied. The investigation is carried oUt using the potentiodynamic method on the oxidized under isopotential conditions (at -0.10-1.65 V) alloy surface. It is shown that during anodic oxidation of the Ti-Ru alloys both components of the alloy are subjected to oxidation. Composition of oxide film depends on the potential. Starting from 1.10 V as a resUlt of oxidation of Ru to higher valent states with Ru transition to solution, selective dissolution of ruthenium constituent takes place and surface layer of oxide film is enriched with TiO2. During prolong polarization at positive enough potentials formation of continuous layer of TiO2 on the surface of oxidated alloy is possible, as a result, reactions of the solution ion oxidation, proceeding in the given range of potentials, will be hampered

  20. Regularities of anodic oxidation and properties of oxidized surface of titanium ruthenium alloys in neutral sulfate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Deryagina, O.G.; Tomashov, N.D.; Makarychev, Yu.B.; Goncharenko, B.A. (AN SSSR, Moscow. Inst. Fizicheskoj Khimii)

    1983-03-01

    Anodic behaviour of the alloys Ti-Ru (0.1-20 weight % of Ru) in pure solution 1NNa/sub 2/So/sub 4/ (pH 5.6) and in solution containing the system Fe(CN)/sub 6//sup 4 -/ Fe(CN)/sub 6//sup 3 -/ has been studied. The investigation is carried out using the potentiodynamic method on the oxidized material under isopotential conditions (at -0.10-1.65 V) alloy surface. It is shown that during anodic oxidation of the Ti-Ru alloys both components of the alloy are subjected to oxidation. Composition of oxide film depends on the potential. Starting from 1.10 V as a result of oxidation of Ru to higher valent states with Ru transition to solution, selective dissolution of ruthenium constituent takes place and surface layer of oxide film is enriched with TiO/sub 2/. During prolong polarization at positive enough potentials formation of continuous layer of TiO/sub 2/ on the surface of oxidated alloy is possible, as a result, reactions of the solution ion oxidation, proceeding in the given range of potentials, will be hampered.

  1. Low Pt content direct methanol fuel cell anode catalyst: nanophase PtRuNiZr

    Science.gov (United States)

    Narayanan, Sekharipuram R. (Inventor); Whitacre, Jay F. (Inventor)

    2010-01-01

    A method for the preparation of a metallic material having catalytic activity that includes synthesizing a material composition comprising a metal content with a lower Pt content than a binary alloy containing Pt but that displays at least a comparable catalytic activity on a per mole Pt basis as the binary alloy containing Pt; and evaluating a representative sample of the material composition to ensure that the material composition displays a property of at least a comparable catalytic activity on a per mole Pt basis as a representative binary alloy containing Pt. Furthermore, metallic compositions are disclosed that possess substantial resistance to corrosive acids.

  2. Pt Monolayer Shell on Nitrided Alloy Core—A Path to Highly Stable Oxygen Reduction Catalyst

    Directory of Open Access Journals (Sweden)

    Jue Hu

    2015-07-01

    Full Text Available The inadequate activity and stability of Pt as a cathode catalyst under the severe operation conditions are the critical problems facing the application of the proton exchange membrane fuel cell (PEMFC. Here we report on a novel route to synthesize highly active and stable oxygen reduction catalysts by depositing Pt monolayer on a nitrided alloy core. The prepared PtMLPdNiN/C catalyst retains 89% of the initial electrochemical surface area after 50,000 cycles between potentials 0.6 and 1.0 V. By correlating electron energy-loss spectroscopy and X-ray absorption spectroscopy analyses with electrochemical measurements, we found that the significant improvement of stability of the PtMLPdNiN/C catalyst is caused by nitrogen doping while reducing the total precious metal loading.

  3. Nanosized IrO(x)-Ir Catalyst with Relevant Activity for Anodes of Proton Exchange Membrane Electrolysis Produced by a Cost-Effective Procedure.

    Science.gov (United States)

    Lettenmeier, Philipp; Wang, Li; Golla-Schindler, Ute; Gazdzicki, Pawel; Cañas, Natalia A; Handl, Michael; Hiesgen, Renate; Hosseiny, Seyed S; Gago, Aldo S; Friedrich, Kaspar A

    2016-01-11

    We have developed a highly active nanostructured iridium catalyst for anodes of proton exchange membrane (PEM) electrolysis. Clusters of nanosized crystallites are obtained by reducing surfactant-stabilized IrCl3 in water-free conditions. The catalyst shows a five-fold higher activity towards oxygen evolution reaction (OER) than commercial Ir-black. The improved kinetics of the catalyst are reflected in the high performance of the PEM electrolyzer (1 mg(Ir) cm(-2)), showing an unparalleled low overpotential and negligible degradation. Our results demonstrate that this enhancement cannot be only attributed to increased surface area, but rather to the ligand effect and low coordinate sites resulting in a high turnover frequency (TOF). The catalyst developed herein sets a benchmark and a strategy for the development of ultra-low loading catalyst layers for PEM electrolysis. PMID:26616747

  4. Behavior of alloying elements during anodizing of Mg-Cu and Mg-W alloys in a fluoride/glycerol electrolyte

    Czech Academy of Sciences Publication Activity Database

    Palagonia, M. S.; Němcová, A.; Kuběna, Ivo; Šmíd, Miroslav; Gao, S.; Liu, H.; Zhong, X. L.; Haigh, S. J.; Santamaria, M.; Di Quarto, F.; Habazaki, H.; Skeldon, P.; Thomson, G.

    2015-01-01

    Roč. 162, č. 9 (2015), C487-C494. ISSN 0013-4651 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : alloying element * anodizing * ion beam analysis * magnesium * TEM Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 3.266, year: 2014 http://jes.ecsdl.org/content/162/9/C487.full

  5. Potentiodynamic studies on anodic dissolution and passivation of tin, indium and tin-indium alloys in some fruit acids solutions

    International Nuclear Information System (INIS)

    The anodic dissolution and passivation of tin, indium and tin-indium alloys were studied in 0.5 M solutions of both malic and citric acids, using potentiodynamic technique and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The E/I curves showed that the anodic behavior of all investigated electrodes exhibits active/passive transition. The active region of tin involves two anodic peaks (I and II) prior to the passive region in both the investigated acids, while indium exhibits two peaks (I and II) in malic and one peak in citric acid. These two peaks (I and II) correspond to the formation of InOOH and In(OH)3/In2O3 system, respectively, but that observed peak in citric acid is to InOOH. The active region for tin-indium alloys (I, II and III) in citric acid showed one peak (I) and shoulders (II). This shoulder predominates with increasing temperature due to little In2O3 formation and its dissolution at higher temperatures. The disappearance of this shoulder for the alloys (IV and V) with high indium percent may be due to the formation of large amounts of In2O3 with tin oxides on the surface.

  6. Long-term performance of different aluminum alloy designs as sacrificial anodes for rebars

    Directory of Open Access Journals (Sweden)

    de Rincón, O.

    2003-12-01

    Full Text Available This paper presents the performance of various cathodic-protection designs using Aluminum alloys to protect prestressed piles. The results obtained with different system designs (bracelete type-Al/Zn/In alloy, thermosprayed aluminum (3-year evaluation and conventional Al/Zn/In anocies in an epoxy-painted steel bracelet (12-year evaluation, indicated that all of these systems may be used as sacrificial anodes for pile protection. However, the thermosprayed aluminum type can not be used in prestressed concrete piles because the very negative potentials ( < -1100 mV vs. Cu/CuSO4 they supply to the reinforcement could lead to hydrogen embrittlement.

    Este trabajo presenta la realización de varios diseños de protección catódica utilizando aleaciones de aluminio para la protección de pilotes pretensados. Los resultados obtenidos con diferentes diseños (aleación de Al/Zn/In, tipo brazalete y aluminio termorociado (3 años de evaluación y ánodos convencionales de Al/Zn/In colocados en un brazalete de acero pintado con epoxy (12 años de evaluación, indicaron que todos estos sistemas pueden ser utilizados como ánodos de sacrificio para la protección de los pilotes. Sin embargo, el sistema con aluminio termorociado no puede ser utilizado en pilotes de acero pretensado debido al potencial muy negativo alcanzado por la armadura (<-1100 mV vs Cu/CuSO4, lo cual podría inducir a daños por hidrógeno.

  7. Study of ethanol electro-oxidation in acid environment on Pt{sub 3}Sn/C anode catalysts prepared by a modified polymeric precursor method under controlled synthesis conditions

    Energy Technology Data Exchange (ETDEWEB)

    De Souza, R.F.B.; Parreira, L.S.; Rascio, D.C.; Silva, J.C.M.; Teixeira-Neto, E.; Santos, M.C. [LEMN - Laboratorio de Eletroquimica e Materiais Nanoestruturados, CCNH - Centro de Ciencias Naturais e Humanas, UFABC - Universidade Federal do ABC, CEP 09.210-170, Rua Santa Adelia 166, Bairro Bangu, Santo Andre, SP (Brazil); Calegaro, M.L. [Grupo de Materiais Eletroquimicos e Metodos Eletroanaliticos, Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 780, 13566-590 Sao Carlos, SP (Brazil); Spinace, E.V.; Neto, A.O. [Instituto de Pesquisas Energeticas e Nucleares, IPEN, CNEN/SP, Av. Prof. Lineu Prestes, 2242 Cidade Universitaria, CEP 05508-900, Sao Paulo, SP (Brazil)

    2010-03-15

    A carbon-supported binary Pt{sub 3}Sn catalyst has been prepared using a modified polymeric precursor method under controlled synthesis conditions. This material was characterized using X-ray diffraction (XRD), and the results indicate that 23% (of a possible 25%) of Sn is alloyed with Pt, forming a dominant Pt{sub 3}Sn phase. Transmission electron microscopy (TEM) shows good dispersion of the electrocatalyst and small particle sizes (3.6 nm {+-}1 nm). The polarization curves for a direct ethanol fuel cell using Pt{sub 3}Sn/C as the anode demonstrated improved performance compared to that of a PtSn/C E-TEK, especially in the intrinsic resistance-controlled and mass transfer regions. This behavior is probably associated with the Pt{sub 3}Sn phase. The maximum power density for the Pt{sub 3}Sn/C electrocatalyst (58 mW cm{sup -2}) is nearly twice that of a PtSn/C E-TEK electrocatalyst (33 mW cm{sup -2}). This behavior is attributed to the presence of a mixed Pt{sub 9}Sn and Pt{sub 3}Sn alloy phase in the commercial catalysts. (author)

  8. Effect of Temperature of Oxalic Acid on the Fabrication of Porous Anodic Alumina from Al-Mn Alloys

    Directory of Open Access Journals (Sweden)

    C. H. Voon

    2013-01-01

    Full Text Available The influence of temperature of oxalic acid on the formation of well-ordered porous anodic alumina on Al-0.5 wt% Mn alloys was studied. Porous anodic alumina has been produced on Al-0.5 wt% Mn substrate by single-step anodising at 50 V in 0.5 M oxalic acid at temperature ranged from 5°C to 25°C for 60 minutes. The steady-state current density increased accordingly with the temperature of oxalic acid. Hexagonal pore arrangement was formed on porous anodic alumina that was formed in oxalic acid of 5, 10 and 15°C while disordered porous anodic alumina was formed in oxalic acid of 20 and 25°C. The temperature of oxalic acid did not affect the pore diameter and interpore distance of porous anodic alumina. Both rate of increase of thickness and oxide mass increased steadily with increasing temperature of oxalic acid, but the current efficiency decreased as the temperature of oxalic acid increased due to enhanced oxide dissolution from pore wall.

  9. High-throughput synthesis and characterization of anodic oxides on Nb-Ti alloys

    International Nuclear Information System (INIS)

    Composition spread thin film samples of Nb and Ti were prepared by co-sputtering. The composition range from Nb-5 at.% Ti to Nb-78 at.% Ti was achieved and characterized by high resolution field emission scanning electron microscopy and grazing angle X-ray diffraction. Nb stabilized the β-Ti phase over the entire range studied. The structure was cubic with a continuous change in the lattice constants with composition. Several distinct compositional zones were identified in the as-deposited film morphology. Then, anodic oxides were grown potentiodynamically and characterized by electrochemical impedance spectroscopy using a scanning droplet cell to yield a comprehensive description of oxide film properties including dielectric permittivity, resistivity, thickness and film formation factor. Mott-Schottky analysis of potentiostatically grown oxides showed how the alloy composition influences the flat band potential and the donor density of the mixed n-type semiconducting oxides. Complementary X-ray photo electron spectroscopy as a chemical analysis revealed differences in the oxide compositions as compared to the as-deposited metal resulting from the different ion transport numbers.

  10. Low-temperature, vapor-liquid-solid, laterally grown silicon films using alloyed catalysts

    Science.gov (United States)

    LeBoeuf, Jerome L.; Brodusch, Nicolas; Gauvin, Raynald; Quitoriano, Nathaniel J.

    2014-12-01

    Using amorphous oxide templates known as micro-crucibles which confine a vapor-liquid-solid catalyst to a specific geometry, two-dimensional silicon thin-films of a single orientation have been grown laterally over an amorphous substrate and defects within crystals have been necked out. The vapor-liquid-solid catalysts consisted nominally of 99% gold with 1% titanium, chromium, or aluminum, and each alloy affected the processing of micro-crucibles and growth within them significantly. It was found that chromium additions inhibited the catalytic effect of the gold catalysts, titanium changed the morphology of the catalyst during processing and aluminum stabilized a potential third phase in the gold-silicon system upon cooling. Two mechanisms for growing undesired nanowires were identified both of which hindered the VLS film growth, fast silane cracking rates and poor gold etching, which left gold nanoparticles near the gold-vapor interface. To reduce the silane cracking rates, growth was done at a lower temperature while an engineered heat and deposition profile helped to reduce NWs caused by the second mechanism. Through experimenting with catalyst compositions, the fundamental mechanisms which produce concentration gradients across the gold-silicon alloy within a given micro-crucible have been proposed. Using the postulated mechanisms, micro-crucibles were designed which promote high-quality, single crystal growth of semiconductors.

  11. Enhancing pitting corrosion resistance of AlxCrFe1.5MnNi0.5 high-entropy alloys by anodic treatment in sulfuric acid

    International Nuclear Information System (INIS)

    High-entropy alloys are a newly developed family of multi-component alloys that comprise various major alloying elements. Each element in the alloy system is present in between 5 and 35 at.%. The crystal structures and physical properties of high-entropy alloys differ completely from those of conventional alloys. The electrochemical impedance spectra (EIS) of the AlxCrFe1.5MnNi0.5 (x = 0, 0.3, 0.5) alloys, obtained in 0.1 M HCl solution, clearly revealed that the corrosion resistance values were determined to increase from 21 to 34 Ωcm2 as the aluminum content increased from 0 to 0.5 mol, and were markedly lower than that of 304 stainless steel (243 Ωcm2). At passive potential, the corresponding current declined with the anodizing time accounting, causing passivity by the growth of the multi-component anodized film in H2SO4 solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surface of anodized Al0.3CrFe1.5MnNi0.5 alloy formed aluminum and chromium oxide film which was the main passivating compound on the alloy. This anodic treatment increased the corrosion resistance in the EIS measurements of the CrFe1.5MnNi0.5 and Al0.3CrFe1.5MnNi0.5 alloys by two orders of magnitude. Accordingly, the anodic treatment of the AlxCrFe1.5MnNi0.5 alloys optimized their surface structures and minimized their susceptibility to pitting corrosion

  12. Corrosion and Discharge Behaviors of Mg-Al-Zn and Mg-Al-Zn-In Alloys as Anode Materials

    Directory of Open Access Journals (Sweden)

    Jiarun Li

    2016-03-01

    Full Text Available The Mg-6%Al-3%Zn and Mg-6%Al-3%Zn-(1%, 1.5%, 2%In alloys were prepared by melting and casting. Their microstructures were investigated via metallographic and energy-dispersive X-ray spectroscopy (EDS analysis. Moreover, hydrogen evolution and electrochemical tests were carried out in 3.5 wt% NaCl solution aiming at identifying their corrosion mechanisms and discharge behaviors. The results suggested that indium exerts an improvement on both the corrosion rate and the discharge activity of Mg-Al-Zn alloy via the effects of grain refining, β-Mg17Al12 precipitation, dissolving-reprecipitation, and self-peeling. The Mg-6%Al-3%Zn-1.5%In alloy with the highest corrosion rate at free corrosion potential did not perform desirable discharge activity indicating that the barrier effect caused by the β-Mg17Al12 phase would have been enhanced under the conditions of anodic polarization. The Mg-6%Al-3%Zn-1.0%In alloy with a relative low corrosion rate and a high discharge activity is a promising anode material for both cathodic protection and chemical power source applications.

  13. Alloyed Ni-Fe nanoparticles as catalysts for NH3 decomposition

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose; Chakraborty, Debasish; Chorkendorff, Ib;

    2012-01-01

    A rational design approach was used to develop an alloyed Ni-Fe/Al2O3 catalyst for decomposition of ammonia. The dependence of the catalytic activity is tested as a function of the Ni-to-Fe ratio, the type of Ni-Fe alloy phase, the metal loading and the type of oxide support. In the tests with hi...... smallest particles in terms of catalytic activity per active site. Compared with SiO2, ZrO2 and TiO2, the support materials Al2O3 or Mg-Al-spinel give the highest performance in the high temperature range....

  14. Nanoporous alumina formed by self-organized two-step anodization of Ni{sub 3}Al intermetallic alloy in citric acid

    Energy Technology Data Exchange (ETDEWEB)

    Stepniowski, Wojciech J., E-mail: wstepniowski@wat.edu.pl [Department of Advanced Materials and Technology, Faculty of New Technologies and Chemistry, Military University of Technology, Kaliskiego 2 Str., 00-908 Warszawa (Poland); Cieslak, Grzegorz; Norek, Malgorzata; Karczewski, Krzysztof; Michalska-Domanska, Marta; Zasada, Dariusz; Polkowski, Wojciech; Jozwik, Pawel; Bojar, Zbigniew [Department of Advanced Materials and Technology, Faculty of New Technologies and Chemistry, Military University of Technology, Kaliskiego 2 Str., 00-908 Warszawa (Poland)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Anodic porous alumina was formed by Ni{sub 3}Al intermetallic alloy anodization. Black-Right-Pointing-Pointer The anodizations were conducted in 0.3 M citric acid. Black-Right-Pointing-Pointer Nanopores geometry depends on anodizing voltage. Black-Right-Pointing-Pointer No barrier layer was formed during anodization. - Abstract: Formation of the nanoporous alumina on the surface of Ni{sub 3}Al intermetallic alloy has been studied in details and compared with anodization of aluminum. Successful self-organized anodization of this alloy was performed in 0.3 M citric acid at voltages ranging from 2.0 to 12.0 V using a typical two-electrode cell. Current density records revealed different mechanism of the porous oxide growth when compared to the mechanism pertinent for the anodization of aluminum. Electrochemical impedance spectroscopy experiments confirmed the differences in anodic oxide growth. Surface and cross-sections of the Ni{sub 3}Al intermetallic alloy with anodic oxide were observed with field-emission scanning electron microscope and characterized with appropriate software. Nanoporous oxide growth rate was estimated from cross-sectional FE-SEM images. The lowest growth rate of 0.14 {mu}m/h was found for the anodization at 0 Degree-Sign C and 2.0 V. The highest one - 2.29 {mu}m/h - was noticed for 10.0 V and 30 Degree-Sign C. Pore diameter was ranging from 18.9 nm (2.0 V, 0 Degree-Sign C) to 32.0 nm (12.0 V, 0 Degree-Sign C). Interpore distance of the nanoporous alumina was ranging from 56.6 nm (2.0 V, 0 Degree-Sign C) to 177.9 nm (12.0 V, 30 Degree-Sign C). Pore density (number of pore occupying given area) was decreasing with anodizing voltage increase from 394.5 pores/{mu}m{sup 2} (2.0 V, 0 Degree-Sign C) to 94.9 pores/{mu}m{sup 2} (12.0 V, 0 Degree-Sign C). All the geometrical features of the anodic alumina formed by two-step self-organized anodization of Ni{sub 3}Al intermetallic alloy are depending on the

  15. Effect of anodic polarization on the free-floating parts at Pt/YSZ catalyst electrode

    International Nuclear Information System (INIS)

    Photoemission electron microscopy (PEEM) was used as spatially resolving method to explore the effect of electrochemical pumping with a positive voltage to porous platinum electrodes interfaced as working electrode to yttrium stabilized zirconia (YSZ). The experiments were conducted under UHV conditions (p ≈ 10−9 mbar). In PEEM a uniform rapid darkening of the Pt surface was observed during anodic polarization followed by the appearance of bright spots on a dark background. The bright spots observed in PEEM images are due to zirconia reduction around electrically isolated Pt islands

  16. Effect of anodic polarization on the free-floating parts at Pt/YSZ catalyst electrode

    Energy Technology Data Exchange (ETDEWEB)

    Toghan, Arafat, E-mail: arafat.toghan@yahoo.com [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, D-91058 Erlangen (Germany); Chemistry Department, Faculty of Science, South Valley University, 83523 Qena (Egypt); Institut für Physikalische Chemie und Elektrochemie, Leibniz-Universität Hannover, Callinstrasse 3-3a, D-30167 Hannover (Germany); Imbihl, R. [Institut für Physikalische Chemie und Elektrochemie, Leibniz-Universität Hannover, Callinstrasse 3-3a, D-30167 Hannover (Germany)

    2015-09-30

    Photoemission electron microscopy (PEEM) was used as spatially resolving method to explore the effect of electrochemical pumping with a positive voltage to porous platinum electrodes interfaced as working electrode to yttrium stabilized zirconia (YSZ). The experiments were conducted under UHV conditions (p ≈ 10{sup −9} mbar). In PEEM a uniform rapid darkening of the Pt surface was observed during anodic polarization followed by the appearance of bright spots on a dark background. The bright spots observed in PEEM images are due to zirconia reduction around electrically isolated Pt islands.

  17. Pre-coating of LSCM perovskite with metal catalyst for scalable high performance anodes

    KAUST Repository

    Boulfrad, Samir

    2013-07-01

    In this work, a highly scalable technique is proposed as an alternative to the lab-scale impregnation method. LSCM-CGO powders were pre-coated with 5 wt% of Ni from nitrates. After appropriate mixing and adequate heat treatment, coated powders were then dispersed into organic based vehicles to form a screen-printable ink which was deposited and fired to form SOFC anode layers. Electrochemical tests show a considerable enhancement of the pre-coated anode performances under 50 ml/min wet H2 flow with polarization resistance decreased from about 0.60cm2 to 0.38 cm2 at 900 C and from 6.70 cm2 to 1.37 cm2 at 700 C. This is most likely due to the pre-coating process resulting in nano-scaled Ni particles with two typical sizes; from 50 to 200 nm and from 10 to 40 nm. Converging indications suggest that the latter type of particle comes from solid state solution of Ni in LSCM phase under oxidizing conditions and exsolution as nanoparticles under reducing atmospheres. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  18. Methanol-Tolerant Cathode Catalyst Composite For Direct Methanol Fuel Cells

    Science.gov (United States)

    Zhu, Yimin; Zelenay, Piotr

    2006-03-21

    A direct methanol fuel cell (DMFC) having a methanol fuel supply, oxidant supply, and its membrane electrode assembly (MEA) formed of an anode electrode and a cathode electrode with a membrane therebetween, a methanol oxidation catalyst adjacent the anode electrode and the membrane, an oxidant reduction catalyst adjacent the cathode electrode and the membrane, comprises an oxidant reduction catalyst layer of a platinum-chromium alloy so that oxidation at the cathode of methanol that crosses from the anode through the membrane to the cathode is reduced with a concomitant increase of net electrical potential at the cathode electrode.

  19. Partial oxidation of dimethyl ether using the structured catalyst Rh/Al2O3/Al prepared through the anodic oxidation of aluminum.

    Science.gov (United States)

    Yu, B Y; Lee, K H; Kim, K; Byun, D J; Ha, H P; Byun, J Y

    2011-07-01

    The partial oxidation of dimethyl ether (DME) was investigated using the structured catalyst Rh/Al2O3/Al. The porous Al2O3 layer was synthesized on the aluminum plate through anodic oxidation in an oxalic-acid solution. It was observed that about 20 nm nanopores were well developed in the Al2O3 layer. The thickness of Al2O3 layer can be adjusted by controlling the anodizing time and current density. After pore-widening and hot-water treatment, the Al2O3/Al plate was calcined at 500 degrees C for 3 h. The obtained delta-Al2O3 had a specific surface area of 160 m2/g, making it fit to be used as a catalyst support. A microchannel reactor was designed and fabricated to evaluate the catalytic activity of Rh/Al2O3/Al in the partial oxidation of DME. The structured catalyst showed an 86% maximum hydrogen yield at 450 degrees C. On the other hand, the maximum syngas yield by a pack-bed-type catalyst could be attained by using a more than fivefold Rh amount compared to that used in the structured Rh/Al2O3/Al catalyst. PMID:22121705

  20. Applications Ni59Nb40Pt(1-x) Xx (X= Sn,Sby and Ru) amorphous alloy as anodes for direct methanol (DMFC) fuel cells

    International Nuclear Information System (INIS)

    The search of new anode materials of amorphous nature for methanol fuel cells is one of the aims of this work.The main problem that fuel cells present is related to the catalytic material and its distribution in a suitable matrix.Amorphous alloys are particularly attractive materials as catalyst supports because of their high conductivity, high corrosion resistance in sulphuric acid, as well as the possibility of a good distribution of the electrocatalytic particles, mainly platinum and platinum-tin, on a conducting matrix.The electrooxidation of methanol, in percloric acid medium, has been used as probe to evaluate the performance of metallic amorphous electrodes, with compositions Ni59Nb40Pt1, Ni59Nb40Pt0.6Sn0.4, Ni59Nb40Pt0.6Sb0.4 and Ni59Nb40Pt0.6Ru0.4.The electrocatalytic activity of the alloyed ribbons of compositions (x = 0.6, 1% at. in platinum) is improved considerably, so much for the change in their composition, as for the roughness degree that the catalytic surfaces present. The increase of the tolerance to adsorbed species, and better resistance to the poisoning of their catalytic centers, can be observed by means of voltammetric experiments at different activation times with HF 48%. The electrooxidation of methanol in the amorphous alloy of composition Ni59Nb40Pt1, is influenced by the nature of the used electrolyte, presenting smaller values of current density in solutions 1M H2SO4 than in 1M of HClO4.This behavior is not observed in the alloy Ni59Nb40Pt0.6Sn0.4, Ni59Nb40Pt0.6Sb0.4 and Ni59Nb40Pt0.6Ru0.4which does not present a poisoning of the catalytic centers depending on the used electrolyte.Adding tin to the alloys showed the existence of a synergetic effect in the methanol electrooxidation process, attaining to a descent of 20 mV vs Ag/AgCl in the onset potential, and about 200 mV in the maximun peak potential

  1. Apatite Formation and Biocompatibility of a Low Young's Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water.

    Directory of Open Access Journals (Sweden)

    Hidetatsu Tanaka

    Full Text Available Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young's modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young's modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank's solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion.

  2. Catalyst-free synthesis of Si-SiOx core-shell nanowire anodes for high-rate and high-capacity lithium-ion batteries.

    Science.gov (United States)

    Lim, Kwan Woo; Lee, Jung-In; Yang, Jieun; Kim, Young-Ki; Jeong, Hu Young; Park, Soojin; Shin, Hyeon Suk

    2014-05-14

    Si-SiOx core-shell nanowires (NWs) ranging from 10 to 30 nm in diameter are prepared by a simple evaporation of silicon monoxide and control of substrate temperatures without any catalyst. The Si-SiOx NWs grown at 735 and 955 °C are strongly anchored to the Cu current collector by forming copper silicide at the interface between Si and Cu, and subsequently used as anodes in lithium-ion batteries, in which no binder or conducting materials are used. The Si-SiOx NWs anodes show excellent electrochemical performances in terms of capacity retention and rate capability. In particular, the Si-SiOx NW anode grown at 955 °C shows a reversible capacity of ∼1000 mAh g(-1) even at a high-rate of 50 C. This catalyst-free synthetic route of Si-SiOx NWs that are strongly anchored to the Cu current collector opens up an effective process for fabricating other high-capacity anodes in lithium-ion batteries (LIBs). PMID:24754908

  3. Electrodeposition, Characterization, and Corrosion Stability of Nanostructured Anodic Oxides on New Ti-15Zr-5Nb Alloy Surface

    OpenAIRE

    Jose M. Calderon Moreno; Cora Vasilescu; Silviu Iulian Drob; Monica Popa; Paula Drob; Ecaterina Vasilescu

    2013-01-01

    A new Ti-15Zr-5Nb alloy with suitable microstructure and mechanical properties was processed by galvanostatic anodization in 0.3 M H3PO4 solution and a continuous nanostructured layer of protective TiO2 oxide was electrodeposited. The obtained anatase oxide layer has a nanotubes-like porosity (SEM observations) and contains significant amount of phosphorus in phosphotitanate compound embedded in the oxide lattice (Raman, FT-IR, SEM, and EDX analysis). This layer composition can stimulate the ...

  4. Effects of Al and Sn on electrochemical properties of Mg-6%Al-1%Sn (mass fraction) magnesium alloy as anode in 3.5%NaCl solution

    Institute of Scientific and Technical Information of China (English)

    黄俏; 余琨; 杨士海; 文利; 戴翼龙; 乔雪岩

    2014-01-01

    Mg-6%Al-1%Sn (mass fraction) alloy is a newly developed anode material for seawater activated batteries. The electrochemical properties of Mg-1%Sn, Mg-6%Al and Mg-6%Al-1%Sn alloys are measured by galvanostatic and potentiodynamic tests. Scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) is used to characterize the microstructures of the experimental alloys. The results show that the Mg-6%Al-1%Sn alloy obtains more negative discharge potential (−1.38 V (vs SCE)) in hot-rolled condition. This is attributed to the fine dynamically recrystallized grains during the hot rolling process. After the experimental alloys are annealed at 473 K for 1 h, the discharge potentials of Mg-6%Al-1%Sn alloy are more negative than those of Mg-6%Al alloy under different current densities. After annealing at 673 K, the discharge potentials of Mg-6%Al-1%Sn alloy become more positive than those of Mg-6%Al alloy. Such phenomenon is due to the coarse grains and the second phase Mg2Sn. The discharge potentials of Mg-1%Sn shift positively obviously in the discharge process compared with Mg-6%Al-1%Sn alloy. This is due to the corrosion products pasting on the discharge surface, which leads to anode polarization.

  5. Effects of half-wave and full-wave power source on the anodic oxidation process on AZ91D magnesium alloy

    Science.gov (United States)

    Wang, Ximei; Zhu, Liqun; Li, Weiping; Liu, Huicong; Li, Yihong

    2009-03-01

    Anodic films have been prepared on the AZ91D magnesium alloys in 1 mol/L Na 2SiO 3 with 10 vol.% silica sol addition under the constant voltage of 60 V at room temperature by half-wave and full-wave power sources. The weight of the anodic films has been scaled by analytical balance, and the thickness has been measured by eddy current instrument. The surface morphologies, chemical composition and structure of the anodic films have been characterized by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the thickness and weight of the anodic films formed by the two power sources both increase with the anodizing time, and the films anodized by full-wave power source grow faster than that by half-wave one. Furthermore, we have fitted polynomial to the scattered data of the weight and thickness in a least-squares sense with MATLAB, which could express the growth process of the anodic films sufficiently. The full-wave power source is inclined to accelerate the growth of the anodic films, and the half-wave one is mainly contributed to the uniformity and fineness of the films. The anodic film consists of crystalline Mg 2SiO 4 and amorphous SiO 2.

  6. Effects of half-wave and full-wave power source on the anodic oxidation process on AZ91D magnesium alloy

    International Nuclear Information System (INIS)

    Anodic films have been prepared on the AZ91D magnesium alloys in 1 mol/L Na2SiO3 with 10 vol.% silica sol addition under the constant voltage of 60 V at room temperature by half-wave and full-wave power sources. The weight of the anodic films has been scaled by analytical balance, and the thickness has been measured by eddy current instrument. The surface morphologies, chemical composition and structure of the anodic films have been characterized by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the thickness and weight of the anodic films formed by the two power sources both increase with the anodizing time, and the films anodized by full-wave power source grow faster than that by half-wave one. Furthermore, we have fitted polynomial to the scattered data of the weight and thickness in a least-squares sense with MATLAB, which could express the growth process of the anodic films sufficiently. The full-wave power source is inclined to accelerate the growth of the anodic films, and the half-wave one is mainly contributed to the uniformity and fineness of the films. The anodic film consists of crystalline Mg2SiO4 and amorphous SiO2

  7. Novel strategy to mitigate cathode catalyst degradation during air/air startup cycling via the atmospheric resistive switching mechanism of a hydrogen anode with a platinum catalyst supported on tantalum-doped titanium dioxide

    Science.gov (United States)

    Shintani, Haruhiko; Kojima, Yuya; Kakinuma, Katsuyoshi; Watanabe, Masahiro; Uchida, Makoto

    2015-10-01

    We propose a new strategy for alleviating the reverse current phenomenon using a unique "atmospheric resistive switching mechanism" (ARSM) of a metal oxide semiconductor support, such that the electrical resistivity changes depending on the gas atmosphere. The membrane-electrode assembly (MEA) using Ta-doped TiO2-supported platinum (Pt/Ta-TiO2) as the anode catalyst showed approximately one order of magnitude greater resistance in air than in hydrogen. The overpotential of the hydrogen oxidation reaction was negligible up to at least 1.5 A cm-2. The losses of electrochemically active surface area and carbon corrosion of the cathode catalyst during air/air startup cycling were significantly suppressed by the use of the Pt/Ta-TiO2 anode. The decrease in the degradation is attributed to a reduction of the reverse current due to a low oxygen reduction reaction rate at the anode, which showed high resistivity in air. These results demonstrate the effectiveness of the ARSM in mitigating cathode catalyst degradation during air/air startup cycling.

  8. Repairing of anodic oxide films on Al-Zn alloy coated steel after removal with photon rupture in solutions

    International Nuclear Information System (INIS)

    Analysis of abrupt destroyed of passive oxide films on Al - Zn alloy layer coated on steel and its repair is important to understand the localized corrosion of steels. In the present investigation, anodic oxide films formed on Al - Zn coated steel specimens were removed by photon rupture method (one pulse of focused pulsed Nb - YAG laser beam irradiation) aat a constant potential in sodium borate solutions, pH = 9.2, with / without chloride ions to monitor the current transient. Irradiation with a pulsed laser in solutions causes abrupt removal of the anodic oxide film on the specimen at the laser-irradiated area. Without chloride ions, oxide films were reformed in the sodium borate solution at - 0.5 to 1 V after removal of the anodic oxide film, However, in chloride ions containing solutions, pitting corrosion of Zn - 55 mass % Al coated layers occurs at high potentials, while film reformation occurs at low potentials. It was also found that chloride ions enhance dissolution of aluminum and zinc at the very initial period after laser irradiation

  9. Mechanism and kinetics of anodic dissolution of aluminium and its alloy with zinc and rare earths in a sodium polyvanadate solution

    International Nuclear Information System (INIS)

    It is established through gravimetry variable-current impedance, roentgenoelectron spectroscopy and measurement of anodic polarization curves method that the Al-Zn (45 mass %) alloy in the NaVO3 (0.5 M) at 298 K is characterized by lower corrosion resistance as compared to the same alloy microalloyed by rare earth metals (0.1 mass %). The minimum value for electrode capacity is noted at the metal/solution interface of the Al-Zn alloy (45 mass %) and the maximum value for the Al-Zn alloy (45 mass %)-Sc (0.1 mass %); in the latter case it is related also to the minimum value of the anodic passivation current density

  10. Oxide-supported PtCo alloy catalyst for intermediate temperature polymer electrolyte fuel cells

    OpenAIRE

    Stassi, Alessandro; Gatto, Irene; Baglio, Vincenzo; Passalacqua, Enza; Aricò, Antonino S.

    2013-01-01

    International audience A Pt-Co alloy catalyst supported on a Ta-doped Ti-oxide was investigated for the oxygen reduction reaction in a polymer electrolyte fuel cell (PEMFC) operating between 80° and 110 °C at different relative humidity (100% and 33% R.H.). A crystalline Anatase phase was obtained for the Ta-doped Ti-oxide support with BET surface area of about 150 m2/g. Pt and Pt3Co1 nanoparticles dispersed on the Ta-doped Ti-oxide showed a crystallite size of 3.9 and 2.9 nm, respectively...

  11. Magnetically stabilized bed reactor for selective hydrogenation of olefins in reformate with amorphous nickel alloy catalyst

    Institute of Scientific and Technical Information of China (English)

    Xuhong; Mu; Enze; Min

    2007-01-01

    A magnetically stabilized bed (MSB) reactor for selective hydrogenation of olefins in reformate was developed by combining the advantages of MSB and amorphous nickel alloy catalyst. The effects of operating conditions, such as temperature, pressure, liquid space velocity, hydrogen-to-oil ratio, and magnetic field intensity on the reaction were studied. A mathematical model of MSB reactor for hydrogenation of olefins in reformate was established. A reforming flow scheme with a post-hydrogenation MSB reactor was proposed. Finally, MSB hydrogenation was compared with clay treatment and conventional post-hydrogenation.

  12. The Integration of a Structural Water Gas Shift Catalyst with a Vanadium Alloy Hydrogen Transport Device

    Energy Technology Data Exchange (ETDEWEB)

    Barton, Thomas; Argyle, Morris; Popa, Tiberiu

    2009-06-30

    This project is in response to a requirement for a system that combines water gas shift technology with separation technology for coal derived synthesis gas. The justification of such a system would be improved efficiency for the overall hydrogen production. By removing hydrogen from the synthesis gas stream, the water gas shift equilibrium would force more carbon monoxide to carbon dioxide and maximize the total hydrogen produced. Additional benefit would derive from the reduction in capital cost of plant by the removal of one step in the process by integrating water gas shift with the membrane separation device. The answer turns out to be that the integration of hydrogen separation and water gas shift catalysis is possible and desirable. There are no significant roadblocks to that combination of technologies. The problem becomes one of design and selection of materials to optimize, or at least maximize performance of the two integrated steps. A goal of the project was to investigate the effects of alloying elements on the performance of vanadium membranes with respect to hydrogen flux and fabricability. Vanadium was chosen as a compromise between performance and cost. It is clear that the vanadium alloys for this application can be produced, but the approach is not simple and the results inconsistent. For any future contracts, large single batches of alloy would be obtained and rolled with larger facilities to produce the most consistent thin foils possible. Brazing was identified as a very likely choice for sealing the membranes to structural components. As alloying was beneficial to hydrogen transport, it became important to identify where those alloying elements might be detrimental to brazing. Cataloging positive and negative alloying effects was a significant portion of the initial project work on vanadium alloying. A water gas shift catalyst with ceramic like structural characteristics was the second large goal of the project. Alumina was added as a

  13. Characterization of anodic coating formed on Mg-3Nd-0.2Zn-0.4Zr Mg alloy in alkaline electrolyte

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Anodization of rare earth-containing Mg alloy of Mg-3Nd-0.2Zn-0.4Zr(mass fraction,%)(NZ30K)was performed in composite electrolyte containing NaOH,KOH,K2SiO3,Na2SiO3,NaF,KF etc.The anodic coating was characterized by using X-ray diffraction(XRD),field emission electron scanning microseope(FE-SEM)and electron probe microscopic analysis(EPMA).The corrosion resistance of the anodized alloy and the substrate was evaluated in 5%NaCl solution using electrochemical impedance spectroscopy(EIS).The results of XRD show that the anodic coating is mainly composed of MgO.EPMA indicates that magnesium and oxygen are almost uniformly distributed across the coating,and the fluorine content decreases gradually from the interface of coating-substrate to the surface,whereas the distribution of silicon is reverse to that of fluorine.The results of EIS analysis shows that the anodic coating exhibits the superior corrosion resistance for NZ30K alloy.

  14. Investigation of carbon supported PtW catalysts as CO tolerant anodes at high temperature in proton exchange membrane fuel cell

    Science.gov (United States)

    Hassan, Ayaz; Paganin, Valdecir A.; Ticianelli, Edson A.

    2016-09-01

    The CO tolerance mechanism and the stability of carbon supported PtW electrocatalysts are evaluated in the anode of a proton exchange membrane fuel cell (PEMFC) at two different temperatures. The electrocatalysts are characterized by energy dispersive spectroscopy, X-ray diffraction, and transmission electron spectroscopy. Employed electrochemical techniques include cyclic voltammetry, CO stripping, fuel cell polarization, and online mass spectrometry. At a cell temperature of 85 °C, the PtW/C catalyst shows higher CO tolerance compared to Pt/C due an electronic effect of WOx in the Pt 5d band, which reduces the CO adsorption. An increase in hydrogen oxidation activity in the presence of CO is observed for both the catalysts at a higher temperature, due to the decrease of the Pt-CO coverage. A reduction in the current densities occurs for the PtW/C catalyst in both polarization curves and cyclic voltammograms after 5000 cycles of the anode in the range of 0.1-0.7 V vs. RHE at 50 mVs-1. This decrease in performance is assigned to the dissolution of W, with a consequent increase in the membrane resistivity. However, the observed decline of performance is small either in the presence of pure H2 or in the presence of H2/CO.

  15. Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells

    International Nuclear Information System (INIS)

    Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs

  16. Anodic corrosion of lead, tin and lead-tin alloys in sulphuric acid solutions. Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Salmi, K.

    1993-01-01

    The electrochemical behavior of lead and tin and the effect of tin on the anodic behavior of lead in sulfuric acid solutions has been studied in relation to the corrosion of the positive grid of the lead acid battery. The release of soluble Pb(IV) species into sulfuric acid during the anodic polarization of lead has been mapped using the ring-disk electrode technique and their role in the electrochemistry of lead is discussed. Part of the tetravalent products formed on lead are reduced only at high negative potentials. The usefulness of the rotating ring-disk electrode for the determination of different soluble corrosion products has been demonstrated. Mechanisms for tin dissolution in different regions (open circuit, active dissolution and passive region) have been proposed. Ex situ surface analysis of the anodic layer formed on the tin electrode showed this to be mainly SnO.

  17. Effects of Cryogenic Forging and Anodization on the Mechanical Properties and Corrosion Resistance of AA6066–T6 Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Teng-Shih Shih

    2016-03-01

    Full Text Available In this study, AA6066 alloy samples were cryogenically forged after annealing and then subjected to solution and aging treatments. Compared with conventional 6066-T6 alloy samples, the cryoforged samples exhibited a 34% increase in elongation but sacrificed about 8%–12% in ultimate tensile strength (UTS and yield stress (YS. Such difference was affected by the constituent phases that changed in the samples’ matrix. Anodization and sealing did minor effect on tensile strength of the 6066-T6 samples with/without cryoforging but it decreased samples’ elongation about 8%–10%. The anodized/sealed anodic aluminum oxide (AAO film enhanced the corrosion resistance of the cryoforged samples.

  18. Activity and Stability of Rare Earth-Based Hydride Alloys as Catalysts of Hydrogen Absorption-Oxidation Reactions

    Institute of Scientific and Technical Information of China (English)

    Ying Taokai(应桃开); Gao Xueping(高学平); Hu Weikang(胡伟康); Noréus Dag

    2004-01-01

    Rare earth-based AB5-type hydrogen storage alloys as catalysts of hydrogen-diffusion electrodes for hydrogen absorption and oxidation reactions in alkaline fuel cells were investigated. It is demonstrated that the meta-hydride hydrogen-diffusion electrodes could be charged by hydrogen gas and electrochemically discharged at the same time to retain a stable oxidation potential for a long period. The catalytic activities and stability are almost comparable with a Pt catalyst on the active carbon. Further improvement of performances is expected via reduction of catalyst size into nanometers.

  19. Rhenium Nanochemistry for Catalyst Preparation

    Directory of Open Access Journals (Sweden)

    Vadim G. Kessler

    2012-08-01

    Full Text Available The review presents synthetic approaches to modern rhenium-based catalysts. Creation of an active center is considered as a process of obtaining a nanoparticle or a molecule, immobilized within a matrix of the substrate. Selective chemical routes to preparation of particles of rhenium alloys, rhenium oxides and the molecules of alkyltrioxorhenium, and their insertion into porous structure of zeolites, ordered mesoporous MCM matrices, anodic mesoporous alumina, and porous transition metal oxides are considered. Structure-property relationships are traced for these catalysts in relation to such processes as alkylation and isomerization, olefin metathesis, selective oxidation of olefins, methanol to formaldehyde conversion, etc.

  20. Effect of Fluoride Ions on the Anodic Behavior of Mill Annealed and Aged Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, M A; Carranza-, R M; Rebak, R B

    2003-10-07

    Alloy 22 (N06022) is the current candidate alloy to fabricate the external wall of the high level nuclear waste containers for the Yucca Mountain repository. It was of interest to study and compare the general and localized corrosion susceptibility of Alloy 22 in saturated NaF solutions ({approx} 1 M NaF) at 90 C. Standard electrochemical tests such as cyclic potentiodynamic polarization, amperometry, potentiometry, and electrochemical impedance spectroscopy were used. Studied variables included the solution pH and the alloy microstructure (thermal aging). Results show that Alloy 22 is highly resistant to general and localized corrosion in pure fluoride solutions. Thermal aging is not detrimental and even seems to be slightly beneficial for general corrosion in alkaline solutions.

  1. Synergistic Effects of Alloying and Thiolate Modification in Furfural Hydrogenation over Cu-Based Catalysts.

    Science.gov (United States)

    Pang, Simon H; Love, Nicole E; Medlin, J Will

    2014-12-01

    Control of bimetallic surface composition and surface modification with self-assembled monolayers (SAMs) represent two methods for modifying catalyst activity and selectivity. However, possible synergistic effects of employing these strategies in concert have not been previously explored. We investigated the effects of modifying Cu/Al2O3 catalysts by alloying with Ni and modifying with octadecanethiol (C18) SAMs, using furfural hydrogenation as a probe reaction. Incorporation of small amounts of Ni (Cu4Ni) improved catalytic activity while slightly reducing hydrogenation selectivity. Further incorporation of Ni resulted in high rates for decarbonylation and ring-opening. Modification of the Cu4Ni catalyst with C18-SAMs resulted in improvement in both the activity and hydrogenation selectivity. X-ray photoelectron spectroscopy experiments on bimetallic thin films and density functional theory calculations revealed that the C18-SAM kinetically stabilized Cu at the surface under hydrogenation conditions. These results indicate that thiolate monolayers can be used to control surface bimetallic composition to improve catalytic performance. PMID:26278941

  2. Effect of nickel content on the anodic dissolution and passivation of zinc–nickel alloys in alkaline solutions by potentiodynamic and potentiostatic techniques

    Indian Academy of Sciences (India)

    Abdel-Rahman El-Sayed; Hany M Abd El-Lateef; Hossnia S Mohran

    2015-04-01

    The effect of systematic increase of Ni on the anodic dissolution and passivation of Zn–Ni alloys in various concentrations of KOH solution (0.1–1 M) was investigated. The anodic dissolution and passivation behaviour for each pure Zn and Ni in the same studied solutions was also investigated, and the obtained data were compared. Potentiodynamic and potentiostatic methods were used, and the corrosion layer formed on each electrode surface was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results of the anodic potentiodynamic measurements exhibited that the polarization curves showed active/passive transition in the case of Ni and active/pseudopassive in the case of both Zn and its alloys. The results showed that the increase in Ni content increases the activation energy (a) and decreases the dissolution rate of the alloys in KOH solution, and the lowest dissolution rate was obtained at 10% Ni. The results of both potentiodynamic and potentiostatic measurements exhibit sudden increase in current density which is observed at certain positive potential (+0.42 V .SCE) in the case of the investigated alloys. This indicates that the addition of Ni to Zn promotes the electrochemical reaction (in the passive region). However, the passivation potential shifted to more positive direction with the increase in Ni content in the alloy.

  3. Electrically conductive anodized aluminum coatings

    Science.gov (United States)

    Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

    2001-01-01

    A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

  4. Fabrication and characterization of anodic oxide films on a Ti-10V-2Fe-3Al titanium alloy

    Institute of Scientific and Technical Information of China (English)

    Jian-hua Liu; Jun-lan Yi; Song-mei Li; Mei Yu; Yong-zhen Xu

    2009-01-01

    Anodic oxide films of the titanium alloy Ti-10V-2Fe-3Al in ammonium tartrate electrolyte without hydrofluoric acid or fluoride were fabricated.The morphology,components,and microstructure of the films were characterized by scanning electron mi-croscopy (SEM),X-ray photoelectron spectroscopy (XPS),X-ray diffraction (XRD),and Raman spectroscopy.The results showed that the films were thick,uniform,and nontransparent.Such films exhibited sedimentary morphology,with a thickness of about 3 μm,and the pore diameters of the deposits ranged from several hundred nanometers to 1.5 μm.The films were mainly titanium dioxide.Some coke-like deposits,which may contain or be changed by OH,NH,C-C,C-O,and C=O groups,were doped in the firms.The films were mainly amorphous with a small amount of anatase and rutile phase.

  5. Enhanced tribological behavior of anodic films containing SiC and PTFE nanoparticles on Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Songmei, E-mail: songmei_li@buaa.edu.cn; Zhu, Mengqi; Liu, Jianhua; Yu, Mei; Wu, Liang; Zhang, Jindan; Liang, Hongxing

    2014-10-15

    Highlights: • An environmental friendly sodium tartrate (C{sub 4}O{sub 6}H{sub 4}Na{sub 2}) electrolyte is used. • SiC and PTFE nanoparticles reduce friction coefficient of composite films. • SiC and PTFE nanoparticles demonstrate a favorable synergistic effect on improving tribological properties of composite films. • Lubricating mechanisms of SiC and PTFE nanoparticles are discussed. - Abstract: Anodic films containing SiC and polytetrafluoroethylene (PTFE) nanoparticles were successfully fabricated on Ti6Al4V alloy by using anodic oxidation method in an environmental friendly electrolyte. The morphology, structure and composition of the films were studied with the scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results showed that the film contained a layered structure and have a surface full of petaloid bulges, which was totally different from the common anodic oxide film of the porous kind. The tribological properties of the films were investigated with dry friction tests in terms of the friction coefficient, wear rate and the morphology of worn surfaces. The results indicated that the SiC/PTFE composite film exhibited much better anti-wear and anti-friction performances than that of the SiC composite film, the PTFE composite film and the ordinary film without nanoparticles. The SiC/PTFE composite film has friction coefficient of 0.1 and wear rate of 20.133 mg/m, which was decreased respectively by 80% and 44.5% compared with that of the ordinary film. The lubricating mechanisms of the composite film containing SiC and PTFE nanoparticles were discussed. PTFE nanoparticles could lead to the formation of lubricating layer while SiC nanoparticles inside the lubricating layer turned sliding friction to rolling friction.

  6. Enhanced tribological behavior of anodic films containing SiC and PTFE nanoparticles on Ti6Al4V alloy

    International Nuclear Information System (INIS)

    Highlights: • An environmental friendly sodium tartrate (C4O6H4Na2) electrolyte is used. • SiC and PTFE nanoparticles reduce friction coefficient of composite films. • SiC and PTFE nanoparticles demonstrate a favorable synergistic effect on improving tribological properties of composite films. • Lubricating mechanisms of SiC and PTFE nanoparticles are discussed. - Abstract: Anodic films containing SiC and polytetrafluoroethylene (PTFE) nanoparticles were successfully fabricated on Ti6Al4V alloy by using anodic oxidation method in an environmental friendly electrolyte. The morphology, structure and composition of the films were studied with the scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results showed that the film contained a layered structure and have a surface full of petaloid bulges, which was totally different from the common anodic oxide film of the porous kind. The tribological properties of the films were investigated with dry friction tests in terms of the friction coefficient, wear rate and the morphology of worn surfaces. The results indicated that the SiC/PTFE composite film exhibited much better anti-wear and anti-friction performances than that of the SiC composite film, the PTFE composite film and the ordinary film without nanoparticles. The SiC/PTFE composite film has friction coefficient of 0.1 and wear rate of 20.133 mg/m, which was decreased respectively by 80% and 44.5% compared with that of the ordinary film. The lubricating mechanisms of the composite film containing SiC and PTFE nanoparticles were discussed. PTFE nanoparticles could lead to the formation of lubricating layer while SiC nanoparticles inside the lubricating layer turned sliding friction to rolling friction

  7. Synthesis And Electrochemical Characteristics Of Mechanically Alloyed Anode Materials SnS2 For Li/SnS2 Cells

    Directory of Open Access Journals (Sweden)

    Hong J.H.

    2015-06-01

    Full Text Available With the increasing demand for efficient and economic energy storage, tin disulfide (SnS2, as one of the most attractive anode candidates for the next generation high-energy rechargeable Li-ion battery, have been paid more and more attention because of its high theoretical energy density and cost effectiveness. In this study, a new, simple and effective process, mechanical alloying (MA, has been developed for preparing fine anode material tin disulfides, in which ammonium chloride (AC, referred to as process control agents (PCAs, were used to prevent excessive cold-welding and accelerate the synthesis rates to some extent. Meanwhile, in order to decrease the mean size of SnS2 powder particles and improve the contact areas between the active materials, wet milling process was also conducted with normal hexane (NH as a solvent PCA. The prepared powders were both characterized by X-ray diffraction, Field emission-scanning electron microscopeand particle size analyzer. Finally, electrochemical measurements for Li/SnS2 cells were takenat room temperature, using a two-electrode cell assembled in an argon-filled glove box and the electrolyte of 1M LiPF6 in a mixture of ethylene carbonate(EC/dimethylcarbonate (DMC/ethylene methyl carbonate (EMC (volume ratio of 1:1:1.

  8. Effect of the composition of Ti alloy on the photocatalytic activities of Ti-based oxide nanotube arrays prepared by anodic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Dingding, E-mail: 13396064706@163.com [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Wang, Yixin, E-mail: 821314137@qq.com [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Zhao, Yuwei, E-mail: 412494599@qq.com [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Yang, Yijia, E-mail: newyang214@126.com [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Zhang, Lieyu, E-mail: zhanglieyu@163.com [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Mao, Xuhui, E-mail: clab@whu.edu.cn [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China)

    2014-11-15

    Highlights: • Effect of Ti alloy composition on the properties of TiO{sub 2} nanotube arrays is studied. • Al and V decrease the growth rate of nanotube arrays and deteriorate the performance. • Nanotube arrays derived from Ti–0.2Pd alloy exhibit enhanced photocatalytic activity. • Nanotube arrays derived from Ti–0.2Pd alloy have preferable stability. • Anodization of Ti alloys provides a way to prepare high-performance doped titania. - Abstract: Three types of Ti-based oxide nanotube arrays are prepared by anodic oxidation of pure Ti and Ti alloys (Ti–0.2Pd and Ti–6Al–4V) in the glycol–2 wt% H{sub 2}O–0.3 wt% NH{sub 4}F solution. The nanotube arrays are characterized by a series of techniques, including SEM, TEM, EIS, XRD, EDS, ICP, XPS and UV–vis DRS, to elucidate the effect of alloying elements on the properties of titania nanotube arrays. The results suggest that aluminium and vanadium elements greatly slow down the growth rate and therefore decrease the yield of nanotube arrays. Al and V deteriorate the photoreactivity of the resultant nanotube arrays. The palladium inside the Ti–0.2Pd alloy-derived nanotube arrays cannot be detected by EDS or XPS, but is quantitatively determined by ICP analysis. Incorporation of Pd significantly improves the photocatalytic activity of the resultant titania nanotube arrays powder. The presence of Pd element not only enhances the light absorption, but also facilitates the separation of photogenerated charge carriers. The uniform doping of Pd into the microstructure endows nanotube arrays with resistance to sulphur poison and preferable stability for organic degradation. This study suggests that anodization of Ti alloys, rather than pure Ti metal, allows to produce micron-sized high-performance photocatalysts for environmental and energy applications.

  9. Effect of the composition of Ti alloy on the photocatalytic activities of Ti-based oxide nanotube arrays prepared by anodic oxidation

    International Nuclear Information System (INIS)

    Highlights: • Effect of Ti alloy composition on the properties of TiO2 nanotube arrays is studied. • Al and V decrease the growth rate of nanotube arrays and deteriorate the performance. • Nanotube arrays derived from Ti–0.2Pd alloy exhibit enhanced photocatalytic activity. • Nanotube arrays derived from Ti–0.2Pd alloy have preferable stability. • Anodization of Ti alloys provides a way to prepare high-performance doped titania. - Abstract: Three types of Ti-based oxide nanotube arrays are prepared by anodic oxidation of pure Ti and Ti alloys (Ti–0.2Pd and Ti–6Al–4V) in the glycol–2 wt% H2O–0.3 wt% NH4F solution. The nanotube arrays are characterized by a series of techniques, including SEM, TEM, EIS, XRD, EDS, ICP, XPS and UV–vis DRS, to elucidate the effect of alloying elements on the properties of titania nanotube arrays. The results suggest that aluminium and vanadium elements greatly slow down the growth rate and therefore decrease the yield of nanotube arrays. Al and V deteriorate the photoreactivity of the resultant nanotube arrays. The palladium inside the Ti–0.2Pd alloy-derived nanotube arrays cannot be detected by EDS or XPS, but is quantitatively determined by ICP analysis. Incorporation of Pd significantly improves the photocatalytic activity of the resultant titania nanotube arrays powder. The presence of Pd element not only enhances the light absorption, but also facilitates the separation of photogenerated charge carriers. The uniform doping of Pd into the microstructure endows nanotube arrays with resistance to sulphur poison and preferable stability for organic degradation. This study suggests that anodization of Ti alloys, rather than pure Ti metal, allows to produce micron-sized high-performance photocatalysts for environmental and energy applications

  10. Improved reversibility in lithium-oxygen battery: Understanding elementary reactions and surface charge engineering of metal alloy catalyst

    Science.gov (United States)

    Kim, Byung Gon; Kim, Hyung-Jin; Back, Seoin; Nam, Kwan Woo; Jung, Yousung; Han, Young-Kyu; Choi, Jang Wook

    2014-02-01

    Most Li-O2 batteries suffer from sluggish kinetics during oxygen evolution reactions (OERs). To overcome this drawback, we take the lesson from other catalysis researches that showed improved catalytic activities by employing metal alloy catalysts. Such research effort has led us to find Pt3Co nanoparticles as an effective OER catalyst in Li-O2 batteries. The superior catalytic activity was reflected in the substantially decreased overpotentials and improved cycling/rate performance compared to those of other catalysts. Density functional theory calculations suggested that the low OER overpotentials are associated with the reduced adsorption strength of LiO2 on the outermost Pt catalytic sites. Also, the alloy catalyst generates amorphous Li2O2 conformally coated around the catalyst and thus facilitates easier decomposition and higher reversibility. This investigation conveys an important message that understanding elementary reactions and surface charge engineering of air-catalysts are one of the most effective approaches in resolving the chronic sluggish charging kinetics in Li-O2 batteries.

  11. A Pd/C-CeO2 Anode Catalyst for High-Performance Platinum-Free Anion Exchange Membrane Fuel Cells.

    Science.gov (United States)

    Miller, Hamish A; Lavacchi, Alessandro; Vizza, Francesco; Marelli, Marcello; Di Benedetto, Francesco; D'Acapito, Francesco; Paska, Yair; Page, Miles; Dekel, Dario R

    2016-05-10

    One of the biggest obstacles to the dissemination of fuel cells is their cost, a large part of which is due to platinum (Pt) electrocatalysts. Complete removal of Pt is a difficult if not impossible task for proton exchange membrane fuel cells (PEM-FCs). The anion exchange membrane fuel cell (AEM-FC) has long been proposed as a solution as non-Pt metals may be employed. Despite this, few examples of Pt-free AEM-FCs have been demonstrated with modest power output. The main obstacle preventing the realization of a high power density Pt-free AEM-FC is sluggish hydrogen oxidation (HOR) kinetics of the anode catalyst. Here we describe a Pt-free AEM-FC that employs a mixed carbon-CeO2 supported palladium (Pd) anode catalyst that exhibits enhanced kinetics for the HOR. AEM-FC tests run on dry H2 and pure air show peak power densities of more than 500 mW cm(-2) . PMID:27062251

  12. Synthesis and Application of Si/Carbon Nanofiber Composites Based on Ni and Mo Catalysts for Anode Material of Lithium Secondary Batteries.

    Science.gov (United States)

    Jang, Eunyi; Park, Heal-Ku; Lee, Chang-Seop

    2016-05-01

    In this paper, carbon nanofibers (CNFs) and Si/carbon nanofiber composites were synthesized for use as the anode material of lithium secondary batteries. Catalysts were prepared based on Ni and Mo metals and CNFs were grown through chemical vapor deposition (CVD). In addition, the grown CNFs were mixed with silicon particles to synthesize Si/carbon nanofibers composites. The physiochemical characteristics of the synthesized CNFs and Si/carbon nanofiber composites were analyzed by SEM, EDS, XRD, Raman, BET and XPS. The electrochemical characteristics were investigated by using cyclic voltammetry and galvanostatic charge-discharge. Using CNFs and Si/carbon nanofiber composites as the anode material, three electrode cells were assembled and the electrochemical characteristics were measured using LiPF6 and LiClO4 as electrolytes. As a result of the galvanostatic charge-discharge of CNFs that were grown through catalysts with Ni and Mo concentration ratio of 6:4, the initial discharge capacity when using LiPF6 as the electrolyte was 570 mAh/g and the retention rate was 15.05%. In the case of using LiClO4 as the electrolyte, the initial discharge capacity was 263 mAh/g and the retention rate was 67.23%. PMID:27483824

  13. AB5-type Hydrogen Storage Alloy Modified with Ti/Zr Used as Anodic Materials in Borohydride Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Lianbang WANG; Chunan MA; Xinbiao MAO; Yuanming SUN; Seijiro SUDA

    2005-01-01

    Fuel cell using borohydride as the fuel has received much attention. AB5-type hydrogen storage alloy used as the anodic material instead of noble metals has been investigated. In order to restrain the generation of hydrogen and enhance the utilization of borohydride, Ti/Zr metal powders has been added into the parent LmNi4.78Mn0.22 (where Lm is La-richened mischmetal) alloy (LNM) by ball milling and heat treatment methods. It is found that the addition of Ti/Zr metal powders lowers the electrochemical catalytic activity of the electrodes, at the same time, restrains the generation of hydrogen and enhances the utilization of the fuel. All the results show that the hydrogen generation rate or the utilization of the fuel is directly relative to the electrochemical catalytic activity or the discharge capability of the electrodes. The utilization of the fuel increases with discharge current density. It is very important to find a balance between the discharge capability and the utilization of the fuel.

  14. The effect of alloyed nitrogen or dissolved nitrate ions on the anodic behaviour of austenitic stainless steel in hydrochloric acid

    International Nuclear Information System (INIS)

    The anodic behaviour of high purity stainless steels, based on a 316L composition, has been studied at room temperature in HCl solutions from 1 to 6 M. For all acid concentrations, the presence of 0.22% nitrogen has little or no effect on the active dissolution kinetics at low over-potentials. The effect on the critical current density for passivation is also small for low HCl concentrations (4.5 M), no passivation occurs and again nitrogen has little effect. However, for HCl concentrations around 4 M nitrogen reversibly impedes active dissolution at a few hundred mA cm-2. The effect does not appear to be an oxide passivation, but is more likely to be due to surface enrichment of nitrogen atoms. Implications for localized corrosion are discussed. An effect similar to that of nitrogen alloying is reproduced on a nitrogen free alloy by adding 2 M NaNO3 to a 4M HCl solution. This effect is distinct from the passivation of salt-covered surfaces and may be preferable to the latter as an explanation of the increase in pitting potential by nitrate additions to NaCl solutions. Passivation under a salt film is retained to explain the passivation of growing pits above the inhibition potential. (authors)

  15. Influence of Ga and Hg on microstructure and electrochemical corrosion behavior of Mg alloy anode materials

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effects of Hg and Ga on the electrochemical corrosion behavior of Mg-5%Hg (molar fraction) alloys were investigated by the measurement of polarization curves and galvanostatic test. The microstructure of the alloys and the corroded surface of the specimens were investigated by scanning electron microscopy, X-ray diffractometry and emission spectrum analysis. It can be concluded that the addition of 1%Ga (molar fraction) reduces corrosion current density from 26.98 mA/cm2 to 2.34 mA/cm2;while the addition of 1%Hg (molar fraction) increases corrosion current density. The addition of Ga and Hg both promotes the electrochemical activity of the alloys and the influence of Ga is more effective than Hg. Mg-5%Hg-1%Ga alloy has the best electrochemical activity, showing mean potential of-1.992 V. The activation mechanism of the magnesium alloy produced by Hg and Ga was put forward. Magnesium atoms are dissolved in liquid Hg and Ga to form amalgam and undergo severe oxidation at the amalgam/electrolyte interface.

  16. Template-free electrodeposition of AlFe alloy nanowires from a room-temperature ionic liquid as an anode material for Li-ion batteries.

    Science.gov (United States)

    Chen, Gang; Chen, Yuqi; Guo, Qingjun; Wang, Heng; Li, Bing

    2016-08-15

    AlFe alloy nanowires were directly electrodeposited on copper substrates from trimethylamine hydrochloride (TMHC)-AlCl3 ionic liquids with small amounts of FeCl3 at room temperature without templates. Coin cells composed of AlFe alloy nanowire electrodes and lithium foils were assembled to characterize the alloy electrochemical properties by galvanostatic charge/discharge tests. Effects of FeCl3 concentration, potential and temperature on the alloy morphology, composition and cyclic performance were examined. Addition of Fe into the alloy changed the nanowires from a 'hill-like' bulk morphology to a free-standing morphology, and increased the coverage area of the alloy on Cu substrates. As an inactive element, Fe could also buffer the alloys' large volume changes during Li intercalation and deintercalation. AlFe alloy nanowires composed of a small amount of Fe with an average diameter of 140 nm exhibited an outstanding cyclic performance and delivered a specific capacity of about 570 mA h g(-1) after 50 cycles. This advanced template-free method for the direct preparation of high performance nanostructure AlFe alloy anode materials is quite simple and inexpensive, which presents a promising prospect for practical application in Li-ion batteries. PMID:27200436

  17. The forming of coke by catalytic cracking of black mineral oil by catalysts on the base of activated aluminium alloys

    International Nuclear Information System (INIS)

    The paper deals with an investigation in coke formation under black mineral oil reactions on oxide catalysts which care based on activated aluminium alloys containing 2-20% of active components of In and Ga. The coke yield is of extreme nature and depends on the content of active components in the catalyst composition. The application of thermogravimetric method shows that the oxidation of coke depositions after black mineral oil cracking proceeds in the same temperature range while after the steam-water treatment of coked catalysts the oxidation of coke deposition proceeds at higher temperatures with different temperature maximums which points to the inhomogeneity of coke depositions. It is shown that the catalyst phase composition changes significantly during the reaction under the effect of reaction mixture. 4 refs., 3 figs

  18. Greatly improved electrochemical performance of lithium-oxygen batteries with a bimetallic platinum-copper alloy catalyst

    Science.gov (United States)

    Lee, Minwook; Hwang, Yubin; Yun, Kyung-Han; Chung, Yong-Chae

    2015-08-01

    Research on the cathode catalysts of lithium-oxygen (Li-O2) batteries is one of the most important branches to commercialize these batteries to overcome the sluggish kinetics during both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). In this study, a high performance catalyst based on a bimetallic Pt-Cu alloy is investigated for Li-O2 batteries using first-principles calculation. The theoretical prediction shows that the Pt-Cu alloy is much more effective than the pure Pt according to the electrochemical performance. In particular, the effectiveness of the catalytic property is maximized in the case of the PtCu (111) surface which greatly reduces the large overpotentials of the original Li-O2 batteries during the OER/ORR. It is identified for the first time that the charge overpotentials are affected mainly by the inherent surface charge character of the alloy catalyst. It is observed that the more negatively charged PtCu (111) surface can act as a weakly positively charged surface for the adsorption of Li-O intermediates and thus result in weak ionic bonding of the intermediates on the surface. As a result, the dominant factor improving the catalytic performance is clearly demonstrated, providing insight into the design of an efficient catalyst for Li-O2 battery technologies.

  19. Inuence of Gold-Copper Alloy Catalyst Composition on Crystal Growth and Dopant Distribution in Silicon and Germanium Nanowires

    Science.gov (United States)

    Connell, Justin G.

    A combination of local electrode atom probe tomography (LEAP) and transmission electron microscopy characterization were used to investigate growth of and dopant incorporation in silicon and germanium nanowires (Si and GeNWs) via the vapor-liquid- solid (VLS) mechanism. A sample structure was developed that enabled isolation of the catalyst-mediated contribution to doping in individual nanowires during LEAP analysis. As a result, the distribution coefficient - a thermodynamic quantity describing axial junction abruptness - was measured in nanowires for the first time, providing a fundamental framework for comparison of junction abruptness in nanowires. These investigations also enabled the identification of a previously unknown radial anisotropy in dopant incorporation through the catalyst, with variations in dopant concentration across the VLS-defined diameter of the nanowire as large as two orders of magnitude. Finite element modeling of the doping process, coupled with in situ TEM observations reported in the literature, suggests that this radially inhomogeneous dopant distribution is a direct consequence of growth from a faceted liquid-solid interface, rather than the commonly assumed planar interface. Au-Cu alloy catalysts were explored as alternatives to Au-catalyzed VLS nanowire growth as a means to alleviate or eliminate axial and radial doping gradients in nanowires. Both an aqueous solution and electron beam lithographic method for creating Au-Cu alloy catalysts of controlled composition were developed, and GeNW growth was demonstrated from both types of catalyst. LEAP characterization of Au-Cu alloy catalyzed P-doped GeNWs revealed that alloying with Cu results in more abrupt axial doping junctions, as well as a more homogeneous radial distribution of dopants within the VLS-defined diameter of the nanowire.

  20. Microstructural characterization and mechanical property of active soldering anodized 6061 Al alloy using Sn–3.5Ag–xTi active solders

    International Nuclear Information System (INIS)

    Active solders Sn–3.5Ag–xTi varied from x = 0 to 6 wt.% Ti addition were prepared by vacuum arc re-melting and the resultant phase formation and variation of microstructure with titanium concentration were analyzed using X-ray diffraction, optical microscopy and scanning electron microscopy. The Sn–3.5Ag–xTi active solders are used as metallic filler to join with anodized 6061 Al alloy for potential applications of providing a higher heat conduction path. Their joints and mechanical properties were characterized and evaluated in terms of titanium content. The mechanical property of joints was measured by shear testing. The joint strength was very dependent on the titanium content. Solder with a 0.5 wt.% Ti addition can successfully wet and bond to the anodized aluminum oxide layers of Al alloy and posses a shear strength of 16.28 ± 0.64 MPa. The maximum bonding strength reached 22.24 ± 0.70 MPa at a 3 wt.% Ti addition. Interfacial reaction phase and chemical composition were identified by a transmission electron microscope with energy dispersive spectrometer. Results showed that the Ti element reacts with anodized aluminum oxide to form Al3Ti-rich and Al3Ti phases at the joint interfaces. - Highlights: ► Active solder joining of anodized Al alloy needs 0.5 wt.% Ti addition for Sn–3.5Ag. ► The maximum bonding strength occurs at 3 wt.% Ti addition. ► The Ti reacts with anodized Al oxide to form Al3Ti-rich and Al3Ti at joint interface.

  1. Core-Shell Sn-Ni-Cu-Alloy@Carbon Nanorods to Array as Three-Dimensional Anode by Nanoelectrodeposition for High-Performance Lithium Ion Batteries.

    Science.gov (United States)

    Peng, Hao; Li, Rui; Hu, Jiangtao; Deng, Wenjun; Pan, Feng

    2016-05-18

    We report the synthesis of a novel three-dimensional anode based on the core-shell Sn-Ni-Cu-alloy@carbon nanorods which was fabricated by pulse nanoelectrodeposition. Li ion batteries equipped with the three-dimensional anode demonstrated almost 100% capacity retention over 400 cycles at 450 mA g(-1) and excellent rate performance even up to 9000 mA g(-1) for advanced Li-ion battery. Insight of the high performance can be attributed to three key factors, Li-Sn alloys for Li-ion storage, Ni-Cu matrix for the electronic conductive and nanorods structure, and the carbon shell for the electronic/Li-ion conductive and holding stable solid electrolyte interphase (SEI), because these shells always kept stable volumes after extension of initial charge-discharge cycles. PMID:27113033

  2. 铝-空气电池铝合金阳极的研究进展%Research progress in aluminum alloy anodes for aluminum-air battery

    Institute of Scientific and Technical Information of China (English)

    鲁火清; 卢周广; 沈冬; 唐有根

    2012-01-01

    The research progress in aluminum (Al) alloy anodes for Al-air battery was reviewed from Al activation-passivation mechanism and effects of alloying elements, such as Ga, In, M g, Sn, Mn, Bi and Pb.%从铝活化-钝化机理、添加合金元素(镓、铟、镁、锡、锰、铋及铅等)对铝阳极性能的影响等方面,综述了铝-空气电池铝合金阳极的发展、研究及应用概况.

  3. Ruthenium behaviour during anodic dissolutjon of ruthenium alloys with iron in sulfuric acid solutions

    International Nuclear Information System (INIS)

    Electrochemical behaviour of the Fe-Ru (1.5 and 10%) alloys in sulfuric acid electrolytes, the rates of ruthenium transition into the solution, Ru distribution between solution and slime and the form of its presence in anolyte has been studied. The investigation was performed under conditions simulating the secondary electrolysis processes. It is established that in the case of alloy dissolution to phisub(a)=1.05 B ruthenium is present in anolytes in the form of Ru(3), at phisub(a)=1.05 to 1.9 B, in the form of Ru(4) in a mixture of anion (50%) aquooxohydroxosulfate complexes. With potentials higher than 1.7 B noticeable RuO4 amounts are formed. It is shown that the ruthenium oxidation rates in anolyte are determined by the iron (2) presence

  4. First-principle study on phase Al0.8NiaSn0.2 in Sn-Ni-Al alloy as anode for lithium ion battery

    Institute of Scientific and Technical Information of China (English)

    Huang Zhao-Wen; Hu She-Jun; Hou Xian-Hua; Zhao Ling-Zhi; Ru Qiang; Li Wei-Shan; Zhang Zhi-Wen

    2010-01-01

    The mechanism of lithium interealation/deintercalation for phase Al0.8Ni3Sn0.2 as anode material used in lithium ion battery was studied carefully based on the first-principle plane wave pseudo-potential method.The calculated results indicated that Sn-Ni-Al alloy had high theoretical capacity when used as anode material,however,there was high initial irreversible capacity loss because of the large volume expansion.Therefore the technological parameters during preparing the Sn-Ni-Al anode should be controlled strictly to make the content of Al0.8NiaSn0.2 phase as low as possible and to make the anode consist of promising Sn-Ni and Al-Ni phases.For comparison,an experiment based on magnetron sputtering was done.The result showed that the calculation is in good agreement with the experiment.We found that the first-principle investigation method is of far-reaching significance in synthesising new commercial anode materials with high capacity and good cycle performance.

  5. Study of the alloying additives and alkaline zincate solution effects on the commercial aluminum as galvanic anode for use in alkaline batteries

    International Nuclear Information System (INIS)

    The corrosion behavior of different grades of commercial aluminum such as AA1040, AA5083, AA6060 and AA7075 in ZnO-containing 4 M NaOH has been determined by using open circuit potential-time measurements (OCP), galvanostatic and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) reveal that ZnO produces the inhibition effect by the formation of a zinc-containing deposit layer on the surface of aluminum electrodes. Although the influence of zincating on the performance of aluminum alloys and considering the amount of alloying elements such as zinc, magnesium and manganese in AA7075 and AA5083 alloys is much more than AA6060 one, the AA6060 aluminum exhibits negligible corrosion rate. Alloying aluminum with other elements and modifying the composition of the electrolyte is a necessary condition for reducing the self-corrosion of the aluminum anodes, whereas the proportion of the amount of additive elements is sufficient and important condition. As AA6060 with a low amount of Zn and Mg, but the high value of the ratio of (Mg/Zn) content (>400) can serve as a good galvanic anode in the alkaline media. - Highlights: • Decreasing the corrosion rate of tested alloys in 4 M NaOH solution specially AA6060. • Lowering the extent of anodic polarization at a current density of 50 mA cm−2. • High inhibitor efficiency about 97% for AA6060

  6. Study of the alloying additives and alkaline zincate solution effects on the commercial aluminum as galvanic anode for use in alkaline batteries

    Energy Technology Data Exchange (ETDEWEB)

    Rashvand avei, M. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Jafarian, M., E-mail: mjafarian@kntu.ac.ir [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Moghanni Bavil Olyaei, H. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Gobal, F. [Department of Chemistry, Sharif University of Technology, P.O. Box 11365-8516, Tehran (Iran, Islamic Republic of); Hosseini, S.M. [Jahad Organization – Science and Technology Center, Tehran (Iran, Islamic Republic of); Mahjani, M.G. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of)

    2013-12-16

    The corrosion behavior of different grades of commercial aluminum such as AA1040, AA5083, AA6060 and AA7075 in ZnO-containing 4 M NaOH has been determined by using open circuit potential-time measurements (OCP), galvanostatic and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) reveal that ZnO produces the inhibition effect by the formation of a zinc-containing deposit layer on the surface of aluminum electrodes. Although the influence of zincating on the performance of aluminum alloys and considering the amount of alloying elements such as zinc, magnesium and manganese in AA7075 and AA5083 alloys is much more than AA6060 one, the AA6060 aluminum exhibits negligible corrosion rate. Alloying aluminum with other elements and modifying the composition of the electrolyte is a necessary condition for reducing the self-corrosion of the aluminum anodes, whereas the proportion of the amount of additive elements is sufficient and important condition. As AA6060 with a low amount of Zn and Mg, but the high value of the ratio of (Mg/Zn) content (>400) can serve as a good galvanic anode in the alkaline media. - Highlights: • Decreasing the corrosion rate of tested alloys in 4 M NaOH solution specially AA6060. • Lowering the extent of anodic polarization at a current density of 50 mA cm{sup −2}. • High inhibitor efficiency about 97% for AA6060.

  7. Enhancing pitting corrosion resistance of Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} high-entropy alloys by anodic treatment in sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C.P.; Chen, Y.Y.; Hsu, C.Y.; Yeh, J.W. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Shih, H.C. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Institute of Materials Science and Nanotechnology, Chinese Culture University, Taipei 111, Taiwan (China)], E-mail: hcshih@mx.nthu.edu.tw

    2008-12-01

    High-entropy alloys are a newly developed family of multi-component alloys that comprise various major alloying elements. Each element in the alloy system is present in between 5 and 35 at.%. The crystal structures and physical properties of high-entropy alloys differ completely from those of conventional alloys. The electrochemical impedance spectra (EIS) of the Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} (x = 0, 0.3, 0.5) alloys, obtained in 0.1 M HCl solution, clearly revealed that the corrosion resistance values were determined to increase from 21 to 34 {omega}cm{sup 2} as the aluminum content increased from 0 to 0.5 mol, and were markedly lower than that of 304 stainless steel (243 {omega}cm{sup 2}). At passive potential, the corresponding current declined with the anodizing time accounting, causing passivity by the growth of the multi-component anodized film in H{sub 2}SO{sub 4} solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surface of anodized Al{sub 0.3}CrFe{sub 1.5}MnNi{sub 0.5} alloy formed aluminum and chromium oxide film which was the main passivating compound on the alloy. This anodic treatment increased the corrosion resistance in the EIS measurements of the CrFe{sub 1.5}MnNi{sub 0.5} and Al{sub 0.3}CrFe{sub 1.5}MnNi{sub 0.5} alloys by two orders of magnitude. Accordingly, the anodic treatment of the Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} alloys optimized their surface structures and minimized their susceptibility to pitting corrosion.

  8. Synthesis and characterization of Pt-Sn-Ni alloys to application as catalysts for direct ethanol fuel cells

    International Nuclear Information System (INIS)

    Direct ethanol fuel cells (DEFCs) have been the focus of recent research due its application in mobile energy sources. In order to obtain the maximum efficiency from these systems, it is necessary the total ethanol oxidation, which implies in C-C bond break. Different catalysts described in literature are employed with this intent. This work consists in studying PtSnNi catalysts supported on carbon Vulcan XC72R, to application in DEFCs. Thus, it was used the impregnation/reduction method, varying the atomic proportion among Pt, Sn and Ni. The alloys were characterized by X-Ray Diffraction, Cyclic Voltammetry and Transmission Microscopy. Preliminary results show that predominant structure on the catalysts is the face centered cubic platinum and the densities currents are dependent on the platinum amount. (author)

  9. A microstructural investigation of gas atomized Raney type Al-27.5 at.% Ni catalyst precursor alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mullis, A.M., E-mail: a.m.mullis@leeds.ac.uk [Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom); Bigg, T.D., E-mail: t.bigg@leeds.ac.uk [Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom); Adkins, N.J., E-mail: n.j.e.adkins@bham.ac.uk [IRC in Materials Processing, University of Birmingham, Edgbaston, Birmingham B15-2TT (United Kingdom)

    2015-11-05

    Quantitative image analysis has been used to investigate the phase composition of gas atomized powders of a Raney type Ni catalyst precursor alloys of composition Al-27.5 at.% Ni in the powder size range 150–212 μm. We find that there are considerable variations in phase composition both between powders from the same batch and as a function distance from the particle surface within individual particles. Such variations may have significant implications for the future production and uptake of such catalysts, including the necessity for post-production crushing of gas atomized powders. Models are proposed to account for both variations. - Highlights: • The phase composition of powder Raney-Ni catalysts has been investigated. • Image analysis is used to quantify differences between and within particles. • Phase composition can vary by up to 10% between the particle surface and centre. • Differences of up to 10% in the mean composition are also found between particles.

  10. Quantification of zinc atoms in a surface alloy on copper in an industrial-type methanol synthesis catalyst

    DEFF Research Database (Denmark)

    Kuld, Sebastian; Moses, Poul Georg; Sehested, Jens;

    2014-01-01

    Methanol has recently attracted renewed interest because of its potential importance as a solar fuel. Methanol is also an important bulk chemical that is most efficiently formed over the industrial Cu/ZnO/Al2O3 catalyst. The identity of the active site and, in particular, the role of ZnO as a...... promoter for this type of catalyst is still under intense debate. Structural changes that are strongly dependent on the pretreatment method have now been observed for an industrial-type methanol synthesis catalyst. A combination of chemisorption, reaction, and spectroscopic techniques provides a consistent...... picture of surface alloying between copper and zinc. This analysis enables a reinterpretation of the methods that have been used for the determination of the Cu surface area and provides an opportunity to independently quantify the specific Cu and Zn areas. This method may also be applied to other systems...

  11. Quantification of zinc atoms in a surface alloy on copper in an industrial-type methanol synthesis catalyst

    DEFF Research Database (Denmark)

    Kuld, Sebastian; Moses, Poul Georg; Sehested, Jens;

    2014-01-01

    Methanol has recently attracted renewed interest because of its potential importance as a solar fuel.1 Methanol is also an important bulk chemical that is most efficiently formed over the industrial Cu/ZnO/Al2O3 catalyst. The identity of the active site and, in particular, the role of ZnO as a...... promoter for this type of catalyst is still under intense debate.2 Structural changes that are strongly dependent on the pretreatment method have now been observed for an industrial-type methanol synthesis catalyst. A combination of chemisorption, reaction, and spectroscopic techniques provides a...... consistent picture of surface alloying between copper and zinc. This analysis enables a reinterpretation of the methods that have been used for the determination of the Cu surface area and provides an opportunity to independently quantify the specific Cu and Zn areas. This method may also be applied to other...

  12. TiN@nitrogen-doped carbon supported Pt nanoparticles as high-performance anode catalyst for methanol electrooxidation

    Science.gov (United States)

    Zhang, Jun; Ma, Li; Gan, Mengyu; Fu, Shenna; Zhao, Yi

    2016-08-01

    In this paper, TiN@nitrogen-doped carbons (NDC) composed of a core-shell structure are successfully prepared through self-assembly and pyrolysis treatment using γ-aminopropyltriethoxysilane as coupling agent, polyaniline as carbon and nitrogen source, respectively. Subsequently, TiN@NDC supporting Pt nanoparticles (Pt/TiN@NDC) are obtained by a microwave-assisted polyol process. The nitrogen-containing functional groups and TiN nanoparticles play a critical role in decreasing the average particle size of Pt and improving the electrocatalytic activity of Pt/TiN@NDC. Transmission electron microscope results reveal that Pt nanoparticles are uniformly dispersed in the TiN@NDC surface with a narrow particle size ranging from 1 to 3 nm in diameter. Moreover, the Pt/TiN@NDC catalyst shows significantly improved catalytic activity and high durability for methanol electrooxidation in comparison with Pt/NDC and commercial Pt/C catalysts, revealed by cyclic voltammetry and chronoamperometry. Strikingly, this novel Pt/TiN@NDC catalyst reveals a better CO tolerance related to Pt/NDC and commercial Pt/C catalysts, which due to the bifunctional mechanism and strong metal-support interaction between Pt and TiN@NDC. In addition, the probable reaction steps for the electrooxidation of CO adspecies on Pt NPs on the basis of the bifunctional mechanism are also proposed. These results indicate that the TiN@NDC is a promising catalyst support for methanol electrooxidation.

  13. Performance Enhancement of Silicon Alloy-Based Anodes Using Thermally Treated Poly(amide imide) as a Polymer Binder for High Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Yang, Hwi Soo; Kim, Sang-Hyung; Kannan, Aravindaraj G; Kim, Seon Kyung; Park, Cheolho; Kim, Dong-Won

    2016-04-01

    The development of silicon-based anodes with high capacity and good cycling stability for next-generation lithium-ion batteries is a very challenging task due to the large volume changes in the electrodes during repeated cycling, which results in capacity fading. In this work, we synthesized silicon alloy as an active anode material, which was composed of silicon nanoparticles embedded in Cu-Al-Fe matrix phases. Poly(amide imide)s, (PAI)s, with different thermal treatments were used as polymer binders in the silicon alloy-based electrodes. A systematic study demonstrated that the thermal treatment of the silicon alloy electrodes at high temperature made the electrodes mechanically strong and remarkably enhanced the cycling stability compared to electrodes without thermal treatment. The silicon alloy electrode thermally treated at 400 °C initially delivered a discharge capacity of 1084 mAh g(-1) with good capacity retention and high Coulombic efficiency. This superior cycling performance was attributed to the strong adhesion of the PAI binder resulting from enhanced secondary interactions, which maintained good electrical contacts between the active materials, electronic conductors, and current collector during cycling. These findings are supported by results from X-ray photoelectron spectroscopy, scanning electron microscopy, and a surface and interfacial cutting analysis system. PMID:27008091

  14. Possibility of Wastewater Treatment Using MFC with Ni-Co Catalyst of Fuel Electrode

    Science.gov (United States)

    Włodarczyk, Paweł P.; Włodarczyk, Barbara

    2016-06-01

    One of the problems with microbial fuel cells is a low current density of those energy sources. Nonetheless, it is possible to increase the current density by using the catalyst for fuel electrode (anode) - as long as a low cost catalyst can be found. The possibility of wastewater treatment using the Ni-Co alloy as catalyst for MFC's is presented in this paper. The alloys were obtained with different concentrations of Co (15 and 50% of Co). The increase of current density with Ni-Co catalyst is approximately 0,1 mA/cm2. So, a fundamental possibility wastewater treatment using the Ni-Co alloy as catalyst for microbial fuel cells was presented.

  15. Mechanical alloying of a hydrogenation catalyst used for the remediation of contaminated compounds

    Science.gov (United States)

    Quinn, Jacqueline W. (Inventor); Clausen, Christian A. (Inventor); Geiger, Cherie L. (Inventor); Aitken, Brian S. (Inventor)

    2012-01-01

    A hydrogenation catalyst including a base material coated with a catalytic metal is made using mechanical milling techniques. The hydrogenation catalysts are used as an excellent catalyst for the dehalogenation of contaminated compounds and the remediation of other industrial compounds. Preferably, the hydrogenation catalyst is a bimetallic particle including zero-valent metal particles coated with a catalytic material. The mechanical milling technique is simpler and cheaper than previously used methods for producing hydrogenation catalysts.

  16. Transient analysis of carbon monoxide poisoning and oxygen bleeding in a PEM fuel cell anode catalyst layer

    Energy Technology Data Exchange (ETDEWEB)

    Zamel, Nada; Li, Xianguo [Department of Mechanical Engineering, University of Waterloo, Waterloo, Ont. (Canada)

    2008-02-15

    The presence of carbon monoxide in the fuel stream hinders the performance of a polymer electrolyte membrane (PEM) fuel cell, known as carbon monoxide (CO) poisoning. Introducing oxygen in the fuel stream lessens CO poisoning. Since CO poisoning is a phenomenon that occurs over a substantial period of time, a transient model has been developed in this study, taking into account the effect of CO concentration, operating pressure and temperature, as well as oxygen bleeding on the performance of the cell. It is found that at a lower CO concentration the poisoning effect takes a much longer time to reach the steady state, even though for a better steady state anode performance. A higher operating temperature results in a better steady state performance, but the performance drops faster toward the steady state value at higher temperature. A higher operating pressure leads to an enhanced performance over the entire transient history, although the benefit diminishes as pressure is increased. Even with a small amount of oxygen (0.5%) introduced into the fuel stream, the anode performance can be improved significantly. Finally, it is observed that the use of pure hydrogen interspersed in carbon monoxide containing fuel improves the anode performance. However, performance recovery when operating on pure hydrogen is much slower than the performance degradation due to the CO poisoning. (author)

  17. Synthesis and electrochemical performances of LiNiCuZn oxides as anode and cathode catalyst for low temperature solid oxide fuel cell.

    Science.gov (United States)

    Jing, Y; Qin, H; Liu, Q; Singh, M; Zhu, B

    2012-06-01

    Low temperature solid oxide fuel cell (LTSOFC, 300-600 degrees C) is developed with advantages compared to conventional SOFC (800-1000 degrees C). The electrodes with good catalytic activity, high electronic and ionic conductivity are required to achieve high power output. In this work, a LiNiCuZn oxides as anode and cathode catalyst is prepared by slurry method. The structure and morphology of the prepared LiNiCuZn oxides are characterized by X-ray diffraction and field emission scanning electron microscopy. The LiNiCuZn oxides prepared by slurry method are nano Li0.28Ni0.72O, ZnO and CuO compound. The nano-crystallites are congregated to form ball-shape particles with diameter of 800-1000 nm. The LiNiCuZn oxides electrodes exhibits high ion conductivity and low polarization resistance to hydrogen oxidation reaction and oxygen reduction reaction at low temperature. The LTSOFC using the LiNiCuZn oxides electrodes demonstrates good cell performance of 1000 mW cm(-2) when it operates at 470 degrees C. It is considered that nano-composite would be an effective way to develop catalyst for LTSOFC. PMID:22905585

  18. Lithium-rich Li2.6BMg0.05 alloy as an alternative anode to metallic lithium for rechargeable lithium batteries

    International Nuclear Information System (INIS)

    Highlights: → Lithium-rich multiphase Li2.6BMg0.05 alloy is first investigated as a high capacity anode to replace metallic lithium for rechargeable lithium batteries. → Li2.6BMg0.05 anode exhibits superior electrochemical performance than pure Li counterpart. → Li2.6BMg0.05 anode can suppress Li dendrites formation during cycling and long-term Li deposition. - Abstract: A lithium-rich multiphase alloy foil with the nominal composition Li2.6BMg0.05 is synthesized for potential anode of rechargeable lithium batteries. Pristine Li2.6BMg0.05 is composed of rhombohedral Li5B4, cubic lithium and Li3Mg7. The overvoltage of Li2.6BMg0.05 based symmetric cells keep steady values of about 0.04 V and 0.1 V respectively at 0.2 and 0.5 mA cm-2 within 50 cycles. By comparison, the overvoltage rises from ca. 0.04 V to 0.08 V at 0.2 mA cm-2 and fluctuates between 0.2 V and 0.4 V at 0.5 mA cm-2 for Li to replace Li2.6BMg0.05. The reduced voltage polarization is further confirmed by a comparison between Li2.6BMg0.05/S and Li/S full cells. Moreover, Li dendrite formation can be suppressed by use of Li2.6BMg0.05 during cycling and long-term deposition. The improvement of the Li2.6BMg0.05 anode may be due to its porous framework structure and slightly decreased reactivity, which reduce the effective current density and benefit the interfacial stability. The test results indicate that lithium-rich multiphase alloys could be promising for anode material of rechargeable lithium batteries.

  19. Effects of anodic passivation on the constitution, stability and resistance to corrosion of passive film formed on an Fe-24Mn-4Al-5Cr alloy

    International Nuclear Information System (INIS)

    The effects of anodic aging time and potential on the corrosion resistance, stability and constitution of the passive film formed on an Fe-24Mn-4Al-5Cr alloy in 50% HNO3 solution were studied by using combined electrochemical measurements and Auger electron spectroscopic (AES)/X-ray photoelectron spectroscopic (XPS) analysis. In the anodic passive region, prolonged anodic aging time or increased passivating potential can induce better protective and stable properties of the passive film and better resistance to corrosion. With increasing aging time from 15 min to 5 h, the time required for the potential decay from the passive to active state increases from about 300 up to above 12,000 s, and the corrosion resistance in 1 mol l-1 Na2SO4 solution of Fe-24Mn-4Al-5Cr alloy, characterized by polarization curves, is superior to that of Fe-13% Cr-0.1% C stainless steel. AES and XPS analyses of the aging passive film show that these improvements of properties are related to modifications of the passive layer with time. The increase of resistance to corrosion is attributed to Al2O3 and Cr2O3 enrichment and oxides of Fe and Mn depletion in the passive film and a thickening of the effective barrier layer of oxides

  20. An investigation into the mechanical and tribological properties of plasma electrolytic oxidation and hard-anodized coatings on 6082 aluminum alloy

    International Nuclear Information System (INIS)

    Highlights: → Mechanical properties of PEO and anodised coatings were studied using ultra-micro hardness tester. → Elastic modulus and hardness of the PEO coating were found much higher than those of the anodised coating. → Improved sliding wear of PEO coating is due to presence of hard α and γ-Al2O3 phases. - Abstract: A ceramic coating on AA6082 aluminum alloy prepared by plasma electrolytic oxidation (PEO) has been studied and compared against a sulphuric acid hard-anodized coating on the same alloy. Surface morphology and microstructures of the coatings have been examined by scanning electron microscopy. X-ray diffraction is used to determine the phase composition of the coatings. The adhesion strength of the coatings has been evaluated using a scratch test method. The coating's mechanical properties such elastic modulus and hardness data have been generated using a dynamic ultra-microhardness tester. Sliding wear tests with different loading rates are performed on the coatings in order to assess their wear resistance. Test results show that the PEO treated samples exhibit significantly better mechanical properties compared to hard anodized samples. The elastic modulus and hardness of the PEO coating are 2-3 times greater than of the hard anodized coating and subsequently, an improved wear resistance of the PEO coating has been achieved. The mechanical properties of the coatings and their relations to their tribological performance are discussed.

  1. Fabrication of CoPd alloy nanowire arrays on an anodic aluminum oxide/Ti/Si substrate and their enhanced magnetic properties

    International Nuclear Information System (INIS)

    An anodic aluminum oxide/Ti/Si substrate was successfully synthesized by the anodization of an aluminum film on a Ti/Si substrate and then used as a template to grow 10 nm diameter CoPd alloy nanowires. X-ray diffraction and energy-dispersed X-ray patterns indicated that Co0.97Pd0.03 nanowire arrays with a preferential orientation of (0 0 2) were formed during electrodeposition. High coercivity (about 1700 Oe) and squareness (about 0.85) were obtained in the samples when the magnetic field was applied parallel to the axis of the nanowires; these values are much larger than those of pure Co nanowire arrays with the same diameters

  2. H2O2 detection analysis of oxygen reduction reaction on cathode and anode catalysts for polymer electrolyte fuel cells

    Science.gov (United States)

    Kishi, Akira; Shironita, Sayoko; Umeda, Minoru

    2012-01-01

    The generation percentage of H2O2 during oxygen reduction reaction (ORR) at practical powder electrocatalysts was evaluated using a scanning electrochemical microscope (SECM). We employed a porous microelectrode that contains electrocatalysts, namely, Pt/C, Pt-Co/C, and Pt-Ru/C as the oxygen reduction electrode of the SECM, and the Pt microelectrode was used as the H2O2 detector. First, the H2O2 generation amount at Pt/Cs was measured by changing the Pt loading amount. A Pt/C with a higher Pt loading has a higher ORR activity and generates a larger amount of H2O2. However, the percentage of H2O2 generated with respect to the ORR is the same regardless of the Pt loading amount. Next, H2O2 generation is markedly suppressed at the Pt-Co/C and Pt-Ru/C in the potential ranges of practical fuel cell cathode and anode, respectively. This explains that the Pt-Co/C is effective when used as a cathode, and the anode Pt-Ru/C enables the reduction of the H2O2 generation even if O2 crossleak occurs in the practical polymer electrolyte fuel cell.

  3. A structure investigation of Pt-Co bimetallic catalysts fabricated by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Lucariello, Marialaura; Penazzi, Nerino [Dipartimento di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, C.so Duca Abruzzi n. 24, I-10129 Torino (Italy); Arca, Elisabetta; Mulas, Gabriele [Dipartimento di Chimica, Universita di Sassari, Via Vienna n. 2, I-07100 Sassari (Italy); Enzo, Stefano [Dipartimento di Chimica, Universita di Sassari, Via Vienna n. 2, I-07100 Sassari (Italy)], E-mail: enzo@uniss.it

    2009-03-15

    Three Pt-Co mixtures of composition Pt{sub 25}Co{sub 75}, Pt{sub 50}Co{sub 50} and Pt{sub 75}Co{sub 25} respectively, were synthesized using the high-energy ball milling technique of the elemental powders with a view to prepare catalysts for fuel cells. The kinetics of phase evolution, their structure and average microstructure properties were quantitatively investigated by X-ray powder diffraction with the Rietveld method. The results show that the ball milling technique is able to produce Pt-Co solid solutions soon after few minutes of mechanical treatment. Of the two polymorphs of cobalt the fcc allotrope appears to be involved preferentially in the early stage of alloying reaction with fcc platinum. For the three compositions, a sigmoidal equation based on an interdiffusion-controlled mechanism satisfactorily accounts for the evolution of the solid solution as a function of mechanical treatment time. A characteristic reaction time of 3-6 h is observed for the solid state transformation reaction with the milling conditions adopted in our reactor. In the case of the Pt{sub 25}Co{sub 75} composition, a competitive-consecutive reaction is observed. Lattice parameters of the solid solutions after extended times of milling and related atomic volumes turn out to be slightly above the values ideally predicted on the basis of the Vegard's law. For the Pt{sub 75}Co{sub 25} composition the average crystallite size is reduced down to ca. 150 A after 12 h when the lattice microstrain is also at a maximum, but further mechanical treatment increases the average crystal size value and to decrease the strain. Similar results are found for equiatomic and Co-rich compositions. Annealing of the alloyed equiatomic powders promotes a cubic-to-tetragonal transformation which is already operative at 600 deg. C. In fact, after this treatment two tetragonal phases are observed. Further thermal treatment and annealing at 700 deg. C induces peak sharpening of the diffraction patterns

  4. Nanoscale alloying effect of gold–platinum nanoparticles as cathode catalysts on the performance of a rechargeable lithium–oxygen battery

    International Nuclear Information System (INIS)

    The understanding of nanoscale alloying or the phase segregation effect of alloy nanoparticles on the catalytic properties is important for a rational design of the desired catalysts for a specific reaction. This paper describes findings of an investigation into this type of structural effect for carbon-supported bimetallic gold–platinum nanoparticles as cathode catalysts in a rechargeable lithium–oxygen battery. The nanoscale structural characteristics in terms of size, alloying and phase segregation were shown to affect the catalytic properties of the catalysts in the Li–O2 battery. In addition to the composition effect, the catalysts with a fully alloyed phase structure were found to exhibit a smaller discharge–charge voltage difference and a higher discharge capacity than those with a partial phase segregation structure. This finding is significant for the design of alloy nanoparticles as air cathode catalysts in rechargeable lithium–air batteries, demonstrating the importance of the control of the nanoscale composition and phase properties. (paper)

  5. Electro-oxidation of ethanol on ternary non-alloyed Pt-Sn-Pr/C catalysts

    Science.gov (United States)

    Corradini, Patricia G.; Antolini, Ermete; Perez, Joelma

    2015-02-01

    Ternary Pt-Sn-Pr/C (70:10:20), (70:15:15) and (45:45:10) electro-catalysts were prepared by a modified formic acid method, and their activity for the ethanol oxidation reaction (EOR) was compared with that of Pt-Pr/C catalysts prepared by the same methods and that of commercial Pt-Sn/C (75:25) and Pt/C catalysts. Among all the catalysts, the Pt-Sn-Pr/C (45:45:10) catalyst presented both the highest mass activity and the highest specific activity. The steady state electrochemical stability of ternary Pt-Sn-Pr catalysts increased with the surface Sn/Pt atomic ratio. Following repetitive potential cycling (RPC), the activity for ethanol oxidation of Pt-Sn-Pr/C catalysts with high surface Sn/Pt atomic ratio was considerably higher than that of the corresponding as-prepared catalysts, and increased with increasing the Sn/Pt ratio. The increase of the EOR mass activity following RPC was ascribed to the increase of either the specific activity (for the Pt-Sn-Pr/C (70:15:15) catalyst) or the electrochemically active surface area (for the Pt-Sn-Pr/C (45:45:10) catalyst). Dissolution of Sn and Pr oxides from Pt-Sn-Pr/C catalyst surface was observed following RPC.

  6. Effect of aluminium alloy surface heterogeneities on anodic layer growth and properties; Efecto de las heterogeneidades superficiales de las aleaciones de aluminio sobre el crecimiento y propiedades de las capas anodicas

    Energy Technology Data Exchange (ETDEWEB)

    Bartolome, M. J.; Feliu, J.V.; Lopez, E.; Gonzalez, J. A.; Feliu, S.

    2007-07-01

    In the present work, X-ray photoelectron spectroscopy (XPS) is used to study sealed and unsealed anodic coatings obtained on pure-Al and on Al-Cu, Al-Mg-Si and Al-Mg alloys. In general, the sealing process is seen to produce a significant increase in the O/A ratio in the anodic coatings. this increase is more considerable with the Al-Cu and Al-Mg alloys than with the pure Al and the Al-Mg-Si alloy, perhaps due to the greater porosity of the coatings obtained on the former. An attempt is made to establish possible relationships between anodic film characteristics and surface heterogeneities, which also act in the phase prior to anodising. According to the results of this work, these heterogeneities affect the degree of dissolution of the metallic substrate during the anodising operation. (Author)

  7. Multiply twinned AgNi alloy nanoparticles as highly active catalyst for multiple reduction and degradation reactions.

    Science.gov (United States)

    Kumar, Mukesh; Deka, Sasanka

    2014-09-24

    Size dependent surface characteristics of nanoparticles lead to use of these nanomaterials in many technologically important fields, including the field of catalysis. Here Ag(1-x)Ni(x) bimetallic alloy nanoparticles have been developed having a 5-fold twinned morphology, which could be considered as an important alloy because of their excellent and unique catalytic and magnetic properties. Alloying between Ag and Ni atoms on a nanoscale has been confirmed with detailed X-ray diffraction, high resolution transmission electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and magnetization measurements. Although introduced for the first time as a catalyst due to having high active surface sites, the as-synthesized nanoparticles showed one of the best multiple catalytic activity in the industrially important (electro)-catalytic reduction of 4-nitrophenol (4-NP) and 4-nitroaniline (4-NA) to corresponding amines with noticeable reduced reaction time and increased rate constant without the use of any large area support. Additionally the same catalyst showed enhanced catalytic activity in degradation of environment polluting dye molecules. The highest ever activity parameter we report here for Ag0.6Ni0.4 composition is 156 s(-1)g(-1) with an apparent rate constant of 31.1 × 10(-3) s(-1) in a 4-NP reduction reaction where the amount of catalyst used was 0.2 mg and the time taken for complete conversion of 4-NP to 4-aminophenol was 60 s. Similarly, an incredible reaction rate constant (115 s(-1)) and activity parameter (576.6 s(-1)g(-1)) were observed for the catalytic degradation of methyl orange dye where 15 s is the maximum time for complete degradation of the dye molecules. The high catalytic performance of present AgNi alloy NPs over the other catalysts has been attributed to size, structural (twinned defect) and electronic effects. This study may lead to use of these bimetallic nanostructures with excellent recyclable catalytic

  8. Optimization of Pt-Pd alloy catalyst and supporting materials for oxygen reduction in air-cathode Microbial Fuel Cells

    International Nuclear Information System (INIS)

    Highlights: • Pt-Pd alloy catalyst was fabricated on carbon paper via electro-deposition. • MFCs with Pt-Pd cathode of 15 deposition cycles generated a maximum power density. • Graphene decoration did not improve ORR activity of the Pt-Pd electrode. • CNT as the supporting material enhanced ORR activity of the Pt-Pd electrode. • CNT-Pt-Pd cathode demonstrates the potential of replacing Pt catalyst in MFCs. - ABSTRACT: In this study, Pt-Pd alloy catalyst was fabricated on carbon papers via electro-deposition as an alternative catalyst for oxygen reduction in air-cathode Microbial Fuel Cells (MFCs). Effects of electro-deposition cycles and supporting materials (graphene and carbon nanotubes (CNTs)) on oxygen reduction reaction (ORR) activity of the Pt-Pd electrode and power generation in MFCs were investigated. The structural and electrochemical properties of the Pt-Pd catalyst were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Results showed that the Pt-Pd electrode showed a good ORR activity. A MFC with a Pt-Pd cathode of 15 deposition cycles produced a maximum power density of 1274 mWm−2, comparable to that with a conventional Pt/C cathode (0.5 mg Pt cm−2). CNT as the supporting material further increased ORR activity of the Pt-Pd electrode and power generation capacity in MFCs, while graphene as the supporting material did not produce positive effects. XRD results confirmed the presence of Pt/Pd elements on the electrode. SEM results showed that decoration using CNT reduced Pt-Pd particle size and promoted them even dispersion on the carbon paper. The Pt-Pd electrode attained a comparable performance to the Pt/C electrode when controlling an optimum deposition cycles and using CNT as the supporting materials, which demonstrates the potential of replacing Pt as an oxygen reduction catalyst in MFCs due to high oxygen reduction activity and relatively low cost

  9. Addition of sulfonated silicon dioxide on an anode catalyst layer to improve the performance of a self-humidifying proton exchange membrane fuel cell

    Science.gov (United States)

    Lin, Chien-Liang; Hsu, Shih-Chieh; Ho, Wei-Yu

    2016-03-01

    Sulfonated SiO2 was added on an anode catalyst layer to manufacture a hygroscopic electrode for self-humidifying proton exchange membrane fuel cells (PEMFCs). The inherent humidity of a proton exchange membrane (PEM) determines the electrical performance of PEMFCs. To maintain the high moisture content of the PEM, self-humidifying PEMFCs can use the water produced by the fuel cell reaction and, thus, do not require external humidification. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and water contact angle measurement tests were performed to characterize the structures and properties of sulfonated SiO2 and the related electrodes, and the electric current and voltage (I-V) performance curve tests for the fuel cells were conducted under differing gas humidification conditions. When 0.01mg/cm2 of sulfonated SiO2 was added, the electrical performance of the fuel cells (50∘C) increased 29% and 59% when the fuel cell reaction gases were humidified at 70∘C and 50∘C, respectively.

  10. Morphology and performances of the anodic oxide films on Ti6Al4V alloy formed in alkaline-silicate electrolyte with aminopropyl silane addition under low potential

    International Nuclear Information System (INIS)

    Oxide films on Ti6Al4V alloy are prepared using sodium hydroxide–sodium silicate as the base electrolyte with addition of aminopropyl trimethoxysilane (APS) as additive by potentiostatic anodizing under 10 V. APS is incorporated into the films during anodizing and the surface morphology of the oxide films is changed from particle stacked to honeycomb-like porous surfaces as shown by scanning electron microscopy (SEM) with Energy Disperse Spectroscopy (EDX). The surface roughness and aminopropyl existence on the oxide films result in their differences in wettability as tested by the surface profile topography and contact angle measurements. The anti-abrasive ability of the anodic films is improved with the addition of APS due to its toughening effects and serving as lubricants in the ceramic oxide films as measured by ball-on-disk friction test. Also, potentiodynamic corrosion test proves that their anticorrosive ability in 3.5 wt.% NaCl is greatly improved as reflected by their much lower corrosion current (Icorr) and higher corrosion potential (Ecorr) than those of the substrate.

  11. Morphology and performances of the anodic oxide films on Ti6Al4V alloy formed in alkaline-silicate electrolyte with aminopropyl silane addition under low potential

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jiali; Wang, Jinwei, E-mail: wangjw@ustb.edu.cn; Yuan, Hongye

    2013-11-01

    Oxide films on Ti6Al4V alloy are prepared using sodium hydroxide–sodium silicate as the base electrolyte with addition of aminopropyl trimethoxysilane (APS) as additive by potentiostatic anodizing under 10 V. APS is incorporated into the films during anodizing and the surface morphology of the oxide films is changed from particle stacked to honeycomb-like porous surfaces as shown by scanning electron microscopy (SEM) with Energy Disperse Spectroscopy (EDX). The surface roughness and aminopropyl existence on the oxide films result in their differences in wettability as tested by the surface profile topography and contact angle measurements. The anti-abrasive ability of the anodic films is improved with the addition of APS due to its toughening effects and serving as lubricants in the ceramic oxide films as measured by ball-on-disk friction test. Also, potentiodynamic corrosion test proves that their anticorrosive ability in 3.5 wt.% NaCl is greatly improved as reflected by their much lower corrosion current (I{sub corr}) and higher corrosion potential (E{sub corr}) than those of the substrate.

  12. Carbon-resistant Ni-Zr0.92Y0.08O2-δ supported solid oxide fuel cells using Ni-Cu-Fe alloy cermet as on-cell reforming catalyst and mixed methane-steam as fuel

    Science.gov (United States)

    Hua, Bin; Li, Meng; Luo, Jing-li; Pu, Jian; Chi, Bo; Li, Jian

    2016-01-01

    Two types of anode-supported cell are fabricated by tape casting, screen printing and sintering processes. The first one is a conventional anode supported cell (ASC); and the other, namely CASC, contains an extra layer of Ni-Cu/Ni-Fe alloys-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (NCF-BZCYYb) cermet catalyst on the surface of the anode-support. Using CH4-3 mol. % H2O as the fuel, the initial performance of the CASC is moderately improved, compared with that of the ASC; the power density of the CASC and ASC at 500 mA cm-2 and 800 °C remain stable on the level of 470 mW cm-2 for approximately 11 and 0.8 h, respectively, before cell disintegration caused by carbon formation. The performances of the CASC in the fuel of CH4-33.3 mol. % H2O are significantly increased above the level of the ASC, demonstrating an initial peak power density ranging from 280 to 1638 mW cm-2 at temperatures between 600 and 800 °C and a stable power density of 485 mW cm-2 at 500 mA cm-2 and 800 °C for 48 h. Carbon deposition in the anode region of the tested CASC cell is not detected, as the NCF-BZCYYb is a more active catalyst than the Ni-Zr0.92Y0.08O2-δ (YSZ) anode-support for CH4 steam reforming.

  13. Influence of Zr Addition on Structure and Performance of Rare Earth Mg-Based Alloys as Anodes in Ni/MH Battery

    Directory of Open Access Journals (Sweden)

    Shujun Qiu

    2015-04-01

    Full Text Available In this study, the substitution of Mg with Zr in La0.7Mg0.3(Ni0.85Co0.153.5 was carried out with the purpose of improving the electrochemical performances. The structural and hydrogen storage properties in both gas-solid reaction and the electrochemical system were systematically studied on La0.7(Mg0.3−xZrx(Ni0.85Co0.153.5 (x = 0.05, 0.1, 0.2, 0.3 alloys. Each tested alloy is composed of LaNi3 phase, LaNi5 phase and ZrNi3 phase with different phase abundances. The electrochemical studies indicated that all Zr-substituted anodes possessed a much higher cycling capacity retention than pristine La0.7Mg0.3(Ni0.85Co0.153.5. However, the maximum discharge capacity was reduced with the increase of Zr content. The potential-step tests showed that the diffusion of hydrogen atoms inside the anodes was decelerated after the introduction of Zr.

  14. Carbon deposition in the Bosch process with ruthenium and ruthenium-iron alloy catalysts. M.S. Thesis. Final Report, Jan. 1981 - Jul. 1982

    Science.gov (United States)

    Manning, M. P.; Reid, R. C.; Sophonpanich, C.

    1982-01-01

    The effectiveness of ruthenium and the alloys 50Ru50Fe and 33Ru67Fe as alternatives to iron, nickel, and cobalt catalysts in recovering oxygen from metabolic carbon dioxide was investigated. Carbon deposition boundaries over the unsupported alloys are reported. Experiments were also carried out over 50Ru50Fe and 97Ru3Fe3 catalysts supported on gamma-alumina to determine their performance in the synthesis of low molecular weight olefins. High production of ethylene and propylene would be beneficial for an improvement of an overall Bosch process, as a gas phase containing high olefin content would enhance carbon deposition in a Bosch reactor.

  15. Identification of non-precious metal alloy catalysts for selective hydrogenation of acetylene

    DEFF Research Database (Denmark)

    Studt, Felix; Abild-Pedersen, Frank; Bligaard, Thomas; Sørensen, Rasmus Zink; Christensen, Claus H.; Nørskov, Jens Kehlet

    2008-01-01

    The removal of trace acetylene from ethylene is performed industrially by palladium hydrogenation catalysts ( often modified with silver) that avoid the hydrogenation of ethylene to ethane. In an effort to identify catalysts based on less expensive and more available metals, density functional...

  16. Grafting of VO x/TiO2 catalyst on anodized aluminum plates for structured catalytic reactors

    International Nuclear Information System (INIS)

    Structured reactors are promising to carry out exothermic reactions because the heat transfer is better controlled than in usual packed-bed reactors. However the coating by oxide powders which must exhibit catalytic activity/selectivity while being mechanically stable is not so straightforward. We have studied the parameters to be controlled to coat aluminum walls by V2O5/TiO2 catalysts which are used in the mild oxidation of hydrocarbons and NO x abatement. The dip-coating technique using metallic alcoholates has been chosen for the grafting of TiO2 on Al2O3/Al, which is controlled by X-ray Photoelectron Spectroscopy (XPS). A monolayer of TiO2 is first grafted, and then a porous film of TiO2-anatase is deposited by sol-gel. Finally, VO x species are grafted on titania and their loading again determined by XPS. Techniques such as Laser Raman Spectroscopy, Scanning Electron Microscopy are used to characterize the samples after each step, and the porous texture is determined. The layers are mechanically and thermally stable. The dispersion and nature of VO x species on TiO2/Al2O3/Al are similar to what is found in literature for TiO2 powders, showing thereby that the shaping of anatase support on plates has not modified the chemical properties of VO x/TiO2-anatase system

  17. Modified surface morphology of a novel Ti-24Nb-4Zr-7.9Sn titanium alloy via anodic oxidation for enhanced interfacial biocompatibility and osseointegration.

    Science.gov (United States)

    Li, Xiang; Chen, Tao; Hu, Jing; Li, Shujun; Zou, Qin; Li, Yunfeng; Jiang, Nan; Li, Hui; Li, Jihua

    2016-08-01

    The Ti-24Nb-4Zr-7.9Sn titanium alloy (Ti2448) has shown potential for use in biomedical implants, because this alloy possesses several important mechanical properties, such as a high fracture strength, low elastic modulus, and good corrosion resistance. In this study, we aimed to produce a hierarchical nanostructure on the surface of Ti2448 to endow this alloy with favorable biological properties. The chemical composition of Ti2448 (64.0wt% Ti, 23.9wt% Nb, 3.9wt% Zr, and 8.1wt% Sn) gives this material electrochemical properties that lead to the generation of topographical features under standard anodic oxidation. We characterized the surface properties of pure Ti (Ti), nanotube-Ti (NT), Ti2448, and nanotube-Ti2448 (NTi2448) based on surface morphology (scanning electron microscopy and atomic force microscopy), chemical and phase compositions (X-ray diffraction and X-ray photoelectron spectroscopy), and wettability (water contact angle). We evaluated the biocompatibility and osteointegration of implant surfaces by observing the behavior of bone marrow stromal cells (BMSCs) cultured on the surfaces in vitro and conducting histological analysis after in vivo implantation of the modified materials. Our results showed that a hierarchical structure with a nanoscale bone-like layer was achieved along with nanotube formation on the Ti2448 surface. The surface characterization data suggested the superior biocompatibility of the NTi2448 surface in comparison with the Ti, NT, and Ti2448 surfaces. Moreover, the NTi2448 surface showed better biocompatibility for BMSCs in vitro and better osteointegration in vivo. Based on these results, we conclude that anodic oxidation facilitated the formation of a nanoscale bone-like structure and nanotubes on Ti2448. Unlike the modified titanium surfaces developed to date, the NTi2448 surface, which presents both mechanical compatibility and bioactivity, offers excellent biocompatibility and osteointegration, suggesting its potential for

  18. Nitrogen-doped carbon onions encapsulating metal alloys as efficient and stable catalysts for dye-sensitized solar cells

    Science.gov (United States)

    Zhu, Chongyang; Xu, Feng; Chen, Jing; Min, Huihua; Dong, Hui; Tong, Ling; Qasim, Khan; Li, Shengli; Sun, Litao

    2016-01-01

    Designing a new class of non-noble metal catalysts with triiodide reduction activity and stability comparable to those of conventional Pt is extremely significant for the application of dye-sensitized solar cells (DSSCs). Here, we demonstrate newly designed counter electrode (CE) materials of onion-like nitrogen-doped carbon encapsulating metal alloys (ONC@MAs) such as FeNi3 (ONC@FeNi3) or FeCo (ONC@FeCo), by a facile and scalable pyrolysis method. The resulting composite catalysts show superior catalytic activities towards the triiodide reduction and exhibit low charge transfer resistance between the electrode surfaces and electrolytes. As a result, the DSSCs based on ONC@FeCo and ONC@FeNi3 achieve outstanding power conversion efficiencies (PCEs) of 8.26% and 8.87%, respectively, which can rival the 8.28% of Pt-based DSSC. Moreover, the excellent electrochemical stabilities for both the two catalysts also have been corroborated by electrochemical impendence spectra and cyclic voltammetry (CV). Noticeably, TEM investigation further reveals that the N-doped graphitic carbon onions exhibit the high structural stability in iodine-containing medium even subject to hundreds of CV scanning. These results make ONC@MAs the promising candidates to supersede costly Pt as efficient and stable CEs for DSSCs.

  19. Improved Osteoblast and Chondrocyte Adhesion and Viability by Surface-Modified Ti6Al4V Alloy with Anodized TiO2 Nanotubes Using a Super-Oxidative Solution

    Directory of Open Access Journals (Sweden)

    Ernesto Beltrán-Partida

    2015-03-01

    Full Text Available Titanium (Ti and its alloys are amongst the most commonly-used biomaterials in orthopedic and dental applications. The Ti-aluminum-vanadium alloy (Ti6Al4V is widely used as a biomaterial for these applications by virtue of its favorable properties, such as high tensile strength, good biocompatibility and excellent corrosion resistance. TiO2 nanotube (NTs layers formed by anodization on Ti6Al4V alloy have been shown to improve osteoblast adhesion and function when compared to non-anodized material. In his study, NTs were grown on a Ti6Al4V alloy by anodic oxidation for 5 min using a super-oxidative aqueous solution, and their in vitro biocompatibility was investigated in pig periosteal osteoblasts and cartilage chondrocytes. Scanning electron microscopy (SEM, energy dispersion X-ray analysis (EDX and atomic force microscopy (AFM were used to characterize the materials. Cell morphology was analyzed by SEM and AFM. Cell viability was examined by fluorescence microscopy. Cell adhesion was evaluated by nuclei staining and cell number quantification by fluorescence microscopy. The average diameter of the NTs was 80 nm. The results demonstrate improved cell adhesion and viability at Day 1 and Day 3 of cell growth on the nanostructured material as compared to the non-anodized alloy. In conclusion, this study evidences the suitability of NTs grown on Ti6Al4V alloy using a super-oxidative water and a short anodization process to enhance the adhesion and viability of osteoblasts and chondrocytes. The results warrant further investigation for its use as medical implant materials.

  20. Activity and stability studies of titanates and titanate-carbon nanotubes supported Ag anode catalysts for direct methanol fuel cell

    Science.gov (United States)

    Mohamed, Mohamed Mokhtar; Khairy, M.; Eid, Salah

    2016-02-01

    Titanate-SWCNT; synthesized via exploiting the interaction between TiO2 anatase with oxygen functionalized SWCNT, supported Ag nanoparticles and Ag/titanate are characterized using XRD, TEM-EDX-SAED, N2 adsorption, Photoluminescence, Raman and FTIR spectroscopy. These samples are tested for methanol electrooxidation via using cyclic voltammetry (CV) and impedance measurements. It is shown that Ag/titanate nanotubes exhibited superior electrocatalytic performance for methanol oxidation (4.2 mA cm-2) than titanate-SWCNT, Ag/titanate-SWCNT and titanate. This study reveals the existence of a strong metal-support interaction in Ag/titanate as explored via formation of Ti-O-Ag bond at 896 cm-1 and increasing surface area and pore volume (103 m2 g-1, 0.21 cm3 g-1) compared to Ag/titanate-SWCNT (71 m2 g-1, 0.175 cm3 g-1) that suffers perturbation and defects following incorporation of SWCNT and Ag. Embedding Ag preferably in SWCNT rather than titanate in Ag/titanate-SWCNT disturbs the electron transfer compared to Ag/titanate. Charge transfer resistance depicted from Nyquist impedance plots is found in the order of titanate > Ag/titanate-SWCNT > titanate-SWCNT > Ag/titanate. Accordingly, Ag/titanate indicates a slower current degradation over time compared to rest of catalysts. Conductivity measurements indicate that it follows the order Ag/titanate > Ag/titanate-SWCNT > titanate > titanate-SWCNT declaring that SWCNT affects seriously the conductivity of Ag(titanate) due to perturbations caused in titanate and sinking of electrons committed by Ago through SWCNT.

  1. Synthesis of Ordered Mesoporous CuO/CeO2 Composite Frameworks as Anode Catalysts for Water Oxidation

    Directory of Open Access Journals (Sweden)

    Vassiliki Markoulaki Ι

    2015-11-01

    Full Text Available Cerium-rich metal oxide materials have recently emerged as promising candidates for the photocatalytic oxygen evolution reaction (OER. In this article, we report the synthesis of ordered mesoporous CuO/CeO2 composite frameworks with different contents of copper(II oxide and demonstrate their activity for photocatalytic O2 production via UV-Vis light-driven oxidation of water. Mesoporous CuO/CeO2 materials have been successfully prepared by a nanocasting route, using mesoporous silica as a rigid template. X-ray diffraction, electron transmission microscopy and N2 porosimetry characterization of the as-prepared products reveal a mesoporous structure composed of parallel arranged nanorods, with a large surface area and a narrow pore size distribution. The molecular structure and optical properties of the composite materials were investigated with Raman and UV-Vis/NIR diffuse reflectance spectroscopy. Catalytic results indicated that incorporation of CuO clusters in the CeO2 lattice improved the photochemical properties. As a result, the CuO/CeO2 composite catalyst containing ~38 wt % CuO reaches a high O2 evolution rate of ~19.6 µmol·h−1 (or 392 µmol·h−1·g−1 with an apparent quantum efficiency of 17.6% at λ = 365 ± 10 nm. This OER activity compares favorably with that obtained from the non-porous CuO/CeO2 counterpart (~1.3 µmol·h−1 and pure mesoporous CeO2 (~1 µmol·h−1.

  2. New Construction and Catalyst Support Materials for Water Electrolysis at Elevated Temperatures

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey

    in question are those for bipolar plates, gas diusion layers (GDLs), catalysts and catalyst supports. This work is focused on developing bipolar plate, GDL and catalyst support materials for the anode compartment of PEM electrolyzers, operating at elevated temperatures. The thesis starts with Chapter...... electrolysis. Chapter 4 reports results of testing dierent types of commercially available stainless steels, Ni-based alloys as well as titanium and tantalum as possible metallic bipolar plates and construction materials for HTPEMEC. The corrosion resistance was measured under simulated conditions of high...

  3. Influence of annealing and deformation on optical properties of ultra precision diamond turned and anodized 6060 aluminium alloy

    DEFF Research Database (Denmark)

    Tabrizian-Ghalehno, Naja; Hansen, Hans Nørgaard; Hansen, P.E.; Ambat, Rajan; Møller, Per

    surface of the forged material was then diamond turned to a mirror like finish. The diamond turned samples were subsequently anodized in a sulphuric acid bath. The microstructure of the samples was analysed using optical microscopy (LOM), scanning electron microscopy (SEM) and energy dispersive X......-ray spectroscopy (EDX). Colour/brightness measurements were carried out using CIE Lab system. An optical method was used to measure the thickness of the oxide film and roughness of the surface was measured before and after anodizing using stylus, a mechanical instrument, and bidirectional reflection distribution...

  4. Mesoporous Silicon-Based Anodes

    Science.gov (United States)

    Peramunage, Dharmasena

    2015-01-01

    For high-capacity, high-performance lithium-ion batteries. A new high-capacity anode composite based on mesoporous silicon is being developed. With a structure that resembles a pseudo one-dimensional phase, the active anode material will accommodate significant volume changes expected upon alloying and dealloying with lithium (Li).

  5. Catalytic Hydrogenation of Levulinic Acid in Water into g-Valerolactone over Bulk Structure of Inexpensive Intermetallic Ni-Sn Alloy Catalysts

    Directory of Open Access Journals (Sweden)

    Rodiansono Rodiansono

    2015-07-01

    Full Text Available A bulk structure of inexpensive intermetallic nickel-tin (Ni-Sn alloys catalysts demonstrated highly selective in the hydrogenation of levulinic acid in water into g-valerolactone. The intermetallic Ni-Sn catalysts were synthesized via a very simple thermochemical method from non-organometallic precursor at low temperature followed by hydrogen treatment at 673 K for 90 min. The molar ratio of nickel salt and tin salt was varied to obtain the corresponding Ni/Sn ratio of 4.0, 3.0, 2.0, 1.5, and 0.75. The formation of Ni-Sn alloy species was mainly depended on the composition and temperature of H2 treatment. Intermetallics Ni-Sn that contain Ni3Sn, Ni3Sn2, and Ni3Sn4 alloy phases are known to be effective heterogeneous catalysts for levulinic acid hydrogenation giving very excellence g-valerolactone yield of >99% at 433 K, initial H2 pressure of 4.0 MPa within 6 h. The effective hydrogenation was obtained in H2O without the formation of by-product. Intermetallic Ni-Sn(1.5 that contains Ni3Sn2 alloy species demonstrated very stable and reusable catalyst without any significant loss of its selectivity. © 2015 BCREC UNDIP. All rights reserved. Received: 26th February 2015; Revised: 16th April 2015; Accepted: 22nd April 2015  How to Cite: Rodiansono, R., Astuti, M.D., Ghofur, A., Sembiring, K.C. (2015. Catalytic Hydrogenation of Levulinic Acid in Water into g-Valerolactone over Bulk Structure of Inexpensive Intermetallic Ni-Sn Alloy Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 192-200. (doi:10.9767/bcrec.10.2.8284.192-200Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.8284.192-200  

  6. Effect of Anodic Current Density on Characteristics and Low Temperature IR Emissivity of Ceramic Coating on Aluminium 6061 Alloy Prepared by Microarc Oxidation

    OpenAIRE

    Al Bosta, Mohannad M. S.; Keng-Jeng Ma; Hsi-Hsin Chien

    2013-01-01

    High emitter MAO ceramic coatings were fabricated on the Al 6061 alloy, using different bipolar anodic current densities, in an alkali silicate electrolyte. We found that, as the current density increased from 10.94 A/dm2 to 43.75 A/dm2, the layer thickness was increased from 10.9 μm to 18.5 μm, the surface roughness was increased from 0.79 μm to 1.27 μm, the area ratio of volcano-like microstructure was increased from 55.6% to 59.6%, the volcano-like density was decreased from 2620 mm−2 to 1...

  7. Hydrogenation of furfuryl alcohol to tetrahydrofurfuryl alcohol on NiB/SiO2 amorphous alloy catalyst

    Institute of Scientific and Technical Information of China (English)

    SONG Yun; LI Wei; ZHANG Minghui; TAO Keyi

    2007-01-01

    NiB/SiO2 amorphous alloy catalyst was prepared by power electroless plating method and characterized by induction coupled plasma (ICP),Brunauer-Emmett-Teller method (BET),transmission electron microscope (TEM)and X-ray diffraction (XRD) techniques.The catalytic performance of NiB/SiO2 was investigated for the hydrogenation of furfuryl alcohol (FA) to tetrahydrofurfuryl alcohol (THFA).The effects of operational conditions,such as reaction temperature,pressure,and stirring rate were carefully studied.The proper conditions were determined as the following:pressure 2.0 MPa,temperature 120℃ and stirring rate 550 r/min.A typical result with FA conversion of 99%and THFA selectivity of 100% was obtained under such conditions,which was close to that over Raney Ni.

  8. Surface structure and chemistry of Pt/Cu/Pt(1 1 1) near surface alloy model catalyst in CO

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Shibi [College of Physical Science and Technology, Central China Normal University, Wuhan 430079 (China); Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States); Nguyen, Luan; Cheng, Fang [Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States); Liu, Lacheng [Department of Physics, Nanchang University, Nanchang 350000 (China); Yu, Ying [College of Physical Science and Technology, Central China Normal University, Wuhan 430079 (China); Tao, Franklin, E-mail: franklin.tao.2011@gmail.com [Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States)

    2014-11-30

    Graphical abstract: - Abstract: Near surface alloy (NSA) model catalyst Pt/Cu/Pt(1 1 1) was prepared on Pt(1 1 1) through a controlled vapor deposition of Cu atoms. Different coordination environments of Pt atoms of the topmost Pt layer with the underneath Cu atoms in the subsurface result in different local electronic structures of surface Pt atoms. Surface structure and chemistry of the NAS model catalyst in Torr pressure of CO were studied with high pressure scanning tunneling microscopy (HP-STM) and ambient pressure X-ray photoelectron spectroscopy (AP-XPS). In Torr pressure of CO, the topmost Pt layer of Pt/Cu/Pt(1 1 1) is restructured to thin nanoclusters with size of about 1 nm. Photoemission feature of O 1s of CO on Pt/Cu/Pt(1 1 1) suggests CO adsorbed on both edge and surface of these formed nanoclusters. This surface is active for CO oxidation. Atomic layers of carbon are formed on Pt/Cu/Pt(1 1 1) at 573 K in 2 Torr of CO.

  9. Etude de l'anode pour la pile à combustible directe aux borohydrures

    OpenAIRE

    Olu, Pierre-Yves

    2015-01-01

    The present work focuses on direct borohydride fuel cell (DBFC) anodes. A first approach to develop a suitable anode design for the DBFC consists in the study of the anode within the real DBFC system. In that frame, carbon-supported platinum and palladium nanoparticles are characterized and compared as anode electrocatalyst in DBFC configuration. Other variables such as the morphology of the anode and the stability of the catalyst nanoparticles are considered.The ideal DBFC anode catalyst sho...

  10. Effect of magnesium on the aluminothermic reduction rate of zinc oxide obtained from spent alkaline battery anodes for the preparation of Al-Zn-Mg alloys

    Institute of Scientific and Technical Information of China (English)

    Rocio Ochoa; Alfredo Flores; Jesus Torres

    2016-01-01

    The aluminothermic reduction of zinc oxide (ZnO) from alkaline battery anodes using molten Al may be a good option for the elaboration of secondary 7000-series alloys. This process is affected by the initial content of Mg within molten Al, which decreases the sur-face tension of the molten metal and conversely increases the wettability of ZnO particles. The effect of initial Mg concentration on the alu-minothermic reduction rate of ZnO was analyzed at the following values:0.90wt%, 1.20wt%, 4.00t%, 4.25wt%, and 4.40wt%. The ZnO par-ticles were incorporated by mechanical agitation using a graphite paddle inside a bath of molten Al maintained at a constant temperature of 1123 K and at a constant agitation speed of 250 r/min, the treatment time was 240 min and the ZnO particle size was 450-500 mesh. The re-sults show an increase in Zn concentration in the prepared alloys up to 5.43wt%for the highest initial concentration of Mg. The reaction products obtained were characterized by scanning electron microscopy and X-ray diffraction, and the efficiency of the reaction was measured on the basis of the different concentrations of Mg studied.

  11. Ultrasmall PtSn alloy catalyst for ethanol electro-oxidation reaction

    Science.gov (United States)

    Kwak, Da-Hee; Lee, Young-Woo; Han, Sang-Beom; Hwang, Eui-Tak; Park, Han-Chul; Kim, Min-Cheol; Park, Kyung-Won

    2015-02-01

    To improve the electrocatalytic properties for an ethanol electro-oxidation reaction, modifications of Pt nanocrystallites have been used by alloying with other elements such as Ru, Sn, and Au. Here we demonstrate carbon supported Pt3Sn alloy electrocatalyst (Pt3Sn/C) synthesized using a thermal-decomposition method. The PtSn/C prepared by the present synthetic process shows a homogeneous distribution of ultrasmall alloy nanoparticles (∼2.5 nm) in the presence of Pt and Sn metallic states. At 0.45 V, the Pt3Sn/C (0.35 mA cm-2) exhibits much higher current density as compared with Pt/C (0.13 mA cm-2). In an electrochemical stability test, the Pt3Sn/C supported quite high current density and thus showed 3% current reduction after the stability test.

  12. Anodizing And Sealing Aluminum In Nonchromated Solutions

    Science.gov (United States)

    Emmons, John R.; Kallenborn, Kelli J.

    1995-01-01

    Improved process for anodizing and sealing aluminum involves use of 5 volume percent sulfuric acid in water as anodizing solution, and 1.5 to 2.0 volume percent nickel acetate in water as sealing solution. Replaces process in which sulfuric acid used at concentrations of 10 to 20 percent. Improved process yields thinner coats offering resistance to corrosion, fatigue life, and alloy-to-alloy consistency equal to or superior to those of anodized coats produced with chromated solutions.

  13. Catalytic Hydrogenation of Levulinic Acid in Water into g-Valerolactone over Bulk Structure of Inexpensive Intermetallic Ni-Sn Alloy Catalysts

    OpenAIRE

    Rodiansono Rodiansono; Maria Dewi Astuti; Abdul Ghofur; Kiky C. Sembiring

    2015-01-01

    A bulk structure of inexpensive intermetallic nickel-tin (Ni-Sn) alloys catalysts demonstrated highly selective in the hydrogenation of levulinic acid in water into g-valerolactone. The intermetallic Ni-Sn catalysts were synthesized via a very simple thermochemical method from non-organometallic precursor at low temperature followed by hydrogen treatment at 673 K for 90 min. The molar ratio of nickel salt and tin salt was varied to obtain the corresponding Ni/Sn ratio of 4.0, 3.0, 2.0, 1.5, a...

  14. Intermetallic Alloys as CO Electroreduction Catalysts-Role of Isolated Active Sites

    DEFF Research Database (Denmark)

    Karamad, Mohammadreza; Tripkovic, Vladimir; Rossmeisl, Jan

    2014-01-01

    potentially selective intermetallic surfaces on which CO can be reduced to methanol at potentials comparable to or even slightly positive than those for CO/CO2 reduction to methane on Cu. Common features shared by most of the selective alloys are single TM sites. The role of single sites is to block parasitic...

  15. Influence of Metal Sulfides as Anode Catalysts on Performance of H2S SOFC%金属硫化物作为阳极材料对H2S固体氧化物燃料电池性能研究

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Two anode catalysts with Pt, MoS2 and composite metal sulfides (MoS2+NiS), are investigated forelectrochemical oxidation of hydrogen sulfide in solid oxide fuel cell (SOFC) at temperatures 750-850℃. Thecatalysts comprising MoS2 and MoS2+NiS exhibited good electrical conductivity and catalytic activity. MoS2 andcomposite catalysts were found to be more active than Pt, a widely used catalyst for high temperature H2S/O2fuel cell at 750-850℃. However, MoS2 itself sublimes above 450℃. In contrast, composite catalysts containingboth Mo and transition metal (Ni) are shown to be stable and effective in promoting the oxidation of H2S in SOFCup to 850℃. However, electric contact is poor between the platinum current collecting layer and the compositemetal sulfide layer, so that the cell performance becomes worse. This problem is overcome by adding conductiveAg powder into the anode layer (forming MoS2+NiS+Ag anode material) to increase anode electrical conductanceinstead of applying a thin layer of platinum on the top of anode.

  16. Temperature dependence of electric resistance of anodic oxide films on niobium base alloy NbTsU

    International Nuclear Information System (INIS)

    Electrical resistance of oxide coatings formed on the surface of the NbTsU niobium alloy in aqueous solutions of alkaline electrolytes is investigated. Some anomalies related to the conditions of coating formation are canceled in temperature dependences of electrical resistance. The values of activation energy of electroconducting processes for different temperature intervals are calculated

  17. Alloy hydride catalyst route for the synthesis of single-walled carbon nanotubes, multi-walled carbon nanotubes and magnetic metal-filled multi-walled carbon nanotubes

    International Nuclear Information System (INIS)

    This paper presents a novel, cost-effective and single-step technique for the synthesis of single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs) and magnetic metal-filled MWNTs using a fixed bed reaction thermal chemical vapour deposition (CVD) using alloy hydride catalyst. The single-step method involves the pyrolysis of methane at suitable temperatures over fine powders of certain Mischmetal-based AB3 alloy hydride catalysts, prepared through the hydrogen decrepitation technique. These carbon nanostructures have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray analysis (EDAX), thermo-gravimetric analysis (TGA) and Raman spectroscopy. The magnetic properties of these metal-filled MWNTs have been studied by vibrating sample magnetometry, and the results are discussed

  18. Effect of Anodic Current Density on Characteristics and Low Temperature IR Emissivity of Ceramic Coating on Aluminium 6061 Alloy Prepared by Microarc Oxidation

    Directory of Open Access Journals (Sweden)

    Mohannad M. S. Al Bosta

    2013-01-01

    Full Text Available High emitter MAO ceramic coatings were fabricated on the Al 6061 alloy, using different bipolar anodic current densities, in an alkali silicate electrolyte. We found that, as the current density increased from 10.94 A/dm2 to 43.75 A/dm2, the layer thickness was increased from 10.9 μm to 18.5 μm, the surface roughness was increased from 0.79 μm to 1.27 μm, the area ratio of volcano-like microstructure was increased from 55.6% to 59.6%, the volcano-like density was decreased from 2620 mm−2 to 1420 mm−2, and the γ-alumina phase was decreased from 66.6 wt.% to 26.2 wt.%, while the α-alumina phase was increased from 3.9 wt.% to 27.6 wt.%. The sillimanite and cristobalite phases were around 20 wt.% and 9 wt.%, respectively, for 10.94 A/dm2 and approximately constant around 40 wt.% and less than 5 wt.%, respectively, for the anodic current densities 14.58, 21.88, and 43.75 A/dm2. The ceramic surface roughness and thickness slightly enhanced the IR emissivity in the semitransparent region (4.0–7.8 μm, while the existing phases contributed together to raise the emissivity in the opaque region (8.6–16.0 μm to higher but approximately the same emissivities.

  19. Nitrogen-doped graphene/CoNi alloy encased within bamboo-like carbon nanotube hybrids as cathode catalysts in microbial fuel cells

    Science.gov (United States)

    Hou, Yang; Yuan, Heyang; Wen, Zhenhai; Cui, Shumao; Guo, Xiaoru; He, Zhen; Chen, Junhong

    2016-03-01

    Cost-effective catalysts are of key importance to the successful deployment of microbial fuel cells (MFCs) for electricity generation from organic wastes. Herein, a novel catalyst prepared by one-step synthesis strategy is reported. The catalyst features N-doped bamboo-like carbon nanotube (BCNT) in which CoNi-alloy is encapsulated at the end and/or the middle section of the tube with many graphene layers inside inner cavities of BCNT (N-G@CoNi/BCNT). The prepared N-G@CoNi/BCNT exhibits a high oxygen reduction reaction (ORR) activity with an early onset potential of 0.06 V vs. Ag/AgCl and a comparable exchange current density to that of commercial Pt/C. The excellent catalytic activity is further evidenced by a high electron transfer number of 3.63. When being applied in MFCs, the N-G@CoNi/BCNT yields an average current density of 6.7 A m-2, slightly lower than that of Pt/C but with a less mass transfer potential loss. The cost of the N-G@CoNi/BCNT for constructing a 1-m2 cathode electrode is 200 times lower than that of Pt/C. With such a competitive price and excellent electrocatalytic-activity resulting from its unique morphology, CoNi-alloy/nitrogen dopants, considerable specific surface area, and carbon-coated alloy/graphene hybridization, the present catalyst is a promising candidate for ORR catalysts in MFCs for energy recovery from wastes.

  20. Formic acid oxidation at platinum-bismuth catalysts

    Directory of Open Access Journals (Sweden)

    Popović Ksenija Đ.

    2015-01-01

    Full Text Available The field of heterogeneous catalysis, specifically catalysis on bimetallic surfaces, has seen many advances over the past few decades. Bimetallic catalysts, which often show electronic and chemical properties that are distinct from those of their parent metals, offer the opportunity to obtain new catalysts with enhanced selectivity, activity, and stability. The oxidation of formic acid is of permanent interest as a model reaction for the mechanistic understanding of the electrooxidation of small organic molecules and because of its technical relevance for fuel cell applications. Platinum is one of the most commonly used catalysts for this reaction, despite the fact that it shows a few significant disadvantages: high cost and extreme susceptibility to poisoning by CO. To solve this problem, several approaches have been used, but generally, they all consist in the modification of platinum with a second element. Especially, bismuth has received significant attention as Pt modifier. According to the results presented in this survey dealing with the effects influencing the formic acid oxidation it was found that two types of Pt-Bi bimetallic catalysts (bulk and low loading deposits on GC showed superior catalytic activity in terms of the lower onset potential and oxidation current density, as well as exceptional stability compared to Pt. The findings in this report are important for the understanding of mechanism of formic acid electrooxidation on a bulk alloy and decorated surface, for the development of advanced anode catalysts for direct formic acid fuel cells, as well as for the synthesis of novel low-loading bimetallic catalysts. The use of bimetallic compounds as the anode catalysts is an effective solution to overcoming the problems of the formic acid oxidation current stability for long term applications. In the future, the tolerance of both CO poisoning and electrochemical leaching should be considered as the key factors in the development

  1. A Platinum Monolayer Core-Shell Catalyst with a Ternary Alloy Nanoparticle Core and Enhanced Stability for the Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Haoxiong Nan

    2015-01-01

    Full Text Available We synthesize a platinum monolayer core-shell catalyst with a ternary alloy nanoparticle core of Pd, Ir, and Ni. A Pt monolayer is deposited on carbon-supported PdIrNi nanoparticles using an underpotential deposition method, in which a copper monolayer is applied to the ternary nanoparticles; this is followed by the galvanic displacement of Cu with Pt to generate a Pt monolayer on the surface of the core. The core-shell Pd1Ir1Ni2@Pt/C catalyst exhibits excellent oxygen reduction reaction activity, yielding a mass activity significantly higher than that of Pt monolayer catalysts containing PdIr or PdNi nanoparticles as cores and four times higher than that of a commercial Pt/C electrocatalyst. In 0.1 M HClO4, the half-wave potential reaches 0.91 V, about 30 mV higher than that of Pt/C. We verify the structure and composition of the carbon-supported PdIrNi nanoparticles using X-ray powder diffraction, X-ray photoelectron spectroscopy, thermogravimetry, transmission electron microscopy, and energy dispersive X-ray spectrometry, and we perform a stability test that confirms the excellent stability of our core-shell catalyst. We suggest that the porous structure resulting from the dissolution of Ni in the alloy nanoparticles may be the main reason for the catalyst’s enhanced performance.

  2. Design of heterogeneous catalysts

    DEFF Research Database (Denmark)

    Frey, Anne Mette

    was inspired by a computational screening, suggesting that alloys such as Ni-Fe, Co-Ni, and Co-Fe should show superior activity to the industrially used nickel catalyst. Especially the Ni-Fe system was considered to be interesting, since such alloy catalysts should be both more active and cheaper than...... turned out to work well, and the best catalyst prepared had a C5+ yield almost a factor of two higher than a standard air calcined Co catalyst. In the NH3-SCR reaction it is desirable to develop an active and stable catalyst for NOx removal in automotive applications, since the traditionally used...

  3. Formation and Characterization of Pd, Pt and Pd-Pt Alloy Films on Polyimide by Catalyst-Enhanced Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jinlan; CHENG Yinhua; Yousuf Hamadan; YU Kaichao

    2007-01-01

    Platinum, palladium and their alloy films on polyimide were formed by catalyst-enhanced chemical vapor deposition (CVD) in the carrier gas (N2, O2) at 220-300 ℃ under reduced pressure and normal pressure. The deposition of palladium complexes [ Pd((η3-allyl)(hfac) and Pd(hfac)2 ] gives pure palladium film,while the deposition of platinum needs the enhancement of palladium complex by mixing precursor platinum complex Pt(COD)Me2 and palladium complex in the same chamber. The co-deposition of Pd and Pt metals was used for the deposition of alloy films. During the CVD of palladium-platinum alloy, the Pd/Pt atomic ratios vary under different co-deposition conditions. These metal films were characterized by XPS and SEM, and show a good adhesive property.

  4. Evaluating the role of Lead In A Novel Ternary Catalysts For DMFCs

    CERN Document Server

    Halder, Aditi; Trahan, Matthew; Mukerjee, Sanjeev

    2012-01-01

    The current density at lower potential is highly desirable in fuel cell technology and crucial center point for designing a new catalyst. By alloying platinum with various other metals, the improvisation of the fuel cell catalyst has achieved a lot of attention and interests. In this article, a novel porous ternary alloy PtPb@Ru as anode catalysts for direct methanol fuel cell had been synthesized by micro-emulsion technique. The catalysts had been characterized by various spectroscopic and microscopic techniques. The activity and durability of the catalysts had been tested by running cyclic voltammetry in 0.1 M HClO4 and 1M Methanol. To explain the many fold increase in current density of the PtPb@Ru catalysts in comparison to the commercial available PtRu catalysts, in situ X-ray absorption spectroscopy (XAS) measurements, at the PtL3 edge (XANES and EXAFS) were carried out on the PtPb@Ru catalysts in an electrochemical cell. The down-shift in the d-band center of platinum observed in the XAS study, might b...

  5. CuAu–ZnO–graphene nanocomposite: A novel graphene-based bimetallic alloy-semiconductor catalyst with its enhanced photocatalytic degradation performance

    International Nuclear Information System (INIS)

    Graphical abstract: In this work, we have successfully synthesized a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite, and which behaved an enhanced photocatalytic activity. - Highlights: • A bimetallic alloy-based catalyst: CuAu–ZnO–Gr is synthesized. • CuAu–ZnO–Gr behaves an enhanced photocatalytic activity. • The detailed explanation of photocatalytic mechanism of CuAu–ZnO–Gr. - Abstract: The bimetallic alloy CuAu nanoparticles (NPs) can produce more photogenerated electrons when compared with single metal Au NPs. Moreover, graphene (Gr) sheets can help the charge separation and slow down the recombination of the electron hole pairs of ZnO. Hence, a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite is synthesized. Due to the synergistic effect among CuAu NPs, ZnO nanopyramids, and Gr sheets, CuAu–ZnO–Gr behaves an enhanced photocatalytic activity for the photocatalytic degradation of synthetic colorants methyl orange (MO), methylene blue (MB), indigotin (IN), sunset yellow (SY), and tartrazine (TT) under the simulated sunlight irradiation. Furthermore, the apparent rate constants (kapp) of MO, MB, IN, SY, and TT degradation are estimated respectively. In addition, the as-prepared CuAu–ZnO–Gr nanocomposite is characterized by X-ray diffraction, UV–vis spectrum, transmission electron microscopy, energy dispersive X-ray analysis (EDX), and EDX mapping. As a result of the facile synthesis route and the enhanced photocatalytic activity, this new material CuAu–ZnO–Gr can be a promising photocatalyst for the degradation of dyes

  6. CuAu–ZnO–graphene nanocomposite: A novel graphene-based bimetallic alloy-semiconductor catalyst with its enhanced photocatalytic degradation performance

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Hong [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Ye, Xiaoliang [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Duan, Kaiyue; Xue, Muyin; Du, Yongling; Ye, Weichun [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Wang, Chunming, E-mail: wangcm@lzu.edu.cn [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)

    2015-07-05

    Graphical abstract: In this work, we have successfully synthesized a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite, and which behaved an enhanced photocatalytic activity. - Highlights: • A bimetallic alloy-based catalyst: CuAu–ZnO–Gr is synthesized. • CuAu–ZnO–Gr behaves an enhanced photocatalytic activity. • The detailed explanation of photocatalytic mechanism of CuAu–ZnO–Gr. - Abstract: The bimetallic alloy CuAu nanoparticles (NPs) can produce more photogenerated electrons when compared with single metal Au NPs. Moreover, graphene (Gr) sheets can help the charge separation and slow down the recombination of the electron hole pairs of ZnO. Hence, a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite is synthesized. Due to the synergistic effect among CuAu NPs, ZnO nanopyramids, and Gr sheets, CuAu–ZnO–Gr behaves an enhanced photocatalytic activity for the photocatalytic degradation of synthetic colorants methyl orange (MO), methylene blue (MB), indigotin (IN), sunset yellow (SY), and tartrazine (TT) under the simulated sunlight irradiation. Furthermore, the apparent rate constants (k{sub app}) of MO, MB, IN, SY, and TT degradation are estimated respectively. In addition, the as-prepared CuAu–ZnO–Gr nanocomposite is characterized by X-ray diffraction, UV–vis spectrum, transmission electron microscopy, energy dispersive X-ray analysis (EDX), and EDX mapping. As a result of the facile synthesis route and the enhanced photocatalytic activity, this new material CuAu–ZnO–Gr can be a promising photocatalyst for the degradation of dyes.

  7. Solid-state-reaction synthesis of cotton-like CoB alloy at room temperature as a catalyst for hydrogen generation.

    Science.gov (United States)

    Wang, Xingpu; Liao, Jinyun; Li, Hao; Wang, Hui; Wang, Rongfang

    2016-08-01

    A novel room-temperature solid-state reaction is developed to synthesize cotton-like CoB alloy (CoBSSR) catalysts with a large specific surface area of 222.4m(2)g(-1). In the hydrolysis of ammonia borane catalyzed by the CoBSSR, the rate of hydrogen generation can reach 68.7mLmin(-1) with a turnover frequency (TOF) value of ca. 6.9Lhydrogenmin(-1)gcatalyst(-1) at 25°C. The TOF value is about 2 times as large as that of CoB alloy prepared by a regular solid-state reaction, which is also much higher than those of the CoB catalysts recently reported in the literature. The activation energy of the hydrolysis of ammonia borane catalyzed by the CoBSSR is as low as 22.78kJmol(-1), hinting that the CoBSSR possesses high catalytic activity, which may be attributed to the large specific surface area and the abundant porous structure. The high catalytic performance, good recoverability and low cost of the CoBSSR enable it to be a promissing catalyst condidate in the hydrolysis of ammonia borane for hydrogen production in commercial application. PMID:27163841

  8. Graphitized nanodiamond supporting PtNi alloy as stable anodic and cathodic electrocatalysts for direct methanol fuel cell

    International Nuclear Information System (INIS)

    Highlights: • The graphitized nanodiamond (GND) showed a higher oxidation-resistance than XC-72. • The PtNi/GND electrocatalytic exhibited greater stability than PtNi/XC-72. • The PtNi/GND had a better catalytic activity for MOR and ORR than Pt/GND. -- Abstract: Surface graphitized nanodiamond (GND) with a diamond core covered by a graphitic carbon shell was prepared by annealing ND at the temperature of 1300 °C in a vacuum of 10−3 Pa. PtNi electrocatalysts were prepared by a microwave heating polyol method using the prepared GND as a support. The composition and morphology of the PtNi electrocatalysts supported on GND (PtNi/GND) were characterized by X-ray diffraction, transmission electron microscopy and energy dispersion spectra. The results showed that nano-scaled PtNi alloy particles with an atomic ratio of approximately 1:1 were uniformly deposited on the GND through co-reduction process. The electrocatalytic activities of the PtNi/GND electrocatalysts for methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) were investigated by cyclic voltammetry, chronoamperometry and linear sweep voltammetry. The PtNi/GND exhibited better electrocatalytic activities than the Pt/GND either for MOR and ORR. In comparison with traditional carbon support Vulcan XC-72, GND showed higher oxidation-resistance, and consequently led to greater stability for the PtNi/GND than PtNi/XC-72

  9. Properties of the hydrogen oxidation reaction on Pt/C catalysts at optimised high mass transport conditions and its relevance to the anode reaction in PEFCs and cathode reactions in electrolysers

    International Nuclear Information System (INIS)

    Using a high mass transport floating electrode technique with an ultra-low catalyst loading (0.84–3.5 μgPt cm−2) of commonly used Pt/C catalyst (HiSPEC 9100, Johnson Matthey), features in the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) were resolved and defined, which have rarely been previously observed. These features include fine structure in the hydrogen adsorption region between 0.18 < V vs. RHE < 0.36 V vs. RHE consisting of two peaks, an asymptotic decrease at potentials greater than 0.36 V vs. RHE, and a hysteresis above 0.1 V vs. RHE which corresponded to a decrease in the cathodic scan current by up to 50% of the anodic scan. These features are examined as a function of hydrogen and proton concentration, anion type and concentration, potential scan limit, and temperature. We provide an analytical solution to the Heyrovsky–Volmer equation and use it to analyse our results. Using this model we are able to extract catalytic properties (without mass transport corrections; a possible source of error) by simultaneously fitting the model to HOR curves in a variety of conditions including temperature, hydrogen partial pressure and anion/H+ concentration. Using our model we are able to rationalise the pH and hydrogen concentration dependence of the hydrogen reaction. This model may be useful in application to fuel cell and electrolyser simulation studies

  10. AuPt Alloy on TiO2: A Selective and Durable Catalyst for L-Sorbose Oxidation to 2-Keto-Gulonic Acid.

    Science.gov (United States)

    Chan-Thaw, Carine E; Chinchilla, Lidia E; Campisi, Sebastian; Botton, Gianluigi A; Prati, Laura; Dimitratos, Nikolaos; Villa, Alberto

    2015-12-21

    Pt nanoparticles were prepared by a sol immobilization route, deposited on supports with different acid/base properties (MgO, activated carbon, TiO2 , Al2O3, H-Mordenite), and tested in the selective oxidation of sorbose to 2-keto-gulonic acid (2-KGUA), an important precursor for vitamin C. In general, as the basicity of the support increased, a higher catalytic activity occurred. However, in most cases, a strong deactivation was observed. The best selectivity to 2-KGUA was observed with acidic supports (TiO2 and H-Mordenite) that were able to minimize the formation of C1/C2 products. We also demonstrated that, by alloying Pt to Au, it is possible to enhance significantly the selectivity of Pt-based catalysts. Moreover, the AuPt catalyst, unlike monometallic Pt, showed good stability in recycling because of the prevention of metal leaching during the reaction. PMID:26611807

  11. Co-Mn-Al Mixed Oxides on Anodized Aluminum Supports and Their Use as Catalysts in the Total Oxidation of Ethanol

    Czech Academy of Sciences Publication Activity Database

    Kovanda, F.; Jirátová, Květa; Ludvíková, Jana; Raabová, H.

    2013-01-01

    Roč. 464, AUG 15 (2013), s. 181-190. ISSN 0926-860X R&D Projects: GA ČR GAP106/10/1762 Institutional support: RVO:67985858 Keywords : layered double hydroxides * hydrothermal reaction * mixed oxides * supported catalysts * ethanol total oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.674, year: 2013

  12. Preparation and study of IrO2/SiC–Si supported anode catalyst for high temperature PEM steam electrolysers

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey; Tomás García, Antonio Luis; Petrushina, Irina;

    2011-01-01

    A novel catalyst material for oxygen evolution electrodes was prepared and characterised by different techniques. IrO2 supported on a SiC–Si composite was synthesised by the Adams fusion method. XRD and nitrogen adsorption experiments showed an influence of the support on the surface properties o...

  13. Final technical report. Bimetallic complexes as methanol oxidation catalysts

    Energy Technology Data Exchange (ETDEWEB)

    McElwee-White, Lisa

    2002-01-21

    Our work on the electrocatalyzed oxidation of methanol was initially motivated by the interest in methanol as an anodic reactant in fuel cells. The literature on electrochemical oxidation of alcohols can be roughly grouped into two sets: fuel cell studies and inorganic chemistry studies. Work on fuel cells primarily focuses on surface-catalyzed oxidation at bulk metal anodes, usually Pt or Pt/Ru alloys. In the surface science/electrochemistry approach to these studies, single molecule catalysts are generally not considered. In contrast, the inorganic community investigates the electrooxidation of alcohols in homogeneous systems. Ruthenium complexes have been the most common catalysts in these studies. The alcohol substrates are typically either secondary alcohols (e.g., isopropanol) such that the reaction stops after 2 e{sup -} oxidation to the aldehyde and 4 e{sup -} oxidation to the carboxylic acid can be observed. Methanol, which can also undergo 6 e{sup -} oxidation to CO{sub 2}, rarely appears in the homogeneous catalysis studies. Surface studies have shown that two types of metal centers with different functions result in more effective catalysts than a single metal; however, application of this concept to homogeneous systems has not been demonstrated. The major thrust of the work is to apply this insight from the surface studies to homogeneous catalysis. Even though homogeneous systems would not be appropriate models for active sites on Pt/Ru anodes, it is possible that heterobimetallic catalysts could also utilize two metal centers for different roles. Starting from that perspective, this work involves the preparation and investigation of heterobinuclear catalysts for the electrochemical oxidation of methanol.

  14. Anodic oxidation

    CERN Document Server

    Ross, Sidney D; Rudd, Eric J; Blomquist, Alfred T; Wasserman, Harry H

    2013-01-01

    Anodic Oxidation covers the application of the concept, principles, and methods of electrochemistry to organic reactions. This book is composed of two parts encompassing 12 chapters that consider the mechanism of anodic oxidation. Part I surveys the theory and methods of electrochemistry as applied to organic reactions. These parts also present the mathematical equations to describe the kinetics of electrode reactions using both polarographic and steady-state conditions. Part II examines the anodic oxidation of organic substrates by the functional group initially attacked. This part particular

  15. Carbon Deposition and Sulfur Tolerant La0.4Sr0.5Ba0.1TiO3–La0.4Ce0.6O1.8 Anode Catalysts for Solid Oxide Fuel Cells

    International Nuclear Information System (INIS)

    Highlights: • Carbon deposition and sulfur tolerant perovskite LSBT–LDC anode was prepared. • LSBT–LDC showed higher electrochemical performance than LSBT anode in sour CH4. • The addition of LDC contributed to the removal of carbon deposition on anode. - Abstract: In this work, LSBT–LDC (La0.4Sr0.5Ba0.1TiO3–La0.4Ce0.6O1.8) was successfully prepared by impregnating LSBT and LDC solutions on porous YSZ matrix. The prepared anode material exhibited higher catalytic performance and better resistance against carbon deposition than LSBT anode material in 5000 ppm H2S containing methane. Electrochemical impedance spectra (EIS) characterizations revealed that the addition of LDC significantly reduces the activation polarization resistance. Energy-dispersive X-ray spectroscopy (EDX) results indicated that the distribution of impregnated oxides in the matrix was uniform. The results of X-ray photoelectron spectroscopy (XPS) and temperature-programed oxidation (TPO) indicated that LSBT–LDC anode could enhance the tolerance against carbon deposition. The gas chromatography (GC) analysis proved that the modification of LDC could effectively promote the activation of methane and contribute to remove carbon deposition formed on the catalyst simultaneously

  16. In Situ Fabrication of PtCo Alloy Embedded in Nitrogen-Doped Graphene Nanopores as Synergistic Catalyst for Oxygen Reduction Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Xing; Wang, Lei; Zhou, Hu; Qin, Yingying; Xu, Wenlei; Jiang, Yu; Sun, Youyi; Shi, Zheqi; Zhuang, Guilin; Li, Xiaonian; Mei, Donghai; Wang, Jian-guo

    2015-11-23

    A novel PtCo alloy in situ etched and embedded in graphene nanopores (PtCo/NPG) as a high-performance catalyst for ORR was reported. Graphene nanopores were fabricated in situ while forming PtCo nanoparticles that were uniformly embedded in the graphene nanopores. Given the synergistic effect between PtCo alloy and nanopores, PtCo/NPG exhibited 11.5 times higher mass activity than that of the commercial Pt/C cathode electrocatalyst. DFT calculations indicated that the nanopores in NPG cannot only stabilize PtCo nanoparticles but can also definitely change the electronic structures, thereby change its adsorption abilities. This enhancement can lead to a favorable reaction pathway on PtCo/NPG for ORR. This study showed that PtCo/NPG is a potential candidate for the next generation of Pt-based catalysts in fuel cells. This study also offered a promising alternative strategy and enabled the fabrication of various kinds of metal/graphene nanopore nanohybrids with potential applications in catalysts and potential use for other technological devices. The authors acknowledge the financial support from the National Basic Research Program (973 program, No. 2013CB733501), Zhejiang Provincial Education Department Research Program (Y201326554) and the National Natural Science Foundation of China (No. 21306169, 21101137, 21136001, 21176221 and 91334013). D. Mei acknowledges the support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) and by the National Energy Research Scientific Computing Center (NERSC).

  17. Electrostatic layer-by-layer a of platinum-loaded multiwall carbon nanotube multilayer: A tunable catalyst film for anodic methanol oxidation

    International Nuclear Information System (INIS)

    A simple layer-by-layer (LBL) electrostatic adsorption technique was developed for deposition of films composed of alternating layers of positively charged poly(diallyldimethylammonium chloride) (PDDA) and negatively charged multiwall carbon nanotubes bearing platinum nanoparticles (Pt-CNTs). PDDA/Pt-CNT film structure and morphology up to six layers were characterized by scanning electron microscopy and ultraviolet-visible spectroscopy, showing the Pt-CNT layers to be porous and uniformly deposited within the multilayer films. Electrochemical properties of the PDDA/Pt-CNT films, as well as electrocatalytic activity toward methanol oxidation, were investigated with cyclic voltammetry. Significant activity toward anodic methanol oxidation was observed and is readily tunable through changing film thickness and/or platinum-nanoparticle loading. Overall, the observed properties of these PDDA/Pt-CNT multilayer films indicated unique potential for application in direct methanol fuel cell

  18. 锂离子电池C-Sn-金属复合负极材料的研究进展%Research Progress of C-Sn-alloy Composite Anode Materials for Li-ion Batteries

    Institute of Scientific and Technical Information of China (English)

    王录娥; 任旭梅; 吴峰

    2011-01-01

    The development status of carbon and tin-alloy composite anode materials is introduced. C-Sn com posite materials are classified into three categories, and the electrochemical performance characteristics for every type of composite materials are analysed. The latest progress of C-Sn-alloy composite materials, which have a higher capaci ty and excellent cycle performance is outlined. Therefore, it is a promising anode material for Li-ion batteries in the future.%综述了锂离子电池碳材料与锡基合金复合材料的发展现状,总结了C-Sn二元复合材料的主要种类,并分析了它们作为负极材料的电化学性能特点;同时阐述了C-Sn-金属三元复合材料的发展,这种复合材料结合了碳材料的循环稳定性和合金材料的高比容量的优势,是具有发展前景的新型锂离子电池负极材料.

  19. Anodic behavior of mechanically alloyed Cu–Ni–Fe and Cu–Ni–Fe–O electrodes for aluminum electrolysis in low-temperature KF-AlF3 electrolyte

    International Nuclear Information System (INIS)

    A comparative study on the anodic behavior of Cu65Ni20Fe15 and (Cu65Ni20Fe15)98.6O1.4 materials during the electrolysis of aluminum was conducted. Both materials were prepared in powder form by ball milling and subsequently consolidated to form dense pellets that were used as anodes. The electrochemical characterization was performed at 700 °C in a potassium cryolite-based electrolyte, and the composition-morphology of the oxide scales formed on both anodes were determined by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction measurements. On Cu65Ni20Fe15, a thick (170 μm) and porous oxide scale is formed after 15 min of electrolysis that readily dissolves (or spalls) before a denser oxide layer is formed after a longer electrolysis time (1 and 5 h). In comparison, a thin (2 μm) and dense oxide layer mainly composed of NiFe2O4 is observed on a (Cu65Ni20Fe15)98.6O1.4 electrode after 15 min of electrolysis. The thickness of this oxide layer increases to 10 and 30 μm after 1 h and 5 h of electrolysis. However, the outward diffusion of Cu to form CuOx at the surface of the electrode is not totally hampered by the presence of NiFe2O4 and a porous Cu-depleted region is formed at the oxide/alloy interface. As a result, electrolyte penetration occurs in the scale, which favors the progressive formation of an iron fluoride layer at the oxide/alloy interface

  20. Carbon nanotube-supported Au-Pd alloy with cooperative effect of metal nanoparticles and organic ketone/quinone groups as a highly efficient catalyst for aerobic oxidation of amines.

    Science.gov (United States)

    Deng, Weiping; Chen, Jiashu; Kang, Jincan; Zhang, Qinghong; Wang, Ye

    2016-05-21

    Functionalised carbon nanotube (CNT)-supported Au-Pd alloy nanoparticles were highly efficient catalysts for the aerobic oxidation of amines. We achieved the highest turnover frequencies (>1000 h(-1)) for the oxidative homocoupling of benzylamine and the oxidative dehydrogenation of dibenzylamine. We discovered a cooperative effect between Au-Pd nanoparticles and ketone/quinone groups on CNTs. PMID:27125360

  1. Performance and life-time behaviour of NiCu-CGO anodes for the direct electro-oxidation of methane in IT-SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Sin, A.; Kopnin, E.; Dubitsky, Y.; Zaopo, A. [Pirelli Labs S.p.A., Viale Sarca 222, I-20126 Milan (Italy); Arico, A.S.; La Rosa, D.; Gullo, L.R.; Antonucci, V. [CNR-ITAE, Via Salita Santa Lucia Sopra Contesse 5, I-98125 Messina (Italy)

    2007-01-10

    An anodic cermet of NiCu alloy and gadolinia doped ceria has been investigated for CH{sub 4} electro-oxidation in IT-SOFCs. Polarization curves have been recorded in the temperature range from 650 to 800{sup o}C. A maximum power density of 320mWcm{sup -2} at 800{sup o}C has been obtained in the presence of dry methane in an electrolyte-supported cell. The electrochemical behaviour during 1300h operation in dry methane and in the presence of redox-cycles has been investigated at 750{sup o}C; variation of the electrochemical properties during these experiments have been interpreted in terms of anode morphology modifications. The methane cracking process at the anode catalyst has been investigated by analysing the oxidative stripping of deposited carbon species. (author)

  2. Low cost fuel cell diffusion layer configured for optimized anode water management

    Science.gov (United States)

    Owejan, Jon P; Nicotera, Paul D; Mench, Matthew M; Evans, Robert E

    2013-08-27

    A fuel cell comprises a cathode gas diffusion layer, a cathode catalyst layer, an anode gas diffusion layer, an anode catalyst layer and an electrolyte. The diffusion resistance of the anode gas diffusion layer when operated with anode fuel is higher than the diffusion resistance of the cathode gas diffusion layer. The anode gas diffusion layer may comprise filler particles having in-plane platelet geometries and be made of lower cost materials and manufacturing processes than currently available commercial carbon fiber substrates. The diffusion resistance difference between the anode gas diffusion layer and the cathode gas diffusion layer may allow for passive water balance control.

  3. Ordered alloy formation for Pt3Fe/C, PtFe/C and Pt5.75Fe5.75Cuy/CO2-reduction electro-catalysts

    International Nuclear Information System (INIS)

    Carbon supported Pt3Fe, PtFe and Pt5.75Fe5.75Cu catalysts are prepared via the impregnation of Fe and/or Cu-nitrate precursor salts onto a preformed nano-sized Pt/C catalyst. They are referred to as Pt3Fe/C, PtFe/C and Pt5.75Fe5.75Cu/C catalysts and the subscripts refer to the nominal Pt, Fe and Cu atomic ratios. The final catalysts are obtained by annealing the impregnated samples in a H2 enriched atmosphere. Pt5.75Fe6.75/C, Pt5.75Cu6.75/C and Pt5.75Fe5.75Cu2/C catalysts were also made. The as-prepared catalysts are characterized using X-ray diffraction, transmission electron microscopy, standard electrochemical methods and probed for the electrochemical O2 reduction reaction (orr). Rietveld analyses reveal that [Fm-3m] Pt, cubic [Pm-3m] Pt3Fe and tetragonal [P4/mmm] PtFe structure types are made. In case of the Pt5.75Fe5.75Cu/C catalyst, a nano-sized carbon-supported single-phase catalyst of [P4/mmm] structure is found to be made at 800 °C, with Pt and Fe ordered on separate lattice planes, while Cu is distributed randomly onto both Pt and Fe atomic planes. The PtFe/C equivalent catalyst contains in addition a separate Fe phase as well as a slightly disordered [P4/mmm] phase. Pt5.75Cu6.75/C forms a disordered cubic [Fm-3m] alloy structure. The activity toward the orr was measured after 70 potential cycling, which can cause beneficial changes to the catalysts. In case of the specific orr activity, a dependence on the catalyst series is observed as follows: Pt5.75Fe5.75Cu/C [P4/mmm] > PtFe/C [P4/mmm] > Pt3Fe/C [Pm-3 m] ≈ Pt5.75Cu6.75/C [Fm-3m] > Pt/C [Fm-3m]. The highest orr mass activities are also found for the Pt5.75Fe5.75Cu/C and subsequently for the PtFe/C catalysts. Estimated orr activities are well within the range reported in the literature. In fact the specific orr activities compare to results reported for so called de-alloyed catalyst that are among the highest orr mass activities reported in the recent literature.

  4. Widely tunable alloy composition and crystal structure in catalyst-free InGaAs nanowire arrays grown by selective area molecular beam epitaxy

    Science.gov (United States)

    Treu, J.; Speckbacher, M.; Saller, K.; Morkötter, S.; Döblinger, M.; Xu, X.; Riedl, H.; Abstreiter, G.; Finley, J. J.; Koblmüller, G.

    2016-02-01

    We delineate the optimized growth parameter space for high-uniformity catalyst-free InGaAs nanowire (NW) arrays on Si over nearly the entire alloy compositional range using selective area molecular beam epitaxy. Under the required high group-V fluxes and V/III ratios, the respective growth windows shift to higher growth temperatures as the Ga-content x(Ga) is tuned from In-rich to Ga-rich InGaAs NWs. Using correlated x-ray diffraction, transmission electron microscopy, and micro-photoluminescence spectroscopy, we identify structural defects to govern luminescence linewidths in In-rich (x(Ga) 0.6) NWs, whereas limitations at intermediate Ga-content (0.4 blue-shifted to red-shifted photoluminescence emission relative to the band edge emission of the bulk ZB InGaAs phase.

  5. Widely tunable alloy composition and crystal structure in catalyst-free InGaAs nanowire arrays grown by selective area molecular beam epitaxy

    International Nuclear Information System (INIS)

    We delineate the optimized growth parameter space for high-uniformity catalyst-free InGaAs nanowire (NW) arrays on Si over nearly the entire alloy compositional range using selective area molecular beam epitaxy. Under the required high group-V fluxes and V/III ratios, the respective growth windows shift to higher growth temperatures as the Ga-content x(Ga) is tuned from In-rich to Ga-rich InGaAs NWs. Using correlated x-ray diffraction, transmission electron microscopy, and micro-photoluminescence spectroscopy, we identify structural defects to govern luminescence linewidths in In-rich (x(Ga) < 0.4) and Ga-rich (x(Ga) > 0.6) NWs, whereas limitations at intermediate Ga-content (0.4 < x(Ga) < 0.6) are mainly due to compositional inhomogeneities. Most remarkably, the catalyst-free InGaAs NWs exhibit a characteristic transition in crystal structure from wurtzite to zincblende (ZB) dominated phase near x(Ga) ∼ 0.4 that is further reflected in a cross-over from blue-shifted to red-shifted photoluminescence emission relative to the band edge emission of the bulk ZB InGaAs phase

  6. Widely tunable alloy composition and crystal structure in catalyst-free InGaAs nanowire arrays grown by selective area molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Treu, J., E-mail: Julian.Treu@wsi.tum.de, E-mail: Gregor.Koblmueller@wsi.tum.de; Speckbacher, M.; Saller, K.; Morkötter, S.; Xu, X.; Riedl, H.; Abstreiter, G.; Finley, J. J.; Koblmüller, G., E-mail: Julian.Treu@wsi.tum.de, E-mail: Gregor.Koblmueller@wsi.tum.de [Walter Schottky Institut, Physik Department, Center of Nanotechnology and Nanomaterials, Technische Universität München, Am Coulombwall 4, Garching 85748 (Germany); Döblinger, M. [Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, Munich 81377 (Germany)

    2016-02-01

    We delineate the optimized growth parameter space for high-uniformity catalyst-free InGaAs nanowire (NW) arrays on Si over nearly the entire alloy compositional range using selective area molecular beam epitaxy. Under the required high group-V fluxes and V/III ratios, the respective growth windows shift to higher growth temperatures as the Ga-content x(Ga) is tuned from In-rich to Ga-rich InGaAs NWs. Using correlated x-ray diffraction, transmission electron microscopy, and micro-photoluminescence spectroscopy, we identify structural defects to govern luminescence linewidths in In-rich (x(Ga) < 0.4) and Ga-rich (x(Ga) > 0.6) NWs, whereas limitations at intermediate Ga-content (0.4 < x(Ga) < 0.6) are mainly due to compositional inhomogeneities. Most remarkably, the catalyst-free InGaAs NWs exhibit a characteristic transition in crystal structure from wurtzite to zincblende (ZB) dominated phase near x(Ga) ∼ 0.4 that is further reflected in a cross-over from blue-shifted to red-shifted photoluminescence emission relative to the band edge emission of the bulk ZB InGaAs phase.

  7. Low voltage aluminium anodes. Optimization of the insert-anode bond

    Energy Technology Data Exchange (ETDEWEB)

    Le Guyader, Herve; Debout, Valerie; Grolleau, Anne-Marie [DCN Cherbourg, Departement 2EI, Place Bruat, BP 440, 50104 Cherbourg-Octeville (France); Pautasso, Jean-Pierre [DGA/CTA 16 bis, avenue Prieur de la Cote D' Or, 94 114 Arcueil Cedex (France)

    2004-07-01

    Zinc or Al/Zn/In sacrificial anodes are widely used to protect submerged marine structures from corrosion. Their Open Circuit Potential range from - 1 V vs. Ag/AgCl for Zn anodes to -1.1 V vs. Ag/AgCl for Al/Zn/In. These potentials are sufficiently electronegative as to reduce the threshold for stress corrosion cracking and/or hydrogen embrittlement, KISCC, especially in the presence of high strength alloys. In the 90's, an extensive research programme was initiated by DGA/DCN to implement a new low voltage material. Laboratory and full scale marine tests performed on industrial castings, as previously reported, led to the development of a new patented Al- 0.1%Ga alloy having a working potential of - 0.80 to - 0.83 V vs. Ag/AgCl. This alloy was also evaluated at full scale at the Naval Research Laboratory anode qualification site in Key West, Fl, and gave satisfactory results. Around 500 cylindrical AlGa anodes were then installed on a submerged marine structure replacing the classical zinc anode. A first inspection, carried out after a few months of service, showed that some of the anodes had not operated as expected, which led to further investigations. The examinations performed indicated that the problem was due to a bad metallurgical compatibility between the insert and the sacrificial materials inducing a poor bond between the anode and the plain rod insert. Progressive loss of contact between the anode and the structure to be protected was then induced by penetration of sea water and corrosion at the anode-insert interface. This phenomenon was aggravated by seawater pressure. Additional studies were therefore launched with two aims: (1) find temporary remedies for the anodes already installed on the structure; (2) correct the anode original design and/or manufacturing process to achieve the maximum performance on new anodes lots. This paper describes the various solutions investigated to improve the insert-anode bond: design of the anode, rugosity and

  8. Improvement in direct methanol fuel cell performance by treating the anode at high anodic potential

    Science.gov (United States)

    Joghee, Prabhuram; Pylypenko, Svitlana; Wood, Kevin; Corpuz, April; Bender, Guido; Dinh, Huyen N.; O'Hayre, Ryan

    2014-01-01

    This work investigates the effect of a high anodic potential treatment protocol on the performance of a direct methanol fuel cell (DMFC). DMFC membrane electrode assemblies (MEAs) with PtRu/C (Hi-spec 5000) anode catalyst are subjected to anodic treatment (AT) at 0.8 V vs. DHE using potentiostatic method. Despite causing a slight decrease in the electrochemical surface area (ECSA) of the anode, associated with ruthenium dissolution, AT results in significant improvement in DMFC performance in the ohmic and mass transfer regions and increases the maximum power density by ∼15%. Furthermore, AT improves the long-term DMFC stability by reducing the degradation of the anode catalyst. From XPS investigation, it is hypothesized that the improved performance of AT-treated MEAs is related to an improved interface between the catalyst and Nafion ionomer. Among potential explanations, this improvement may be caused by incorporation of the ionomer within the secondary pores of PtRu/C agglomerates, which generates a percolating network of ionomer between PtRu/C agglomerates in the catalyst layer. Furthermore, the decreased concentration of hydrophobic CF2 groups may help to enhance the hydrophilicity of the catalyst layer, thereby increasing the accessibility of methanol and resulting in better performance in the high current density region.

  9. Thermodynamic Constraints in Using AuM (M = Fe, Co, Ni, and Mo) Alloys as N2 Dissociation Catalysts: Functionalizing a Plasmon-Active Metal.

    Science.gov (United States)

    Martirez, John Mark P; Carter, Emily A

    2016-02-23

    The Haber-Bosch process for NH3 synthesis is arguably one of the greatest inventions of the 20th century, with a massive footprint in agriculture and, historically, warfare. Current catalysts for this reaction use Fe for N2 activation, conducted at high temperatures and pressures to improve conversion rate and efficiency. A recent finding shows that plasmonic metal nanoparticles can either generate highly reactive electrons and holes or induce resonant surface excitations through plasmonic decay, which catalyze dissociation and redox reactions under mild conditions. It is therefore appealing to consider AuM (M = Fe, Co, Ni, and Mo) alloys to combine the strongly plasmonic nature of Au and the catalytic nature of M metals toward N2 dissociation, which together might facilitate ammonia production. To this end, through density functional theory, we (i) explore the feasibility of forming these surface alloys, (ii) find a pathway that may stabilize/deactivate surface M substituents during fabrication, and (iii) define a complementary route to reactivate them under operational conditions. Finally, we evaluate their reactivity toward N2, as well as their ability to support a pathway for N2 dissociation with a low thermodynamic barrier. We find that AuFe possesses similar appealing qualities, including relative stability with respect to phase separation, reversibility of Fe oxidation and reduction, and reactivity toward N2. While AuMo achieves the best affinity toward N2, its strong propensity toward oxidation could greatly limit its use. PMID:26831377

  10. CVD growth of carbon nanotubes on thin-film Ni20Ti35N45 alloy catalyst

    Science.gov (United States)

    Gromov, D. G.; Pavlov, A. A.; Skorik, S. N.; Trifonov, A. Yu.; Shulyat'ev, A. S.

    2015-12-01

    The possibility of forming carbon nanotube (CNT) arrays on a Ni-Ti-N catalytic alloy with low nickel content by chemical vapor deposition (CVD) is demonstrated. Adding nitrogen to the Ni-Ti alloy composition favors the formation of TiN compound and segregation of Ni on the surface, where it produces a catalytic effect on the CNT growth. It is found that, using CVD from acetylene gas phase at a substrate temperature of 650°C, a CNT array of 9-µm height can be grown for 2 min.

  11. 铝及铝合金阳极氧化膜的绿色封闭工艺研究进展%Development of Green Sealing Technology of Anodized Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    李利

    2012-01-01

    New green sealing technology of anodic aluminum oxide film is summarized, with the emphasis on processes of rare earth sealing, sol sealing and hydration sealing with microwaves. The sealing mechanisms of these three new green sealing technology are briefly presented, and the development of more sealing technology of anodized aluminum alloys which is green, effective and easy for commercial production is proposed.%本文概述了铝及铝合金阳极氧化膜的新型封闭方法,着重介绍了稀土盐封闭、溶胶封闭和微波水合封闭三种新型绿色封闭的工艺及发展,并对其封闭机理作了简要概述,指出更多绿色、高效且易于工业化生产的铝及其合金阳极氧化膜封闭工艺将被开发.

  12. Corrosion protection of clad 2024 aluminum alloy anodized in tartaric-sulfuric acid bath and protected with hybrid sol–gel coating

    International Nuclear Information System (INIS)

    Clad AA2024 T3 specimens were anodized in a tartaric-sulfuric acid bath (TSA) and subsequently protected either by classical Cr-free water sealing treatment or by application of a hybrid sol–gel coating. The sol–gel coating was prepared using a solution with high water content (58 %v/v) and obtained by the hydrolysis and condensation of tetraethoxysilane (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS). The morphology of the sealed anodic films and their thicknesses were evaluated by scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM) and glow discharge optical emission spectrometry (GDOES). The corrosion resistance of the samples was evaluated by electrochemical impedance spectroscopy (EIS) and salt-spray test. The results showed that the treatment with the hybrid sol–gel increased the resistive properties of the pores compared to the classical water sealing, delaying the access of aggressive species to the barrier layer

  13. Copper and nickel adherently electroplated on titanium alloy

    Science.gov (United States)

    Brown, E. E.

    1967-01-01

    Anodic treatment of titanium alloy enables electroplating of tightly adherent coatings of copper and nickel on the alloy. The alloy is treated in a solution of hydrofluoric and acetic acids, followed by the electroplating process.

  14. Anodic oxidation of 6063 aluminum alloy with intermittent high current density%6063铝合金的大电流密度间歇式阳极氧化

    Institute of Scientific and Technical Information of China (English)

    黄元盛; 陈焕明

    2014-01-01

    The 6063 aluminum alloy was treated by anodic oxidation with high current density and intermittent current .The effects of anodic oxidation process on microstructure, thickness and properties of the oxide layer were investigated.The results show that with the anodic oxidation solution used in the experiment, the proper process parameters for anodic oxidation are determined with current density of 42-53 A/dm2 , on-off time ratio of 1∶1, and each conduction time of 0.5 s.The oxide layer prepared by the proper process parameters has micropores in the surface layer while the inner layer has no micropores , and the interface between film and substrate has high density .The maximum thickness and microhardness of the oxide layer can reach above 75 μm and 735 HV0.5 respectively, and the oxide layer shows excellent corrosion resistance in NaCl solution .%采用大电流密度间歇式电流阳极氧化工艺对6063铝合金进行氧化处理,研究了阳极氧化工艺对氧化层组织、厚度和性能的影响。结果表明,在试验用阳极氧化溶液下,确定了合理的阳极氧化工艺参数为:电流密度42~53 A/dm2,通断电时间比为1∶1,每次通电0.5 s。采用此工艺制得的氧化层表层有微孔,而内层未见有微孔,膜/基界面致密度高,氧化层的最大厚度达75μm以上,最大硬度达735 HV0.5,氧化层耐NaCl溶液腐蚀能力极好。

  15. Synthesis and characterization of Pt-Sn-Ni alloys to application as catalysts for direct ethanol fuel cells; Sintese e caracterizacao de ligas de Pt-Sn-Ni para aplicacao como caztalisadores em celulas a combustivel do tipo DEFC

    Energy Technology Data Exchange (ETDEWEB)

    Silva, E.L. da; Correa, P.S.; Oliveira, E.L. de; Takimi, A.S.; Malfatti, C.F., E-mail: celia.malfatti@ufrgs.b [Universidade Federal do Rio Grande do Sul (LAPEC/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica. Lab. de Pesquisa em Corrosao; Radtke, C. [Universidade Federal do Rio Grande do Sul (IQ/UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica

    2010-07-01

    Direct ethanol fuel cells (DEFCs) have been the focus of recent research due its application in mobile energy sources. In order to obtain the maximum efficiency from these systems, it is necessary the total ethanol oxidation, which implies in C-C bond break. Different catalysts described in literature are employed with this intent. This work consists in studying PtSnNi catalysts supported on carbon Vulcan XC72R, to application in DEFCs. Thus, it was used the impregnation/reduction method, varying the atomic proportion among Pt, Sn and Ni. The alloys were characterized by X-Ray Diffraction, Cyclic Voltammetry and Transmission Microscopy. Preliminary results show that predominant structure on the catalysts is the face centered cubic platinum and the densities currents are dependent on the platinum amount. (author)

  16. Correlation between diffusion barriers and alloying energy in binary alloys

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg; Rossmeisl, Jan; Stephens, Ifan; Schiøtz, Jakob

    2016-01-01

    In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells.......In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells....

  17. Formation of double ring patterns on Co2MnSi Heusler alloy thin film by anodic oxidation under scanning probe microscope

    International Nuclear Information System (INIS)

    Double ring formation on Co2MnSi (CMS) films is observed at electrical breakdown voltage during local anodic oxidation (LAO) using atomic force microscope (AFM). Corona effect and segregation of cobalt in the vicinity of the rings is studied using magnetic force microscopy and energy dispersive spectroscopy. Double ring formation is attributed to the interaction of ablated material with the induced magnetic field during LAO. Steepness of forward bias transport characteristics from the unperturbed region of the CMS film suggest a non equilibrium spin contribution. Such mesoscopic textures in magnetic films by AFM tip can be potentially used for memory storage applications.

  18. Inertial friction welding process for making an anode assembly

    International Nuclear Information System (INIS)

    A method is specified for fixing a stem to a disc which includes an x-ray target to a selected surface area of a substrate to make an anode assembly for a rotating x-ray anode tube. The disc, wherein the substrate comprises molybdenum or molybdenum based alloys, and the stem which comprises columbium or columbium alloys are welded together in a butt joint by inertial friction. (U.K.)

  19. 合金元素对Mg-Hg-Ga阳极材料电化学行为的影响%Influence of Alloying Elements on Electrochemical Behavior of Mg-Hg-Ga Anodes

    Institute of Scientific and Technical Information of China (English)

    冯艳; 王日初; 彭超群

    2011-01-01

    用恒电流法,析氢法和交流阻抗法等方法测试了合金元素Hg和Ga对镁阳极电化学腐蚀行为的影响,并用扫描电镜和X射线衍射法分析了合金元素Hg和Ga对镁阳极的显微组织和相结构的影响。结果表明:铸态的Mg-4.8%Hg-8.8Ga合金晶界析出Mg5Ga2和Mg21Ga5Hg3相,铸态的Mg-8.8%Hg-8%Ga和Mg-7.2%Hg-8%Ga合金晶界析出Mg21Ga5Hg3相,铸态的Mg-7.2%Hg-2.6%Ga合金析出Mg3Hg和Mg21Ga5Hg3相。各合金析氢速率从小到大依次为:Mg-7.2%Hg-2.6%Ga合金,Mg-4.8%Hg-8%Ga合金,Mg-7.2%Hg-8%Ga合金和Mg-8.8%Hg-8%Ga合金。最小的析氢速率为1.75ml/(cm2.min)。各合金电化学活性从大到小依次为:Mg-8.8%Hg-8%Ga合金,Mg-7.2%Hg-8%Ga合金,Mg-4.8%Hg-8%Ga合金和Mg-7.2%Hg-2.6%Ga合金。在200 mA/cm2恒电流测试中最负的稳定电位-1.932 V出现在Mg-8.8%Hg-8%Ga合金中。%The effects of alloying elements Hg and Ga on the electrochemical corrosion behavior of Mg anodes were studied by galvanostatic tests,hydrogen evolution tests and electrochemical impedance spectra(EIS) measurements under different polarization conditions.Scanning electron microscopy(SEM) and X-ray diffractometry(XRD) were employed to detect the microstructure and phase relationship of the above alloys.Attention was paid to the combined effect of Hg and Ga on electrochemical properties and microstructures.The results show that Mg5Ga2 and Mg21Ga5Hg3 phases precipitated along the grain boundaries in cast Mg-4.8%Hg-8%Ga alloy.Mg21Ga5Hg3 phases precipitated in cast Mg-8.8%Hg-8%Ga and Mg-7.2%Hg-8%Ga alloys.Mg3Hg and Mg21Ga5Hg3 phases precipitated in cast Mg-7.2%Hg-2.6%Ga alloy.The sequential order of the hydrogen evolution corrosion rates from small to large is Mg-7.2%Hg-2.6%Ga alloy,Mg-4.8%Hg-8%Ga alloy,Mg-7.2%Hg-8%Ga alloy,and Mg-8.8%Hg-8%Ga alloy.The smallest hydrogen evolution corrosion rate is 1.75 ml/(cm2·min).The sequential order of the electrochemical activity from large to small is Mg-8.8%Hg-8

  20. Anodizing of High Electrically Stressed Components

    Energy Technology Data Exchange (ETDEWEB)

    Flores, P. [NSTec; Henderson, D. J. [NSTec; Good, D. E. [NSTec; Hogge, K. [NSTec; Mitton, C. V. [NSTec; Molina, I. [NSTec; Naffziger, C. [NSTec; Codova, S. R. [SNL; Ormond, E. U. [SNL

    2013-06-01

    Anodizing creates an aluminum oxide coating that penetrates into the surface as well as builds above the surface of aluminum creating a very hard ceramic-type coating with good dielectric properties. Over time and use, the electrical carrying components (or spools in this case) experience electrical breakdown, yielding undesirable x-ray dosages or failure. The spool is located in the high vacuum region of a rod pinch diode section of an x-ray producing machine. Machine operators have recorded decreases in x-ray dosages over numerous shots using the reusable spool component, and re-anodizing the interior surface of the spool does not provide the expected improvement. A machine operation subject matter expert coated the anodized surface with diffusion pump oil to eliminate electrical breakdown as a temporary fix. It is known that an anodized surface is very porous, and it is because of this porosity that the surface may trap air that becomes a catalyst for electrical breakdown. In this paper we present a solution of mitigating electrical breakdown by oiling. We will also present results of surface anodizing improvements achieved by surface finish preparation and surface sealing. We conclude that oiling the anodized surface and using anodized hot dip sealing processes will have similar results.

  1. Examining the surfaces in used platinum catalysts

    OpenAIRE

    Trumić B.; Stanković D.; Trujić V.

    2009-01-01

    For the purpose of finding more advanced platinum catalyst manufacturing technologies and achieving a higher degree of ammonia oxidation, metallographic characterization has been done on the surface of catalyst gauzes and catalyst gripper gauzes made from platinum and palladium alloys. For the examined samples of gauzes as well as the cross section of the wires, a chemical analysis was provided. The purpose of this paper is the metallographic characterization of examined alloys carried out by...

  2. Vacuum arc anode phenomena

    International Nuclear Information System (INIS)

    A brief review of anode phenomena in vacuum arcs is presented. Discussed in succession are: the transition of the arc into the anode spot mode; the temperature of the anode before, during and after the anode spot forms; and anode ions. Characteristically the anode spot has a temperature of the order of the atmospheric boiling point of the anode material and is a copious source of vapor and energetic ions. The dominant mechanism controlling the transition of the vacuum arc into the anode spot mode appears to depend upon the electrode geometry, the electrode material, and the current waveform of the particular vacuum arc being considered. Either magnetic constriction in the gap plasma or gross anode melting can trigger the transition; indeed, a combination of the two is a common cause of anode spot formation

  3. CdSxSe1−x alloyed quantum dots-sensitized solar cells based on different architectures of anodic oxidation TiO2 film

    International Nuclear Information System (INIS)

    Nanostructured TiO2 translucent films with different architectures including TiO2 nanotube (NT), TiO2 nanowire (NW), and TiO2 nanowire/nanotube (NW/NT) have been produced by second electrochemical oxidization of TiO2 NT with diameter around 90–110 nm via modulation of applied voltage. These TiO2 architectures are sensitized with CdSxSe1−x alloyed quantum dots (QDs) in sizes of around 3–5 nm aiming to tune the response of the photoelectrochemical properties in the visible region. One-step hydrothermal method facilitates the deposition of CdSxSe1−x QDs onto TiO2 films. These CdSxSe1−x QDs exhibit a tunable range of light absorption with changing the feed molar ratio of S:Se in precursor solution, and inject electrons into TiO2 films upon excitation with visible light, enabling their application as photosensitizers in sensitized solar cells. Power conversion efficiency (PCE) of 2.00, 1.72, and 1.06 % are achieved with CdSxSe1−x (obtained with S:Se = 0:4) alloyed QDs sensitized solar cells based on TiO2 NW/NT, TiO2 NW, and TiO2 NT architectures, respectively. The significant enhancement of power conversion efficiency obtained with the CdSxSe1−x/TiO2 NW/NT solar cell can be attributed to the extended absorption of light region tuned by CdSxSe1−x alloyed QDs and enlarged deposition of QDs and efficient electrons transport provided by TiO2 NW/NT architecture

  4. Recovery of plutonium from electrorefining anode heels at Savannah River

    International Nuclear Information System (INIS)

    In a joint effort, the Savannah River Laboratory (SRL), Savannah River Plant (SRP), and the Rocky Flats Plant (RFP) have developed two processes to recover plutonium from electrorefining anode heel residues. Aqueous dissolution of anode heel metal was demonstrated at SRL on a laboratory scale and on a larger pilot scale using either sulfamic acid or nitric acid-hydrazine-fluoride solutions. This direct anode heel metal dissolution requires the use of a geometrically favorable dissolver. The second process developed involves first diluting the plutonium in the anode heel residues by alloying with aluminum. The alloyed anode heel plutonium can then be dissolved using a nitric acid-fluoride-mercury(II) solution in large non-geometrically favorable equipment where nuclear safety is ensured by concentration control

  5. Surface treatment of new type aluminum lithium alloy and fatigue crack behaviors of this alloy plate bonded with Ti–6Al–4V alloy strap

    International Nuclear Information System (INIS)

    Highlights: ► A new generation aluminum lithium alloy which special made for Chinese commercial plane was investigated. ► Pattern of aluminum lithium alloy and Ti alloy were shown after anodization. ► Crack propagation of samples bonded with different wide Ti straps were studied in this paper. -- Abstract: Samples consisting of new aluminum lithium alloy (Al–Li alloy) plate developed by the Aluminum Company of America and Ti–6Al–4V alloy (Ti alloy) plate were investigated. Plate of 400 mm × 140 mm × 2 mm with single edge notch was anodized in phosphoric solution and Ti alloy plate of 200 mm × 20 (40) mm × 2 mm was anodized in alkali solution. Patterns of two alloys were studied at original/anodized condition. And then, aluminum alloy and Ti alloy plates were assembled into a sample with FM 94 film adhesive. Fatigue crack behaviors of the sample were investigated under condition of nominal stress σ = 36 MPa and 54 MPa, stress ratio of 0.1. Testing results show that anodization treatment modifies alloys surface topography. Ti alloy bonding to Al–Li alloy plate effectively retards crack growth than that of Al–Li alloy plate. Fatigue life of sample bonded with Ti alloy strap improves about 62.5% than that of non-strap plate.

  6. Influence of Nano-Al2O3 Powder on Micro-arc Anodic Oxidation Film of Magnesium Alloy%Al2O3纳米粉体对镁合金微弧氧化陶瓷膜性能的影响

    Institute of Scientific and Technical Information of China (English)

    包晗; 邵忠财; 刘鹏

    2013-01-01

    Nano-Al2O3 powder are added into magnesium alloy during melting process,then the prepared composite material are treated by micro-arc oxidation; also the magnesium alloy are treated by micro-arc oxidation with nano-Al2O3 powder in the electrolyte.Scanning electron microscope (SEM),X-ray diffraction (XRD) and electrochemical tests are used to analyze the influence of nano-Al2O3 powder on micro-arc anodic oxidation film.Results show that both of the two methods of adding Al2O3 powder can improve the corrosion resistance of magnesium alloy micro-arc oxidation ceramic film,but the first one is better.%在熔炼镁合金过程中加入Al2O3纳米粉体的复合材料进行微弧氧化处理;在微弧氧化电解液中加入Al2O3粉体并对镁合金基体进行微弧氧化.采用扫描电镜、X-射线衍射和电化学测试分析Al2O3粉体对镁合金微弧氧化膜层耐蚀性的影响.结果表明,两种方式加入Al2O3粉体都会提高镁合金微弧氧化陶瓷膜的耐蚀性,而熔炼过程中加入效果更佳.

  7. 铝合金阳极氧化无镍封孔工艺研究%The study of Aluminum alloy anodic oxidation and nickel hole sealing process

    Institute of Scientific and Technical Information of China (English)

    刘岩; 刘桂宏; 朱鸿昌; 张万龙; 高敏亮; 王亮; 王梅丰

    2015-01-01

    铝阳极氧化膜在不同封孔溶液中封闭后,其使用寿命和耐蚀性会各不相同。采用了磷铬酸失重法、电化学极化曲线法、交流阻抗法研究了铝合金阳极氧化膜在氟锆酸钾、HX-588封闭剂、钼酸钠、亚硝酸钠和纯水的高温水溶液封闭后的耐蚀性,比较其间的差异,并找出其变化规律,反映出五种溶液的封闭效果。数据表明:封闭效果优劣排序依次为HX-588封闭剂、氟锆酸钾、钼酸钠、亚硝酸钠、纯水。说明氟锆酸钾可以作为一种绿色无镍封孔剂进行工业生产。%The service life and corrosion resistance of sealed Aluminum anodic oxide film in different hole sealing solution will be different. The corrosion resistance of the sealed Aluminum oxide film in Zirconium fluoride acid potassium,HX-588 sealing agent,sodium molybdate,sodium nitrite and pure water of high temperature solution were studied by phosphorus-chromium acid weight-loss method and electrochemical polarization-curve method,electrochemical impedance spectros-copy,compare their differences and find out its change rule,reflects the sealing effect of 5 kinds of solution. The statistic shows that the sequence of sealing effect from excellent is HX-588 sealants,zirconium fluoride acid potassium,sodium mo-lybdate,sodium nitrite,pure water. That zirconium fluoride potassium can serve as a kind of green and nickel hole sealing a-gent for industrial production.

  8. Electrocatalysis of anodic oxidation of ethanol

    International Nuclear Information System (INIS)

    The results of fundamental and applied studies in the field of electrocatalysis of anodic oxidation of ethanol in fuel cells are considered. Features of the mechanism of ethanol electrooxidation are discussed as well as the structure and electrochemical properties of the most widely used catalysts of this process. The prospects of further studies of direct ethanol fuel cells with alkaline and acidic electrolytes are outlined. The bibliography includes 166 references

  9. Supported PtAu catalysts with different nano-structures for ethanol electrooxidation

    International Nuclear Information System (INIS)

    Two bimetallic Pt-Au catalysts supported on carbon, namely core-shell structured nanoparticles (Au@Pt/C) and alloy-like nanoparticles (AuPt/C), were synthesized and tested for ethanol electro-oxidation in acidic environment. The catalysts were characterized by X-ray diffraction; X-ray photoelectron spectroscopy and transmission electron microscopy. Catalytic activity was quantified by anodic CO-stripping voltammetry, and cyclic voltammetry of ethanol electro-oxidation. The electronic interaction between Pt and Au was demonstrated by X-ray photoelectron spectroscopy and the effect was found to be more prominent in the alloy-like PtAu nanoparticles. X-ray diffraction revealed expanded Pt lattice parameter and interatomic distance in the PtAu nanoparticles. The interaction between Pt and Au of PtAu/C and Au@Pt/C samples was the main cause of the enhanced CO tolerance. The stronger Pt-Au interaction and the expanded Pt lattice parameter in alloyed PtAu/C contributed to the higher specific activity towards ethanol electro-oxidation of PtAu/C compared to Au@Pt/C

  10. Distribution of soluble and precipitated iron and chromium products generated by anodic dissolution of 316L stainless steel and alloy C-22: final report

    Energy Technology Data Exchange (ETDEWEB)

    Estill, J; Farmer, J; Gordon, S; King, K; Logotetta, L; Silberman, D

    1999-08-11

    At near neutral pH and at applied potentials above the threshold potential for localized breakdown of the passive film, virtually all of the dissolved chromium appeared to be in the hexavalent oxidation state (Cr(VI)). In acidic environments, such as crevice solutions formed during the crevice corrosion of 316L and C-22 samples in 4 M NaCl, virtually all of the dissolved chromium appeared to be in the trivalent oxidation state (Cr(III)). These general observations appear to be consistent with the Pourbaix diagram for chromium (Pourbaix 1974), pp. 307-321. At high pH and high anodic polarization (pH {approximately} 8 and 800 mV vs. SHE), the predominate species is believed to be the soluble chromate anion (CrO{sub 4}{sup 2{minus}}). At the same pH, but lower polarization (pH {approximately} 8 and 0 mV vs. SHE), the predominate species are believed to be precipitates such as trivalent Cr(OH){sub 3} {center_dot} n(H{sub 2}O) and hexavalent Cr{sub 2}O{sub 3}. In acidified environments such as those found in crevices (pH < 3), soluble Cr{sup 3+} is expected to form over a wide range of potential extending from 400 mV vs. SHE to approximately 1200 mV vs. SHE. Again, this is consistent with the observations from the creviced samples. In earlier studies by the principal investigator, it has been found that low-level chromium contamination in ground water is usually in the hexavalent oxidation state (Farmer et al. 1996). In general, dissolved iron measured during the crevice experiments appears to be Fe(II) in acidic media and Fe(III) in near-neutral and alkaline solutions (table 3). In the case of cyclic polarization measurements, the dissolved iron measured at the end of some cyclic polarization measurements with C-22 appeared to be in the Fe(III) state. This is probably due to the high electrochemical potential at which these species were generated during the potential scan. Note that the reversal potential was approximately 1200 mV vs. Ag/AgCl during these scans. These

  11. Excitation of anodized alumina films with a light source

    DEFF Research Database (Denmark)

    Aggerbeck, Martin; Canulescu, Stela; Rechendorff, K.;

    Optical properties of anodized aluminium alloys were determined by optical diffuse reflectance spectroscopy of such films. Samples with different concentrations of dopants were excited with a white-light source combined with an integrating sphere for fast determination of diffuse reflectance. The...... UV-VIS reflectance of Ti-doped anodized aluminium films was measured over the wavelength range of 200 nm to 900 nm. Titanium doped-anodized aluminium films with 5-15 wt% Ti were characterized. Changes in the diffuse light scattering of doped anodized aluminium films, and thus optical appearance, with...... doping are discussed. Using the Kubelka-Munk model on the diffuse reflectance spectra of such films, the bandgap Eg of the oxide alloys can be determined....

  12. A comparison of chromic acid and sulfuric acid anodizing

    Science.gov (United States)

    Danford, M. D.

    1992-01-01

    Because of federal and state mandates restricting the use of hexavalent chromium, it was deemed worthwhile to compare the corrosion protection afforded 2219-T87 aluminum alloy by both Type I chromic acid and Type II sulfuric acid anodizing per MIL-A-8625. Corrosion measurements were made on large, flat 2219-T87 aluminum alloy sheet material with an area of 1 cm(exp 2) exposed to a corrosive medium of 3.5-percent sodium chloride at pH 5.5. Both ac electrochemical impedance spectroscopy and the dc polarization resistance techniques were employed. The results clearly indicate that the corrosion protection obtained by Type II sulfuric acid anodizing is superior, and no problems should result by substituting Type II sulfuric acid anodizing for Type I chromic acid anodizing.

  13. The effect of ruthenium crossover in polymer electrolyte fuel cells operating with platinum-ruthenium anode

    OpenAIRE

    Anna Trendewicz

    2011-01-01

    Proton exchange membrane fuel cells with PtRu anode catalyst and Pt cathode suffer from severe performance degradation due to ruthenium dissolution from the anode, migration through Nafion® membrane, and deposition on the surface of cathode catalyst where it inhibits ORR. A detailed analysis of ruthenium crossover mechanism for a 5 cm2 active area direct methanol fuel cell was performed to quantify the contamination rate and degree starting from contamination during manufacturing process, thr...

  14. An inert metal anode for magnesium electrowinning

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J. F.; Hryn, J. N.; Pellin, M. J.; Calaway, W. F.; Watson, K.

    1999-12-01

    Results from the development of a novel type of anode for electrowinning Mg are reported. A tailored alloy system based on the binary Cu-Al can be made to form a thin alumina layer on its surface that is relatively impervious to attack by the molten chloride melt at high temperature. This barrier is thin enough (5--50 nm) to conduct electrical current without significant IR loss. As the layer slowly dissolves, the chemical potential developed at the surface drives the diffusion of aluminum from the bulk alloy to reform (heal) the protective alumina layer. In this way, an anode that generates Cl{sub 2} (melt electrolysis) and O{sub 2} (wet feed hydrolysis) and no chlorocarbons can be realized. Further, the authors expect the rate of loss of the anode to be dramatically less than the coke-derived carbon anodes typically in use for this technology, leading to substantial cost savings and ancillary pollution control by eliminating coke plant emissions, as well as eliminating chlorinated hydrocarbon emissions from Mg electrowinning cells.

  15. Anodic Activation of Aluminum by Trace Element Tin

    OpenAIRE

    Tan, Juan

    2011-01-01

    Anodic activation of commercial and model aluminum alloys in chloride solution became of practical importance in connection with filiform corrosion of painted aluminum sheet in architectural application and aluminum components of brazed heat exchangers. Activation in chloride solution manifests itself in the form of a significant negative shift in the pitting potential relative to pure aluminum and a significant increase in the anodic current output at potentials where aluminum is normally ex...

  16. Full Ceramic Fuel Cells Based on Strontium Titanate Anodes, An Approach Towards More Robust SOFCs

    DEFF Research Database (Denmark)

    Holtappels, Peter; Irvine, J.T.S.; Iwanschitz, B.;

    2013-01-01

    intact and tolerant to redox cycles, cell performance degradation appears linked to the infiltrated electro catalysts. The materials have also been assessed with respect to their electrical and mechanical properties, in order to further evaluate their potential use as anode and anode support layers in...

  17. Inert Anode Life in Low Temperature Reduction Process

    Energy Technology Data Exchange (ETDEWEB)

    Bradford, Donald R.

    2005-06-30

    The production of aluminum metal by low temperature electrolysis utilizing metal non-consumable anodes and ceramic cathodes was extensively investigated. Tests were performed with traditional sodium fluoride--aluminum fluoride composition electrolytes, potassium fluoride-- aluminum fluoride electrolytes, and potassium fluoride--sodium fluoride--aluminum fluoride electrolytes. All of the Essential First-Tier Requirements of the joint DOE-Aluminum Industry Inert Anode Road Map were achieved and those items yet to be resolved for commercialization of this technology were identified. Methods for the fabrication and welding of metal alloy anodes were developed and tested. The potential savings of energy and energy costs were determined and potential environmental benefits verified.

  18. Nano-Engineered Catalysts for Direct Methanol Fuel Cells

    Science.gov (United States)

    Myung, Nosang; Narayanan, Sekharipuram; Wiberg, Dean

    2008-01-01

    Nano-engineered catalysts, and a method of fabricating them, have been developed in a continuing effort to improve the performances of direct methanol fuel cells as candidate power sources to supplant primary and secondary batteries in a variety of portable electronic products. In order to realize the potential for high energy densities (as much as 1.5 W h/g) of direct methanol fuel cells, it will be necessary to optimize the chemical compositions and geometric configurations of catalyst layers and electrode structures. High performance can be achieved when catalyst particles and electrode structures have the necessary small feature sizes (typically of the order of nanometers), large surface areas, optimal metal compositions, high porosity, and hydrophobicity. The present method involves electrodeposition of one or more catalytic metal(s) or a catalytic-metal/polytetrafluoroethylene nanocomposite on an alumina nanotemplate. The alumina nanotemplate is then dissolved, leaving the desired metal or metal/polytetrafluoroethylene-composite catalyst layer. Unlike some prior methods of making fine metal catalysts, this method does not involve processing at elevated temperature; all processing can be done at room temperature. In addition, this method involves fewer steps and is more amenable to scaling up for mass production. Alumina nanotemplates are porous alumina membranes that have been fabricated, variously, by anodizing either pure aluminum or aluminum that has been deposited on silicon by electronbeam evaporation. The diameters of the pores (7 to 300 nm), areal densities of pores (as much as 7 x 10(exp 10)sq cm), and lengths of pores (up to about 100 nm) can be tailored by selection of fabrication conditions. In a given case, the catalytic metal, catalytic metal alloy, or catalytic metal/ polytetrafluoroethylene composite is electrodeposited in the pores of the alumina nanotemplate. The dimensions of the pores, together with the electrodeposition conditions

  19. Simultaneous Use Of Zr And Mg Anodes In XPS

    Science.gov (United States)

    Allgeyer, D. F.; Pratz, E. H.

    1996-01-01

    Improved x-ray source for x-ray photoelectron spectroscopy (XPS) contains both zirconium anode with beryllium window and magnesium anode with aluminum window. Previously unresolvable peaks of electron-energy spectrum become resolvable. Developed specifically for use in analyzing distributions of chemical constituents in surface layers of specimens of 2219 aluminum alloy and in determining the depths of surface oxide layers and relative proportions of aluminum and oxide in layers. Also used to study chemical constituents of surface layers in other material systems - for example, thin oxide films on silicon-based semiconductor devices, oxide films on alloys, and surface layers affecting adhesion of paints or bonding materials.

  20. New High-Energy Nanofiber Anode Materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiangwu; Fedkiw, Peter; Khan, Saad; Huang, Alex; Fan, Jiang

    2013-11-15

    The overall goal of the proposed work was to use electrospinning technology to integrate dissimilar materials (lithium alloy and carbon) into novel composite nanofiber anodes, which simultaneously had high energy density, reduced cost, and improved abuse tolerance. The nanofiber structure allowed the anodes to withstand repeated cycles of expansion and contraction. These composite nanofibers were electrospun into nonwoven fabrics with thickness of 50 μm or more, and then directly used as anodes in a lithium-ion battery. This eliminated the presence of non-active materials (e.g., conducting carbon black and polymer binder) and resulted in high energy and power densities. The nonwoven anode structure also provided a large electrode-electrolyte interface and, hence, high rate capacity and good lowtemperature performance capability. Following are detailed objectives for three proposed project periods. • During the first six months: Obtain anodes capable of initial specific capacities of 650 mAh/g and achieve ~50 full charge/discharge cycles in small laboratory scale cells (50 to 100 mAh) at the 1C rate with less than 20 percent capacity fade; • In the middle of project period: Assemble, cycle, and evaluate 18650 cells using proposed anode materials, and demonstrate practical and useful cycle life (750 cycles of ~70% state of charge swing with less than 20% capacity fade) in 18650 cells with at least twice improvement in the specific capacity than that of conventional graphite electrodes; • At the end of project period: Deliver 18650 cells containing proposed anode materials, and achieve specific capacities greater than 1200 mAh/g and cycle life longer than 5000 cycles of ~70% state of charge swing with less than 20% capacity fade.

  1. Supported molten-metal catalysts

    Science.gov (United States)

    Datta, Ravindra; Singh, Ajeet; Halasz, Istvan; Serban, Manuela

    2001-01-01

    An entirely new class of catalysts called supported molten-metal catalysts, SMMC, which can replace some of the existing precious metal catalysts used in the production of fuels, commodity chemicals, and fine chemicals, as well as in combating pollution. SMMC are based on supporting ultra-thin films or micro-droplets of the relatively low-melting (<600.degree. C.), inexpensive, and abundant metals and semimetals from groups 1, 12, 13, 14, 15 and 16, of the periodic table, or their alloys and intermetallic compounds, on porous refractory supports, much like supported microcrystallites of the traditional solid metal catalysts. It thus provides orders of magnitude higher surface area than is obtainable in conventional reactors containing molten metals in pool form and also avoids corrosion. These have so far been the chief stumbling blocks in the application of molten metal catalysts.

  2. Ultra-structural evaluation of an anodic oxidated titanium dental implant.

    Science.gov (United States)

    Yamagami, Akiyoshi; Nagaoka, Noriyuki; Yoshihara, Kumiko; Nakamura, Mariko; Shirai, Hajime; Matsumoto, Takuya; Suzuki, Kazuomi; Yoshida, Yasuhiro

    2014-01-01

    Anodic oxidation is used for the surface treatment of commercial implants to improve their functional properties for clinical success. Here we conducted ultrastructural and chemical investigations into the micro- and nanostructure of the anodic oxide film of a titanium implant. The anodic oxidized layer of a Ti6Al4V alloy implant was examined ultrastructurally by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). They were also analyzed using energy dispersive X-ray spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS). The TEM revealed that the oxide layer of the Ti6Al4V implant prepared through anodic oxidation was separated into two layers. Al and V were not present on the top surface of the anodic oxide. This can be attributed to the biocompatibility of the anodic oxidized Ti6Al4V alloy implant, because the release of harmful metal ions such as Al and V can be suppressed by the biocompatibility. PMID:25483382

  3. Anodization and Optical Appearance of Sputter Deposited Al-Zr Coatings

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Canulescu, Stela; Shabadi, Rajashekhara;

    2014-01-01

    Anodized Al alloy components are extensively used in various applications like architectural, decorative and automobiles for corrosion protection and/or decorative optical appearance. However, tailoring the anodized layer for specific optical appearance is limited due to variation in composition...... and microstructure of the commercial alloys, and even more difficult with recycled alloys. Sputter coating methods promise to control the chemical composition of the Al alloy surfaces and eventually modify the microstructure of the surfaces with heat treatments thus enabling the freedom on the...... substrate quality. This paper evaluates the use of magnetron sputtered Al-Zr coatings on Al combined with heat treatment and anodizing for obtaining required optical properties. Metallurgical and optical characterization was carried out to investigate the effect of coating microstructure and anodizing...

  4. Nanoshell Encapsulated Li-ion Battery Anodes for Long Cycle Life Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new high capacity rechargeable Li battery anode based on Li metal alloys protected by carbon nanoshells will be developed. A reversible Li-ion capacity exceeding...

  5. Anodizing Aluminum with Frills.

    Science.gov (United States)

    Doeltz, Anne E.; And Others

    1983-01-01

    "Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are also…

  6. Anodized aluminum on LDEF

    Science.gov (United States)

    Golden, Johnny L.

    1993-01-01

    A compilation of reported analyses and results obtained for anodized aluminum flown on the Long Duration Exposure Facility (LDEF) was prepared. Chromic acid, sulfuric acid, and dyed sulfuric acid anodized surfaces were exposed to the space environment. The vast majority of the anodized surface on LDEF was chromic acid anodize because of its selection as a thermal control coating for use on the spacecraft primary structure, trays, tray clamps, and space end thermal covers. Reports indicate that the chromic acid anodize was stable in solar absorptance and thermal emittance, but that contamination effects caused increases in absorptance on surfaces exposed to low atomic oxygen fluences. There were some discrepancies, however, in that some chromic acid anodized specimens exhibited significant increases in absorptance. Sulfuric acid anodized surfaces also appeared stable, although very little surface area was available for evaluation. One type of dyed sulfuric acid anodize was assessed as an optical baffle coating and was observed to have improved infrared absorptance characteristics with exposure on LDEF.

  7. Friction stir processed Al - Metal oxide surface composites: Anodization and optical appearance

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Jensen, Flemming; Canulescu, Stela;

    2014-01-01

    Multiple-pass friction stir processing (FSP) was employed to impregnate metal oxide (TiO2, Y2O3 and CeO2) particles into the surface of an Aluminium alloy. The surface composites were then anodized in a sulphuric acid electrolyte. The effect of anodizing parameters on the resulting optical...

  8. Black anodic coatings for space applications: study of the process parameters, characteristics and mechanical properties

    OpenAIRE

    Goueffon, Yann; Arurault, Laurent; Mabru, Catherine; Tonon, Claire; Guigue, Pascale

    2009-01-01

    Black inorganic anodized aluminium alloys are used for managing passive thermal control on spacecraft and for avoiding stray light in optical equipment. Spalling of these coatings has sometimes been observed after thermal cycling on 2XXX and 7XXX aluminium alloys. This phenomenon could generate particulate contamination in satellites and may affect mission lifetime. In this work, the influences of the four main steps of the process (pretreatments, sulphuric anodizing, colouring and sealing) o...

  9. Pt-Ni and Pt-Co Catalyst Synthesis Route for Fuel Cell Applications

    Science.gov (United States)

    Firdosy, Samad A.; Ravi, Vilupanur A.; Valdez, Thomas I.; Kisor, Adam; Narayan, Sri R.

    2013-01-01

    Oxygen reduction reactions (ORRs) at the cathode are the rate-limiting step in fuel cell performance. The ORR is 100 times slower than the corresponding hydrogen oxidation at the anode. Speeding up the reaction at the cathode will improve fuel cell efficiency. The cathode material is generally Pt powder painted onto a substrate (e.g., graphite paper). Recent efforts in the fuel cell area have focused on replacing Pt with Pt-X alloys (where X = Co, Ni, Zr, etc.) in order to (a) reduce cost, and (b) increase ORR rates. One of these strategies is to increase ORR rates by reducing the powder size, which would result in an increase in the surface area, thereby facilitating faster reaction rates. In this work, a process has been developed that creates Pt-Ni or Pt-Co alloys that are finely divided (on the nano scale) and provide equivalent performance at lower Pt loadings. Lower Pt loadings will translate to lower cost. Precursor salts of the metals are dissolved in water and mixed. Next, the salt mixtures are dried on a hot plate. Finally, the dried salt mixture is heattreated in a furnace under flowing reducing gas. The catalyst powder is then used to fabricate a membrane electrode assembly (MEA) for electrochemical performance testing. The Pt- Co catalyst-based MEA showed comparable performance to an MEA fabri cated using a standard Pt black fuel cell catalyst. The main objective of this program has been to increase the overall efficiencies of fuel cell systems to support power for manned lunar bases. This work may also have an impact on terrestrial programs, possibly to support the effort to develop a carbon-free energy source. This catalyst can be used to fabricate high-efficiency fuel cell units that can be used in space as regenerative fuel cell systems, and terrestrially as primary fuel cells. Terrestrially, this technology will become increasingly important when transition to a hydrogen economy occurs.

  10. Near-surface alloys for hydrogen fuel cell applications

    DEFF Research Database (Denmark)

    Greeley, Jeffrey Philip; Mavrikakis, Manos

    2006-01-01

    facile H-2 activation. These NSAs could, potentially, facilitate highly selective hydrogenation reactions at low temperatures. In the present work, the suitability of NSAs for use as hydrogen fuel cell anodes has been evaluated: the combination of properties, possessed by selected NSAs, of weak binding......Near-surface alloys (NSAs) possess a variety of unusual catalytic properties that could make them useful candidates for improved catalysts in a variety of chemical processes. It is known from previous work, for example, that some NSAs bind hydrogen very weakly while, at the same time, permitting...... variety of such materials for use in fuel cells and in an ever. increasing range of catalytic applications. Furthermore, we introduce a new concept for NSA-defect sites, which could be responsible for the promotional catalytic effects of a second metal added. even in minute quantities, to a host metal...

  11. Study of La1-χCaχCrO3 as anode catalysts for sulfur-oxygen SOFC%La1-xCaxCrO3对硫-氧燃料电池催化性能的研究

    Institute of Scientific and Technical Information of China (English)

    朱伟长; 卢异飞; 俞海云; 郑翠红; 闫勇; 孙颜刚

    2011-01-01

    La1-χCaχCrO3 (x=0,0.1,0.2,0.3) were prepared by co-precipitation method and acted as anode catalysts of sulfur-oxygen SOFC with YSZ as electrolyte material and LSCF as cathode material. The open circuit voltage of cells was tested. The results of the OBV test indicate that in the range of 700-8800 ℃, La1-χCaχCrO3(x=0T0.1,0.2,0.3) has clear catalysis effect on sulfur-oxygen SOFC. When La08Ca0.2CrO3 was selected as anode catalyst, at 800 ℃, the OGV is 0.560 V, which reaches 75% of the theoretical OCV value. Furthermore, the rest of the catalytic effect is: La0.9Ca0.1CrO3> LaCrO3>La0.7Ca0.3CrO3.%通过共沉淀法制备出La1-xCaxCrO3(x=0,0.1,0.2,0.3)作为阳极催化剂,分别以钇稳定氧化锆(YSZ)粉体和La0.66Sr0.4Co0.2Fe0.8O3-x(LSCF)粉体作为硫-氧燃料电池的电解质材料和阴极材料.发现在700~800 ℃时,La1-xCaxCrO3(x=0,0.1,0.2,0.3)对硫-氧燃料电池具有明显的催化效果,当选择La0.8Ca0.2CrO3为阳极催化剂时,测得800 ℃时单电池开路电压为560 mV,达到理论计算值的75%.其余催化效果由大到小依次为:La0.9Ca0.1CrO3、LaCrO3、La0.7Ca0.3CrO3.

  12. Effects of anodizing parameters and heat treatment on nanotopographical features, bioactivity, and cell culture response of additively manufactured porous titanium.

    Science.gov (United States)

    Amin Yavari, S; Chai, Y C; Böttger, A J; Wauthle, R; Schrooten, J; Weinans, H; Zadpoor, A A

    2015-06-01

    Anodizing could be used for bio-functionalization of the surfaces of titanium alloys. In this study, we use anodizing for creating nanotubes on the surface of porous titanium alloy bone substitutes manufactured using selective laser melting. Different sets of anodizing parameters (voltage: 10 or 20V anodizing time: 30min to 3h) are used for anodizing porous titanium structures that were later heat treated at 500°C. The nanotopographical features are examined using electron microscopy while the bioactivity of anodized surfaces is measured using immersion tests in the simulated body fluid (SBF). Moreover, the effects of anodizing and heat treatment on the performance of one representative anodized porous titanium structures are evaluated using in vitro cell culture assays using human periosteum-derived cells (hPDCs). It has been shown that while anodizing with different anodizing parameters results in very different nanotopographical features, i.e. nanotubes in the range of 20 to 55nm, anodized surfaces have limited apatite-forming ability regardless of the applied anodizing parameters. The results of in vitro cell culture show that both anodizing, and thus generation of regular nanotopographical feature, and heat treatment improve the cell culture response of porous titanium. In particular, cell proliferation measured using metabolic activity and DNA content was improved for anodized and heat treated as well as for anodized but not heat-treated specimens. Heat treatment additionally improved the cell attachment of porous titanium surfaces and upregulated expression of osteogenic markers. Anodized but not heat-treated specimens showed some limited signs of upregulated expression of osteogenic markers. In conclusion, while varying the anodizing parameters creates different nanotube structure, it does not improve apatite-forming ability of porous titanium. However, both anodizing and heat treatment at 500°C improve the cell culture response of porous titanium. PMID

  13. Passivation of alloys on titanium base

    International Nuclear Information System (INIS)

    Results of passivation studies on Ti-base alloys show that the inhibition of anodic processes on these alloys is determined not by the total thickness of passive film, but by its barrier layer. The protective properties of the barrier layer increase if the passive film is formed at anodic potentials more positive than +1.4V. They were determined not by chemical stability of barrier layer, but by an inhibition which is produced by this layer for ionic current along the anodic direction. The protective properties are related to character defectiveness and semiconductor properties of the barrier layer. Additions of Al, V, Mo, Zr, and Nb to titanium increase the anodic current in the passive state. Additions of Cr and Mn decrease this current, and Sn does not influence it. The direct electrochemical transition of titanium ions into solution (as TiO2+) is a main anodic process of titanium dissolution and its low alloyed alloys in the passive state. Double phase titanium alloys (after tempering) have a lower corrosion resistance than those in the homogeneous single phase state (after hardening). The less passive phase of double phase alloys dissolves perferentially. The less passive phases are: in the active state, α-phase; in transpassive state for Ti--Mo alloys, β-phase, containing in a high Mo percentage; and for Ti--Cr alloys, γ-phase, having more chromium. (U.S.)

  14. CO methanation over supported bimetallic Ni-Fe catalysts: From computational studies towards catalyst optimization

    DEFF Research Database (Denmark)

    Kustov, Arkadii; Frey, Anne Mette; Larsen, Kasper Emil;

    2007-01-01

    DFT calculations combined with a computational screening method have previously shown that bimetallic Ni-Fe alloys should be more active than the traditional Ni-based catalyst for CO methanation. That was confirmed experimentally for a number of bimetallic Ni-Fe catalysts supported on MgAl2O4. He...

  15. Homogeneous catalysts

    CERN Document Server

    Chadwick, John C; Freixa, Zoraida; van Leeuwen, Piet W N M

    2011-01-01

    This first book to illuminate this important aspect of chemical synthesis improves the lifetime of catalysts, thus reducing material and saving energy, costs and waste.The international panel of expert authors describes the studies that have been conducted concerning the way homogeneous catalysts decompose, and the differences between homogeneous and heterogeneous catalysts. The result is a ready reference for organic, catalytic, polymer and complex chemists, as well as those working in industry and with/on organometallics.

  16. Iron migration from the anode surface in alumina electrolysis

    Science.gov (United States)

    Zhuravleva, Elena N.; Drozdova, Tatiana N.; Ponomareva, Svetlana V.; Kirik, Sergei D.

    2013-01-01

    Corrosion destruction of two-component iron-based alloys used as an anode in high-temperature alumina electrolysis in the melt of NaF/KF/AlF3 electrolyte has been considered. Ni, Si, Cu, Cr, Mn, Al, Ti in the amount of up to 10% have been tested as the dopants to an anode alloys. The composition of the corrosion products has been studied using X-ray diffraction, scanning electron microscopy and electron microprobe analysis. It has been established that the anode corrosion is induced by a surface electrochemical polarization and iron atom oxidation. Iron ions come into an exchange interaction with the fluoride components of the melted electrolyte, producing FeF2. The last interacts with oxyfluoride species transforming into the oxide forms: FeAl2O4, Fe3O4, Fe2O3. Due to the low solubility, the iron oxides are accumulated in the near-electrode sheath. The only small part of iron from anode migrates to cathode that makes an production of high purity aluminum of a real task. The alloy dopants are also subjected to corrosion in accordance with electromotive series resulting corrosion tunnels on the anode surface. The oxides are final compounds which collect in the same area. The corrosion products form an anode shell which is electronic conductor at electrolysis temperature. The electrolysis of alumina occurs beyond the corrosion shell. The rate limiting step in the corrosion is the electrolyte penetration through corrosion shell to the anode surface. The participation of the released oxygen in the corrosion has not been observed.

  17. Anodic oxidation of benzoquinone using diamond anode.

    Science.gov (United States)

    Panizza, Marco

    2014-01-01

    The anodic degradation of 1,4-benzoquinone (BQ), one of the most toxic xenobiotic, was investigated by electrochemical oxidation at boron-doped diamond anode. The electrolyses have been performed in a single-compartment flow cell in galvanostatic conditions. The influence of applied current (0.5-2 A), BQ concentration (1-2 g dm(-3)), temperature (20-45 °C) and flow rate (100-300 dm(3) h(-1)) has been studied. BQ decay kinetic, the evolution of its oxidation intermediates and the mineralization of the aqueous solutions were monitored during the electrolysis by high-performance liquid chromatograph (HPLC) and chemical oxygen demand (COD) measurements. The results obtained show that the use of diamond anode leads to total mineralization of BQ in any experimental conditions due to the production of oxidant hydroxyl radicals electrogenerated from water discharge. The decay kinetics of BQ removal follows a pseudo-first-order reaction, and the rate constant increases with rising current density. The COD removal rate was favoured by increasing of applied current, recirculating flow rate and it is almost unaffected by solution temperature. PMID:24710725

  18. Bimetallic Catalysts.

    Science.gov (United States)

    Sinfelt, John H.

    1985-01-01

    Chemical reaction rates can be controlled by varying composition of miniscule clusters of metal atoms. These bimetallic catalysts have had major impact on petroleum refining, where work has involved heterogeneous catalysis (reacting molecules in a phase separate from catalyst.) Experimentation involving hydrocarbon reactions, catalytic…

  19. Influence of silicon on the growth of barrier-type anodic films on titanium

    OpenAIRE

    Tanvir, M. Tauseef; Fushimi, K; Shimizu, K.; Nagata, S; Skeldon, P; Thompson, G.E.; Habazaki, H.

    2007-01-01

    Amorphous anodic titania, stabilised by incorporation of silicon species, is shown to grow to high voltages on sputter-deposited, single-phase Ti–Si alloys during anodizing at a constant current density in ammonium pentaborate electrolyte. The films comprise two main layers, with silicon species confined to the inner layers. An amorphous-to-crystalline transition occurs at 60 V on the Ti–6 at.% Si alloy, while the transition is suppressed to voltages above 140 V on alloys with 12 and 26 at.% ...

  20. The study of aluminium anodes for high power density AL-air batteries with brine electrolytes

    OpenAIRE

    Nestoridi, Maria

    2009-01-01

    In this thesis aluminium alloys containing small additions of both tin (~ 0.1 wt %) and gallium (~ 0.05 wt %) dissolve anodically at high rates in brine media; at room temperature, current densities > 0.2 A cm-2 can be obtained at potentials close to the open circuit potential, ~ -1.5 V vs SCE. Alloys without both tin and gallium do not dissolve at such a negative potential. The tin exists in the alloys as a second phase, typically as ~ 1 ?m inclusions throughout the aluminium structure. Anod...

  1. Effects of anodizing parameters and heat treatment on nanotopographical features, bioactivity, and cell culture response of additively manufactured porous titanium

    International Nuclear Information System (INIS)

    Anodizing could be used for bio-functionalization of the surfaces of titanium alloys. In this study, we use anodizing for creating nanotubes on the surface of porous titanium alloy bone substitutes manufactured using selective laser melting. Different sets of anodizing parameters (voltage: 10 or 20 V anodizing time: 30 min to 3 h) are used for anodizing porous titanium structures that were later heat treated at 500 °C. The nanotopographical features are examined using electron microscopy while the bioactivity of anodized surfaces is measured using immersion tests in the simulated body fluid (SBF). Moreover, the effects of anodizing and heat treatment on the performance of one representative anodized porous titanium structures are evaluated using in vitro cell culture assays using human periosteum-derived cells (hPDCs). It has been shown that while anodizing with different anodizing parameters results in very different nanotopographical features, i.e. nanotubes in the range of 20 to 55 nm, anodized surfaces have limited apatite-forming ability regardless of the applied anodizing parameters. The results of in vitro cell culture show that both anodizing, and thus generation of regular nanotopographical feature, and heat treatment improve the cell culture response of porous titanium. In particular, cell proliferation measured using metabolic activity and DNA content was improved for anodized and heat treated as well as for anodized but not heat-treated specimens. Heat treatment additionally improved the cell attachment of porous titanium surfaces and upregulated expression of osteogenic markers. Anodized but not heat-treated specimens showed some limited signs of upregulated expression of osteogenic markers. In conclusion, while varying the anodizing parameters creates different nanotube structure, it does not improve apatite-forming ability of porous titanium. However, both anodizing and heat treatment at 500 °C improve the cell culture response of porous titanium

  2. Effects of anodizing parameters and heat treatment on nanotopographical features, bioactivity, and cell culture response of additively manufactured porous titanium

    Energy Technology Data Exchange (ETDEWEB)

    Amin Yavari, S., E-mail: s.aminyavari@tudelft.nl [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); Chai, Y.C. [Prometheus, Division of Skeletal Tissue Engineering, Bus 813, O& N1, Herestraat 49, KU Leuven, 3000 Leuven (Belgium); Tissue Engineering Laboratory, Skeletal Biology and Engineering Research Center, Bus 813, O& N1, Herestraat 49, KU Leuven, 3000 Leuven (Belgium); Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Böttger, A.J. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); Wauthle, R. [KU Leuven, Department of Mechanical Engineering, Section Production Engineering, Machine Design and Automation (PMA), Celestijnenlaan 300B, 3001 Leuven (Belgium); 3D Systems — LayerWise NV, Grauwmeer 14, 3001 Leuven (Belgium); Schrooten, J. [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 — PB2450, B-3001 Heverlee (Belgium); Weinans, H. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); Department of Orthopedics and Dept. Rheumatology, UMC Utrecht, Heidelberglaan100, 3584CX Utrecht (Netherlands); Zadpoor, A.A. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands)

    2015-06-01

    Anodizing could be used for bio-functionalization of the surfaces of titanium alloys. In this study, we use anodizing for creating nanotubes on the surface of porous titanium alloy bone substitutes manufactured using selective laser melting. Different sets of anodizing parameters (voltage: 10 or 20 V anodizing time: 30 min to 3 h) are used for anodizing porous titanium structures that were later heat treated at 500 °C. The nanotopographical features are examined using electron microscopy while the bioactivity of anodized surfaces is measured using immersion tests in the simulated body fluid (SBF). Moreover, the effects of anodizing and heat treatment on the performance of one representative anodized porous titanium structures are evaluated using in vitro cell culture assays using human periosteum-derived cells (hPDCs). It has been shown that while anodizing with different anodizing parameters results in very different nanotopographical features, i.e. nanotubes in the range of 20 to 55 nm, anodized surfaces have limited apatite-forming ability regardless of the applied anodizing parameters. The results of in vitro cell culture show that both anodizing, and thus generation of regular nanotopographical feature, and heat treatment improve the cell culture response of porous titanium. In particular, cell proliferation measured using metabolic activity and DNA content was improved for anodized and heat treated as well as for anodized but not heat-treated specimens. Heat treatment additionally improved the cell attachment of porous titanium surfaces and upregulated expression of osteogenic markers. Anodized but not heat-treated specimens showed some limited signs of upregulated expression of osteogenic markers. In conclusion, while varying the anodizing parameters creates different nanotube structure, it does not improve apatite-forming ability of porous titanium. However, both anodizing and heat treatment at 500 °C improve the cell culture response of porous titanium

  3. Electroplating Zn-Al Alloy Technology

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The method of controlling separating anode and separating power source was used to perform orthogonal optimization for the parameters in electroplating Zn-Al alloy.The electroplating Zn-Al alloy technology was decided, in which the content of Al is about 12%-15%.

  4. Manufacture of Catalyst Systems for Ammonia Conversion

    Institute of Scientific and Technical Information of China (English)

    GAKH S.V.; SAVENKOV D.A.

    2012-01-01

    Platinum catalyst gauzes have been in use since the moment of development of the process of catalyst oxidation of ammonia for production of nitric acid or hydrocyanic acid.Catalyst gauzes are usually made of platinum or its alloys with rhodium and palladium.These precious metals have remarkable properties that make them ideal catalysts for acceleration of the ammonia/oxygen reaction.In 2008,OJSC "SIC ‘Supermetal’" and Umicore AG&Co.KG launched a production line for Pt-alloy-based catalyst systems to be used for ammonia oxidation in the production of weak nitric acid.Catalyst systems consist of a pack of catalyst gauzes and a pack of catchment gauzes,which are made using flat-bed knitting machines and wire-cloth looms.Today,up-to-date catalyst systems MKSpreciseTM are being manufactured,the basic advantages of which are an individual structure of gauzes and composition of the material,which allows to define precisely the position of each gauze in the catalyst pack,a high activity of the catalyst pack,direct catching of platinum and rhodium in the catalyst system,and a reasonable combination of single- and multilayer types of gauzes.This makes it possible to vary the configuration of the catalyst and select an optimum composition of the system to ensure the maximum efficiency of the ammonia oxidation process.We also produce the catchment systems that allow to find the best decision from the economic point view for each individual case.

  5. An Analysis of Mechanical Properties of Anodized Aluminum Film at High Stress

    Science.gov (United States)

    Zhao, Xixi; Wei, Guoying; Yu, Yundan; Guo, Yuemei; Zhang, Ao

    2015-10-01

    In this paper, a new environmental-friendly electrolyte containing sulfuric acid and tartaric acid has been used as the substitute of chromic acid for anodization. The work discussed the influence of anodizing voltages on the fatigue life of anodized Al 2024-T3 by performing fatigue tests with 0.1 stress ratio (R) at 320 MPa. Meanwhile the fatigue cycles to failure, yield strength, tensile strength and fracture surface of anodic films at different conditions were investigated. The results showed that the fatigue life of anodized and sealed specimens reduced a lot compared to aluminum alloy, which can be attributed to the crack sites initiated at the oxide layer. The fracture surface analyses also revealed that the number of crack initiation sites enlarged with the increase of anodizing voltage.

  6. Catalysts, Protection Layers, and Semiconductors

    DEFF Research Database (Denmark)

    Chorkendorff, Ib

    2015-01-01

    Hydrogen is the simplest solar fuel to produce and in this presentation we shall give a short overview of the pros and cons of various tandem devices [1]. The large band gap semiconductor needs to be in front, but apart from that we can chose to have either the anode in front or back using either...... acid or alkaline conditions. Since most relevant semiconductors are very prone to corrosion the advantage of using buried junctions and using protection layers offering shall be discussed [2-4]. Next we shall discuss the availability of various catalysts for being coupled to these protections layers...... and how their stability may be evaluated [5, 6]. Examples of half-cell reaction using protection layers for both cathode and anode will be discussed though some of recent examples under both alkaline and acidic conditions. Si is a very good low band gap semiconductor and by using TiO2 as a protection...

  7. Fabrication of Corrosion Resistance Micro-Nanostructured Superhydrophobic Anodized Aluminum in a One-Step Electrodeposition Process

    OpenAIRE

    Ying Huang; Dilip K. Sarkar; X.-Grant Chen

    2016-01-01

    The formation of low surface energy hybrid organic-inorganic micro-nanostructured zinc stearate electrodeposit transformed the anodic aluminum oxide (AAO) surface to superhydrophobic, having a water contact angle of 160°. The corrosion current densities of the anodized and aluminum alloy surfaces are found to be 200 and 400 nA/cm2, respectively. In comparison, superhydrophobic anodic aluminum oxide (SHAAO) shows a much lower value of 88 nA/cm2. Similarly, the charge transfer resistance, Rct, ...

  8. Na-Ion Battery Anodes: Materials and Electrochemistry.

    Science.gov (United States)

    Luo, Wei; Shen, Fei; Bommier, Clement; Zhu, Hongli; Ji, Xiulei; Hu, Liangbing

    2016-02-16

    The intermittent nature of renewable energy sources, such as solar and wind, calls for sustainable electrical energy storage (EES) technologies for stationary applications. Li will be simply too rare for Li-ion batteries (LIBs) to be used for large-scale storage purposes. In contrast, Na-ion batteries (NIBs) are highly promising to meet the demand of grid-level storage because Na is truly earth abundant and ubiquitous around the globe. Furthermore, NIBs share a similar rocking-chair operation mechanism with LIBs, which potentially provides high reversibility and long cycling life. It would be most efficient to transfer knowledge learned on LIBs during the last three decades to the development of NIBs. Following this logic, rapid progress has been made in NIB cathode materials, where layered metal oxides and polyanionic compounds exhibit encouraging results. On the anode side, pure graphite as the standard anode for LIBs can only form NaC64 in NIBs if solvent co-intercalation does not occur due to the unfavorable thermodynamics. In fact, it was the utilization of a carbon anode in LIBs that enabled the commercial successes. Anodes of metal-ion batteries determine key characteristics, such as safety and cycling life; thus, it is indispensable to identify suitable anode materials for NIBs. In this Account, we review recent development on anode materials for NIBs. Due to the limited space, we will mainly discuss carbon-based and alloy-based anodes and highlight progress made in our groups in this field. We first present what is known about the failure mechanism of graphite anode in NIBs. We then go on to discuss studies on hard carbon anodes, alloy-type anodes, and organic anodes. Especially, the multiple functions of natural cellulose that is used as a low-cost carbon precursor for mass production and as a soft substrate for tin anodes are highlighted. The strategies of minimizing the surface area of carbon anodes for improving the first-cycle Coulombic efficiency are

  9. Tin-phosphate glass anode for sodium ion batteries

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Honma

    2013-11-01

    Full Text Available The electrochemical property of tin-phosphate (designate as GSPO glass anode for the sodium ion battery was studied. During the first charge process, sodium ion diffused into GSPO glass matrix and due to the reduction of Sn2+ to Sn0 state sodiated tin metal nano-size particles are formed in oxide glass matrix. After the second cycle, we confirmed the steady reversible reaction ∼320 mAh/g at 0–1 V cutoff voltage condition by alloying process in NaxSn4. The tin-phosphate glass is a promising candidate of new anode active material that realizes high energy density sodium ion batteries.

  10. Iron migration from the anode surface in alumina electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhuravleva, Elena N.; Drozdova, Tatiana N.; Ponomareva, Svetlana V. [Siberian Federal University, Krasnoyarsk, 660041 (Russian Federation); Kirik, Sergei D., E-mail: kiriksd@yandex.ru [Siberian Federal University, Krasnoyarsk, 660041 (Russian Federation); Institute of Chemistry and Chemical Technology SB RAS, Krasnoyarsk, 660036 (Russian Federation)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Corrosion destruction of two-component iron-based alloys in high-temperature aluminum electrolysis in the cryolite alumina melt has been studied. Black-Right-Pointing-Pointer It was found that at the first stage oxidative polarization of iron atoms on the anode surface into Fe{sup 2+} takes place. Black-Right-Pointing-Pointer Fe{sup 2+} interacts with cryolite melt producing FeF{sub 2}. Black-Right-Pointing-Pointer FeF{sub 2} gives oxides FeAl{sub 2}O{sub 4}, Fe{sub 3}O{sub 4}, Fe{sub 2}O{sub 3}. Black-Right-Pointing-Pointer The participation of oxygen in the corrosion has not been observed. - Abstract: Corrosion destruction of two-component iron-based alloys used as an anode in high-temperature alumina electrolysis in the melt of NaF/KF/AlF{sub 3} electrolyte has been considered. Ni, Si, Cu, Cr, Mn, Al, Ti in the amount of up to 10% have been tested as the dopants to an anode alloys. The composition of the corrosion products has been studied using X-ray diffraction, scanning electron microscopy and electron microprobe analysis. It has been established that the anode corrosion is induced by a surface electrochemical polarization and iron atom oxidation. Iron ions come into an exchange interaction with the fluoride components of the melted electrolyte, producing FeF{sub 2}. The last interacts with oxyfluoride species transforming into the oxide forms: FeAl{sub 2}O{sub 4}, Fe{sub 3}O{sub 4}, Fe{sub 2}O{sub 3}. Due to the low solubility, the iron oxides are accumulated in the near-electrode sheath. The only small part of iron from anode migrates to cathode that makes an production of high purity aluminum of a real task. The alloy dopants are also subjected to corrosion in accordance with electromotive series resulting corrosion tunnels on the anode surface. The oxides are final compounds which collect in the same area. The corrosion products form an anode shell which is electronic conductor at electrolysis temperature. The

  11. Iron migration from the anode surface in alumina electrolysis

    International Nuclear Information System (INIS)

    Highlights: ► Corrosion destruction of two-component iron-based alloys in high-temperature aluminum electrolysis in the cryolite alumina melt has been studied. ► It was found that at the first stage oxidative polarization of iron atoms on the anode surface into Fe2+ takes place. ► Fe2+ interacts with cryolite melt producing FeF2. ► FeF2 gives oxides FeAl2O4, Fe3O4, Fe2O3. ► The participation of oxygen in the corrosion has not been observed. - Abstract: Corrosion destruction of two-component iron-based alloys used as an anode in high-temperature alumina electrolysis in the melt of NaF/KF/AlF3 electrolyte has been considered. Ni, Si, Cu, Cr, Mn, Al, Ti in the amount of up to 10% have been tested as the dopants to an anode alloys. The composition of the corrosion products has been studied using X-ray diffraction, scanning electron microscopy and electron microprobe analysis. It has been established that the anode corrosion is induced by a surface electrochemical polarization and iron atom oxidation. Iron ions come into an exchange interaction with the fluoride components of the melted electrolyte, producing FeF2. The last interacts with oxyfluoride species transforming into the oxide forms: FeAl2O4, Fe3O4, Fe2O3. Due to the low solubility, the iron oxides are accumulated in the near-electrode sheath. The only small part of iron from anode migrates to cathode that makes an production of high purity aluminum of a real task. The alloy dopants are also subjected to corrosion in accordance with electromotive series resulting corrosion tunnels on the anode surface. The oxides are final compounds which collect in the same area. The corrosion products form an anode shell which is electronic conductor at electrolysis temperature. The electrolysis of alumina occurs beyond the corrosion shell. The rate limiting step in the corrosion is the electrolyte penetration through corrosion shell to the anode surface. The participation of the released oxygen in the corrosion has

  12. Composite anodes for lithium-ion batteries: status and trends

    Directory of Open Access Journals (Sweden)

    Alain Mauger

    2016-07-01

    Full Text Available Presently, the negative electrodes of lithium-ion batteries (LIBs is constituted by carbon-based materials that exhibit a limited specific capacity 372 mAh g−1 associated with the cycle between C and LiC6. Therefore, many efforts are currently made towards the technological development nanostructured materials in which the electrochemical processes occurs as intercalation, alloying or conversion reactions with a good accommodation of dilatation/contraction during cycling. In this review, attention is focused on advanced anode composite materials based on carbon, silicon, germanium, tin, titanium and conversion anode composite based on transition-metal oxides.

  13. Influence of Electrolyte on the Properties of Hard Anodic Oxide Coating on 2 A12 Aluminium Alloy%电解液对2A12铝合金硬质阳极氧化膜层性能的影响

    Institute of Scientific and Technical Information of China (English)

    钱建才; 邹洪庆; 许斌; 吴厚昌; 吕基成; 方敏

    2015-01-01

    目的 对硫酸、混合酸电解液体系中制备的2 A12铝合金硬质阳极氧化膜层性能进行研究,找出混合酸电解液体系对2 A12铝合金硬质阳极氧化过程的影响机理,为改善膜层的耐蚀性能提供一种思路.方法 通过对膜层厚度、显微硬度、微观形貌、极化曲线、交流阻抗试验结果进行分析,研究不同电解液对2 A12硬质阳极氧化膜层性能的影响. 结果 在有机酸的活性吸附作用下,混和酸电解液解决了硫酸电解液制备2A12铝合金硬质阳极氧化膜存在的厚度、硬度不均匀及烧蚀现象,制备的膜层厚度范围为35~38μm,硬度范围为386~407HV0. 05,具有厚度和硬度分布均匀、离散性小的特点. 极化曲线及电化学交流阻抗分析表明,混合酸电解液体系中制备的2 A12铝合金硬质阳极氧化膜层未进行封孔处理时,膜层的自腐蚀电位为-619. 93 mV,阻挡层电阻为1. 4 ×105 Ω·cm2;封孔处理后,膜层的自腐蚀电位为-74. 69 mV,阻挡层电阻为2. 376×106Ω·cm2. 这说明封孔处理能够改善阻挡层的质量,显著提高膜层的耐腐蚀性能. 结论 采用混合酸电解液体系能够稳定制备出2 A12铝合金硬质阳极氧化膜层,制备的膜层应进行封孔处理.%Objective To study the properties of hard anodic oxidation coatings on 2A12 aluminum alloy prepared in the electro-lyte of sulphuric acids and hybrid acids separately,in order to find out the influencing mechanism of hybrid acids on hard anodic ox-idation process of 2A12 aluminum alloy, and provide method to enhance the coating corrosion resistance. Methods The properties of hard anodic oxide coatings prepared in different electrolytes were analyzed and characterized by thickness, micro-hardness, SEM morphology, polarization curve and AC impedance spectroscopic to investigate the influence of different electrolytes on the perform-ance of hard anodic oxidation coatings on 2A12 aluminum alloy. Results The phenomenon

  14. Alternative Anodes for the Electrolytic Reduction of Uranium Dioxide

    Science.gov (United States)

    Merwin, Augustus

    Reprocessing of spent nuclear fuel is an essential step in closing the nuclear fuel cycle. In order to consume current stockpiles, ceramic uranium dioxide spent nuclear fuel will be subjected to an electrolytic reduction process. The current reduction process employs a platinum anode and a stainless steel alloy 316 cathode in a molten salt bath consisting of LiCl-2wt% Li 2O and occurs at 700°C. A major shortcoming of the existing process is the degradation of the platinum anode under the severely oxidizing conditions encountered during electrolytic reduction. This work investigates alternative anode materials for the electrolytic reduction of uranium oxide. The high temperature and extreme oxidizing conditions encountered in these studies necessitated a unique set of design constraints on the system. Thus, a customized experimental apparatus was designed and constructed. The electrochemical experiments were performed in an electrochemical reactor placed inside a furnace. This entire setup was housed inside a glove box, in order to maintain an inert atmosphere. This study investigates alternative anode materials through accelerated corrosion testing. Surface morphology was studied using scanning electron microscopy. Surface chemistry was characterized using energy dispersive spectroscopy and Raman spectroscopy. Electrochemical behavior of candidate materials was evaluated using potentiodynamic polarization characteristics. After narrowing the number of candidate electrode materials, ferrous stainless steel alloy 316, nickel based Inconel 718 and elemental tungsten were chosen for further investigation. Of these materials only tungsten was found to be sufficiently stable at the anodic potential required for electrolysis of uranium dioxide in molten salt. The tungsten anode and stainless steel alloy 316 cathode electrode system was studied at the required reduction potential for UO2 with varying lithium oxide concentrations. Electrochemical impedance spectroscopy

  15. Double anodization experiments in tantalum

    Energy Technology Data Exchange (ETDEWEB)

    Albella, J.M.; Fernandez, M.; Gomez-Aleixandre, C.; Martinez-Duart, J.M.; Montero, I.

    1985-10-01

    Based on our previous model of anodization, a new formula is given for the relation between the breakdown voltage V /SUB B/ during the anodic oxidation of tantalum and the anodization parameters. The formula predicts the well known diminution of V /SUB B/ with the logarithm of the electrolyte concentration. The model also explains the experimentally-observed fact that V /SUB B/ is solely determined by the latter electrolyte in double anodization experiments.

  16. Anodes for Solid Oxide Fuel Cells Operating at Low Temperatures

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain

    An important issue that has limited the potential of Solid Oxide Fuel Cells (SOFCs) for portable applications is its high operating temperatures (800-1000 ºC). Lowering the operating temperature of SOFCs to 400-600 ºC enable a wider material selection, reduced degradation and increased lifetime....... On the other hand, low-temperature operation poses serious challenges to the electrode performance. Effective catalysts, redox stable electrodes with improved microstructures are the prime requisite for the development of efficient SOFC anodes. The performance of Nb-doped SrT iO3 (STN) ceramic anodes...... at 400ºC. The potential of using WO3 ceramic as an alternative anode materials has been explored. The relatively high electrode polarization resistance obtained, 11 Ohm cm2 at 600 ºC, proved the inadequate catalytic activity of this system for hydrogen oxidation. At the end of this thesis...

  17. Chemically tuned anode with tailored aqueous hydrocarbon binder for direct methanol fuel cells.

    Science.gov (United States)

    Lee, Chang Hyun; Lee, So Young; Lee, Young Moo; McGrath, James E

    2009-07-21

    An anode for direct methanol fuel cells was chemically tuned by tailoring an aqueous hydrocarbon catalyst (SPI-BT) binder instead of using a conventional perfluorinated sulfonic acid ionomer (PFSI). SPI-BT designed in triethylamine salt form showed lower proton conductivity than PFSI, but it was stable in the catalyst ink forming the aqueous colloids. The aqueous colloidal particle size of SPI-BT was much smaller than that of PFSI. The small SPI-BT colloidal particles contributed to forming small catalyst agglomerates and simultaneously reducing their pore volume. Consequently, the high filling level of binders in the pores, where Pt-Ru catalysts are mainly located on the wall and physically interconnected, resulted in increased electrochemical active surface area of the anode, leading to high catalyst utilization. In addition, the chemical affinity between the SPI-BT binder and the membrane material derived from their similar chemical structure induced a stable interface on the membrane-electrode assembly (MEA) and showed low electric resistance. Upon adding SPI-BT, the synergistic effect of high catalyst utilization, improved mass transfer behavior to Pt-Ru catalyst, and low interfacial resistance of MEA became greater than the influence of reduced proton conductivity in the electrochemical performance of single cells. The electrochemical performance of MEAs with SPI-BT anode was enhanced to almost the same degree or somewhat higher than that with PFSI at 90 degrees C. PMID:19485372

  18. Photo-oxidation catalysts

    Science.gov (United States)

    Pitts, J. Roland; Liu, Ping; Smith, R. Davis

    2009-07-14

    Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.

  19. Superhydrophobicity of Bionic Alumina Surfaces Fabricated by Hard Anodizing

    Institute of Scientific and Technical Information of China (English)

    Jing Li; Feng Du; Xianli Liu; Zhonghao Jiang; Luquan Ren

    2011-01-01

    Bionic alumina samples were fabricated on convex dome type aluminum alloy substrate using hard anodizing technique.The convex domes on the bionic sample were fabricated by compression molding under a compressive stress of 92.5 MPa.The water contact angles of the as-anodized bionic samples were measured using a contact angle meter (JC2000A) with the 3 μL water drop at room temperature.The measurement of the wetting property showed that the water contact angle of the unmodified as-anodized bionic alumina samples increases from 90° to 137° with the anodizing time.The increase in water contract angle with anodizing time arises from the gradual formation of hierarchical structure or composite structure.The structure is composed of the micro-scaled alumina columns and pores.The height of columns and the depth of pores depend on the anodizing time.The water contact angle increases significantly from 96° to 152° when the samples were modified with self-assembled monolayer of octadecanethiol (ODT),showing a change in the wettability from hydrophobicity to super-hydrophobicity.This improvement in the wetting property is attributed to the decrease in the surface energy caused by the chemical modification.

  20. Inert Anode Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    1999-07-01

    This ASME report provides a broad assessment of open literature and patents that exist in the area of inert anodes and their related cathode systems and cell designs, technologies that are relevant for the advanced smelting of aluminum. The report also discusses the opportunities, barriers, and issues associated with these technologies from a technical, environmental, and economic viewpoint.

  1. Anodes for alkaline electrolysis

    Science.gov (United States)

    Soloveichik, Grigorii Lev

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  2. Design of TEOS-GPTMS sol-gel coatings on rare-earth magnesium alloys employed in the manufacture of orthopaedic implants

    Science.gov (United States)

    Rueda, L. M.; Nieves, C.; Hernández Barrios, C. A.; Coy, A. E.; Viejo, F.

    2016-02-01

    In the present work hybrid sol-gel coatings were synthesized on different magnesium alloys with potential interest in the fabrication of orthopaedic implants. Hybrid sols were obtained from a mixture of the inorganic precursor tetraethoxysilane (TEOS) and the organic precursor 3-glycidoxypropyltrimethoxysilane (GPTMS), employing ethanol as solvent and acetic acid as catalyst. The characterization of the sols was performed using pH measurements, rheological tests and infrared spectroscopy (FTIR) for different aging times. On the other hand, the coatings were characterized by scanning electron microscopy (SEM), while the corrosion resistance was evaluated using anodic polarization in SBF solution at 37±2°C. The results confirmed that, under specific conditions, uniform and homogeneous sol-gel coatings were obtained, which enhanced the corrosion resistance so that the corrosion current density was reduced in about two orders of magnitude with regard to the parent alloy.

  3. Combinatorial synthesis and screening of fuel cell catalysts

    Science.gov (United States)

    Jayaraman, Shrisudersan

    Polymer electrolyte membrane fuel cells (PEMFCs) are compact power sources that can operate with high efficiencies and low emission of environmentally harmful gases. One of the major barriers impeding the development of PEMFCs as a competitive energy source is the inability of existing anode catalysts to oxidize fuels other than hydrogen at sufficient levels due to catalyst deactivation by carbon monoxide (CO) and other partial oxidation products. The focus of this research is the development and application of combinatorial strategies to construct and interrogate electrooxidation (anode) catalysts pertaining to PEMFCs to discover catalysts with enhanced performance in catalyst deactivating environments. A novel method (known as the "gel-transfer" method) for synthesizing catalyst composition gradient libraries for combinatorial catalyst discovery was developed. This method involved transferring a spatial concentration gradient of precursor metal salts created within a polymer gel on to a solid conducting substrate by electrochemical reduction. Chemically sensitive surface-imaging techniques, namely, scanning electrochemical microscopy (SECM) and optical screening with a pH-dependent fluorescence probe were used to characterize the combinatorial catalyst samples. The utility of SECM as a screening tool to measure the activity of multicomponent catalyst libraries towards fuel cell electrooxidation reactions was established with simple catalyst libraries including a platinum coverage gradient and platinum-ruthenium and platinum-ruthenium-molybdenum arrays. A platinum-ruthenium surface composition gradient was constructed through the gel-transfer method and its reactivity towards hydrogen oxidation in the presence of a catalyst poison (CO) was mapped using the SECM. Ruthenium composition between 20 and 30% exhibited superior performance than the rest of the binary. The gel-transfer method was extended to construct a ternary platinum-ruthenium-rhodium catalyst library

  4. CO-Tolerant Pt–BeO as a Novel Anode Electrocatalyst in Proton Exchange Membrane Fuel Cells

    Directory of Open Access Journals (Sweden)

    Kyungjung Kwon

    2016-05-01

    Full Text Available Commercialization of proton exchange membrane fuel cells (PEMFCs requires less expensive catalysts and higher operating voltage. Substantial anodic overvoltage with the usage of reformed hydrogen fuel can be minimized by using CO-tolerant anode catalysts. Carbon-supported Pt–BeO is manufactured so that Pt particles with an average diameter of 4 nm are distributed on a carbon support. XPS analysis shows that a peak value of the binding energy of Be matches that of BeO, and oxygen is bound with Be or carbon. The hydrogen oxidation current of the Pt–BeO catalyst is slightly higher than that of a Pt catalyst. CO stripping voltammetry shows that CO oxidation current peaks at ~0.85 V at Pt, whereas CO is oxidized around 0.75 V at Pt–BeO, which confirms that the desorption of CO is easier in the presence of BeO. Although the state-of-the-art PtRu anode catalyst is dominant as a CO-tolerant hydrogen oxidation catalyst, this study of Be-based CO-tolerant material can widen the choice of PEMFC anode catalyst.

  5. X-ray absorption spectroscopy for characterisation of catalysts for PEM fuel cells; Roentgenabsorptionsspektroskopie zur Charakterisierung von Katalysatoren fuer die PEM-Brennstoffzelle

    Energy Technology Data Exchange (ETDEWEB)

    Koehl, G.

    2001-10-01

    The investigation of bimetallic nanoparticles is of great interest for the development of powerful anode catalysts in PEM fuel cells. The determination of their electronic and geometric structure is crucial for the optimization of the activity and selectivity in the fuel cell. Especially carbon supported PtRu particles have shown superior activity as anode catalysts due to their high CO tolerance. To state the reason on an atomic level, X-ray absorption spectroscopy (XAS) with synchrotron radiation has been used to examine several Pt and PtRu nanoparticle systems. They were either prepared on the basis of preformed PtRu alloy colloids stabilized by different surfactants or by chemical reduction of precursors, Na{sub 6}Pt(SO{sub 3}){sub 4} and Na{sub 6}Ru(SO{sub 3}){sub 4}. Although a PtRu interaction was observed in all systems, a nonstatistical distribution of Pt and Ru atoms in the nanoparticles could be verified. In additional investigations the reaction mechanism during the synthesis of an organometallic stabilized Pt colloid was examined. In-situ measurements revealed the formation of an hitherto unknown Pt complex as intermediate state prior to the nucleation of the particles. (orig)

  6. Discovery of technical methanation catalysts based on computational screening

    DEFF Research Database (Denmark)

    Sehested, Jens; Larsen, Kasper Emil; Kustov, Arkadii;

    2007-01-01

    Methanation is a classical reaction in heterogeneous catalysis and significant effort has been put into improving the industrially preferred nickel-based catalysts. Recently, a computational screening study showed that nickel-iron alloys should be more active than the pure nickel catalyst and at ...

  7. Vacuum Evaporation Technology for Treating Antimony-Rich Anode Slime

    Science.gov (United States)

    Qiu, Keqiang; Lin, Deqiang; Yang, Xuelin

    2012-11-01

    A vacuum evaporation technology for treating antimony-rich anode slime was developed in this work. Experiments were carried out at temperatures from 873 K to 1073 K and residual gas pressures from 50 Pa to 600 Pa. During vacuum evaporation, silver from the antimony-rich anode slime was left behind in the distilland in a silver alloy containing antimony and lead, and antimony trioxide was evaporated. The experimental results showed that 92% by weight of antimony can be removed, and the silver content in the alloy was up to 12.84%. The antimony trioxide content in the distillate was more than 99.7%, and the distillate can be used directly as zero-grade antimony trioxide (China standard).

  8. Highly active carbon supported palladium-rhodium PdXRh/C catalysts for methanol electrooxidation in alkaline media and their performance in anion exchange direct methanol fuel cells (AEM-DMFCs)

    International Nuclear Information System (INIS)

    Highlights: • Synthesis and physical evaluation of carbon supported, Rh containing Pd electrocatalysts. • Electroactivity towards methanol oxidation strongly enhanced in alkaline media. • Bimetallic catalyst show low CO oxidation and OH adsorption potentials. • CO2 current efficiency higher for bimetallic catalysts than for Pt/C or Pd/C. • Power density of 105 mW cm−2 for platinum-free alkaline direct methanol fuel cell. - Abstract: In this study carbon supported PdXRh electrocatalysts synthesized by wet chemical reduction process were tested for the potential use in anion-exchange membrane direct methanol fuel cells (AEM-DMFC) and compared to Pd/C and commercially available Pt/C. A metal loading of 20wt% on carbon was confirmed by thermogravimetric analysis (TGA) and catalyst compositions of PdRh3/C, PdRh/C and Pd3Rh/C were found via inductively coupled plasma optical emission spectroscopy (ICP-OES). Transmission electron microscopy (TEM) and x-ray diffraction (XRD) studies showed that the average particle and crystallite sizes of the PdXRh/C catalysts are in the range of 3.1 to 4.3 nm. It was also found that these catalysts are not alloyed. Cyclic voltammetry (CV) data reveals a 85–140 mV lower CH3OH oxidation onset potential and higher mass current densities for PdXRh/C catalysts compared with Pd/C. Steady-state measurements via chronoamperometry (CA) showed a good stability against poisoning during methanol oxidation and higher mass activities for PdRh/C and Pd3Rh/C compared to Pt/C. By using differential electrochemical mass spectrometry (DEMS) it was successfully shown that adding Rh to Pd results in an enhanced CO2 current efficiency (CCE) compared to Pd/C or Pt/C. AEM-DMFCs free from platinum were fabricated and single cell tests at 60 °C showed a significant increase of power density at 0.5 V cell potential from 4.8 mW cm−2 for Pd/C to 16.5 mW cm−2 for PdRh/C with the anode and cathode fed with 1 M methanol + 2 M KOH and synthetic air

  9. Catalysts for Efficient Production of Carbon Nanotubes

    Science.gov (United States)

    Sun, Ted X.; Dong, Yi

    2009-01-01

    Several metal alloys have shown promise as improved catalysts for catalytic thermal decomposition of hydrocarbon gases to produce carbon nanotubes (CNTs). Heretofore almost every experiment on the production of carbon nanotubes by this method has involved the use of iron, nickel, or cobalt as the catalyst. However, the catalytic-conversion efficiencies of these metals have been observed to be limited. The identification of better catalysts is part of a continuing program to develop means of mass production of high-quality carbon nanotubes at costs lower than those achieved thus far (as much as $100/g for purified multi-wall CNTs or $1,000/g for single-wall CNTs in year 2002). The main effort thus far in this program has been the design and implementation of a process tailored specifically for high-throughput screening of alloys for catalyzing the growth of CNTs. The process includes an integral combination of (1) formulation of libraries of catalysts, (2) synthesis of CNTs from decomposition of ethylene on powders of the alloys in a pyrolytic chemical-vapor-decomposition reactor, and (3) scanning- electron-microscope screening of the CNTs thus synthesized to evaluate the catalytic efficiencies of the alloys. Information gained in this process is put into a database and analyzed to identify promising alloy compositions, which are to be subjected to further evaluation in a subsequent round of testing. Some of these alloys have been found to catalyze the formation of carbon nano tubes from ethylene at temperatures as low as 350 to 400 C. In contrast, the temperatures typically required for prior catalysts range from 550 to 750 C.

  10. Catalyst Architecture

    DEFF Research Database (Denmark)

    Kiib, Hans; Marling, Gitte; Hansen, Peter Mandal

    2014-01-01

    How can architecture promote the enriching experiences of the tolerant, the democratic, and the learning city - a city worth living in, worth supporting and worth investing in? Catalyst Architecture comprises architectural projects, which, by virtue of their location, context and their combination...... of programs, have a role in mediating positive social and/or cultural development. In this sense, we talk about architecture as a catalyst for: sustainable adaptation of the city’s infrastructure appropriate renovation of dilapidated urban districts strengthening of social cohesiveness in the city...

  11. Fuel cell development for transportation: Catalyst development

    Energy Technology Data Exchange (ETDEWEB)

    Doddapaneni, N. [Sandia National Lab., Albuquerque, NM (United States)

    1996-04-01

    Fuel cells are being considered as alternate power sources for transportation and stationary applications. With proton exchange membrane (PEM) fuel cells the fuel crossover to cathodes causes severe thermal management and cell voltage drop due to oxidation of fuel at the platinized cathodes. The main goal of this project was to design, synthesize, and evaluate stable and inexpensive transition metal macrocyclic catalysts for the reduction of oxygen and be electrochemically inert towards anode fuels such as hydrogen and methanol.

  12. Anodic bonded graphene

    OpenAIRE

    Balan, Adrian; Kumar, Rakesh; Boukhicha, Mohamed; Beyssac, Olivier; Bouillard, Jean-Claude; Taverna, Dario; Sacks, William; Marangolo, Massimiliano; Lacaze, Emmanuelle; Escoffier, Walter; Poumirol, Jean-Marie; Shukla, Abhay

    2010-01-01

    Abstract We show how to prepare graphene samples on a glass substrate with the anodic bonding method. In this method, a graphite precursor in flake form is bonded to a glass substrate with the help of an electrostatic field and then cleaved off to leave few layer graphene on the substrate. Now that several methods are available for producing graphene, the relevance of our method is in its simplicity and practicality for producing graphene samples of about 100 ?m lateral dimensions. This me...

  13. Effect of heat treatment on anodic activation of aluminium by trace element indium

    Energy Technology Data Exchange (ETDEWEB)

    Graver, Brit [Department of Materials Science and Engineering, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Helvoort, Antonius T.J. van [Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Nisancioglu, Kemal, E-mail: kemal.nisancioglu@material.ntnu.n [Department of Materials Science and Engineering, Norwegian University of Science and Technology, N-7491 Trondheim (Norway)

    2010-11-15

    Research highlights: {yields} Indium segregation activates AlIn alloy surface anodically in chloride solution. {yields} Enrichment of In on Al surface can occur thermally by heat treatment at 300 {sup o}C. {yields} Increasing temperature homogenises indium in aluminium reducing anodic activation. {yields} Indium can activate AlIn surface by segregating through dealloying of aluminium. {yields} Anodic activation is caused by AlIn amalgam formation at aluminium surface. - Abstract: The presence of trace elements in Group IIIA-VA is known to activate aluminium anodically in chloride environment. The purpose of this paper is to investigate the surface segregation of trace element In by heat treatment and resulting surface activation. Model binary AlIn alloys, containing 20 and 1000 ppm by weight of In, were characterized after heat treatment at various temperatures by use of glow discharge optical emission spectroscopy, electron microscopy and electrochemical polarization. Heat treatment for 1 h at 300 {sup o}C gave significant segregation of discrete In particles (thermal segregation), which activated the surface. Indium in solid solution with aluminium, obtained by 1 h heat treatment at 600 {sup o}C, also activated by surface segregation of In on alloy containing 1000 ppm In, resulting from the selective dissolution of the aluminium component during anodic oxidation (anodic segregation). The effect of anodic segregation was reduced by decreasing indium concentration in solid solution; it had negligible effect at the 20 ppm level. The segregated particles were thought to form a liquid phase alloy with aluminium during anodic polarization, which in turn, together with the chloride in the solution destabilized the oxide.

  14. The role of electronic properties of Pt and Pt alloys for enhanced reformate electro-oxidation in polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    One major challenge of PEM fuel cells development is to overcome the activity and durability issues of the current anode materials which are susceptible to hydrogen impurities. To design stable and efficient catalysts with enhanced reformate tolerance, a comprehensive understanding of the underlying mechanisms is crucial. In this work, the CO and CO2 tolerance of a series of Pt-based catalysts are tested in a PEM fuel cell. We report that the CO tolerance is the highest for PtMo/C followed by PtCoMo/C, PtRuMo/C, PtRuPb/C, PtRu/C, PtCo/C, PtFe/C, PtNi/C and Pt/C; while the CO2 tolerance increases in the order: PtCo, PtNi> PtRuPb> PtRu> PtCoMo> PtRuMo> PtFe> Pt> PtMo. In situ XAS measurements in combination with FEFF8 calculations are performed to correlate the CO and CO2 tolerance trends with the electronic properties of these Pt-based alloy catalysts. We find that the anode overpotential in the presence of CO2 can be generally related to the experimental Pt d-band vacancy or calculated d-band center, and thus governed by the Pt electronic properties modified by the alloyed metal(s). No such correlation is observed between the anode overpotential in the presence of CO and Pt electronic properties, which highlights the key roles of Mo or Ru in improving CO tolerance via promotion and bifunctional mechanisms. Building upon these results a new ternary alloy PtCoMo/C was synthesized. This electrocatalyst shows the best reformate tolerance in low temperature PEM fuel cells by taking advantage of the bifunctional mechanism induced by Mo and the ligand effect induced by Co simultaneously. Our findings put forward a theory which gives a strong perspective for further research and development of new inexpensive catalysts with superior CO tolerance and durability

  15. Highly active gauze-supported skeletal nickel catalysts

    OpenAIRE

    Fow, Kam Loon; Ganapathi, Murugan; Stassen, Ivo; Fransaer, Jan; Binnemans, Koen; De Vos, Dirk E.

    2013-01-01

    Gauze-supported skeletal nickel catalysts were prepared by electrodeposition of Ni–Zn alloys from an acetamide–DMSO2–NiCl2–ZnCl2 quaternary melt, followed by chemical or electrochemical leaching of zinc from the alloys. The activity and selectivity of the structured RANEY® nickel surpass those of commercial RANEY® nickel in the hydrogenation of acetophenone.

  16. Anode glow and double layer in DC magnetron anode plasma

    International Nuclear Information System (INIS)

    Sputtering magnetron is widely used device in research and industry alike. DC planar magnetron employs series of magnets to create magnetic field above the electrode surface which traps electrons in closed E-bar x B-bar drift. Similar device used in reversed polarity power was reported for use in various applications. In contrast to its normal counterpart there is no closed drift effect in there. This device has very limited understanding. We here investigate this device for its discharge properties. Our device is dominated by anode glow. The anode glow is expected to have the electron sheath which provides energy to electron to excite the neutrals. Where as many experimental studies have been reported for anode glow and anode double layer, many of them uses auxiliary anode in the discharge. Most of the cases anode double layer (fire ball/fire rod) is small structures very near to anode surface which in itself is required to be small. The DC planar magnetron biased in reverse polarity have glow only near anode. Measurements confirm it as anode glow and the presence of electrons sheath is proven. The double layer structure was observed and measured in two mutually perpendicular directions. The double layer shows sub MHz oscillation that is typical of the unstable anode double layer. The dimension of anode glow is relatively large and is primarily in magnetic field free region making it easy to probe. The potential structure still shows large cathode fall but surprisingly visible cathode glow is not present. The device operates very stable for pressure bellow 0.01 mbar. But it shows instabilities such as unstable anode double layer above said pressure. (author)

  17. Improvement of the current capacity of Al-Zn-In anode by casting parameters and magnesium addition

    Energy Technology Data Exchange (ETDEWEB)

    Saremi, M.; Keyvani, A.; Sina, H.; Emamy, M. [Metallurgy and Materials Department, University of Tehran, P.O.Box 11365/4563, Tehran (Iran)

    2004-07-01

    In the present work the effects of mold temperature and casting temperature have been studied on the potential and current capacity of Al-Zn-In anodes. Electrochemical polarization and NACE standard methods were used to evaluate the anodic behavior, potential and current capacity of the anodes. It is shown that metallic molds having higher temperatures could provide better condition for obtaining homogenous structures with minor inclusions. The optimum condition of anode operation may be provided where mold and pouring temperatures equal to 400 and 710 deg. C respectively, in which a fine structure, phase distribution and lack of casting faults are obtained. Some alloying elements such as Mg, Mn, Ti, Zr, Sr are added to the base alloy in order to improve its efficiency together with its capacity. In this study the anodic behavior of influence of mold temperature and Al-Zn-In alloy at different concentration of magnesium of 1 to 4 wt. %, is studied. The result of experiments of this anode shows that 2 wt. % Mg, casting and mold temperature at 730 and 350 deg. C are obtained the consumption decrease from about 3.8 to 3.3 Kg.Ay{sup -1}. Anode capacity also increases and potential of this anode stands to about -1045 mV. (author)

  18. Fabrication of Corrosion Resistance Micro-Nanostructured Superhydrophobic Anodized Aluminum in a One-Step Electrodeposition Process

    Directory of Open Access Journals (Sweden)

    Ying Huang

    2016-02-01

    Full Text Available The formation of low surface energy hybrid organic-inorganic micro-nanostructured zinc stearate electrodeposit transformed the anodic aluminum oxide (AAO surface to superhydrophobic, having a water contact angle of 160°. The corrosion current densities of the anodized and aluminum alloy surfaces are found to be 200 and 400 nA/cm2, respectively. In comparison, superhydrophobic anodic aluminum oxide (SHAAO shows a much lower value of 88 nA/cm2. Similarly, the charge transfer resistance, Rct, measured by electrochemical impedance spectroscopy shows that the SHAAO substrate was found to be 200-times larger than the as-received aluminum alloy substrate. These results proved that the superhydrophobic surfaces created on the anodized surface significantly improved the corrosion resistance property of the aluminum alloy.

  19. Anodization Mechanism on SiC Nanoparticle Reinforced Al Matrix Composites Produced by Power Metallurgy

    Directory of Open Access Journals (Sweden)

    Sonia C. Ferreira

    2014-12-01

    Full Text Available Specimens of aluminum-based composites reinforced by silicon carbide nanoparticles (Al/SiCnp produced by powder metallurgy (PM were anodized under voltage control in tartaric-sulfuric acid (TSA. In this work, the influence of the amount of SiCnp on the film growth during anodizing was investigated. The current density versus time response and the morphology of the porous alumina film formed at the composite surface are compared to those concerning a commercial aluminum alloy (AA1050 anodized under the same conditions. The processing method of the aluminum alloys influences the efficiency of the anodizing process, leading to a lower thicknesses for the unreinforced Al-PM alloy regarding the AA1050. The current density versus time response is strongly dependent on the amount of SiCnp. The current peaks and the steady-state current density recorded at each voltage step increases with the SiCnp volume fraction due to the oxidation of the SiCnp. The formation mechanism of the anodic film on Al/SiCnp composites is different from that occurring in AA1050, partly due the heterogeneous distribution of the reinforcement particles in the metallic matrix, but also to the entrapment of SiCnp in the anodic film.

  20. Electrochemical behaviors of anodic alumina sealed by Ce-Mo in NaCl solutions

    Institute of Scientific and Technical Information of China (English)

    TIAN Lian-peng; ZHAO Xu-hui; ZHAO Jing-mao; ZHANG Xiao-feng; ZUO Yu

    2006-01-01

    The elimination of toxic materials in sealing methods for anodic films on 1070 aluminum alloy was studied. The new process uses chemical treatments in cerium solution and an electrochemical treatment in a molybdate solution. Potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) were used to study the influences of sealing methods on the corrosion behavior of anodic films in NaCl solutions. The results show that the Ce-Mo sealing makes the surface structure and morphology of anodic films uniform and compact. Ce and Mo produce a cooperative effect to improve the corrosion resistance of anodic films. Anodic films sealed by Ce-Mo provide high corrosion resistance both in acidic and basic solutions.

  1. Process for anodizing aluminum foil

    International Nuclear Information System (INIS)

    In an integrated process for the anodization of aluminum foil for electrolytic capacitors including the formation of a hydrous oxide layer on the foil prior to anodization and stabilization of the foil in alkaline borax baths during anodization, the foil is electrochemically anodized in an aqueous solution of boric acid and 2 to 50 ppm phosphate having a pH of 4.0 to 6.0. The anodization is interrupted for stabilization by passing the foil through a bath containing the borax solution having a pH of 8.5 to 9.5 and a temperature above 800 C. and then reanodizing the foil. The process is useful in anodizing foil to a voltage of up to 760 V

  2. Plant-scale anodic dissolution of unirradiated IFR fuel pins

    International Nuclear Information System (INIS)

    This report discusses anodic dissolution which is a major operation in the pyrometallurgical process for recycling spent metal fuels from the Integral Fast Reactor (IFR), an advanced reactor design developed at Argonne National Laboratory. This process involves electrorefining the heavy metals (uranium and plutonium) from chopped, steel-clad fuel segments. The heavy metals are electrotransported from anodic dissolution baskets to solid and liquid cathodes in a molten salt electrolyte (LiCl-KCI) at 500 degrees C. Uranium is recovered on a solid cathode mandrel, while a uranium-plutonium mixture is recovered in a liquid cadmium cathode. The anode configuration consists of four baskets mounted on an anode shaft. These baskets provide parallel circuits in the electrolyte and salt flow through the chopped fuelbed as the baskets are rotated. The baskets for the engineering-scale tests were sized to contain up to 2.5 kg of heavy metal. Anodic dissolution of 10 kg batches of chopped, steel-clad simulated tuel (U-10% Zr and U-Zr-Fs alloy) was demonstrated

  3. Photoelectrochemical cell with nondissolving anode

    Science.gov (United States)

    Ellis, A. B.; Kaiser, S. W.; Wrighton, M. S.

    1980-01-01

    Improved electrolytic cells have efficiencies comparable to those of best silicon solar cells but are potentially less expensive to manufacture. Cells consist of light-sensitive n-type semiconductor anode and metallic cathode immersed in electrolytic solution. Reversible redox cells produce no chemical change in electrolyte and stabilize anode against dissolving. Cell can produce more than 500 mW of power per square centimeter of anode area at output voltage of 0.4 V.

  4. Examining the surfaces in used platinum catalysts

    Directory of Open Access Journals (Sweden)

    Trumić B.

    2009-01-01

    Full Text Available For the purpose of finding more advanced platinum catalyst manufacturing technologies and achieving a higher degree of ammonia oxidation, metallographic characterization has been done on the surface of catalyst gauzes and catalyst gripper gauzes made from platinum and palladium alloys. For the examined samples of gauzes as well as the cross section of the wires, a chemical analysis was provided. The purpose of this paper is the metallographic characterization of examined alloys carried out by way of electronic microscopic scanning, X-rays as well as chemical assays which contributed greatly to a better understanding of the surface deactivation, in other words a better consideration of structural changes occurring on the wire surface.

  5. Electronic-Structure-Based Design of Ordered Alloys

    DEFF Research Database (Denmark)

    Bligaard, Thomas; Andersson, M.P.; Jacobsen, Karsten Wedel; Skriver, Hans Lomholt; Christensen, Claus H.; Nørskov, Jens Kehlet

    2006-01-01

    We describe some recent advances in the methodology of using electronic structure calculations for materials design. The methods have been developed for the design of ordered metallic alloys and metal alloy catalysts, but the considerations we present are relevant for the atomic-scale computational...... discovery of a promising catalytic metal alloy surface with high reactivity and low cost....

  6. Operando XAFS study of carbon supported Ni, NiZn, and Co catalysts for hydrazine electrooxidation for use in anion exchange membrane fuel cells

    International Nuclear Information System (INIS)

    Carbon supported Ni, Ni0.87Zn0.13, and Co hydrazine electrooxidation catalysts were synthesized by an impregnation/freeze-drying procedure followed by thermal annealing for use as anode catalyst of direct hydrazine hydrate fuel cells (DHFCs). The cell performance of DHFCs changed significantly when different catalysts were used as anode. Ammonia generation from anode outlet at open circuit voltage (OCV) condition was higher for Co/C than for Ni-based catalysts. To better understand the cause of different performance and selectivity of each anode catalyst, extensive ex-situ and operando characterization was carried out. Operando XAFS measurement of Ni–K and Co–K edge shows the potential dependence of atomic structure of Ni/C, Ni0.87Zn0.13/C, and Co/C during hydrazine electrooxidation reaction

  7. Anodic bonded graphene

    Energy Technology Data Exchange (ETDEWEB)

    Balan, Adrian; Kumar, Rakesh; Boukhicha, Mohamed; Beyssac, Olivier; Bouillard, Jean-Claude; Taverna, Dario; Sacks, William; Shukla, Abhay [Universite Pierre et Marie Curie-Paris 6, CNRS-UMR7590, Institut de Mineralogie et de Physique des Milieux Condenses, 140 rue de Lourmel, Paris, F-75015 France (France); Marangolo, Massimiliano; Lacaze, Emanuelle; Gohler, Roger [Universite Pierre et Marie Curie-Paris 6, CNRS-UMR7588, Institut des Nanosciences de Paris, 140 rue de Lourmel, Paris, F-75015 France (France); Escoffier, Walter; Poumirol, Jean-Marie, E-mail: abhay.shukla@upmc.f [Laboratoire National des Champs Magnetiques Intenses, INSA UPS CNRS, UPR 3228, Universite de Toulouse, 143 avenue de Rangueil, 31400 Toulouse (France)

    2010-09-22

    We show how to prepare graphene samples on a glass substrate with the anodic bonding method. In this method, a graphite precursor in flake form is bonded to a glass substrate with the help of an electrostatic field and then cleaved off to leave few layer graphene on the substrate. Now that several methods are available for producing graphene, the relevance of our method is in its simplicity and practicality for producing graphene samples of about 100 {mu}m lateral dimensions. This method is also extensible to other layered materials. We discuss some detailed aspects of the fabrication and results from Raman spectroscopy, local probe microscopy and transport measurements on these samples.

  8. Designed hybrid nanostructure with catalytic effect: beyond the theoretical capacity of SnO2 anode material for lithium ion batteries

    Science.gov (United States)

    Wang, Ye; Huang, Zhi Xiang; Shi, Yumeng; Wong, Jen It; Ding, Meng; Yang, Hui Ying

    2015-01-01

    Transition metal cobalt (Co) nanoparticle was designed as catalyst to promote the conversion reaction of Sn to SnO2 during the delithiation process which is deemed as an irreversible reaction. The designed nanocomposite, named as SnO2/Co3O4/reduced-graphene-oxide (rGO), was synthesized by a simple two-step method composed of hydrothermal (1st step) and solvothermal (2nd step) synthesis processes. Compared to the pristine SnO2/rGO and SnO2/Co3O4 electrodes, SnO2/Co3O4/rGO nanocomposites exhibit significantly enhanced electrochemical performance as the anode material of lithium-ion batteries (LIBs). The SnO2/Co3O4/rGO nanocomposites can deliver high specific capacities of 1038 and 712 mAh g−1 at the current densities of 100 and 1000 mA g−1, respectively. In addition, the SnO2/Co3O4/rGO nanocomposites also exhibit 641 mAh g−1 at a high current density of 1000 mA g−1 after 900 cycles, indicating an ultra-long cycling stability under high current density. Through ex-situ TEM analysis, the excellent electrochemical performance was attributed to the catalytic effect of Co nanoparticles to promote the conversion of Sn to SnO2 and the decomposition of Li2O during the delithiation process. Based on the results, herein we propose a new method in employing the catalyst to increase the capacity of alloying-dealloying type anode material to beyond its theoretical value and enhance the electrochemical performance. PMID:25776280

  9. Designed hybrid nanostructure with catalytic effect: beyond the theoretical capacity of SnO2 anode material for lithium ion batteries

    Science.gov (United States)

    Wang, Ye; Huang, Zhi Xiang; Shi, Yumeng; Wong, Jen It; Ding, Meng; Yang, Hui Ying

    2015-03-01

    Transition metal cobalt (Co) nanoparticle was designed as catalyst to promote the conversion reaction of Sn to SnO2 during the delithiation process which is deemed as an irreversible reaction. The designed nanocomposite, named as SnO2/Co3O4/reduced-graphene-oxide (rGO), was synthesized by a simple two-step method composed of hydrothermal (1st step) and solvothermal (2nd step) synthesis processes. Compared to the pristine SnO2/rGO and SnO2/Co3O4 electrodes, SnO2/Co3O4/rGO nanocomposites exhibit significantly enhanced electrochemical performance as the anode material of lithium-ion batteries (LIBs). The SnO2/Co3O4/rGO nanocomposites can deliver high specific capacities of 1038 and 712 mAh g-1 at the current densities of 100 and 1000 mA g-1, respectively. In addition, the SnO2/Co3O4/rGO nanocomposites also exhibit 641 mAh g-1 at a high current density of 1000 mA g-1 after 900 cycles, indicating an ultra-long cycling stability under high current density. Through ex-situ TEM analysis, the excellent electrochemical performance was attributed to the catalytic effect of Co nanoparticles to promote the conversion of Sn to SnO2 and the decomposition of Li2O during the delithiation process. Based on the results, herein we propose a new method in employing the catalyst to increase the capacity of alloying-dealloying type anode material to beyond its theoretical value and enhance the electrochemical performance.

  10. Nanosegregated bimetallic oxide anode catalyst for proton exchange membrane electrolyzer

    Energy Technology Data Exchange (ETDEWEB)

    Danilovic, Nemanja; Kang, Yijin; Markovic, Nenad; Stamenkovic, Vojislav; Myers, Deborah J.; Subbaraman, Ram

    2016-08-23

    A surface segregated bimetallic composition of the formula Ru.sub.1-xIr.sub.x wherein 0.1.ltoreq.x.ltoreq.0.75, wherein a surface of the material has an Ir concentration that is greater than an Ir concentration of the material as a whole is provided. The surface segregated material may be produced by a method including heating a bimetallic composition of the formula Ru.sub.1-xIr.sub.x, wherein 0.1.ltoreq.x.ltoreq.0.75, at a first temperature in a reducing environment, and heating the composition at a second temperature in an oxidizing environment. The surface segregated material may be utilized in electrochemical devices.

  11. Modelling study of CO 2 poisoning on PEMFC anodes

    Science.gov (United States)

    Janssen, G. J. M.

    The CO 2 poisoning effect on anodes for the proton-exchange-membrane fuel cell (PEMFC) was examined by model studies. It was assumed that the reverse water gas shift reaction (RWGS) is the origin of the CO 2 poisoning effects. The relation between the anode polarisation losses and the catalytic properties of the catalyst was investigated with a kinetic model and with a fuel cell model including finite utilisation of the fuel. It was found that the main effect of the occurrence of the reverse water gas shift reaction is that a large part of the catalytic surface area becomes inactive for hydrogen dissociation. Desorption of CO formed by reduction of CO 2 followed by transport down the anode gas channel and subsequent re-adsorption on the catalyst was shown to play a minor role. In reformate gas, where besides CO 2 traces of CO are present, CO 2 poisoning will have the largest effect when the CO content is small and at relatively low current density.

  12. Performance of laboratory polymer electrolyte membrane hydrogen generator with sputtered iridium oxide anode

    Science.gov (United States)

    Labou, D.; Slavcheva, E.; Schnakenberg, U.; Neophytides, S.

    The continuous improvement of the anode materials constitutes a major challenge for the future commercial use of polymer electrolyte membranes (PEM) electrolyzers for hydrogen production. In accordance to this direction, iridium/titanium films deposited directly on carbon substrates via magnetron sputtering are operated as electrodes for the oxygen evolution reaction interfaced with Nafion 115 electrolyte in a laboratory single cell PEM hydrogen generator. The anode with 0.2 mg cm -2 Ir catalyst loading was electrochemically activated by cycling its potential value between 0 and 1.2 V (vs. RHE). The water electrolysis cell was operated at 90 °C with current density 1 A cm -2 at 1.51 V without the ohmic contribution. The corresponding current density per mgr of Ir catalyst is 5 A mg -1. The achieved high efficiency is combined with sufficient electrode stability since the oxidation of the carbon substrate during the anodic polarization is almost negligible.

  13. Highly active carbon supported ternary PdSnPtx (x=0.1-0.7) catalysts for ethanol electro-oxidation in alkaline and acid media.

    Science.gov (United States)

    Wang, Xiaoguang; Zhu, Fuchun; He, Yongwei; Wang, Mei; Zhang, Zhonghua; Ma, Zizai; Li, Ruixue

    2016-04-15

    A series of trimetallic PdSnPtx (x=0.1-0.7)/C catalysts with varied Pt content have been synthesized by co-reduction method using NaBH4 as a reducing agent. These catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and chronoamperometry (CA). The electrochemical results show that, after adding a minor amount of Pt dopant, the resultant PdSnPtx/C demonstrated more superior catalytic performance toward ethanol oxidation as compared with that of mono-/bi-metallic Pd/C or PdSn/C in alkaline solution and the PdSnPt0.2/C with optimal molar ratio reached the best. In acid solution, the PdSnPt0.2/C also depicted a superior catalytic activity relative to the commercial Pt/C catalyst. The possible enhanced synergistic effect between Pd, Sn/Sn(O) and Pt in an alloyed state should be responsible for the as-revealed superior ethanol electro-oxidation performance based upon the beneficial electronic effect and bi-functional mechanism. It implies the trimetallic PdSnPt0.2/C with a low Pt content has a promising prospect as anodic electrocatalyst in fields of alkali- and acid-type direct ethanol fuel cells. PMID:26851453

  14. Silicon Based Anodes for Li-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiguang; Wang, Wei; Xiao, Jie; Xu, Wu; Graff, Gordon L.; Yang, Zhenguo; Choi, Daiwon; Li, Xiaolin; Wang, Deyu; Liu, Jun

    2012-06-15

    Silicon is environmentally benign and ubiquitous. Because of its high specific capacity, it is considered one of the most promising candidates to replace the conventional graphite negative electrode used in today's Li ion batteries. Silicon has a theoretical specific capacity of nearly 4200 mAh/g (Li21Si5), which is 10 times larger than the specific capacity of graphite (LiC6, 372 mAh/g). However, the high capacity of silicon is associated with huge volume changes (more than 300 percent) when alloyed with lithium, which can cause severe cracking and pulverization of the electrode and lead to significant capacity loss. Significant scientific research has been conducted to circumvent the deterioration of silicon based anode materials during cycling. Various strategies, such as reduction of particle size, generation of active/inactive composites, fabrication of silicon based thin films, use of alternative binders, and the synthesis of 1-D silicon nanostructures have been implemented by a number of research groups. Fundamental mechanistic research has also been performed to better understand the electrochemical lithiation and delithiation process during cycling in terms of crystal structure, phase transitions, morphological changes, and reaction kinetics. Although efforts to date have not attained a commercially viable Si anode, further development is expected to produce anodes with three to five times the capacity of graphite. In this chapter, an overview of research on silicon based anodes used for lithium-ion battery applications will be presented. The overview covers electrochemical alloying of the silicon with lithium, mechanisms responsible for capacity fade, and methodologies adapted to overcome capacity degradation observed during cycling. The recent development of silicon nanowires and nanoparticles with significantly improved electrochemical performance will also be discussed relative to the mechanistic understanding. Finally, future directions on the

  15. Screened Anode N2 Laser

    OpenAIRE

    Sabry, M. Montaser Foad

    1985-01-01

    An experimental study of the effect of screening the discharge channel on the output energy is presented. It has been found that a screened anode nitrogen laser generates higher output energy than that of a screened cathode, and also higher than that when both cathode and anode are unshielded at higher pressures.

  16. Electrooxidation of 2-propanol and 2-butanol on the Pt–Ni alloy nanoparticles in acidic media

    International Nuclear Information System (INIS)

    Graphical abstract: Schematic representation of 2-propanol electrooxidation on the Pt–Ni alloy. Highlights: ► Electrocatalytic oxidation of 2-propanol and 2-butanol on the Pt–Ni nanoparticles. ► High stability and reproducibility of the Pt–Ni nanoparticles at the CCE. ► Pt–Ni/CCE as a potent electrocatalyst in the oxidation of alcohols in DAFCs. -- Abstract: The platinum–nickel nanoparticles carbon-ceramic modified electrode (Pt–Ni/CCE) was used as a potent electrocatalyst for the electrooxidation of 2-propanol and 2-butanol in a mixture of 0.15 M 2-propanol (or 0.15 M 2-butanol) and 0.1 M H2SO4 solutions. The Pt–Ni/CCE catalyst shows excellent electrocatalytic activity for electrooxidation of these fuels in comparison with platinum nanoparticles of carbon-ceramic modified (Pt/CCE) and smooth Pt electrodes due to the presence of Ni atoms in the alloy which enhances the electrocatalytic activity of Pt toward the oxidation of 2-propanol and 2-butanol and reduces the amount of Pt in the anodic material of direct 2-propanol and 2-butanol fuel cells. Furthermore, the Pt–Ni/CCE catalyst has satisfactory stability and reproducibility for the electrooxidation of 2-propanol and 2-butanol in acidic media when stored in ambient conditions or when used in constant potential applying (chronoamperometry) and continuous potential cycling (cyclic voltammetry) which makes it more attractive for alcohol-based fuel cell applications

  17. Unifying the templating effects of porous anodic alumina on metallic nanoparticles for carbon nanotube synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Haase, Mark R., E-mail: Mark.R.Haase@gmail.com, E-mail: haasemr@mail.uc.edu; Alvarez, Noe T.; Malik, Rachit; Schulz, Mark; Shanov, Vesselin [580 Engineering Research Center, Department of Biomedical, Chemical and Environmental Engineering (United States)

    2015-09-15

    Carbon nanotubes (CNTs) are a promising material for many applications, due to their extraordinary properties. Some of these properties vary in relation to the diameter of the nanotubes; thus, precise control of CNT diameter can be critical. Porous anodic alumina (PAA) membranes have been successfully used to template electrodeposited catalyst. However, the catalysts used in CNT synthesis are frequently deposited with more precise techniques, such as electron beam deposition. We test the efficacy of PAA as a template for electron beam-deposited catalyst by studying the diameter distribution of CNTs grown catalyst of various thicknesses supported by PAA. These are then compared by ANOVA to the diameter distributions of CNTs grown on metal catalyst supported by a conventional alumina film. These results also allow a unified description of two templating effects, the more common particles-in-pores model, and the recently described particles-between-pores.

  18. Structure of anodized Al-Zr sputter deposited coatings and effect on optical appearance

    Science.gov (United States)

    Gudla, Visweswara Chakravarthy; Canulescu, Stela; Shabadi, Rajashekhara; Rechendorff, Kristian; Dirscherl, Kai; Ambat, Rajan

    2014-10-01

    The mechanism of interaction of light with the microstructure of anodized layer giving specific optical appearance is investigated using Al-Zr sputter deposited coating as a model system on an AA6060 substrate. Differences in the oxidative nature of various microstructural components result in the evolution of typical features in the anodized layer, which are investigated as a function of microstructure and correlated with its optical appearance. The Zr concentration in the coating was varied from 6 wt.% to 23 wt.%. Heat treatment of the coated samples was carried out at 550 °C for 4 h in order to evolve Al-Zr based second phase precipitates in the microstructure. Anodizing was performed using 20 wt.% sulphuric acid at 18 °C with an intention to study the effect of anodizing on the Al-Zr based precipitates in the coating. Detailed microstructural characterization of the coating and anodized layer was carried out using high resolution scanning and transmission electron microscopy, grazing incidence X-ray diffraction analysis, glow discharge optical emission spectroscopy, and optical appearance using spectrophotometry. The evolution of microstructure in the anodized layer as a function of anodizing parameters and their influence on the interaction of light is investigated and the results in general are applicable to discolouration of anodized layer on recycled aluminium alloys due to intermetallics.

  19. CdS{sub x}Se{sub 1−x} alloyed quantum dots-sensitized solar cells based on different architectures of anodic oxidation TiO{sub 2} film

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhen; Yu, Libo; Liu, Yingbo; Sun, Shuqing, E-mail: sunshuqing@tju.edu.cn [Tianjin University, Department of Chemistry (China)

    2014-12-15

    Nanostructured TiO{sub 2} translucent films with different architectures including TiO{sub 2} nanotube (NT), TiO{sub 2} nanowire (NW), and TiO{sub 2} nanowire/nanotube (NW/NT) have been produced by second electrochemical oxidization of TiO{sub 2} NT with diameter around 90–110 nm via modulation of applied voltage. These TiO{sub 2} architectures are sensitized with CdS{sub x}Se{sub 1−x} alloyed quantum dots (QDs) in sizes of around 3–5 nm aiming to tune the response of the photoelectrochemical properties in the visible region. One-step hydrothermal method facilitates the deposition of CdS{sub x}Se{sub 1−x} QDs onto TiO{sub 2} films. These CdS{sub x}Se{sub 1−x} QDs exhibit a tunable range of light absorption with changing the feed molar ratio of S:Se in precursor solution, and inject electrons into TiO{sub 2} films upon excitation with visible light, enabling their application as photosensitizers in sensitized solar cells. Power conversion efficiency (PCE) of 2.00, 1.72, and 1.06 % are achieved with CdS{sub x}Se{sub 1−x} (obtained with S:Se = 0:4) alloyed QDs sensitized solar cells based on TiO{sub 2} NW/NT, TiO{sub 2} NW, and TiO{sub 2} NT architectures, respectively. The significant enhancement of power conversion efficiency obtained with the CdS{sub x}Se{sub 1−x}/TiO{sub 2} NW/NT solar cell can be attributed to the extended absorption of light region tuned by CdS{sub x}Se{sub 1−x} alloyed QDs and enlarged deposition of QDs and efficient electrons transport provided by TiO{sub 2} NW/NT architecture.

  20. Study and development of membrane electrode assemblies for Proton Exchange Membrane Fuel Cell (PEMFC) with palladium based catalysts

    International Nuclear Information System (INIS)

    PEMFC systems are capable of generating electricity with high efficiency and low or no emissions, but durability and cost issues prevent its large commercialization. In this work MEA with palladium based catalysts were developed, Pd/C, Pt/C and alloys PdPt/C catalysts with different ratios between metals and carbon were synthesized and characterized. A study of the ratio between catalyst and Nafion Ionomer for formation of high performance triple-phase reaction was carried out, a mathematical model to implement this adjustment to catalysts with different relations between metal and support taking into account the volumetric aspects of the catalyst layer was developed and then a study of the catalyst layer thickness was performed. X-ray diffraction, Transmission and Scanning Electron Microscopy, X-ray Energy Dispersive, Gas Pycnometry, Mercury Intrusion Porosimetry, Gas adsorption according to the BET and BJH equations, and Thermo Gravimetric Analysis techniques were used for characterization and particle size, specific surface areas and lattice parameters determinations were also carried out. All catalysts were used on MEAs preparation and evaluated in 5 cm2 single cell from 25 to 100 °C at 1 atm and the best composition was also evaluated at 3 atm. In the study of metals for reactions, to reduce the platinum applied to the electrodes without performance losses, Pd/C and PdPt/C 1:1 were selected for anodes and cathodes, respectively. The developed MEA structure used 0,25 mgPt.cm-2, showing power densities up to 550 mW.cm-2 and power of 2.2 kWnet per gram of platinum. The estimated costs showed that there was a reduction of up to 64.5 %, compared to the MEA structures previously known. Depending on the temperature and operating pressure, values from US$ 1,475.30 to prepare MEAs for each installed kilowatt were obtained. Taking into account recent studies, it was concluded that the cost of the developed MEA is compatible with PEMFC stationary application. (author)

  1. Optimization of anodized aluminum oxide pore morphology for GaAs nanowire growth

    Directory of Open Access Journals (Sweden)

    Regine A. Loberternos

    2010-06-01

    Full Text Available Anodic Aluminum oxide films were produced by anodization of sputtered Aluminum thin films on Silicon substrates. The effects of anodization voltage and aqueous oxalic acid solution on the pore diameter and interpore distance were studied. Parameters were sequentially varied to optimize the pore uniformity. Pore morphology was most uniform at 40V anodization voltage and 0.3M solution concentration. Average pore diameter and interpore distance for these parameters are 26.14nm ± 13% and 74.62 ± 8%, respectively. Pore diameter uniformity was further improved by etching with phosphoric acid solution. The AAO films were also successfully used to pattern gold nanoparticle catalysts for the synthesis of semiconductor nanowires.

  2. Corrosion behavior of Alloy 690 and Alloy 693 in simulated nuclear high level waste medium

    Energy Technology Data Exchange (ETDEWEB)

    Samantaroy, Pradeep Kumar; Suresh, Girija; Paul, Ranita [Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Kamachi Mudali, U., E-mail: kamachi@igcar.gov.in [Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Raj, Baldev [Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2011-11-15

    Highlights: > Alloy 690 and Alloy 693, both possess good corrosion resistance in simulated HLW. > SEM and EDS confirms the presence of Cr rich precipitates for both the alloys. > Passive film stability of Alloy 690 was found to be higher than Alloy 693. > Both alloys possess few micro pits even at a concentration of 100 ppm Cl{sup -} ion. - Abstract: Nickel based alloys are candidate materials for the storage of high level waste (HLW) generated from reprocessing of spent nuclear fuel. In the present investigation Alloy 690 and Alloy 693 are assessed by potentiodynamic anodic polarization technique for their corrosion behavior in 3 M HNO{sub 3}, 3 M HNO{sub 3} containing simulated HLW and in chloride medium. Both the alloys were found to possess good corrosion resistance in both the media at ambient condition. Microstructural examination was carried out by SEM for both the alloys after electrolytic etching. Compositional analysis of the passive film formed on the alloys in 3 M HNO{sub 3} and 3 M HNO{sub 3} with HLW was carried out by XPS. The surface of Alloy 690 and Alloy 693, both consists of a thin layer of oxide of Ni, Cr, and Fe under passivation in both the media. The results of investigation are presented in the paper.

  3. Synthesis and Electrocatalytic Performance of Multi-Component Nanoporous PtRuCuW Alloy for Direct Methanol Fuel Cells

    Directory of Open Access Journals (Sweden)

    Xiaoting Chen

    2015-06-01

    Full Text Available We have prepared a multi-component nanoporous PtRuCuW (np-PtRuCuW electrocatalyst via a combined chemical dealloying and mechanical alloying process. The X-ray diffraction (XRD, transmission electron microscopy (TEM and electrochemical measurements have been applied to characterize the microstructure and electrocatalytic activities of the np-PtRuCuW. The np-PtRuCuW catalyst has a unique three-dimensional bi-continuous ligament structure and the length scale is 2.0 ± 0.3 nm. The np-PtRuCuW catalyst shows a relatively high level of activity normalized to mass (467.1 mA mgPt−1 and electrochemically active surface area (1.8 mA cm−2 compared to the state-of-the-art commercial PtC and PtRu catalyst at anode. Although the CO stripping peak of np-PtRuCuW 0.47 V (vs. saturated calomel electrode, SCE is more positive than PtRu, there is a 200 mV negative shift compared to PtC (0.67 V vs. SCE. In addition, the half-wave potential and specific activity towards oxygen reduction of np-PtRuCuW are 0.877 V (vs. reversible hydrogen electrode, RHE and 0.26 mA cm−2, indicating a great enhancement towards oxygen reduction than the commercial PtC.

  4. A Study of Making Iron Aluminide Alloy Powders with New Rotating Electrode Technology

    Institute of Scientific and Technical Information of China (English)

    S; S; LIAN; M; L; SHI

    2002-01-01

    A new process was used for producing FeAl alloy pow de rs with double consumable rotating electrodes and the powders made in this appar atus were analyzed. In this new technology, tungsten rod serves as a cathode ele ctrode, while the alloy rod as an anode electrode. The conventional rotating ele ctrode process must have an anode with pre-melting alloys; however, in this new process, using pure iron as cathode electrode and pure aluminum as anode electr ode can eliminate the step of pre-melting. The e...

  5. Efficient ceramic anodes infiltrated with binary and ternary electrocatalysts for SOFCs operating at low temperatures

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain; Høgh, Jens Valdemar Thorvald; Zhang, Wei;

    2012-01-01

    the binary Pd–CGO and Pt–CGO due to the particle coarsening of Ni nanoparticles. High resolution transmission electron microscopic analysis on the best performing Ni–Pt–CGO electrocatalyst infiltrated anode reveals the formation of Ni–Pt nanocrystalline alloy and a homogenous distribution of nanoparticles...

  6. Magnesium Sulphide as Anode Material for Lithium-Ion Batteries

    International Nuclear Information System (INIS)

    Highlights: • A single step preparation method of magnesium sulphide-carbon composite by mechanically milling the elemental mixture is reported. • The as-prepared MgS-carbon composite was investigated as an anode for lithium-ion batteries. • From XRD and electrochemical studies a reversible lithiation/delithiation mechanism of MgS is concluded. • The practicality of MgS-carbon composite anode in full cell using lithium nickel manganese cobalt oxide (LNMC) and lithium iron phosphate (LFP) as cathodes are evaluated. -- Abstract: Herein, we report magnesium sulphide (MgS) as an anode for lithium ion batteries. Magnesium sulphide-carbon composite is directly synthesized by mechanically milling the elemental mixture. A possible lithiation and delithiation mechanism for MgS is proposed based on electrochemical and ex-situ XRD studies. The electrochemical reaction of MgS with lithium results in the formation of Li2S and Mg, the as-formed Mg simultaneously reacts with lithium and forms LixMg alloy further contributing to the capacity. A stable reversible capacity of 530 mAh g−1 was achieved after 100 cycles within the voltage window of 0.001–2.5 V. The compatibility of MgS anode was tested in full cell using lithium nickel manganese cobalt oxide (LNMC) and lithium iron phosphate (LFP) as cathodes

  7. 锂离子电池锡合金负极薄膜材料制备及性能%Preparation and performance of tin alloy film anode materials for lithium-ion battery

    Institute of Scientific and Technical Information of China (English)

    王连邦; 褚君尉; 张品杰; 姚金翰; 马淳安

    2012-01-01

    Tin thin-film electrodes were prepared by electroless plating on copper foil as anode of lithium-ion battery. There were three samples with different thickness and structure obtained depend on different deposited conditions. Their structure and properties were characterized and studied by X-ray diffration, scanning electron microscopy, charging/discharging test, cyclic voltammetry. The tin-thin film deposited for 10 minutes exhibited a structure of tetragonal crystal. The tin-thin film was composed of tin particles with the size of around 4 μm,and the tin particle was full of similar holes, which enhanced the specific furface area of electrode. The tin-thin film electrode showed high charge-discharge capacity. At potential of 0. 01 - 1. 00 V, The first discharge capacity of the tin-thin film electrode was 885. 7 mAh/g, its discharge capacity remained over 460 mAh/g after 100 cycles.%采用化学沉积的方法在铜箔上制备锡薄膜,通过改变沉积条件,制得三种不同厚度和结构的锡合金负极材料.运用XRD、SEM、充放电和循环伏安等多种方法对电极结构和性能进行表征和研究.研究表明:沉积时间为10 min的锡薄膜负极材料具有四方晶系结构,其表面由尺寸在4μm左右的合金颗粒构成,颗粒有大小均匀的孔洞结构,增加了电极的比表面积.该锡薄膜电极具有较高的容量,在0.01~1.00 V电压区间内,电极的首次放电容量为885.7 mAh/g,循环100周后放电容量仍保持在460 mAh/g以上.

  8. Tungsten materials as durable catalyst supports for fuel cell electrodes

    Science.gov (United States)

    Perchthaler, M.; Ossiander, T.; Juhart, V.; Mitzel, J.; Heinzl, C.; Scheu, C.; Hacker, V.

    2013-12-01

    Durable platinum catalyst support materials, e.g. tungsten carbide (WC), tungsten oxide (WOx) and self-synthesized tungsten oxide (WOxs) were evaluated for the use in High-Temperature Proton Exchange Fuel Cells (HT-PEM) based on phosphoric acid doped polybenzimidazole as electrolyte. The support materials and the catalyst loaded support materials were characterized ex-situ by cyclic voltammetry in HClO4, potential cycling, CO-stripping, electron microscopy and X-ray diffraction measurements. The tungsten oxide and tungsten carbide based supported catalysts were compared to High Surface Area Carbon (HSAC), each coated with platinum via the same in-house manufacturing procedures. The in-house manufacturing procedures resulted in catalyst particle sizes on HSAC of 3-4 nm with a uniform distribution. The in-situ Potential Cycling experiments of WOx or WOxs supported catalysts showed much lower degradation rates compared to High Surface Area Carbons. The formation of WOx species on WC was proven by ex- and in-situ cyclic voltammetric studies and thermogravimetric analyses. X-ray diffraction, ex-situ cyclic voltammetry and in-situ cyclic voltammetry showed that WOx is formed from WC as starting material under oxidizing conditions. Finally a 1000 h durability test with WOx as catalyst support material on the anode was done in a HT-PEM fuel cell with reformed methanol on the anode.

  9. Durable transition-metal-carbide-supported Pt-Ru anodes for direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Nishanth, K.G.; Sridhar, P.; Pitchumani, S. [CSIR-Central Electrochemical Research Institute, Madras Unit, CSIR Madras Complex, Chennai (India); Shukla, A.K. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore (India)

    2012-02-15

    Molybdenum carbide (MoC) and tungsten carbide (WC) are synthesized by direct carbonization method. Pt-Ru catalysts supported on MoC, WC, and Vulcan XC-72R are prepared, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy in conjunction with electrochemistry. Electrochemical activities for the catalysts towards methanol electro-oxidation are studied by cyclic voltammetry. All the electro-catalysts are subjected to accelerated durability test (ADT). The electrochemical activity of carbide-supported electro-catalysts towards methanol electro-oxidation is found to be higher than carbon-supported catalysts before and after ADT. The study suggests that Pt-Ru/MoC and Pt-Ru/WC catalysts are more durable than Pt-Ru/C. Direct methanol fuel cells (DMFCs) with Pt-Ru/MoC and Pt-Ru/WC anodes also exhibit higher performance than the DMFC with Pt-Ru/C anode. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. The Technological Improvements of Aluminum Alloy Coloring by Electrolysis

    Institute of Scientific and Technical Information of China (English)

    LI Nai-jun

    2004-01-01

    The technological process of coloring golden-tawny on aluminum alloy by electrolysis was improved in this paper. The optimum composition of electrolyte was found, the conditions of deposition and anodic oxidation by electrolysis were studied. The oxidative membrane on aluminum alloy was satisfying, the colored aluminum alloy by electrolysis is uniformity,bright and beautiful, and the coloring by electrolysis is convenient and no pollution.

  11. Effect of Fe state on electrocatalytic activity of Pd-Fe/C catalyst for oxygen reduction

    International Nuclear Information System (INIS)

    The carbon-supported Pd-Fe catalyst (Pd-Fe/C) is prepared in the H2O/tetrahydrofuran (THF) mixture solvent under the low temperature. The homemade Pd-Fe/C catalyst contains two forms of iron species, alloying and non-alloying Fe. The alloying Fe species is hardly dissolved in 0.5 M H2SO4 solution, while the non-alloying Fe species is easily dissolved in 0.5 M H2SO4 solution. The electrochemical measurements show the electrocatalytic activity of the Pd-Fe/C catalyst with the acid treatment for the oxygen reduction is higher than that of the Pd-Fe/C catalyst without the acid treatment, illustrating that the non-alloying Fe species suppresses the electrocatalytic activity of the Pd-Fe/C catalyst. In contrast, the alloying Fe species promotes the electrocatalytic activity of the Pd-Fe/C catalyst for the oxygen reduction, which is likely attributed to the change of the electron structure of Pd atom and/or bond length of Pd-Pd in the Pd-Fe/C catalyst.

  12. Solvent effects on Pt-Ru/C catalyst for methanol electro-oxidation

    Institute of Scientific and Technical Information of China (English)

    Jinwei Chen; Chunping Jiang; Hui Lu; Lan Feng; Xin Yang; Liangqiong Li; Ruilin Wang

    2009-01-01

    Alloying degree,particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent(s) used in the preparation process can affect the particle size and alloying degree of the object substance,which lead to a great positive impact on its properties. In this work,three types of solvents and their mixtures were used in preparation of the Pt-Ru/C catalysts by chemical reduction of metal precursors with sodium borohydride at room temperature. The structure of the catalysts was characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The catalytic activity and stability for methanol electro-oxidation were studied by Cyclic Voltammetry (CV) and Chronoamperometry (CA). Pt-Ru/C catalyst prepared in H_2O or binary solvents of H_2O and isopropanol had large particle size and low alloying degree leading to low catalytic activity and less stability in methanol electro-oxidation. When tetrahydrofuran was added to the above solvent systems,Pt-Ru/C catalyst prepared had smaller particle size and higher alloying degree which resulted in better catalytic activity,lower onset and peak potentials,compared with the above catalysts. Moreover,the catalyst prepared in ternary solvents of isopropanol,water and tetrahydrofuran had the smallest particle size,and the high alloying degree and the dispersion kept unchanged. Therefore,this kind of catalyst showed the highest catalytic activity and good stability for methanol electro-oxidation.

  13. Multi-metallic anodes for solid oxide fuel cell applications

    International Nuclear Information System (INIS)

    A new method for direct preparation of materials for solid oxide fuel cell anode - Ni- YSZ cermets - based on mechanical alloying (MA) of the original powders is developed, allowing to admix homogeneously any component. Additive metals are selected from thermodynamic criteria, leading to compacts consolidation through sintering by activated surface (SAS). The combined process MA-SSA can reduce the sintering temperature by 300 deg C, yielding porous anodes. Densification mechanisms are discussed from quasi-isothermal sintering kinetics results. Doping with Ag, W, Cu, Mo, Nb, Ta, in descending order, promotes the densification of pellets through liquid phase sintering and evaporation of metals and oxides, which allow reducing the sintering temperature. Powders and pellets characterization by electronic microscopy and X-ray diffraction completes the result analyses. (author)

  14. CoPt patterned media in anodized aluminum oxide templates

    International Nuclear Information System (INIS)

    Patterned recording media consisting of a vertically aligned array of L10 phase CoPt nanowires embedded in a thin anodized aluminum oxide (AAO) template on silicon has been prepared. A sputter deposited thin film of aluminum on silicon was anodized and a CoPt magnetic alloy was electrodeposited into the pores of the AAO. The vertically aligned arrays of CoPt nanowires were about ∼100 nm tall with ∼20 nm average diameter. Since the CoPt nanowire array is laterally constrained by the surrounding AAO, the nanowire diameter is maintained without coarsening during the L10 phase conversion heat treatment at 700 deg. C. After annealing and conversion to the L10 phase, the ∼20 nm CoPt nanowires exhibit a large coercivity of ∼8 kOe measured in the in-plane and perpendicular directions

  15. Electrically Conductive Anodized Aluminum Surfaces

    Science.gov (United States)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In

  16. Cyclic and Linear Polarization of Yttrium-Containing Iron-Based Amorphous Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Day, S D; Lian, T; Farmer, J C; Rebak, R B

    2007-08-10

    Iron-based amorphous alloys are produced by rapid solidification from the melt. These alloys may possess unique mechanical and corrosion resistant properties. The chemical composition of the alloy may influence the cooling rate that is necessary for the alloys to be completely vitreous. At the same time, the corrosion resistance of the amorphous alloys may also depend on their chemical composition. This paper examines the anodic behavior of iron-based amorphous alloys containing three different concentrations (1, 3 and 5 atomic %) of yttrium (Y) in several electrolyte solutions. Results from polarization resistance potentiodynamic polarization show that when the alloy contains 5% atomic Y, the corrosion resistance decreases.

  17. Nano structural anodes for radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cordaro, Joseph V.; Serkiz, Steven M.; McWhorter, Christopher S.; Sexton, Lindsay T.; Retterer, Scott T.

    2015-07-07

    Anodes for proportional radiation counters and a process of making the anodes is provided. The nano-sized anodes when present within an anode array provide: significantly higher detection efficiencies due to the inherently higher electric field, are amenable to miniaturization, have low power requirements, and exhibit a small electromagnetic field signal. The nano-sized anodes with the incorporation of neutron absorbing elements (e.g., .sup.10B) allow the use of neutron detectors that do not use .sup.3He.

  18. Three-dimensional anode engineering for the direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, A.; Oloman, C.W.; Gyenge, E.L. [Department of Chemical and Biological Engineering, The University of British Columbia, 2360 East Mall, Vancouver, BC (Canada)

    2009-09-05

    Catalyzed graphite felt three-dimensional anodes were investigated in direct methanol fuel cells (DMFCs) operated with sulfuric acid supporting electrolyte. With a conventional serpentine channel flow field the preferred anode thickness was 100 {mu}m, while a novel flow-by anode showed the best performance with a thickness of 200-300 {mu}m. The effects of altering the methanol concentration, anolyte flow rate and operating temperature on the fuel cell superficial power density were studied by full (2{sup 3} + 1) factorial experiments on a cell with anode area of 5 cm{sup 2} and excess oxidant O{sub 2} at 200 kPa(abs). For operation in the flow-by mode with 2 M methanol at 2 cm{sup 3} min{sup -1} and 353 K the peak power density was 2380 W m{sup -2} with a PtRuMo anode catalyst, while a PtRu catalyst yielded 2240 W m{sup -2} under the same conditions. (author)

  19. Effect of Anodization on the Graphitization of PANbased Carbon Fibers of PAN-based Carbon Fibers

    Institute of Scientific and Technical Information of China (English)

    HE Dongmei; YAO Yinghua; XU Shihai; CAI Qingyun

    2011-01-01

    One-step pretreatment,anodization,is used to activate the polyacrylonitrile (PAN)-based carbon fibers instead of the routine two-step pretreatment,sensitization with SnCl2 and activation with PdCl2 The effect of the anodization pretreatment on the graphitization of PAN-based carbon fibers is investigated as a function of Ni-P catalyst.The PAN-based carbon fibers are anodized in H3PO4 electrolyte resulting in the formation of active sites,which thereby facilitates the following electroless Ni-P coating.Carbon fibers in the presence and absence of Ni-P coatings are heat treated and the structural changes are characterized by X-ray diffraction and Raman spectroscopy,both of which indicate that the graphitization of PAN-based carbon fibers are accelerated by both the anodization treatment and the catalysts Ni-E Using the anodized carbon fibers,the routine two-step pretreatment,sensitization and activation,is not needed.

  20. Effect of alloying elements Zr,Cr,V on corrosion behavior of Ti-Ni-Nb shape memory alloy

    International Nuclear Information System (INIS)

    In this paper, by testing anodic polarization curves of Ti-Ni-Nb based shape memory alloys, the stability of passive film was investigated after alloying with elements Zr,Cr,V. In artificial sea water (3.5%NaCl) and physiological solution (5%NaCl+0.1%H2O2), the results show that the alloying elements influence the corrosion behavior of Ti-Ni-Nb alloy. Generally, Zr improves the corrosion resistance of Ti-Ni-Nb alloy, Cr reduces its corrosion resistance and V does not change the property. (orig.)

  1. Anodized Steel Electrodes for Supercapacitors.

    Science.gov (United States)

    Sagu, Jagdeep S; Wijayantha, K G Upul; Bohm, Mallika; Bohm, Siva; Kumar Rout, Tapan

    2016-03-01

    Steel was anodized in 10 M NaOH to enhance its surface texture and internal surface area for application as an electrode in supercapacitors. A mechanism was proposed for the anodization process. Field-emission gun scanning electron microscopy (FEGSEM) studies of anodized steel revealed that it contains a highly porous sponge like structure ideal for supercapacitor electrodes. X-ray photoelectron spectroscopy (XPS) measurements showed that the surface of the anodized steel was Fe2O3, whereas X-ray diffraction (XRD) measurements indicated that the bulk remained as metallic Fe. The supercapacitor performance of the anodized steel was tested in 1 M NaOH and a capacitance of 18 mF cm(-2) was obtained. Cyclic voltammetry measurements showed that there was a large psueudocapacitive contribution which was due to oxidation of Fe to Fe(OH)2 and then further oxidation to FeOOH, and the respective reduction of these species back to metallic Fe. These redox processes were found to be remarkably reversible as the electrode showed no loss in capacitance after 10000 cycles. The results demonstrate that anodization of steel is a suitable method to produce high-surface-area electrodes for supercapacitors with excellent cycling lifetime. PMID:26891093

  2. Etching Behavior of Aluminum Alloy Extrusions

    Science.gov (United States)

    Zhu, Hanliang

    2014-11-01

    The etching treatment is an important process step in influencing the surface quality of anodized aluminum alloy extrusions. The aim of etching is to produce a homogeneously matte surface. However, in the etching process, further surface imperfections can be generated on the extrusion surface due to uneven materials loss from different microstructural components. These surface imperfections formed prior to anodizing can significantly influence the surface quality of the final anodized extrusion products. In this article, various factors that influence the materials loss during alkaline etching of aluminum alloy extrusions are investigated. The influencing variables considered include etching process parameters, Fe-rich particles, Mg-Si precipitates, and extrusion profiles. This study provides a basis for improving the surface quality in industrial extrusion products by optimizing various process parameters.

  3. Corrosion of aluminum alloys as a function of alloy composition

    International Nuclear Information System (INIS)

    A study was initiated which included nineteen aluminum alloys. Tests were conducted in high purity water at 3600C and flow tests (approx. 20 ft/sec) in reactor process water at 1300C (TF-18 loop tests). High-silicon alloys and AlSi failed completely in the 3600C tests. However, coupling of AlSi to 8001 aluminum suppressed the failure. The alloy compositions containing iron and nickel survived tht 3600C autoclave exposures. Corrosion rates varied widely as a function of alloy composition, but in directions which were predictable from previous high-temperature autoclave experience. In the TF-18 loop flow tests, corrosion penetrations were similar on all of the alloys and on high-purity aluminum after 105 days. However, certain alloys established relatively low linear corrosion rates: Al-0.9 Ni-0.5 Fe-0.1 Zr, Al-1.0 Ni-0.15 Fe-11.5 Si-0.8 Mg, Al-1.2 Ni-1.8 Fe, and Al-7.0 Ni-4.8 Fe. Electrical polarity measurements between AlSi and 8001 alloys in reactor process water at temperatures up to 1500C indicated that AlSi was anodic to 8001 in the static autoclave system above approx. 500C

  4. Characterization of titanium thin films anodically grown in phosphoric acid; Caracterisation des films d'oxyde de titane obtenus anodiquement dans l'acide phosphorique

    Energy Technology Data Exchange (ETDEWEB)

    Khadiri, M.E.; Benyaich [Faculte des Sciences Semlalia, Lab. d' Electrochimie et Chimie Analytique, Marakech (Morocco); Oueriagli, A.; Outzourhit, A.; Ameziane, E.L. [Faculte des Sciences Semlalia, Lab. de Physique du Solide et des Couches Minces, Marakech (Morocco)

    2004-08-01

    Ti-Cu(2%) alloy was anodized in a 5 M phosphoric acid solution under various voltages ranging from 10 to 35 V. The composition, the structural and optical properties of the as-grown oxide films were studied. It was found that the color of the anodized substrates varied from yellow to blue depending on the anodizing voltage. The films formed on the alloy are amorphous and the oxidation state of Ti on their surface is mainly +4. On the other hand it was found that the thickness of the films increases linearly with anodization voltage at rate of 1.94 nm/V, while the refractive index at the wavelength corresponding to the reflectance minimum was practically constant. These films were also found to have excellent protective properties for the examined alloy. (authors)

  5. SnO2 nanocluster supported Pt catalyst with high stability for proton exchange membrane fuel cells

    International Nuclear Information System (INIS)

    Tin oxide nanocluster (SnO2) with parallel nanorods was synthesized via a hard template method and explored as the anode catalyst support for proton exchange membrane fuel cells (PEMFCs). Single cell test demonstrated that SnO2 supported Pt catalyst (Pt/SnO2) exhibited comparable anode performance with conventional Pt/C. Electrochemical measurements showed that Pt/SnO2 exhibited significantly enhanced electrochemical stability than Pt/C under high potential electro-oxidation and potential cycling. The Pt/SnO2 catalyst reserved most of its electrochemically active surface area (ECA) under 10 h potential hold at 1.6 V while its ECA degradation rate was one order of magnitude lower than Pt/C under potential cycling between 0.6 and 1.2 V. Therefore, SnO2 nanocluster can be considered as a promising alternative anode catalyst support for PEMFCs

  6. Field emission properties of low-density carbon nanotubes prepared on anodic aluminum-oxide template

    International Nuclear Information System (INIS)

    Anodic aluminum-oxide (AAO) templates were fabricated by two-step anodizing an Al film. After the Co catalyst had been electrochemically deposited onto the bottom of the AAO template, carbon nanotubes (CNTs) were grown by using catalytic pyrolysis of C2H2 and H2 at 650 .deg. C. Overgrowth of CNTs with low density on the AAO templates was observed. The field-emission measurements on the samples showed a turn-on field of 2.17 V/μm and a field enhancement factor of 5700. The emission pattern on a phosphor screen was quite homogeneous over the area at a relatively low electric field.

  7. Enhancing hybrid direct carbon fuel cell anode performance using Ag2O

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

    2015-01-01

    A hybrid-direct carbon fuel cell (HDCFC), consisting of a molten slurry of solid carbon black and (Li-K)2CO3 added to the anode chamber of a solid oxide fuel cell, was characterized using current-potential-power density curves, electrochemical impedance spectroscopy, and cyclic voltammetry. Two...... temperature (700-800 °C) and anode sweep gas (N2, 4-100% CO2 in N2-CO2). It was shown that the addition of silver based catalysts (Ag, Ag2O, Ag2CO3) into the carbon-carbonate slurry enhanced the performance of the HDCFC....

  8. Research progress of alloyed electrocatalysts for low temperature fuel cell%低温燃料电池合金催化剂研究进展

    Institute of Scientific and Technical Information of China (English)

    符蓉; 郑俊生; 张元鲲; 王喜照; 马建新

    2012-01-01

    The catalyst for low temperature fuel cell is still the ptatinum, which is expensive and lack of resource. And this is one of the reasons that cause the high cost of proton exchange membrane fuel cell (PEMFC) and direct methane fuel cell (DMFC, which significantly limits their wide use. The applying of platinum alloyed catalysts can reduce the amount of platinum and the alloyed structure is favorable for enhancing the catalytic activity. The mechanism of the alloy catalysts on the anode and cathode for the low temperature fuel cell was introduced. The deposition-reduction thermal treatment, the improved microemulsion, microwave and some new technologies and methods of preparation of alloyed catalysts in recent years were reviewed mainly. The effect of the alloying elements, the metal precursor, atomic composition, temperature of the heat treatment and the pH value on the catalytic activity were summarized.%低温燃料电池所用电催化剂以铂为主,但铂的价格昂贵,资源匮乏,造成PEMFC和DMFC成本提高,限制了应用.合金催化剂可以大大减小Pt用量,降低催化剂成本,而且其结构对提高催化剂活性非常有利,有广泛的发展空间.简要介绍了合金催化剂对低温燃料电池的作用机理;综述了沉积-还原热处理,改进微乳法,微波法及一些近年来制备合金催化剂的新技术和新方法;归纳了合金元素,金属前驱体,原子组成,热处理温度和pH值等条件对电催化活性影响的研究.

  9. Anodic-Cathodic Electrocatalytic Degradation of Phenol with Oxygen Sparged in the Presence of Iron(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Under oxygen sparged, the synergetic effects of both anodic-cathodic electrocatalysis(ACE) and ferrous ion catalyzed anodic-cathodic electrocatalysis(FeACE) on phenol degradation were observed in an undivided cell composed of a β-PbO2 anode modified with fluorine resin and a nickel-chromium-titanium alloy net cathode. Oxygen sparging rate, ferrous concentration, and current significantly affect phenol destruction. The phenol was removed by 10%-13% increasingly under FeACE vs. ACE, and by 12%-15% under ACE vs. anodic electrocatalysis(AE). The phenol destruction was due to the formation of hydroxyl oxidant on the surface of lead oxide at the anode and the reduction of oxygen at the cathode.

  10. RECYCLING TECHNOLOGY INTO INDUSTRIAL TURNOVER OF BISMUTH AND MOLYBDENUM FROM DEAD CATALYST

    Directory of Open Access Journals (Sweden)

    O. S. Komarov

    2015-05-01

    Full Text Available The technology of separate extraction of bismuth and molybdenum from spent catalyst was presented and information on the effectiveness of its use in a composition of comprehensive modifier in the iron-carbon alloy was given.

  11. The influence of carbon dioxide on PEM fuel cell anodes

    Science.gov (United States)

    de Bruijn, F. A.; Papageorgopoulos, D. C.; Sitters, E. F.; Janssen, G. J. M.

    The influence of CO 2 on the performance of PEM fuel cells was investigated by means of fuel cell experiments and cyclic voltammetry. Depending on the composition and microstructure of the fuel cell anode, the effect varies from small to significant. Adsorbed hydrogen plays a dominant role in the formation of CO-like species via the reverse water-gas shift reaction. Platinum sites which are not utilized in the electrochemical oxidation of hydrogen are thought to catalyze this reverse-shift reaction. Alloying with ruthenium suppresses the reverse-shift reaction.

  12. High capacity anode materials for lithium ion batteries

    Science.gov (United States)

    Lopez, Herman A.; Anguchamy, Yogesh Kumar; Deng, Haixia; Han, Yongbon; Masarapu, Charan; Venkatachalam, Subramanian; Kumar, Suject

    2015-11-19

    High capacity silicon based anode active materials are described for lithium ion batteries. These materials are shown to be effective in combination with high capacity lithium rich cathode active materials. Supplemental lithium is shown to improve the cycling performance and reduce irreversible capacity loss for at least certain silicon based active materials. In particular silicon based active materials can be formed in composites with electrically conductive coatings, such as pyrolytic carbon coatings or metal coatings, and composites can also be formed with other electrically conductive carbon components, such as carbon nanofibers and carbon nanoparticles. Additional alloys with silicon are explored.

  13. Fabrication, characterization and wear corrosion testing of bioactive hydroxyapatite/nano-TiO2 composite coatings on anodic Ti–6Al–4V substrate for biomedical applications

    International Nuclear Information System (INIS)

    Highlights: ► Anodic oxide film of Ti–6Al–4V fabricated in phosphoric acid was TiO2 and phosphates. ► The oxide thickness and microhardness increased with increasing anodizing duration. ► The bioactive HA formed on the anodic Ti–6Al–4V substrate was HA composite. ► Nanocomposite HA/TiO2 possessed an excellent wear corrosion protection ability. - Abstract: This study elucidated structure and mechanical properties of the electroplated hydroxyapatite/nano-TiO2 composite coatings on Ti–6Al–4V alloy. Their effect on the corrosion and wear corrosion resistance in Hanks’ solution was examined as well. The anodizing process was performed on Ti–6Al–4V alloy surface to enhance the adhesion of these composite coatings on Ti alloy. Anodizing treatment was then conducted at 10 V at room temperature with different times of 40, 50, 60, 120 and 180 min. Experimental results indicate that the hardness of Ti–6Al–4V alloy was increased due to the anodizing treatment, capable of improving the adhesion of electroplated calcium phosphate coating in addition to the electroplated hydroxyapatite/nano-TiO2 composite coatings. Additionally, the coatings on anodic substrate exhibited a higher uniformity and Ca/P ratio and thickness than that on nonanodized substrate. The nano-TiO2 particles could be co-deposited on the Ti–6Al–4V alloys and capable of reinforcing the hydroxyapatite coating, subsequently increasing the hardness and refining the structure. Moreover, the corrosion and wear corrosion resistance of the electroplated hydroxyapatite/nano-TiO2 composite coatings were also improved significantly when increasing the duration of anodizing alloy substrates.

  14. Methanol Electro-Oxidation on Pt-Ru Alloy Nanoparticles Supported on Carbon Nanotubes

    OpenAIRE

    Yangchuan Xing; Liang Li

    2009-01-01

    Carbon nanotubes (CNTs) have been investigated in recent years as a catalyst support for proton exchange membrane fuel cells. Improved catalyst activities were observed and attributed to metal-support interactions. We report a study on the kinetics of methanol electro-oxidation on CNT supported Pt-Ru alloy nanoparticles. Alloy catalysts with different compositions, Pt 53 Ru 47 /CNT, Pt 69 Ru 31 /CNT and Pt 77 Ru 23 /CNT, were prepared and investigated in detail. Experiments were conducted at ...

  15. Preparation of Pt/CeO2/HCSs anode electrocatalysts for direct methanol fuel cells

    International Nuclear Information System (INIS)

    Hollow carbon spheres (HCSs) were prepared through a simple hydrothermal method using silica particles and glucose as the template and carbon precursor, respectively. HCSs used as supports for platinum catalysts deposited with cerium oxide (CeO2) were prepared for application as anode catalysts in direct methanol fuel cells. The composition and structure of the samples were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The electrocatalytic properties of the as-prepared catalysts for methanol oxidation were investigated by cyclic voltammetry (CV). The Pt/CeO2/HCSs catalyst heated at 550 oC for 1 h exhibited the best catalytic activity for methanol oxidation.

  16. Preparation and Evaluation of Multi-Layer Anodes of Solid Oxide Fuel Cell

    Science.gov (United States)

    Santiago, Diana; Farmer, Serene C.; Setlock, John A.

    2012-01-01

    The development of an energy device with abundant energy generation, ultra-high specific power density, high stability and long life is critical for enabling longer missions and for reducing mission costs. Of all different types of fuel cells, the solid oxide fuel cells (SOFC) is a promising high temperature device that can generate electricity as a byproduct of a chemical reaction in a clean way and produce high quality heat that can be used for other purposes. For aerospace applications, a power-to-weight of (is) greater than 1.0 kW/kg is required. NASA has a patented fuel cell technology under development, capable of achieving the 1.0 kW/kg figure of merit. The first step toward achieving these goals is increasing anode durability. The catalyst plays an important role in the fuel cells for power generation, stability, efficiency and long life. Not only the anode composition, but its preparation and reduction are key to achieving better cell performance. In this research, multi-layer anodes were prepared varying the chemistry of each layer to optimize the performance of the cells. Microstructure analyses were done to the new anodes before and after fuel cell operation. The cells' durability and performance were evaluated in 200 hrs life tests in hydrogen at 850 C. The chemistry of the standard nickel anode was modified successfully reducing the anode degradation from 40% to 8.4% in 1000 hrs and retaining its microstructure.

  17. Foundation Flash Catalyst

    CERN Document Server

    Goralski, Greg

    2010-01-01

    This book offers an introduction to Flash Catalyst for designers with intermediate to advanced skills. It discusses where Catalyst sits within the production process and how it communicates with other programs. It covers all of the features of the Flash Catalyst workspace, teaching you how to create designs from scratch, how to build application designs and add functionality, and how to master the Catalyst/Flex workflow. * Introduces Flash Catalyst * Focuses on production process * Covers the interrelation between Flash Catalyst and Photoshop/Illustrator/Flex/Flash What you'll learn Starting f

  18. Design criteria for stable Pt/C fuel cell catalysts

    Directory of Open Access Journals (Sweden)

    Josef C. Meier

    2014-01-01

    Full Text Available Platinum and Pt alloy nanoparticles supported on carbon are the state of the art electrocatalysts in proton exchange membrane fuel cells. To develop a better understanding on how material design can influence the degradation processes on the nanoscale, three specific Pt/C catalysts with different structural characteristics were investigated in depth: a conventional Pt/Vulcan catalyst with a particle size of 3–4 nm and two Pt@HGS catalysts with different particle size, 1–2 nm and 3–4 nm. Specifically, Pt@HGS corresponds to platinum nanoparticles incorporated and confined within the pore structure of the nanostructured carbon support, i.e., hollow graphitic spheres (HGS. All three materials are characterized by the same platinum loading, so that the differences in their performance can be correlated to the structural characteristics of each material. The comparison of the activity and stability behavior of the three catalysts, as obtained from thin film rotating disk electrode measurements and identical location electron microscopy, is also extended to commercial materials and used as a basis for a discussion of general fuel cell catalyst design principles. Namely, the effects of particle size, inter-particle distance, certain support characteristics and thermal treatment on the catalyst performance and in particular the catalyst stability are evaluated. Based on our results, a set of design criteria for more stable and active Pt/C and Pt-alloy/C materials is suggested.

  19. Vertical single- and double-walled carbon nanotubes grown from modified porous anodic alumina templates

    International Nuclear Information System (INIS)

    Vertical single-walled and double-walled carbon nanotube (SWNT and DWNT) arrays have been grown using a catalyst embedded within the pore walls of a porous anodic alumina (PAA) template. The initial film structure consisted of a SiOx adhesion layer, a Ti layer, a bottom Al layer, a Fe layer, and a top Al layer deposited on a Si wafer. The Al and Fe layers were subsequently anodized to create a vertically oriented pore structure through the film stack. CNTs were synthesized from the catalyst layer by plasma-enhanced chemical vapour deposition (PECVD). The resulting structure is expected to form the basis for development of vertically oriented CNT-based electronics and sensors

  20. TOPICAL REVIEW: Nanostructured catalysts in fuel cells

    Science.gov (United States)

    Zhong, Chuan-Jian; Luo, Jin; Fang, Bin; Wanjala, Bridgid N.; Njoki, Peter N.; Loukrakpam, Rameshwori; Yin, Jun

    2010-02-01

    One of the most important challenges for the ultimate commercialization of fuel cells is the preparation of active, robust, and low-cost catalysts. This review highlights some findings of our investigations in the last few years in developing advanced approaches to nanostructured catalysts that address this challenge. Emphasis is placed on nanoengineering-based fabrication, processing, and characterization of multimetallic nanoparticles with controllable size (1-10 nm), shape, composition (e.g. MlnM2100-n, M1nM2mM3100-n-m, M1@M2, where M (1 or 2) = Pt, Co, Ni, V, Fe, Cu, Pd, W, Ag, Au etc) and morphology (e.g. alloy, core@shell etc). In addition to an overview of the fundamental issues and the recent progress in fuel cell catalysts, results from evaluations of the electrocatalytic performance of nanoengineered catalysts in fuel cell reactions are discussed. This approach differs from other traditional approaches to the preparation of supported catalysts in the ability to control the particle size, composition, phase, and surface properties. An understanding of how the nanoscale properties of the multimetallic nanoparticles differ from their bulk-scale counterparts, and how the interaction between the nanoparticles and the support materials relates to the size sintering or evolution in the thermal activation process, is also discussed. The fact that the bimetallic gold-platinum nanoparticle system displays a single-phase character different from the miscibility gap known for its bulk-scale counterpart serves as an important indication of the nanoscale manipulation of the structural properties, which is useful for refining the design and preparation of the bimetallic catalysts. The insight gained from probing how nanoparticle-nanoparticle and nanoparticle-substrate interactions relate to the size evolution in the activation process of nanoparticles on planar substrates serves as an important guiding principle in the control of nanoparticle sintering on different

  1. Preparation and performance characterization of the Fe-Ni/ScSZ cermet anode for oxidation of ethanol fuel in SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Bo; Wang, S.R.; Liu, R.Z.; Wen, T.L. [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS), 1295 Dingxi Road, Shanghai 200050 (China)

    2007-05-15

    An anodic cermet of Fe-Ni alloy and scandia stabilized zirconia (ScSZ) has been investigated for a solid oxide fuel cell (SOFC) running on ethanol fuel. Composite anodes having alloy compositions of 0, 12.5, 25, 37.5, 50 and 100 wt.% Ni were exposed to ethanol stream at 700 C for 12 h to demonstrate that carbon formation is greatly suppressed on the Fe-Ni alloys compared to that of pure Ni. Then the short-term stability for the cells with the Ni/ScSZ and Fe{sub 0.5}Ni{sub 0.5}/ScSZ anodes in ethanol stream at 700 C was checked over a relative long period of operation. Open circuit voltages (OCVs) increased from 1.03 to 1.1 V, and power densities increased from 120 to 460 mW cm{sup 2} as the operating temperature of a SOFC with Fe{sub 0.5}Ni{sub 0.5}/ScSZ anode was increased from 700 to 850 C in ethanol stream. Electrochemical impedance spectra (EIS) illustrated that the cell with Ni/ScSZ anode exhibits slightly less total impedance than that observed for the cell with Fe{sub 0.5}Ni{sub 0.5}/ScSZ anode. The performance of a fuel cell made with the Ni/ScSZ and Fe{sub 0.5}Ni{sub 0.5}/ScSZ anodes was tested in ethanol stream for 48 h and showed a significant decrease in polarization resistance with time. Impedance spectra of similar fuel cells suggest that small carbon deposits are formed with time and that the decrease in polarization resistance is due to enhanced electronic conductivity in the anode. (author)

  2. Anodic behavior of stainless-steel substrate in organic electrolyte solutions containing different lithium salts

    International Nuclear Information System (INIS)

    Highlights: • We investigated anodic behavior of stainless-steel in organic electrolytes for advanced capacitor. • Anion of the electrolyte affected the anodic stability of the alloy. • Anodic passivation occurs in LiPF6 solution but pitting or active dissolution proceeds in other electrolyte solutions. • Fluoride source in the solution contributes to forming a stable surface layer on the stainless steel. - Abstract: The anodic behavior of austenitic stainless-steel, SUS304, as a current collector of positive electrode in lithium-ion battery/capacitor has been investigated in organic electrolyte solutions based on a mixed alkyl carbonate solvent with different lithium salts. Stable passivation characteristics were observed for the stainless-steel in the LiPF6 solution, but pitting corrosion or active dissolution proceeded in the solutions containing other anions, BF4-, (CF3SO2)2N- (TFSA-) and ClO4-. The mass ratios of the dissolved metal species in the solutions of LiTFSA and LiClO4 were equivalent to that of the alloy composition, which suggests that no preferential dissolution occurs during the anodic polarization in these electrolyte solutions. An HF component formed by decomposition of PF6- with the contaminate water will act as an F- source for the formation of a surface fluoride layer, that will contribute to the anodic stability of SUS304 in the LiPF6 solution. The anodic corrosion in the LiTFSA solution was suppressed in part by mixing the PF6 salt or adding HF in the electrolyte

  3. Investigation of surface layer composition of the rhodium-ruthenium catalysts by means of auger spectroscopy

    International Nuclear Information System (INIS)

    The surface layer composition of skeleton catalysts of the rhodium-ruthenium system by means of Auger-electron spectroscopy and electron spectroscopy for the chemical analysis is investigated. It is shown that apart from rhodium, ruthenium aluminium and silicon there is a certain quantity of chemosorbed oxygen accumulated in case of catalysts conservation over a long period of time. The dependence of filling catalysts by chemosorbed oxygen on the alloy composition has been found

  4. Electrochemical response of scratched Alloy 600 in simulated primary water and its influence with hydrogen entry

    International Nuclear Information System (INIS)

    The effect of scratches on oxidation evolution of Alloy 600 was monitored by EIS in 290℃ simulated primary water. EIS result indicates that oxide film reached a stable condition until 7 days' immersion. The scratched Alloy 600 possessed almost the same evolution of oxide film with plain specimens. Anodic polarization was performed to study combined effect of scratches and changed hydrogen. The anodic current changes of scratched Alloy 600 after hydrogen charging were not the simple superimposition between that of scratched and charged plain Alloy 600. Alloy 600 after scratching was supposed to trap more hydrogen because of introduction of cold work. The trapped hydrogen could accelerate the oxidation by enhancing dissolution of chromium oxides. Thus, the oxides became less protective and anodic current increased considerably over more noble potential range. (author)

  5. Nano-gold Catalyst for Direct Alcohol Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    Z.Ogumi; K.Miyazaki; Y.Iriyama; T.Abe

    2007-01-01

    1 Results Direct alcohol fuel cells have been regarded as attractive power sources for portable electric devices. One of the major roadblocks to the implementation of direct alcohol fuel cells is the exploration of the anode catalyst that can electrochemically oxidize alcohols at lower potentials. Carbon-monoxide (CO) produced through alcohol oxidation deteriorates catalytic activity of Pt, and therefore, the high tolerance for CO poisoning is an important issue to attain high voltage from direct alcoho...

  6. Assembly of a Cost-Effective Anode Using Palladium Nanoparticles for Alkaline Fuel Cell Applications

    OpenAIRE

    Feliciano-Ramos, Ileana; Casañas-Montes, Barbara; García-Maldonado, María M.; Menéndez, Christian L.; Mayol, Ana R.; Díaz-Vázquez, Liz M.; Cabrera, Carlos R.

    2014-01-01

    Nanotechnology allows the synthesis of nanoscale catalysts, which offer an efficient alternative for fuel cell applications. In this laboratory experiment, the student selects a cost-effective anode for fuel cells by comparing three different working electrodes. These are commercially available palladium (Pd) and glassy carbon (GC) electrodes, and a carbon paste (CP) electrode that is prepared by the students in the laboratory. The GC and CP were modified with palladium nanoparticles (PdNP) s...

  7. Temperature dependence of CO desorption kinetics at a novel Pt-on-Au/C PEM fuel cell anode

    DEFF Research Database (Denmark)

    Pitois, A.; Pilenga, A.; Pfrang, A.; Tsotridis, G.; Abrams, Billie; Chorkendorff, Ib

    2010-01-01

    degrees C. The dependence in temperature of the desorption rate constants for the novel Pt-on-Au/C system is however much lower than that observed for the Pt/C system. This suggests that the nature of the substrate has a significant influence on the catalyst surface properties. It shows that, in surface-modified...... catalysts, the interactions between underlayer and overlayer materials are worthy of consideration, since they can significantly modify the intrinsic properties of the active sites. The kinetics of the CO desorption process have been discussed with regard to the CO tolerance issue at the PEM fuel cell anode.......A Pt-on-Au/C fuel cell anode catalyst has been obtained by electrochemical deposition of platinum on carbon-supported gold nanoparticles. Its composition, structure and nanoparticle size distribution have been characterised before and after the desorption experiments using microstructural...

  8. Struvite precipitation and phosphorus removal using magnesium sacrificial anode.

    Science.gov (United States)

    Kruk, Damian J; Elektorowicz, Maria; Oleszkiewicz, Jan A

    2014-04-01

    Struvite precipitation using magnesium sacrificial anode as the only source of magnesium is presented. High-purity magnesium alloy cast anode was found to be very effective in recovery of high-quality struvite from water solutions and from supernatant of fermented waste activated sludge from a wastewater treatment plant that does not practice enhanced biological phosphorus removal. Struvite purity was strongly dependent on the pH and the electric current density. Optimum pH of the 24 mM phosphorus and 46 mM ammonia solution (1:1.9 P:N ratio) was in the broad range between 7.5 and 9.3, with struvite purity exceeding 90%. Increasing the current density resulted in elevated struvite purity. No upper limits were observed in the studied current range of 0.05-0.2 A. Phosphorus removal rate was proportional to the current density and comparable for tests with water solutions and with the supernatant from fermented sludge. The highest P-removal rate achieved was 4.0 mg PO4-P cm(-2) h(-1) at electric current density of 45 A m(-2). Initial substrate concentrations affected the rate of phosphorus removal. The precipitated struvite accumulated in bulk liquid with significant portions attached to the anode surface from which regular detachment occurred. PMID:24387911

  9. Stable anodes for lithium ion batteries made of self-organized mesoporous silicon

    Science.gov (United States)

    Wolter, Sascha J.; Köntges, Marc; Bahnemann, Detlef; Brendel, Rolf

    2016-01-01

    Alloy-forming compounds, such as electrodes for lithium ion batteries, stand out in terms of their theoretical specific charge capacity while still lacking in mechanical stability due to significant volume changes during operation. Herein, we examine the approach of combining low structural dimensions of the active material with built-in expansion volumes and assess their benefit for silicon anodes in lithium ion batteries. Consequently, self-organized mesoporous silicon is prepared as a suitable anode material for lithium ion batteries without any pre-structuring methods. The anodes are made by employing electrochemical etching methods in a scalable process and are characterized by ellipsometry. Thermally evaporated copper is utilized as the current collector. A sheet of freestanding silicon in contact with copper is used as an anode material with a thickness of 3 μm. After an initialization phase, electrochemical characterization reveals an anode stability of more than 160 cycles with a specific charge capacity of 730 mAh/g. The mechanical stability of the anode is examined by taking SEM measurements of the used electrode material.

  10. Electrochemical coating of dental implants with anodic porous titania for enhanced osteointegration

    Directory of Open Access Journals (Sweden)

    Amirreza Shayganpour

    2015-11-01

    Full Text Available Clinical long-term osteointegration of titanium-based biomedical devices is the main goal for both dental and orthopedical implants. Both the surface morphology and the possible functionalization of the implant surface are important points. In the last decade, following the success of nanostructured anodic porous alumina, anodic porous titania has also attracted the interest of academic researchers. This material, investigated mainly for its photocatalytic properties and for applications in solar cells, is usually obtained from the anodization of ultrapure titanium. We anodized dental implants made of commercial grade titanium under different experimental conditions and characterized the resulting surface morphology with scanning electron microscopy equipped with an energy dispersive spectrometer. The appearance of nanopores on these implants confirm that anodic porous titania can be obtained not only on ultrapure and flat titanium but also as a conformal coating on curved surfaces of real objects made of industrial titanium alloys. Raman spectroscopy showed that the titania phase obtained is anatase. Furthermore, it was demonstrated that by carrying out the anodization in the presence of electrolyte additives such as magnesium, these can be incorporated into the porous coating. The proposed method for the surface nanostructuring of biomedical implants should allow for integration of conventional microscale treatments such as sandblasting with additive nanoscale patterning. Additional advantages are provided by this material when considering the possible loading of bioactive drugs in the porous cavities.

  11. Electrochemical coating of dental implants with anodic porous titania for enhanced osteointegration

    Science.gov (United States)

    Shayganpour, Amirreza; Rebaudi, Alberto; Cortella, Pierpaolo; Diaspro, Alberto

    2015-01-01

    Summary Clinical long-term osteointegration of titanium-based biomedical devices is the main goal for both dental and orthopedical implants. Both the surface morphology and the possible functionalization of the implant surface are important points. In the last decade, following the success of nanostructured anodic porous alumina, anodic porous titania has also attracted the interest of academic researchers. This material, investigated mainly for its photocatalytic properties and for applications in solar cells, is usually obtained from the anodization of ultrapure titanium. We anodized dental implants made of commercial grade titanium under different experimental conditions and characterized the resulting surface morphology with scanning electron microscopy equipped with an energy dispersive spectrometer. The appearance of nanopores on these implants confirm that anodic porous titania can be obtained not only on ultrapure and flat titanium but also as a conformal coating on curved surfaces of real objects made of industrial titanium alloys. Raman spectroscopy showed that the titania phase obtained is anatase. Furthermore, it was demonstrated that by carrying out the anodization in the presence of electrolyte additives such as magnesium, these can be incorporated into the porous coating. The proposed method for the surface nanostructuring of biomedical implants should allow for integration of conventional microscale treatments such as sandblasting with additive nanoscale patterning. Additional advantages are provided by this material when considering the possible loading of bioactive drugs in the porous cavities. PMID:26665091

  12. Anodes for Rechargeable Lithium-Sulfur Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Ruiguo; Xu, Wu; Lu, Dongping; Xiao, Jie; Zhang, Jiguang

    2015-04-10

    In this work, we will review the recent developments on the protection of Li metal anode in Li-S batteries. Various strategies used to minimize the corrosion of Li anode and reducing its impedance increase will be analyzed. Other potential anodes used in sulfur based rechargeable batteries will also be discussed.

  13. Pd Close Coupled Catalyst

    Institute of Scientific and Technical Information of China (English)

    Zhong Hua SHI; Mao Chu GONG; Yao Qiang CHEN

    2006-01-01

    A catalyst comprised novel high surface area alumina support was prepared to control emission of automobiles. The results showed that prepared catalyst could satisfy the requirements of a high performance close coupled catalyst for its good catalytic activity at low temperature and good stability at high temperature.

  14. Anodic oxidation of Zircaloy-2

    Energy Technology Data Exchange (ETDEWEB)

    Conte, A.; Borello, A.; Cabrini, A.

    1976-07-01

    The anodic polarization of zircaloy-2 in different electrolytic baths has been investigated in order to obtain thick oxide films with properties suitable for wear applications. The operative conditions to obtain hard, thick, compact oxide films resistant to thermal shocks have been determined. The influence of the bath composition and temperature on the oxide growth is reported.

  15. Synthesis, Characterization, and Optimization of Novel Solid Oxide Fuel Cell Anodes

    Science.gov (United States)

    Miller, Elizabeth C.

    This dissertation presents research on the development of novel materials and fabrication procedures for solid oxide fuel cell (SOFC) anodes. The work discussed here is divided into three main categories: all-oxide anodes, catalyst exsolution oxide anodes, and Ni-infiltrated anodes. The all-oxide and catalyst exsolution anodes presented here are further classi?ed as Ni-free anodes operating at the standard 700-800°C SOFC temperature while the Ni-infiltrated anodes operate at intermediate temperatures (≤650°C). Compared with the current state-of-the-art Ni-based cermets, all-oxide, Ni-free SOFC anodes offer fewer coking issues in carbon-containing fuels, reduced degradation due to fuel contaminants, and improved stability during redox cycling. However, electrochemical performance has proven inferior to Ni-based anodes. The perovskite oxide Fe-substituted strontium titanate (STF) has shown potential as an anode material both as a single phase electrode and when combined with Gd-doped ceria (GDC) in a composite electrode. In this work, STF is synthesized using a modified Pechini processes with the aim of reducing STF particle size and increasing the electrochemically active area in the anode. The Pechini method produced particles ? 750 nm in diameter, which is signi°Cantly smaller than the typically micron-sized solid state reaction powder. In the first iteration of anode fabrication with the Pechini powder, issues with over-sintering of the small STF particles limited gas di?usion in the anode. However, after modifying the anode firing temperature, the Pechini cells produced power density comparable to solid state reaction based cells from previous work by Cho et al. Catalyst exsolution anodes, in which metal cations exsolve out of the lattice under reducing conditions and form nanoparticles on the oxide surface, are another Ni-free option for standard operating temperature SOFCs. Little information is known about the onset of nanoparticle formation, which

  16. Ellipsometry of anodic film growth

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.G.

    1978-08-01

    An automated computer interpretation of ellisometer measurements of anodic film growth was developed. Continuous mass and charge balances were used to utilize more fully the time dependence of the ellipsometer data and the current and potential measurements. A multiple-film model was used to characterize the growth of films which proceeds via a dissolution--precipitation mechanism; the model also applies to film growth by adsorption and nucleation mechanisms. The characteristic parameters for film growth describe homogeneous and heterogeneous crystallization rates, film porosities and degree of hydration, and the supersaturation of ionic species in the electrolyte. Additional descriptions which may be chosen are patchwise film formation, nonstoichiometry of the anodic film, and statistical variations in the size and orientation of secondary crystals. Theories were developed to describe the optical effects of these processes. An automatic, self-compensating ellipsometer was used to study the growth in alkaline solution of anodic films on silver, cadmium, and zinc. Mass-transport conditions included stagnant electrolyte and forced convection in a flow channel. Multiple films were needed to characterize the optical properties of these films. Anodic films grew from an electrolyte supersatuated in the solution-phase dissolution product. The degree of supersaturation depended on transport conditions and had a major effect on the structure of the film. Anodic reaction rates were limited by the transport of charge carriers through a primary surface layer. The primary layers on silver, zinc, and cadmium all appeared to be nonstoichiometric, containing excess metal. Diffusion coefficients, transference numbers, and the free energy of adsorption of zinc oxide were derived from ellipsometer measurements. 97 figures, 13 tables, 198 references.

  17. Anodic behaviour of WC-Co type hardmetal

    Energy Technology Data Exchange (ETDEWEB)

    Bozzini, B.; Fanigliulo, A.; Mele, C. [INFM - Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, v. Monteroni, I-73100 Lecce (Italy); De Gaudenzi, G.P. [Harditalia s.r.l. (OMCD Group) v. Genova 9, I-21040 Oggiona con S. Stefano (Italy)

    2003-05-01

    An understanding of the anodic behaviour of WC-Co type hardmetals is vital for the functional behaviour of this class of materials. The anodic oxidation of WC-13Co grade hardmetal in 0.1 M H{sub 2}SO{sub 4} was investigated. This study is based on electrochemical (linear sweep voltammetry, cyclic voltammetry, impedance spectroscopy), compositional (energy dispersive spectroscopy), structural (X-ray diffraction) and morphological (scanning electron microscopy) investigations. The potential range in which the oxidation of the Co-alloy takes place with respect to the nobler carbide phase was defined. Within this potential interval a passivating behaviour for the binder alloy was shown. The potential threshold for WC oxidation was identified by monitoring the inception of the electrochromic loop. The anodic attack gives rise to the formation of hydrous WO{sub 3}. The attack morphology is characterised by the alteration of the grain shape with formation of jelly-like microscopic and flaky macroscopic structures. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Das Verstaendnis des anodischen Verhaltens von Hartmetallen des Typs WC-Co ist entscheidend fuer das funktionale Verhalten dieser Werkstoffklasse. Das anodische Verhalten des Hartmetalls WC-13Co wurde in 0,1 M H{sub 2}SO{sub 4} untersucht. Diese Studie basiert auf elektrochemischen (lineare Abtastvoltammetrie, zyklische Voltammetrie, Impedanzspektroskopie), strukturellen (Roentgendiffraktometrie), morphologischen (Rasterelektronenmikroskopie) sowie Untersuchungen zur Zusammensetzung (energiedispersive Spektroskopie). Der Potentialbereich, in dem die Oxidation der Co-Legierung bezueglich der edleren Karbidphase stattfindet, wurde bestimmt. Innerhalb dieses Potentialintervalls konnte ein passivierendes Verhalten fuer die Bindemittelphase gezeigt werden. Der Potentialgrenzwert fuer die WC-Oxidation wurde durch Ueberwachung des Beginns der elektrochromischen Schleife identifiziert. Der anodische Angriff

  18. Preparation and Hydrodesulfurization Performance of Ni-B Amorphous Alloy Catalyst Supported by APTS Modified SBA-15%APTS改性SBA-15负载Ni-B非晶态合金催化剂的制备及加氢脱硫性能

    Institute of Scientific and Technical Information of China (English)

    谌伟庆; 黄勇; 石秋杰

    2012-01-01

    SBA-15 was modified by APTS with covalent grafting method,and then Ni-B amorphous alloy catalysts were prepared by using APTS modified SBA-15 and unmodified SBA-15 as supports.The catalytic activities of both catalysts were characterized,and thiophene hydrodesulfurization was selected as probe reaction.The results show that thiophene conversation of Ni-B/SBA-15-APTS is 50.8%,which is higher than the one of Ni-B/SBA-15.The complexation between NH2 and Ni2+ would be benefit for dispersion of Ni-B alloy particles and reduction of Ni2+.According to ICP results,Ni-B/SBA-15-APTS show bigger quantity of Ni in support and higher content of Ni in Ni-B amorphous alloy than Ni-B/SBA-15,resulting in the higher activity.%采用共价接枝法制备APTS改性介孔分子筛SBA-15,将氨基官能团接枝到SBA-15表面.并采用化学还原法制备了Ni-B/SBA-15-APTS非晶态合金催化剂,以噻吩加氢脱硫为探针反应,研究了其催化加氢脱硫性能.结果表明,240℃时,APTS改性SBA-15所负载的Ni-B催化剂噻吩转化率达到50.8%,较未改性SBA-15所负载的催化剂噻吩转化率有显著地提高.由于氨基与Ni2+的配合作用,有助于Ni在催化剂中的分散,因而更容易被还原.ICP结果表明,在相同的制备条件下,相比未改性的SBA-15,APTS改性SBA-15使其催化剂中Ni的负载量增加,并且非晶态合金组成中Ni的含量也增大,B的含量降低,有利于提高催化剂的活性.

  19. Effect of Surface Pretreatment on Adhesive Properties of Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    Jinsheng ZHANG; Xuhui ZHAO; Yu ZUO; Jinping XIONG; Xiaofeng ZHANG

    2008-01-01

    The lap-shear strength and durability of adhesive bonded AI alloy joints with different pretreatments were studied by the lap-shear test and wedge test. The results indicate that the maximum lap-shear strength and durability of the bonding joints pretreated by different processes are influenced by the grade of abrasive papers and can be obviously improved by phosphoric acid anodizing. Alkali etching can obviously improve the durability of bonding joints although it slightly influences the maximum lap-shear strength. The process which is composed of grit-finishing, acetone degreasing, alkali etching and phosphoric acid anodizing, provides a better adhesive bonding property of AI alloy.

  20. Anode sheath transition in an anodic arc for synthesis of nanomaterials

    Science.gov (United States)

    Nemchinsky, V. A.; Raitses, Y.

    2016-06-01

    The arc discharge with ablating anode or so-called anodic arc is widely used for synthesis of nanomaterials, including carbon nanotubes and fullerens, metal nanoparticles etc. We present the model of this arc, which confirms the existence of the two different modes of the arc operation with two different anode sheath regimes, namely, with negative anode sheath and with positive anode sheath. It was previously suggested that these regimes are associated with two different anode ablating modes—low ablation mode with constant ablation rate and the enhanced ablation mode (Fetterman et al 2008 Carbon 46 1322). The transition of the arc operation from low ablation mode to high ablation mode is determined by the current density at the anode. The model can be used to self-consistently determine the distribution of the electric field, electron density and electron temperature in the near-anode region of the arc discharge. Simulations of the carbon arc predict that for low arc ablating modes, the current is driven mainly by the electron diffusion to the anode. For positive anode sheath, the anode voltage is close to the ionization potential of anode material, while for negative anode sheath, the anode voltage is an order of magnitude smaller. It is also shown that the near-anode plasma, is far from the ionization equilibrium.

  1. Surface characterization and cytotoxicity response of biodegradable magnesium alloys

    International Nuclear Information System (INIS)

    Magnesium alloys have raised an immense amount of interest to many researchers because of their evolution as a new kind of third generation materials. Due to their biocompatibility, density, and mechanical properties, magnesium alloys are frequently reported as prospective biodegradable implant materials. Moreover, magnesium alloys experience a natural phenomenon to biodegrade in aqueous solutions due to its corrosion activity, which is excellent for orthopedic and cardiovascular applications. However, a major concern with such alloys is fast and non-uniform corrosion degradation. Controlling the degradation rate in the physiological environment determines the success of biodegradable implants. In this investigation, three different grades of magnesium alloys: AZ31B, AZ91E and ZK60A were studied for their corrosion resistance and biocompatibility. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and contact angle meter are used to study surface morphology, chemistry, roughness and wettability, respectively. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium based bio-assay, MTS. - Highlights: • Micro-textured features formed after the anodization of magnesium alloys. • Contact angle increased and surface free energy decreased by anodization. • Corrosion rate increased for anodized surfaces compared to untreated samples. • Cell viability was greater than 75% implying the cytocompatibility of Mg alloys

  2. Studies on PEM Fuel Cell Noble Metal Catalyst Dissolution

    DEFF Research Database (Denmark)

    Ma, Shuang; Skou, Eivind Morten

    . Membrane Electrode Assembly (MEA) is commonly considered as the heart of cell system [2]. Degradation of the noble metal catalysts in MEAs especially Three-Phase-Boundary (TPB) is a key factor directly influencing fuel cell durability. In this work, electrochemical degradation of Pt and Pt/Ru alloy were...

  3. Low voltage cathodic protection for high strength steels. Part 1: Definition of a new aluminum galvanic anode material

    Energy Technology Data Exchange (ETDEWEB)

    Pautasso, J.P. [Ministry of Defense, Paris (France); Le Guyader, H.; Debout, V. [Direction des Constructions Navales Cherbourg (France)

    1998-12-31

    Zn or Al-Zn-In sacrificial anodes are commonly used to protect submerged marine structures from general corrosion and galvanic corrosion. However, such electronegative alloys can also induce stress corrosion cracking or hydrogen embrittlement on high strength steels. Decreasing the electronegative potential applied to the structure, in the suitable range (around {minus}0.80 V vs Ag/AgCl) can significantly reduce the amount of hydrogen produced by the cathodic reaction and thus limit the risk of hydrogen embrittlement. The present work has consisted in determining the criteria for a new cathodic protection system with low voltage anodes and selecting one anode that matches the determined requirements, on the basis of laboratory tests. Among the various alloys tested the Al-O.1% Ga anode provided the most promising results and therefore was selected. The first full scale marine tests performed on an industrial casting of this anode have shown the effectiveness of the Al-O.1% Ga anode in the chosen potential range, with a satisfactory galvanic efficiency in real environments.

  4. -Based Cermet Inert Anodes for Aluminum Electrolysis

    Science.gov (United States)

    Tian, ZhongLiang; Lai, YanQing; Li, ZhiYou; Chai, DengPeng; Li, Jie; Liu, YeXiang

    2014-11-01

    The new aluminum electrolysis technology based on inert electrodes has received much interest for several decades because of the environment and energy advantages. The key to realize this technique is the inert anode. This article presents China's recent developments of NiFe2O4-based cermet inert anodes, which include the optimization of material performance, the joint between the cermet inert anode and metallic bar, as well as the results of 20 kA pilot testing for a large-size inert anode group. The problems NiFe2O4-based cermet inert anodes face are also discussed.

  5. [Vernier Anode Design and Image Simulation].

    Science.gov (United States)

    Zhao, Ai-rong; Ni, Qi-liang; Song, Ke-fei

    2015-12-01

    Based-MCP position-sensitive anode photon-counting imaging detector is good at detecting extremely faint light, which includes micro-channel plate (MCP), position-sensitive anode and readout, and the performances of these detectors are mainly decided by the position-sensitive anode. As a charge division anode, Vernier anode using cyclically varying electrode areas which replaces the linearly varying electrodes of wedge-strip anode can get better resolution and greater electrode dynamic range. Simulation and design of the Vernier anode based on Vernier's decode principle are given here. Firstly, we introduce the decode and design principle of Vernier anode with nine electrodes in vector way, and get the design parameters which are the pitch, amplitude and the coarse wavelength of electrode. Secondly, we analyze the effect of every design parameters to the imaging of the detector. We simulate the electron cloud, the Vernier anode and the detector imaging using Labview software and get the relationship between the pitch and the coarse wavelength of the anode. Simultaneously, we get the corresponding electron cloud for the designing parameters. Based on the result of the simulation and the practical machining demand, a nine electrodes Vernier anode was designed and fabricated which has a pitch of 891 µm, insulation width of 25 µm, amplitude of 50 µm, coarse pixel numbers of 5. PMID:26964205

  6. Electrocatalysis of carbon anode in aluminium electrolysis

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The anodic overvoltage of the carbon anode in aluminum electrolysis isof the order of 0.6 V at normal current densities. However, it can be reduced somewhat by doping the anode carbon with various inorganic compounds. A new apparatus was designed to improve the precision of overvoltage measurements. Anodes were doped with MgAl2O4 and AlF3 both by impregnation of the coke and by adding powder, and the measured overvoltage was compared with that of undoped samples. For prebake type anodes baked at around 1150 oC, the anodic overvoltage was reduced by 40-60 mV, and for Soderberg type anodes, baked at 950 oC, by 60-80 mV.

  7. In silico search for novel methane steam reforming catalysts

    Science.gov (United States)

    Xu, Yue; Lausche, Adam C.; Wang, Shengguang; Khan, Tuhin S.; Abild-Pedersen, Frank; Studt, Felix; Nørskov, Jens K.; Bligaard, Thomas

    2013-12-01

    This paper demonstrates a method for screening transition metal and metal alloy catalysts based on their predicted rates and stabilities for a given catalytic reaction. This method involves combining reaction and activation energies (available to the public via a web-based application ‘CatApp’) with a microkinetic modeling technique to predict the rates and selectivities of a prospective material. This paper illustrates this screening technique using the steam reforming of methane to carbon monoxide and hydrogen as a test reaction. While catalysts are already commercially available for this process, the method demonstrated in this paper is very general and could be applied to a wide range of catalytic reactions. Following the steps outlined herein, such an analysis could potentially enable researchers to understand reaction mechanisms on a fundamental level and, on this basis, develop leads for new metal alloy catalysts.

  8. In silico search for novel methane steam reforming catalysts

    International Nuclear Information System (INIS)

    This paper demonstrates a method for screening transition metal and metal alloy catalysts based on their predicted rates and stabilities for a given catalytic reaction. This method involves combining reaction and activation energies (available to the public via a web-based application ‘CatApp’) with a microkinetic modeling technique to predict the rates and selectivities of a prospective material. This paper illustrates this screening technique using the steam reforming of methane to carbon monoxide and hydrogen as a test reaction. While catalysts are already commercially available for this process, the method demonstrated in this paper is very general and could be applied to a wide range of catalytic reactions. Following the steps outlined herein, such an analysis could potentially enable researchers to understand reaction mechanisms on a fundamental level and, on this basis, develop leads for new metal alloy catalysts. (paper)

  9. Nickel-base alloys combat corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, D.C. [VDM Technologies Corp., Houston, TX (United States); Herda, W. [Krupp-VDM GmbH, Werdohl (Germany)

    1995-06-01

    The modern chemical process industry must increase production efficiency to remain competitive. Manufacturers typically meet this challenge by utilizing higher temperatures and pressures, and more-corrosive catalysts. At the same time, the industry has to solve the technical and commercial problems resulting from rigid environmental regulations. To overcome these obstacles, new alloys having higher levels of corrosion resistance have been developed. These materials are based on increased understanding of the physical metallurgy of nickel-base alloys, especially the role of alloying elements. Results of many studies have led to innovations in nickel-chromium-molybdenum alloys containing both high and low amounts of nickel. Higher molybdenum and chromium contents, together with nitrogen additions, have opened up an entirely new class of alloys having unique properties. In addition, a new chromium-base, fully wrought super stainless steel shows excellent promise in solving many corrosion problems. These newer alloys have the ability to combat uniform corrosion, localized corrosion, and stress-corrosion cracking in the harsh halogenic environment of the chemical process industry. This article briefly lists some of the major highlights and corrosion data on recent nickel-chromium-molybdenum and nickel-molybdenum alloys, and the development of a chromium-base, wrought super-austenitic alloy known as Nicrofer 3033 (Alloy 33). Some comparisons with existing alloys are presented, along with a few commercial applications.

  10. Effect of Process Variables on the Formation of Streak Defects on Anodized Aluminum Extrusions: An Overview

    Science.gov (United States)

    Zhu, Hanliang; Couper, Malcolm J.; Dahle, Arne K.

    2012-04-01

    Streak defects are often present on anodized extrusions of 6xxx series aluminum alloys, increasing the fabrication cost of these products. Moreover, streaking often only becomes visible after etching and anodizing treatments, rather than in the as-extruded condition, making it difficult to identify the original causes and influencing factors of these defects. In this paper, various process variables that influence the formation of streak defects on anodized aluminium extrusions are reviewed on the basis of a literature review, industrial practice and experimental results. The influencing factors involved in various processing steps such as billet quality, extrusion process, die design and etching process are considered. Effective measures for preventing the formation of streak defects in industrial extrusion products are discussed.

  11. Vapor phase hydrogenation of furfural over nickel mixed metal oxide catalysts derived from layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Sulmonetti, Taylor P.; Pang, Simon H.; Claure, Micaela Taborga; Lee, Sungsik; Cullen, David A.; Agrawal, Pradeep K.; Jones, Christopher W.

    2016-05-01

    The hydrogenation of furfural is investigated over various reduced nickel mixed metal oxides derived from layered double hydroxides (LDHs) containing Ni-Mg-Al and Ni-Co-Al. Upon reduction, relatively large Ni(0) domains develop in the Ni-Mg-Al catalysts, whereas in the Ni-Co-Al catalysts smaller metal particles of Ni(0) and Co(0), potentially as alloys, are formed, as evidenced by XAS, XPS, STEM and EELS. All the reduced Ni catalysts display similar selectivities towards major hydrogenation products (furfuryl alcohol and tetrahydrofurfuryl alcohol), though the side products varied with the catalyst composition. The 1.1Ni-0.8Co-Al catalyst showed the greatest activity per titrated site when compared to the other catalysts, with promising activity compared to related catalysts in the literature. The use of base metal catalysts for hydrogenation of furanic compounds may be a promising alternative to the well-studied precious metal catalysts for making biomass-derived chemicals if catalyst selectivity can be improved in future work by alloying or tuning metal-oxide support interactions.

  12. PtNi alloy nanoparticles supported on carbon-doped TiO2 nanotube arrays for photo-assisted methanol oxidation

    International Nuclear Information System (INIS)

    To develop anode catalysts for photo-assisted direct methanol fuel cell (PDMFC), carbon-doped TiO2 nanotube arrays-supported PtNi alloy nanoparticles with different Pt/Ni atomic ratio (PtNi/C-TiO2NTs) prepared by pulsed electrodeposition method are evaluated as catalysts for photo-assisted methanol oxidation. The cyclic voltammetry (CV) and chronoamperometry results show that the PtNi/C-TiO2NTs prepared at tonPt:tonNi: = 10:7 (ton is the current-on time) with a Pt:Ni atomic ratio of 6.1:5.7 presents the highest catalytic activity for methanol oxidation both in the dark and under illumination. In addition, according to the results obtained from the CO stripping voltammetry and electrochemical impedance spectroscopy (EIS) tests, it was found that the light play an accelerative role in the oxidation of methanol on PtNi/C-TiO2NTs under illumination. The effect of illumination which enhancing the catalytic activity of PtNi/C-TiO2NTs are attributed to (1) methanol and the intermediates be oxidized directly on C-TiO2NTs for the light-induced catalytic effect; (2) more abundant oxygen-donating species be produced on C-TiO2NTs in the presence of light; (3) less COads adsorbing on catalysts due to the presence of stronger metal–support interactions between PtNi alloy nanoparticles and C-TiO2NTs under illumination

  13. Discovering Inexpensive, Effective Catalysts for Solar Energy Conversion: An Authentic Research Laboratory Experience

    Science.gov (United States)

    Shaner, Sarah E.; Hooker, Paul D.; Nickel, Anne-Marie; Leichtfuss, Amanda R.; Adams, Carissa S.; de la Cerda, Dionisia; She, Yuqi; Gerken, James B.; Pokhrel, Ravi; Ambrose, Nicholas J.; Khaliqi, David; Stahl, Shannon S.; Schuttlefield Christus, Jennifer D.

    2016-01-01

    Electrochemical water oxidation is a major focus of solar energy conversion efforts. A new laboratory experiment has been developed that utilizes real-time, hands-on research to discover catalysts for solar energy conversion. The HARPOON, or Heterogeneous Anodes Rapidly Perused for Oxygen Overpotential Neutralization, experiment allows an array of…

  14. Effects of single and two stages anodizing on nonporous anodic alumina template at different potentials

    International Nuclear Information System (INIS)

    The porous anodic alumina has extensive applications as mold or template for filling the highly ordered patterned ID nanomaterials (semiconductors, magnetic nanowires etc.) and as a mask for nano dots of different materials. Pores in anodic alumina synthesized under appropriate conditions are self organized. Pore density, pore diameter, interpore distance may be changed through variation of different parameter such as anodic potential, choice of electrolyte, temperature and kind of pre-treatment. The porous anodic alumina has been synthesized by single and double stage anodizing at different potentials. The potentials used were 40V, 50V, 60V and 70V. By comparison of ordered pore formation under both the conditions, it has been found that pores formed in doubly anodized alumina are more ordered/organized than in singly anodized anodic alumina at same potential used for both type of synthesis. SEM images revealed that the pore density in the singly anodized alumina was greater than in doubly anodized alumina prepared under the same potential. Using the SEM image, the pore diameter in the case of doubly anodized alumina was found to be in the range of 50- 70 nm, whereas, for singly anodized alumina pore diameter was found to be in the range of 50-100 nm. Scanning electron Microscope images and electrochemical parameters showed that two stage anodizing is better than single stage anodizing to achieve highly ordered nanoporous alumina template. (author)

  15. Anodic fabrication and bioactivity of Nb-doped TiO2 nanotubes.

    Science.gov (United States)

    Ding, Dongyan; Ning, Congqin; Huang, Lin; Jin, Fangchun; Hao, Yongqiang; Bai, Shuo; Li, Yan; Li, Ming; Mao, Dali

    2009-07-29

    We report anodic formation of Ti-Nb-O nanotubes on top of a Ti35Nb alloy, and in vitro bioactivity and stem cell response of the anodic nanotubes. It was found that the amorphous Ti-Nb-O nanotubes presented a significantly enhanced in vitro bioactivity (in simulated body fluids) compared to those of undoped TiO2 nanotubes and porous Ti-Nb-O without nanotubular structure. Similar to undoped TiO2 nanotubes, the Ti-Nb-O nanotubes also promote mesenchymal stem cell adhesion and fast formation of extracellular matrix (ECM) materials. The above findings make it possible to further explore the biological properties, such as cell proliferation and drug delivery, of a variety of Ti-alloy-based oxide nanotubes. PMID:19581696

  16. Metalloporphyrin catalysts for oxygen reduction developed using computer-aided molecular design

    Energy Technology Data Exchange (ETDEWEB)

    Ryba, G.N.; Hobbs, J.D.; Shelnutt, J.A. [and others

    1996-04-01

    The objective of this project is the development of a new class of metalloporphyrin materials used as catalsyts for use in fuel cell applications. The metalloporphyrins are excellent candidates for use as catalysts at both the anode and cathode. The catalysts reduce oxygen in 1 M potassium hydroxide, as well as in 2 M sulfuric acid. Covalent attachment to carbon supports is being investigated. The computer-aided molecular design is an iterative process, in which experimental results feed back into the design of future catalysts.

  17. Application of anodizing as a pre-treatment for nickel plating on aluminum

    International Nuclear Information System (INIS)

    Effect of anodizing on subsequent electroplating of nickel on aluminum was investigated. Electroplated nickel did not exhibit any adhesion with un-anodized aluminum. Formation of a very thin anodized alumina film prior to nickel plating led to an excellent adhesion between the nickel film and the substrate. If the thickness of the alumina film increased, adhesion of electroplated nickel was significantly deteriorated and became similar to that of un-anodized bare aluminum. The study revealed that deposition proceeded through pores and defects in the insulator alumina film. These pores and defects also acted as nucleation and anchor points for nickel deposit. There was larger number of nucleation/ anchor points on thin alumina films. This provided better adhesion of nickel with the substrate as well as excellent coverage in relatively shorter times. On the other hand, very rough and poorly adherent nickel deposits formed on thick anodized films. Therefore, it may be used as precursor for producing nickel powder with controlled particle size as well as a catalyst with high specific surface area for hydrogenation and dehydrogenation reactions. (author)

  18. Boosting the performance of Pt electro-catalysts toward formic acid electro-oxidation by depositing sub-monolayer Au clusters

    Energy Technology Data Exchange (ETDEWEB)

    Bi Xuanxuan; Wang Rongyue [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Ding Yi, E-mail: yding@sdu.edu.cn [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2011-11-30

    Highlights: > Au decoration on Pt nanoparticles simultaneously increases the activity and stability. > Sub-monolayer Au decoration changes the reaction path and results in the activity improvement. > Increasing the Au coverage will increase the specific activity. > Proper Au coverage results in a maximum mass specific activity. - Abstract: CO poisoning is the main obstacle to the application of Pt nanoparticles as anode catalysts in direct formic acid fuel cells (DFAFCs). Significant types of Pt alloys have been investigated, which often demonstrate evidently improved catalytic performance governed by difference mechanisms. By using a well-known electrochemical technique of under potential deposition and in situ redox replacement, sub-monolayer Au clusters are deposited onto Pt nanoparticle surfaces in a highly controlled manner, generating a unique surface alloy structure. Under optimum conditions, the modified Pt nanoparticles can exhibit greatly enhanced specific activity (up to 23-fold increase) at potential of -0.2 V vs. MSE toward formic acid electro-oxidation (FAEO). Interestingly, the mass specific activity can also be improved by a factor of 2.3 at potential of -0.35 V vs. MSE although significant amount of surface Pt atoms are covered by the overlayer Au clusters. The much enhanced catalytic activity can be ascribed to a Pt surface ensemble effect, which induces change of the reaction path. Moreover, the sub-monolayer Au coating on the surface also contributes to the enhanced catalyst durability by inhibiting the Pt oxidation. These results show great potential to rationally design more active and stable nanocatalysts by modifying the Pt surface with otherwise inactive materials.

  19. EFFECT OF THE HEAT AND SURFACE LASER TREATMENT ON THE CORROSION DEGRADATION OF THE Mg-Al ALLOYS

    OpenAIRE

    Dobrzański, Leszek A.; Tomasz Tański; Szymon Malara

    2011-01-01

    In this paper there is presented the corrosion behavior of the cast magnesium alloys as cast state, after heat and laser treatment. Pitting corrosion resistance of the analyzed alloys was carried out using the potentiodynamic electrochemical method (direct current), based on a anodic polarization curve. On the basis of the achieved anodic polarization curves, using the Tefel extrapolation method near to the corrosion potential, the quantitative data were determined, which describe the electro...

  20. Biogas Catalytic Reforming Studies on Nickel-Based Solid Oxide Fuel Cell Anodes

    DEFF Research Database (Denmark)

    Johnson, Gregory B.; Hjalmarsson, Per; Norrman, Kion;

    2016-01-01

    experiments were performed to study catalytic activity and effect of sulfur poisoning: (i) CH4 and CO2 dissociation; (ii) biogas (60% CH4 and 40% CO2) temperature-programmed reactions (TPRxn); and (iii) steady-state biogas reforming reactions followed by postmortem catalyst characterization by temperature...... of Pd-CGO helped to mitigate sulfur deactivation effect; e.g. lowering the onset temperature (up to 190°C) for CH4 conversion during temperature-programmed reactions. Both Ni/ScYSZ and Ni/ScYSZ/Pd-CGO anode catalysts were more active for dry reforming of biogas than they were for steam reforming....... Deactivation of reforming activity by sulfur was much more severe under steam reforming conditions than dry reforming; a result of greater sulfur retention on the catalyst surface during steam reforming....