WorldWideScience

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...... of the novel catalyst material for synthesising hydrogen peroxide from oxygen and hydrogen, or from oxygen and water....

  4. Electrochemical Characteristics of LaNi4.5Al0.5 Alloy Used as Anodic Catalyst in a Direct Borohydride Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Lianbang Wang; Guobin Wu; Zhenzhen Yang; Yunfang Gao; Xinbiao Mao; Chun'an Ma

    2011-01-01

    Fuel cells using borohydride as the fuel have received much attention because of high energy density and theoretical working potential. In this work, LaNi4.5Al0.5 hydrogen storage alloy used as the anodic material has been investigated. It was found that the increasing; operation temperature was helpful to the open-circuit potential, the discharge potential and the power density, but showed a negative effect on the utilization of the fuel due to the accelerated hydrogen evolution. The high KOH concentration was favorable for high-rate discharge capability. The adsorption and transformation of hydrogen on LaNi4.5Al0.5 alloy electrode has been observed, but its contribution to the discharge capability during a high-rate discharge was small.

  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. 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.

  7. 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.

  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. 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...

  10. Bacterial adherence to anodized titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Peremarch, C Perez-Jorge; Tanoira, R Perez; Arenas, M A; Matykina, E; Conde, A; De Damborenea, J J; Gomez Barrena, E; Esteban, J, E-mail: cperemarch@fjd.es

    2010-11-01

    The aim of this study was to evaluate Staphylococcus sp adhesion to modified surfaces of anodized titanium alloy (Ti-6Al-4V). Surface modification involved generation of fluoride-containing titanium oxide nanotube films. Specimens of Ti-6Al-4V alloy 6-4 ELI-grade 23- meets the requirements of ASTM F136 2002A (AMS 2631B class A1) were anodized in a mixture of sulphuric/hydrofluoric acid at 20 V for 5 and 60 min to form a 100 nm-thick porous film of 20 nm pore diameter and 230 nm-thick nanotube films of 100 nm in diameter. The amount of fluorine in the oxide films was of 6% and of 4%, respectively. Collection strains and six clinical strains each of Staphylococcus aureus and Staphylococcus epidermidis were studied. The adherence study was performed using a previously published protocol by Kinnari et al. The experiments were performed in triplicates. As a result, lower adherence was detected for collection strains in modified materials than in unmodified controls. Differences between clinical strains were detected for both species (p<0.0001, Kruskal-Wallis test), although global data showed similar results to that of collection strains (p<0.0001, Kruskal-Wallis test). Adherence of bacteria to modified surfaces was decreased for both species. The results also reflect a difference in the adherence between S. aureus and S. epidermidis to the modified material. As a conclusion, not only we were able to confirm the decrease of adherence in the modified surface, but also the need to test multiple clinical strains to obtain more realistic microbiological results due to intraspecies differences.

  11. Surface Modification of a MCFC Anode by Electrochemical Alloying

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Considering the properties of the valve metal alloys with specific corrosion resistance and electrocatalytic ac tivity, an investigation was made to examine if nickel-niobium alloy could serve as the anode material for molten carbo nate fuel cell (MCFC). An attempt was made to produce nickel-niobium surface alloy by an electrochemical process in the molten fluorides and to testify its performance required by the MCFC anode. Experimental results indicated that the corrosion resistance as well as polarization performance of the nickel electrode was improved by the surface alloying.As far as the corrosion resistance and polarization performance is concerned, the nickel-niobium surface alloy can be considered as a candidate material for the anode of MCFC.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Carbon Supported Polyaniline as Anode Catalyst: Pathway to Platinum-Free Fuel Cells

    CERN Document Server

    Zabrodskii, A G; Malyshkin, V G; Sapurina, I Y

    2006-01-01

    The effectiveness of carbon supported polyaniline as anode catalyst in a fuel cell (FC) with direct formic acid electrooxidation is experimentally demonstrated. A prototype FC with such a platinum-free composite anode exhibited a maximum room-temperature specific power of about 5 mW/cm2

  18. 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......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....

  19. 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.

  20. Ni3Mo3C as anode catalyst for high-performance microbial fuel cells.

    Science.gov (United States)

    Zeng, Li-Zhen; Zhao, Shao-Fei; Li, Wei-Shan

    2015-03-01

    Ni3Mo3C was prepared by a modified organic colloid method and explored as anode catalyst for high-performance microbial fuel cell (MFC) based on Klebsiella pneumoniae (K. pneumoniae). The prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET). The activity of the sample as anode catalyst for MFC based on K. pneumoniae was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and polarization curve measurement. The results show that the adding of nickel in Mo2C increases the BET surface area of Mo2C and improves the electrocatalytic activity of Mo2C towards the oxidation of microbial fermentation products. The power density of MFC with 3 mg cm(-2) Ni3Mo3C anode is far higher than that of the MFC with carbon felt as anode without any catalyst, which is 19 % higher than that of Mo2C anode and produced 62 % as much as that of Pt anode, indicating that Ni3Mo3C is comparative to noble metal platinum as anode electrocatalyst for MFCs by increasing the loading.

  1. 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.

  2. Building Self-Healing Alloy Architecture for Stable Sodium-Ion Battery Anodes: A Case Study of Tin Anode Materials.

    Science.gov (United States)

    Mao, Jianfeng; Fan, Xiulin; Luo, Chao; Wang, Chunsheng

    2016-03-23

    The rational design of anode materials is a challenge in developing sodium ion batteries. Alloy anodes provide high gravimetric and volumetric capacities but suffer the short cycle life as a result of the continuous and accumulated pulverization, resulting from a large volume change during the cycling process. Herein, using pure Sn, an irreversible conversion reaction combined with an alloy reaction (SnO), and a reversible conversion reaction combined with an alloy reaction (Sn4P3) as samples, we demonstrate that the pulverization and aggregation of the alloy anode can be partially recovered and the accumulation of pulverization and aggregation during charge/discharge cycles can be terminated using a reversible conversion reaction combined with an alloy reaction. The cycling stability of three Sn-based anodes increases in order of Sn4P3 > SnO > Sn. The enhancement in Sn4P3 can be attributed to a reversible reaction of Sn4P3 + 9Na ↔ 4Sn + 3Na3P, which repairs the cracks, damage, and aggregation of Sn particles that occurred in the alloy process of 4Sn + 15Na ↔ Na15Sn4 during cycling and, hence, terminates the pulverization. The repair mechanism looks like the self-healing feature in nature, where the damage can be healed by itself. Therefore, the suggested mechanism can be called self-healing, while the repaired anode can be termed as the self-healing anode. The use of self-healing strategies to build an electrode architecture is new and highly desirable because it can increase the cycle life and provide a general approach toward stable electrode materials. PMID:26937998

  3. 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.

  4. 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)

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. ANODE CATALYST MATERIALS FOR USE IN FUEL CELLS

    DEFF Research Database (Denmark)

    2002-01-01

    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....

  10. 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)

  11. Cell response of anodized nanotubes on titanium and titanium alloys.

    Science.gov (United States)

    Minagar, Sepideh; Wang, James; Berndt, Christopher C; Ivanova, Elena P; Wen, Cuie

    2013-09-01

    Titanium and titanium alloy implants that have been demonstrated to be more biocompatible than other metallic implant materials, such as Co-Cr alloys and stainless steels, must also be accepted by bone cells, bonding with and growing on them to prevent loosening. Highly ordered nanoporous arrays of titanium dioxide that form on titanium surface by anodic oxidation are receiving increasing research interest due to their effectiveness in promoting osseointegration. The response of bone cells to implant materials depends on the topography, physicochemistry, mechanics, and electronics of the implant surface and this influences cell behavior, such as adhesion, proliferation, shape, migration, survival, and differentiation; for example the existing anions on the surface of a titanium implant make it negative and this affects the interaction with negative fibronectin (FN). Although optimal nanosize of reproducible titania nanotubes has not been reported due to different protocols used in studies, cell response was more sensitive to titania nanotubes with nanometer diameter and interspace. By annealing, amorphous TiO2 nanotubes change to a crystalline form and become more hydrophilic, resulting in an encouraging effect on cell behavior. The crystalline size and thickness of the bone-like apatite that forms on the titania nanotubes after implantation are also affected by the diameter and shape. This review describes how changes in nanotube morphologies, such as the tube diameter, the thickness of the nanotube layer, and the crystalline structure, influence the response of cells.

  12. 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.

  13. 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

  14. Surface integrity after pickling and anodization of Ti-6Al-4V titanium alloy

    Science.gov (United States)

    Vermesse, Eric; Mabru, Catherine; Arurault, Laurent

    2013-11-01

    The surface integrity of Ti-6Al-4V titanium alloy was studied at different stages of surface treatments, especially pickling and compact anodization, through surface characteristics potentially worsening fatigue resistance.

  15. 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

  16. 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...

  17. 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.

  18. 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...

  19. 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.

  20. 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.

  1. 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

  2. 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 compositi...... 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....

  3. ENVIRONMENTAL FRIENDLY ANODIZING ON AZ91D MAGNESIUM ALLOYS AND COATING CHARACTERISTICS

    Institute of Scientific and Technical Information of China (English)

    A. Saijo; M. Hino; M. Hiramatsu; T. Kanadani

    2005-01-01

    An environmental friendly anodizing treatment (Anomag) from a phosphate-based solution without heavy metals on AZ91D magnesium alloy was studied. The characteristics of the coatings,such as structure, composition and corrosion resistance were investigated. The effects of this anodizing treatment on the mechanical properties were examined. X-ray diffraction (XRD) analysis revealed that the structure of the coatings is amorphous or glassy. In salt spray tests coatings with an average thickness of 10μm had an anticorrosive performance of over 1000 hours. Fatigue tests revealed that anodizing onto AZ91D magnesium alloy does not affect the fatigue strength. These results demonstrate the utility of this anodizing treatment on magnesium alloy for application as a structural material, such as in the automotive field.

  4. 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).

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

    Energy Technology Data Exchange (ETDEWEB)

    Paez, M. A.; Skeldon, P.; Thompson, G. E.; Saez, M.; Bustos, O.; Monsalve, A.

    2003-07-01

    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 oxides 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 super pure 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 ar residual second phase, with the development of stresses in the film and, the consequence of these effects on film cracking during film growth. (Author) 10 refs.

  6. 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...

  7. Photoelectrochemical evidence of nitrogen incorporation during anodizing sputtering--deposited Al-Ta alloys.

    Science.gov (United States)

    Zaffora, A; Santamaria, M; Di Franco, F; Habazaki, H; Di Quarto, F

    2016-01-01

    Anodic films were grown to 20 V on sputtering-deposited Al-Ta alloys in ammonium biborate and borate buffer solutions. According to glow discharge optical emission spectroscopy, anodizing in ammonium containing solution leads to the formation of N containing anodic layers. Impedance measurements did not evidence significant differences between the dielectric properties of the anodic films as a function of the anodizing electrolyte. Photoelectrochemical investigation allowed evidencing that N incorporation induces a red-shift in the light absorption threshold of the films due to the formation of allowed localized states inside their mobility gap. The estimated Fowler threshold for the internal photoemission processes of electrons resulted to be independent of the anodizing electrolyte confirming that N incorporation does not appreciably affect the density of states distribution close to the conduction band mobility edge. The transport of photogenerated carriers has been rationalized according to the Pai-Enck model of geminate recombination.

  8. 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

  9. 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)

  10. 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.

  11. 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...

  12. 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...

  13. 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 located in a TiO2 unit in the oxide layer, but rather in a mixed Ti-Al oxide layer. The optical band gap energy of the anodic oxide layers was determined by vacuum ultraviolet spectroscopy in the energy range from 4.1 to 9.2 eV (300–135 nm). The results indicate that amorphous anodic Al2O3 has a direct...

  14. Morphological and Chemical Relationships in Nanotubes Formed by Anodizing of Ti6al4v Alloy

    Directory of Open Access Journals (Sweden)

    Kaczmarek- Pawelska A.

    2014-12-01

    Full Text Available The electrochemical formation of oxide nanotubes on the Ti6Al4V alloy has been so far difficult due to easy dissolution of vanadium reach β-phase of the two phase material. Due to the topographical heterogeneity of the anodic layer in nano and microscale at anodizing of the Ti6Al4V alloy we focused to establish the relationships between nanotube diameters on both phases of the alloy and fluorides concentration in electrolyte. We studied the effect of fluoride concentration (0.5-0.7 wt.% in 99% ethylene glycol on morphological parameters of nanotube layer on the Ti6Al4V alloy anodized at 20V for 20 min. Nanotubes with diameter ~40-50 nm ±5nm on the entire Ti6Al4V alloy surface in electrolyte containing 0.6% wt. NH4F were obtained. Microscale roughness studies revealed that nanotubular layer on α-phase is thicker than on β-phase. The annealing of nanotube layers at 600°C for 2h in air, nitrogen and argon, typically performed to improve their electrical properties, influenced chemical composition and morphology of nanotubes on the Ti6Al4V alloy. The vanadium oxides (VO2, V2O3, V2O5 were present in surface nanotube layer covering both phases of the alloy and the shape of nanotubes was preserved after annealing in nitrogen.

  15. 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.

  16. 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...

  17. Calcination/acid-activation treatment of an anodic oxidation TiO2/Ti film catalyst

    Institute of Scientific and Technical Information of China (English)

    YAO Zhongping; JIANG Yanli; JIANG Zhaohua; ZHU Hongkui; BAI Xuefeng

    2009-01-01

    The aim of this work was to investigate the effects of calcination/acid-activation on the composition, structure, and photocatalytic (PC) re-duction property of an anodic oxidation TiO2/Ti film catalyst. The surface morphology and phase composition were examined by scanning electron microscopy and X-ray diffraction. The catalytic property of the film catalysts was evaluated through the removal rate of potassium chromate during the PC reduction process. The results showed that the film catalysts were composed of anatase and mtile TiO2 with a mi-cro-porous surface structure. The calcination treatment increased the content of TiO2 in the film, changed the relative ratio of anatase and rutile TiO2, and decreased the size of the micro pores of the film cat.a/ysts. The removal rate of potassium chromate was related to the tech-nique parameters of calcination/acid-activation treatment. When the anodic oxidation TiO2Ti film catalyst was calcined at 873 K for 30 min and then acid-activated in the concentrated H2SO4 for 60 min, it presented the highest catalytic property, with the removal rate of potassium chromate of 96.3% during the PC reduction process under the experimental conditions.

  18. Tailoring of anodic surface layer properties on titanium and its implant alloys for biomedical purposes

    Directory of Open Access Journals (Sweden)

    E. Krasicka-Cydzik

    2010-11-01

    Full Text Available and nanostructural titania and alloy component oxides. Evaluation of their properties for various biomedical applications in implantology and biosensing.Design/methodology/approach: Samples of titanium and its alloys were anodized in phosphoric acid solutions at different concentrations (0.5 ~ 4 M with or without additions according to appropriate polarization regimes. Anodized samples were characterized by SED+EDS, electrochemical and impedance (EIS tests and biocompability examination. Titanium and its alloys (Ti6Al4V and Ti6Al7Nb samples were also used to form the nanostructural layer (nanotubes by anodizing. The latter was used as a platform for glucose biosensing.Findings: Anodizing of titanium materials in phosphoric acid solutions allowed to obtain surface layers of various morphology and topography. They differ in porosity, thickness and chemical composition and according to their specific properties can be used in various biomedical applications. The development of gel-like layer and formation of nanotube layer was observed while anodizing in higher concentration of electrolyte or anodizing in the presence of fluorides. Both surface layers are much more bioactive than anodic barrier oxide layers on titanium. The primary tests to use nanostructured layer as platform for the third generation biosensors were promising.Practical implications: Use of medical implants covered with porous and nanostructural anodic layers tailored to particular biomedical purposes enables new practical applications in implantology and biosensing.Originality/value: Phosphate gel-like layer over surface oxide layer on titanium materials and nanostructural surface layer rich in both: phosphates and fluorides, are highly bioactive, which is the desirable property of implant materials.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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).

  4. 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).

  5. Study of Composite Hardcoat Anodizing of Aluminum Alloy 6063 and Its Friction Behaviors

    Institute of Scientific and Technical Information of China (English)

    LIU Shi-yong; ZHANG Hui-chen; GAO Xue-min; LIU Wei; SHI Ya-qin

    2004-01-01

    A composite hard-anodized coating containing micro PTFE (polytetrafluoroethylene) particles on aluminum alloy 6063 was produced by adding micro PTFE particles into the traditional hardcoat anodizing solution. The size of the PTFE particles is around 2 μ m in diameter and the content of the PTFE particles in the composite coating is within 2%-3% by area percentage. Thickness of the composite coating can reach up to 70 μ m after one hour's anodizing. Surface hardness of the composite coating is between 400-480 HV0.1. The average friction coefficient of the composite coating against steel under dry friction test is 0.11, which is 17% lower than that obtained by traditional hardcoat anodizing.

  6. Study of Composite Hardcoat Anodizing of Aluminum Alloy 6063 and Its Friction Behaviors

    Institute of Scientific and Technical Information of China (English)

    LIUShi-yong; ZHANGHui-chen; GAOXue-min; LIUWei; SHIYa-qin

    2004-01-01

    A composite hard-anodized coating containing micro PTFE (polytetrafluoroethylene) particles on aluminum alloy 6063 was produced by adding micro PTFE particles into the traditional hardcoat anodizing solution. The size of the PTFE particles is around 2μm in diameter and the content of the PTFE particles in the composite coating is within 2%-3% by area percentage. Thickness of the composite coating cart reach up to 70μm after one hour's anodizing. Surface hardness of the composite coating is between 4(RI-480 HV0.1, The average friction coefficient of the composite coating against steel under dry friction tost is 0.11, which is 17% lower than that obtained by traditional hardcoat anodizing.

  7. Carbon treated commercial aluminium alloys as anodes for aluminium-air batteries in sodium chloride electrolyte

    Science.gov (United States)

    Pino, M.; Herranz, D.; Chacón, J.; Fatás, E.; Ocón, P.

    2016-09-01

    An easy treatment based in carbon layer deposition into aluminium alloys is presented to enhance the performance of Al-air primary batteries with neutral pH electrolyte. The jellification of aluminate in the anode surface is described and avoided by the carbon covering. Treated commercial Al alloys namely Al1085 and Al7475 are tested as anodes achieving specific capacities above 1.2 Ah g-1vs 0.5 Ah g-1 without carbon covering. The influence of the binder proportion in the treatment as well as different carbonaceous materials, Carbon Black, Graphene and Pyrolytic Graphite are evaluated as candidates for the covering. Current densities of 1-10 mA cm-2 are measured and the influence of the alloy explored. A final battery design of 4 cells in series is presented for discharges with a voltage plateau of 2 V and 1 Wh g-1 energy density.

  8. ANODIC BEHAVIOR OF ALLOY 22 IN HIGH NITRATE BRINES AT TEMPERATURES HIGHER THAN 100C

    Energy Technology Data Exchange (ETDEWEB)

    G.O. LLEVBARE; J.C. ESTILL; A. YILMAZ; R.A. ETIEN; G.A. HUST M.L. STUART

    2006-04-20

    Alloy 22 (N06022) may be susceptible to crevice corrosion in chloride solutions. Nitrate acts as an inhibitor to crevice corrosion. Several papers have been published regarding the effect of nitrate on the corrosion resistance of Alloy 22 at temperatures 100 C and lower. However, very little is known about the behavior of this alloy in highly concentrated brines at temperatures above 100 C. In the current work, electrochemical tests have been carried out to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 160 C at ambient atmospheres. Even though Alloy 22 may adopt corrosion potentials in the order of +0.5 V (in the saturated silver chloride scale), it does not suffer crevice corrosion if there is high nitrate in the solution. That is, the inhibitive effect of nitrate on crevice corrosion is active for temperatures higher than 100 C.

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

    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; Sun, Ying-Sui; Huang, Hsun-Miao [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)

    2013-12-31

    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.

  10. 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

  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. 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.

  13. 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.

  14. Surface Characteristics and Electrochemical Impedance Investigation of Spark-Anodized Ti-6Al-4V Alloy

    Science.gov (United States)

    Garsivaz jazi, M. R.; Golozar, M. A.; Raeissi, K.; Fazel, M.

    2014-04-01

    In this study, the surface characteristic of oxide films on Ti-6Al-4V alloy formed by an anodic oxidation treatment in H2SO4/H3PO4 electrolyte at potentials higher than the breakdown voltage was evaluated. Morphology of the surface layers was studied by scanning electron microscope. The results indicated that the diameter of pores and porosity of oxide layer increase by increasing the anodizing voltage. The thickness measurement of the oxide layers showed a linear increase of thickness with increasing the anodizing voltage. The EDS analysis of oxide films formed in H2SO4/H3PO4 at potentials higher than breakdown voltage demonstrated precipitation of sulfur and phosphor elements from electrolyte into the oxide layer. X-ray diffraction was employed to exhibit the effect of anodizing voltage on the oxide layer structure. Roughness measurements of oxide layer showed that in spark anodizing, the Ra and Rz parameters would increase by increasing the anodizing voltage. The structure and Corrosion properties of oxide layers were studied using electrochemical impedance spectroscopy (EIS) techniques, in 0.9 wt.% NaCl solution. The obtained EIS spectra and their interpretation in terms of an equivalent circuit with the circuit elements indicated that the detailed impedance behavior is affected by three regions of the interface: the space charge region, the inner compact layer, and outer porous layer.

  15. 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.

  16. 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.

  17. 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

  18. Corrosion behavior of Cu-Ni-Ag-Al alloy anodes in aluminium electrolysis

    Institute of Scientific and Technical Information of China (English)

    徐君莉; 石忠宁; 邱竹贤

    2004-01-01

    The behavior of Cu-Ni-Ag-Al alloy used as anode for aluminum electrolysis was directly visualized in a two-compartment see-through cell during electrolysis, and its performances were tested at 850℃ in acidic electrolyte molten salts consisting of 39.3 % NaF-43.7 % AlF3-8 % NaCl-5 % CAF2-4 % Al2 O3 for 40 h in a laboratory cell. The results show that nascent oxygen oxidizes the anodic surface to form oxide film at the beginning of electrolysis. X-ray diffraction analysis of alloy surface show that the oxide film on the anodic surface consists of CuO, NiO, Al2O3,CuAl2 O4 and NiAl2 O4. However, SEM image shows the oxide film is porous, loose and easy to fall into electrolyte and to contaminate aluminum. The corrosion mechanism of metal anodes was analyzed.

  19. Study on the Rare Earth Sealing Procedure of the Porous Film of Anodized 2024 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The rare earth sealing procedure of the porous film of anodized aluminum alloy 2024 was studied with the fieldemission scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS). The results show thatRE solution can form cerium oxide/hydroxides precipitation in the pores of the anodized coating at the beginning ofsealing. At the same time, the spherical deposits formed on the surface of the anodized coating created a barrierto the precipitation of RE solution in the pores. When the pore-structured anodizing film is covered all with thespherical deposits, RE conversion coating will form on the surface of the anodized coating. The reaction of thecoating formation was investigated by employing cyclic voltammetry. The results indicate that accelerator H2O2 actsas the source of O2 by carrying chemical reaction in course of coating formation. In the mean time, it maybe carrieselectrochemical reaction to generate alkaline condition to accelerate the coating formation. The porous structure ofthe film is beneficial to the precipitation of the cerium hydroxides film.

  20. Advanced image analysis of the surface pattern emerging in Ni3Al intermetallic alloys on anodization

    Directory of Open Access Journals (Sweden)

    Marco Salerno

    2016-07-01

    Full Text Available Anodization of Ni3Al alloy is of interest in the field of industrial manufacturing, thanks to the formation of protective oxide layer on the materials working in corrosive environments and high temperatures. However, homogeneous surface treatment is paramount for technological applications of this material. The anodization conditions have to be set outside the ranges of corrosion and burning, which is the electric field enhanced anodic dissolution of the metal. In order to check against occurrence of these events, proper quantitative means for assessing the surface quality have to be developed and established. We approached this task by advanced analysis of scanning electron microscope images of anodized Ni3Al plates. The anodization was carried out in 0.3 M citric acid at two temperatures of 0 and 30°C and at voltages in the range of 2 12 V. Different figures can be used to characterize the quality of the surface, in terms of uniformity. Here, the concept of regularity ratio spread is used for the first time on surfaces of technological interest. Additionally, the Minkowski parameters have been calculated and their meaning is discussed.

  1. Surface characteristics and electrochemical corrosion behavior of a pre-anodized microarc oxidation coating on titanium alloy.

    Science.gov (United States)

    Cui, W F; Jin, L; Zhou, L

    2013-10-01

    A porous bioactive titania coating on biomedical β titanium alloy was prepared by pre-anodization followed by micro arc oxidation technology. The effects of pre-anodization on the phase constituent, morphology and electrochemical corrosion behavior of the microarc oxidation coating were investigated. The results show that pre-anodization has less influence on the phase constituent and the surface morphology of the microarc oxidation coating, but improves the inner layer density of the microarc oxidation coating. The decrease of plasma discharge strength due to the presence of the pre-anodized oxide film contributes to the formation of the compact inner layer. The pre-anodized microarc oxidation coating effectively inhibits the penetration of the electrolyte in 0.9% NaCl solution and thus increases the corrosion resistance of the coated titanium alloy in physiological solution.

  2. 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

  3. 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.

  4. 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

  5. ROLE OF ULTRASOUND IN MECHANISMS OF ANODE-CATHODE INTERACTIONS DURING ELECTROSPARK ALLOYING

    Directory of Open Access Journals (Sweden)

    N. M. Chigrinova

    2016-01-01

    Full Text Available The paper reveals results of investigations on mass transfer kinetics and dynamics of coating formation while using integral electrospark alloying method with additional ultrasonic exposure at different stages of formation. Nowadays, a classical method for electrospark alloying with hard-alloy anodes and impulse AC voltage frequency on the vibration exciter coil from 20 to 1600 Hz has been mainly used for application of protective and strengthening coatings within permissible thickness and characteristics. The key aspect of ultrasonic exposure application (frequency 22–44 kHz during electrospark alloying is the possibility to increase further thickness of coatings to be formed even after reaching a brittle fracture threshold of the coating material. Methodology of the executed research activity has been based on integrated studies (gravimetric, metallographic, X-ray diffraction and electron microscopic of coatings which are to be formed through compositions produced while using method of high-energy hot compaction and a “refractory carbide (WC and a binding material“ system in the form of alloy based on nickel from the series of “colmonoy” Ni – Ni3B system which is alloyed with additions of copper and silicon. The initial surface treatment within ultrasonic frequency range (22–44 kHz contributes to a noticeable increase in the mass transfer rate, which is primarily determined by chemical composition and thermodynamic stability of anodes. It is due to surface activation in the process of its preliminary deformation at ultrasonic frequency which creates additional conditions for striking of a spark.The final ultrasonic treatment improves coating quality due to its additional forging that leads to an increase of its structure homogeneity and density.

  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. 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...... focus on the surface properties. Based on a genetic algorithm (GA) we introduce and discuss efficient permutation operations that work by interchanging positions of elements depending on their local environment and position in the cluster. We discuss the fact that in order to be efficient, the operators...... have to be dynamic, i.e. change their behavior during the course of an algorithm run. The implementation of the GA including the customized operators is freely available at http://svn.fysik.dtu. dk/projects/pga....

  9. 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.

  10. Optimization of Manganese and Magnesium Contents in As-cast Aluminum-Zinc-Indium Alloy as Sacrificial Anode

    Institute of Scientific and Technical Information of China (English)

    Mohammed R. Saeri; Ahmad Keywni

    2011-01-01

    In this study, effects of manganese and magnesium content on the electrochemical properties of Al-Zn-ln sacrificial anode were studied in 0.5 mol/L NaCl solution (pH=5). The aluminum base alloy with different amounts of Mn and Mg were melted at 750℃, then casted at molds at 25℃. Corrosion experiments were mounted to determine the optimal effect of Mn and Mg on the efficiencies of the aluminum alloy anodes. The corroded and unexposed sample surfaces were subjected to microstructure characterization by optical and scanning electron microscopy. AI-Zn-ln alloy doped with 0%, 0.01%, 0.05%.0.2% and 0.3% by weights of Mn and 0%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5% and 3.0% by weights of Mg were prepared to determine the effect of Mn and Mg on anode efficiency in the environment. The different microstructures of the evolved AI- Zn-ln-Mg-Mn alloy were correlated with the anode efficiencies. The Al-5.0%Zn-2.0%Mg-0.15%Mn-0.02%ln gave the best anode efficiency (about 83%). The microstructures of the corroded surface of the optimized alloy revealed decreased distribution of the pockets of localized attacks which are characteristics of pitting (or crevice) corrosion.

  11. 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.

  12. Surface integrity after pickling and anodization of Ti–6Al–4V titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Vermesse, Eric [Institut Clément Ader (ICA), Université de Toulouse, ISAE, Toulouse (France); Université de Toulouse, Institut Carnot CIRIMAT, UMR CNRS-UPS-INP 5085, Université Paul Sabatier, 118, route de Narbonne, 31062 Toulouse cedex 9 (France); Mabru, Catherine [Institut Clément Ader (ICA), Université de Toulouse, ISAE, Toulouse (France); Arurault, Laurent, E-mail: arurault@chimie.ups-tlse.fr [Université de Toulouse, Institut Carnot CIRIMAT, UMR CNRS-UPS-INP 5085, Université Paul Sabatier, 118, route de Narbonne, 31062 Toulouse cedex 9 (France)

    2013-11-15

    The surface integrity of Ti–6Al–4V titanium alloy was studied at different stages of surface treatments, especially pickling and compact anodization, through surface characteristics potentially worsening fatigue resistance. No significant changes of the equiaxe microstructure were detected between sample core and surface, or after the pickling and anodization steps. Surface hydrogen and oxygen superficial contents were found to remain unchanged. Roughness characteristics (i.e. R{sub a}, R{sub z} but also local K{sub t} factor) similarly showed only slight modifications, although SPM and SEM revealed certain random local surface defaults, i.e. pits about 400 nm in depth. Finally internal stresses, evaluated using X-ray diffraction, highlighted a significant decrease of the compressive internal stresses, potentially detrimental for fatigue resistance.

  13. 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

  14. Effects of graphite on Zn-Sb alloys as anode materials for lithium-ion batteries

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The electrochemical properties of multiphases Zn4Sb3C7 and ZnSbC2 as new lithium-ion anode materials wereinvestigated. The composition and microstructures of these multiphase materials were analyzed by XRD and TEM. It wasfound that the addition of graphite modifies the microstructures of pure alloys. The capacities and the cycle stability of theanodes are greatly improved. The reversible capacity of Zn4Sb3C7 reaches as high as 510 mAh/g at the first cycle, andkeeps higher than 300 mAh/g after 10 charge/discharge cycles

  15. 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.

  16. 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...

  17. 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.

  18. 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)

  19. 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.

  20. 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.)

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

    DEFF Research Database (Denmark)

    Studt, Felix; Abild-Pedersen, Frank; Bligaard, Thomas;

    2008-01-01

    calculations were performed that identified relations in heats of adsorption of hydrocarbon molecules and fragments on metal surfaces. This analysis not only verified the facility of known catalysts but identified nickel- zinc alloys as alternatives. Experimental studies demonstrated that these alloys...... dispersed on an oxide support were selective for acetylene hydrogenation at low pressures....

  2. 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 high...

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

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg

    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 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...

  4. 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.

  5. 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.

  6. 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...

  7. Performance of commercial aluminium alloys as anodes in gelled electrolyte aluminium-air batteries

    Science.gov (United States)

    Pino, M.; Chacón, J.; Fatás, E.; Ocón, P.

    2015-12-01

    The evaluation of commercial aluminium alloys, namely, Al2024, Al7475 and Al1085, for Al-air batteries is performed. Pure Al cladded Al2024 and Al7475 are also evaluated. Current rates from 0.8 mA cm-2 to 8.6 mA cm-2 are measured in a gel Al-air cell composed of the commercial alloy sample, a commercial air-cathode and an easily synthesizable gelled alkaline electrolyte. The influence of the alloying elements and the addition to the electrolyte of ZnO and ZnCl2, as corrosion inhibitors is studied and analysed via EDX/SEM. Specific capacities of up to 426 mAh/g are obtained with notably flat potential discharges of 1.3-1.4 V. The competition between self-corrosion and oxidation reactions is also discussed, as well as the influence of the current applied on that process. Al7475 is determined to have the best behaviour as anode in Al-air primary batteries, and cladding process is found to be an extra protection against corrosion at low current discharges. Conversely, Al1085 provided worse results because of an unfavourable metallic composition.

  8. 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.

  9. 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

  10. Electron microscopic studies of anodic oxide films on the AZ91HP alloy

    Directory of Open Access Journals (Sweden)

    D. Peixoto Barbosa

    2003-01-01

    Full Text Available A Mg-9wt.Al-1wt.%Zn-alloy was anodized up to 90 V with constant current/constant voltage in an electrolyte which contained the compounds of the HAE-process (KOH, Al(OH3, KF, Na3PO4 and KMnO4. Electron microscopic examinations revealed a highly porous and irregular film structure. The distribution of the elements in the film was measured with energy dispersive spectrometry on specimens prepared in cross section for the transmission electron microscope. The main characteristic found was a fluoride-enriched zone of about 100 nm thickness at the metal / film interface. Practically no manganese from the permanganate was detected in this fluoride-enriched zone.

  11. 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.

  12. 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)

  13. Evaluation of AA5052 alloy anode in alkaline electrolyte with organic rare-earth complex additives for aluminium-air batteries

    Science.gov (United States)

    Wang, Dapeng; Li, Heshun; Liu, Jie; Zhang, Daquan; Gao, Lixin; Tong, Lin

    2015-10-01

    Behaviours of the AA5052 aluminium alloy anode of the alkaline aluminium-air battery are studied by the hydrogen evolution test, the electrochemical measurements and the surface analysis method. The combination of amino-acid and rare earth as electrolyte additives effectively retards the self-corrosion of AA5052 aluminium alloy in 4 M NaOH solution. It shows that the combination of L-cysteine and cerium nitrate has a synergistic effect owing to the formation of a complex film on AA5052 alloy surface. The organic rare-earth complex can decrease the anodic polarisation, suppress the hydrogen evolution and increase the anodic utilization rate.

  14. 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.

  15. 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)

  16. 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.

  17. 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

  18. A Novel Ultrafine Ru-B Amorphous Alloy Catalyst for Glucose Hydrogenation to Sorbitol

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An ultrafine Ru-B amorphous alloy catalyst was prepared by chemical reduction with KBH4 in aqueous solution, which exhibited perfect selectivity to sorbitol (~100%) and very high activity during the liquid phase glucose hydrogenation, much higher than the corresponding crystallized Ru-B, the pure Ru powder, and Raney Ni catalysts. The correlation of the catalytic activity to both the structural and surface electronic characteristics was discussed briefly.

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

    Institute of Scientific and Technical Information of China (English)

    MuXuhong; ZongBaoning; 等

    2002-01-01

    Amorphous nickel based alloy catalysts(denoted as the SRNA series catalysts)were prepared via rapid quenching method followed by alkali leaching and other activation procedures.The physicochemical characterizations show that nickel,the active component in these catalysts,exists in the amorphous state,and the catalyst particles possess many nanosized voids leading to large surface area(the highest is 145m2/g).The evaluation results in some model reactions show that the SRNA series catalysts have 2 to 4 times higher activity and selectivity than conventional Raney Ni catalyst for the hydrogenation of compounds with unsatur-ated functional groups.At present,the SRNA series catalysts have been successfully used in hydrogenation of glucose,hydrogenation of pharmaceutical intermediates and purification of caprolactam.In order to use these catalysts efficiently,a magnetically stabilized bed(MSB) technology has been developed by combining the ferromagnetic property of the catalyst with the good mass transfer characteristics of MSB.The demonstration unit of MSB hydrogenation technology has been set up and has kept running for 2800 hours.The results show that,after running 2800 hours,the catalyst still retained good activity; meanwhile,the hydrogenation effi-ciency had been improved 10 times in comparison with the traditional CSTR process.

  20. Evaluation of Al and Some of Its Alloys as Anode Materials vs γ-MnO2 as Cathode Material and Ore Produced γ-MnO2 vs Zn Anode in KOH Solution

    Institute of Scientific and Technical Information of China (English)

    A.M.A.Hashem; Kh.S. Abou-El-Sherbini; S. Zein El Abedin; H. Abbas

    2006-01-01

    In this study electrochemical performance of Al and some of its alloys (Al-Zn, Al-Mg and Al-Mn) anodes vs MnO2 cathode were carried out in alkaline solution. The results show that the Al-Zn alloy anode has the best cell capacity among the other alloys. Cell capacity values go in the order Al-Zn>Al-Mg>Al>Al-Mn. This result is probably related to the nature of passive films formed on the surface of the alloys which examined by scanning electron microscopy (SEM). SEM morphologies of Al and its alloys showed coarse grains of passive films formed on the surface of these anode materials while Al-Mn morphology shows a needle-like structure.Electrolytic manganese dioxide (EMD) produced by electrodepositing on platinum anode from liquor resulting from reduction of low grade pyrolusite ore (β-MnO2) by sulfur slag was characterized as cathode in alkaline Zn-MnO2 batteries. Ore produced sample (EMD1) was performed well in comparison with EMD standard (EMD2) (commercial battery grade electrolytic manganese dioxide, TOSOH-Hellas GH-S). SEM morphology of Zn anode after cell reaction was carried out and showed that Zn anode has fine grains of passive film on its surface.

  1. 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

  2. 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.

  3. Carbon-coated Ni 20Si 80 alloy-graphite composite as an anode material for lithium-ion batteries

    Science.gov (United States)

    Lee, Heon-Yong; Kim, Young-Lae; Hong, Moon-Ki; Lee, Sung-Man

    A carbon-coated Ni 20Si 80 alloy-graphite composite has been studied as the anode for lithium-ion batteries. The composite is prepared by simple heat-treatment of a mixture of coal tar pitch and a Ni 20Si 80-graphite composite at 900 °C and under argon. The Ni 20Si 80 alloy powders are synthesized by mechanical alloying. The composite demonstrates promising electrochemical properties such as high reversible capacity, excellent cycle performance, and sufficiently high initial charge-discharge coulombic efficiency. This suggests buffering and conductive actions on the main active material, viz., Ni 20Si 80 alloy, of the graphite. These two effects are strongly enhanced by the carbon coating treatment.

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

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Amorphous nickel based alloy catalysts (denoted as the SRNA series catalysts) were prepared viarapid quenching method followed by alkali leaching and other activation procedures. The physicochemicalcharacterizations show that nickel, the active component in these catalysts, exists in the amorphous state, andthe catalyst particles possess many nanosized voids leading to large surface area (the highest is 145m2/g). Theevaluation results in some model reactions show that the SRNA series catalysts have 2 to 4 times higheractivity and selectivity than conventional Raney Ni catalyst for the hydrogenation of compounds with unsatur-ated functional groups. At present, the SRNA series catalysts have been successfully used in hydrogenation ofglucose, hydrogenation of pharmaceutical intermediates and purification of caprolactam. In order to use thesecatalysts efficiently, a magnetically stabilized bed (MSB) technology has been developed by combining theferromagnetic property of the catalyst with the good mass transfer characteristics of MSB. The demonstrationunit of MSB hydrogenation technology has been set up and has kept running for 2800 hours. The results showthat, after running 2800 hours, the catalyst still retained good activity; meanwhile, the hydrogenation effi-ciency had been improved 10 times in comparison with the traditional CSTR process.

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

    Institute of Scientific and Technical Information of China (English)

    Mu Xuhong; Zong Baoning; Meng Xiangkun; Min Enze

    2002-01-01

    Amorphous nickel based alloy catalysts (denoted as the SRNAseries catalysts) were prepared viarapid quenching method followed by alkali leaching and other activation procedures. The physicochemicalcharacterizations show that nickel, the active component in these catalysts, exists in the amorphous state, andthe catalyst particles possess many nanosized voids leading to large surface area (the highest is 145m2/g). Theevaluation results in some model reactions show that the SRNA series catalysts have 2 to 4 times higheractivity and selectivity than conventional Raney Ni catalyst for the hydrogenation of compounds with unsatur-ated functional groups. At present, the SRNA series catalysts have been successfully used in hydrogenation ofglucose, hydrogenation of pharmaceutical intermediates and purification of caprolactam. In order to use thesecatalysts efficiently, a magnetically stabilized bed (MSB) technology has been developed by combining theferromagnetic property of the catalyst with the good mass transfer characteristics of MSB. The demonstrationunit of MSB hydrogenation technology has been set up and has kept running for 2800 hours. The results showthat, after running 2800 hours, the catalyst still retained good activity; meanwhile, the hydrogenation effi-ciency had been improved 10 times in comparison with the traditional CSTR process.

  6. 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.

  7. 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.

  8. Performance of AA5052 alloy anode in alkaline ethylene glycol electrolyte with dicarboxylic acids additives for aluminium-air batteries

    Science.gov (United States)

    Wang, DaPeng; Zhang, DaQuan; Lee, KangYong; Gao, LiXin

    2015-11-01

    Dicarboxylic acid compounds, i.e. succinic acid (SUA), adipic acid (ADA) and sebacic acid (SEA), are used as electrolyte additives in the alkaline ethylene glycol solution for AA5052 aluminium-air batteries. It shows that the addition of dicarboxylic acids lowers the hydrogen gas evolution rate of commercial AA5052 aluminium alloy anode. AA5052 aluminium alloy has wide potential window for electrochemical activity and better discharge performance in alkaline ethylene glycol solution containing dicarboxylic acid additives. ADA has the best inhibition effect for the self-corrosion of AA5052 anode among the three dicarboxylic acid additives. Fourier transform infrared spectroscopy (FT-IR) reveals that dicarboxylic acids and aluminium ions can form coordination complexes. Quantum chemical calculations shows that ADA has a smaller energy gap (ΔE, the energy difference between the lowest unoccupied orbital and the highest occupied orbital), indicating that ADA has the strongest interaction with aluminium ions.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Alliages intermétalliques du magnésium, anodes pour MAFC ? Magnesium intermetallic alloys, anodes for MAFC?

    Directory of Open Access Journals (Sweden)

    Montagné Pierre

    2013-11-01

    Full Text Available Des composés intermétalliques sélectionnés ont été étudiés en vue d'une utilisation en remplacement de l'anode métallique dans des batteries de type métal air. Ces composés présentent des structures cristallines très différentes : structure lamellaire pour MgB2, structure covalente simple pour Mg2Si et structure complexe basée sur un empilement compact de polyèdres pour Mg2Al3. Les meilleurs résultats sont obtenus pour ce dernier composé avec une réactivité vis-à-vis des électrolytes testés sensiblement inférieure à celle du magnésium et une cinétique de réaction plus lente. Le potentiel en fonctionnement au sein de la batterie est sensiblement plus faible que celui du magnésium mais il présente une stabilité remarquable au cours du temps. Selected intermetallic compounds have been studied as anodic materials in metal air fuel cells. These compounds have different structural types, MgB2 displays a lamellar structure, Mg2Si a simple covalent structure while Mg2Al3 has a complex structure based on compact polyhedral packing. Best electrochemical results are obtained for the latter, with a lower reactivity towards magnesium in the two electrolytes and with lower kinetics of reaction. The operating potential of the battery with a Mg2Al3 anode is noticeably lower than with a Mg anode, but it presents a very good stability over time.

  14. 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.

  15. 直接甲烷SOFC阳极催化剂研究进展%Review of anode catalyst development of direct methane SOFC

    Institute of Scientific and Technical Information of China (English)

    由宏新; 刘瑞瑞; 刘瑞杰; 阿布理提·阿布都拉

    2011-01-01

    For the problem of carbon deposits on the anode of sclid oxide fuel cell (SOFC) with methane as the direct fuel. the recent progress of the anode catalyst was summarized, and the properties of the Ni, Ce, Cu-based modified bi-metallic solid solution anode catalyst, perovskite-type oxide anode with MIEC mixture of ionic and electronic conductivty), and other complex oxiade catalyst was reviewed. The prospect of the anode of direct methane SOFC was also put forward.%针对直接甲烷为固体氧化物燃料电池燃料时,阳极催化剂的抗积碳性,总结了近年来阳极催化剂的研究进展,对Ni、Ce、Cu基催化剂改性的双金属固熔体阳极,混合了离子和电子导电的钙钛矿型氧化物阳极以及其它复合氧化物催化剂性能进行评述,分析得出了今后直接甲烷燃料SOFC阳极的发展方向.

  16. 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.

  17. 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.

  18. Synthesis and Characterization of Niobium-doped TiO2 Nanotube Arrays by Anodization of Ti-20Nb Alloys

    Institute of Scientific and Technical Information of China (English)

    Zhengchao Xu; Qi Li; Shian Gao; Jianku Shangi

    2012-01-01

    Well crystallized niobium-doped TiO; nanotube arrays (TiNbO-NT) were successfully synthesized via the anodization of titanium/niobium alloy sheets, followed with a heat treatment at 550 ℃ for 2 h. Morphology analysis results demonstrated that both the titanium/niobium alloy microstructure and the dissolution strength of electrolyte played major roles in the formation of nanotube structure. A single-phase microstructure was more favorable to the formation of uniform nanotube arrays, while modulating the dissolution strength of electrolyte was required to obtain nanotube arrays from the alloys with multi-phase microstructures. X-ray diffraction (XRD) and X-ray photoelectron (XPS) analysis results clearly demonstrated that niobium dopants (Nb^5+) were successfully doped into TiO2 anatase lattice by substituting Ti^4+ in this approach.

  19. Carbon-supported platinum alloy catalysts for phenol hydrogenation for making industrial chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, S.T.; Song, C.

    1999-07-01

    Phenol is available in large quantities in liquids derived from coal and biomass. Phenol hydrogenation is an industrially important reaction to produce cyclohexanone and cyclohexanol. Cyclohexane, cyclohexene and benzene are obtained as minor products in this reaction. Cyclohexanone is an important intermediate in the production of caprolactam for nylon 6 and cyclohexanol for adipic acid production. In USA, cyclohexanol and cyclohexanone are produced by benzene hydrogenation to cyclohexane over nickel or noble metal catalysts, followed by oxidation of cyclohexane to produce a mixture of cyclohexanol and cyclohexanone. Then cyclohexanol is dehydrogenated in the presence of Cu-Zn catalyst to cyclohexanone. Usually phenol hydrogenation is also carried out by using Ni catalyst in liquid phase. However, a direct single-step vapor phase hydrogenation of phenol to give cyclohexanone selectively is more advantageous in terms of energy savings and process economics, since processing is simplified and the endothermic step of cyclohexanol dehydrogenation can be avoided, as demonstrated by Montedipe and Johnson Matthey using promoted Pd/Al{sub 2}O{sub 3} catalyst. While it is not the purpose of this paper to dwell on the relative merits of these routes, it is necessary to mention that while using monometallic catalysts, generally the problem of catalyst deactivation of sintering as well as coking is frequently encountered. Addition and alloying of noble metal (e.g. Pt) with a second metal can result in a catalyst with better selectivity and activity in the reaction which is more resistant to deactivation. This paper presents the results on the single-step vapor phase hydrogenation of phenol over carbon-supported Pt-M (M=Cr, V, Zr) alloy catalysts to yield mainly cyclohexanone or cyclohexanol.

  20. 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

  1. 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.

  2. Fabrication of Ni-Ti-O nanotube arrays by anodization of NiTi alloy and their potential applications

    Science.gov (United States)

    Hang, Ruiqiang; Liu, Yanlian; Zhao, Lingzhou; Gao, Ang; Bai, Long; Huang, Xiaobo; Zhang, Xiangyu; Tang, Bin; Chu, Paul K.

    2014-12-01

    Nickel-titanium-oxide (Ni-Ti-O) nanotube arrays (NTAs) prepared on nearly equiatomic NiTi alloy shall have broad application potential such as for energy storage and biomedicine, but their precise structure control is a great challenge because of the high content of alloying element of Ni, a non-valve metal that cannot form a compact electronic insulating passive layer when anodized. In the present work, we systemically investigated the influence of various anodization parameters on the formation and structure of Ni-Ti-O NTAs and their potential applications. Our results show that well controlled NTAs can be fabricated during relatively wide ranges of the anodization voltage (5-90 V), electrolyte temperature (10-50°C) and electrolyte NH4F content (0.025-0.8 wt%) but within a narrow window of the electrolyte H2O content (0.0-1.0 vol%). Through modulating these parameters, the Ni-Ti-O NTAs with different diameter (15-70 nm) and length (45-1320 nm) can be produced in a controlled manner. Regarding potential applications, the Ni-Ti-O NTAs may be used as electrodes for electrochemical energy storage and non-enzymic glucose detection, and may constitute nanoscaled biofunctional coating to improve the biological performance of NiTi based biomedical implants.

  3. Anodic oxides on a beta type Nb-Ti alloy and their characterization by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Woldemedhin, Michael Teka; Hassel, Achim Walter [Max Planck Institut fuer Eisenforschung GmbH, Duesseldorf (Germany); Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Linz (Austria); Raabe, Dierk [Max Planck Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    2010-04-15

    Anodic oxides were grown on the surface of an electropolished (Ti-30 at% Nb) beta-titanium ({beta}-Ti) alloy by cyclic voltammetry. The scan rate was 100 mV s{sup -1} between 0 and 8 V in increments of l V in an acetate buffer of pH 6.0. Electrochemical impedance spectroscopy was carried out right after each anodic oxide growth increment to study the electronic properties of the oxide/electrolyte interface in a wide frequency range from 100 kHz to 10 MHz with an AC perturbation voltage of 10 mV. A film formation factor of 2.4 nm V{sup -1} was found and a relative permittivity number (dielectric constant) of 42.4 was determined for the oxide film formed. Mott-Schottky analysis on a potentiostatically formed 7 nm thick oxide film was performed to assess the semiconducting properties of the mixed anodic oxide grown on the alloy. A flat band potential of -0.47 V (standard hydrogen electrode, SHE) was determined, connected to a donor density of 8.2 x 10{sup 17} cm{sup -3}. {beta}-Ti being highly isotropic in terms of mechanical properties should be superior to the stiffer {alpha}-Ti compound. Its application, however, requires a passivation behaviour comparable or better than {alpha}-Ti which in fact is found. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  4. Effects of Anodic Voltages on Microstructure and Properties of Plasma Electrolytic Oxidation Coatings on Biomedical NiTi Alloy

    Institute of Scientific and Technical Information of China (English)

    Jilin Xu; Fu Liu; Junming Luo; Liancheng Zhao

    2013-01-01

    Plasma electrolytic oxidation (PEO) coatings,formed under various anodic voltages (320-440 V) on biomedical NiTi alloy,are mainly composed of γ-Al2O3 crystal phase.The evolution of discharging sparks during the PEO process under different anodic voltages was observed.The surface and cross-sectional morphologies,composition,bonding strength,wear resistance and corrosion resistance of the coatings were investigated by scanning electron microscopy (SEM),thin-film X-ray diffraction (TF-XRD),energy dispersive X-ray spectrometry (EDS),surface roughness,direct pull-off test,ball-on-disk friction and wear test and potentiodynamic polarization test,respectively.The results showed that the evolution of discharging sparks during the PEO process directly influenced the microstructure of the PEO coatings and further influences the properties.When the anodic voltage increased from 320 V to 400 V,the corrosion resistance and wear resistance of the coatings slowly increased,and all the bonding strength was higher than 60 MPa; further increasing the anodic voltages,especially up to 440 V,although the thickness and γ-Al2O3 crystallinity of the coatings further increased,the microstructure and properties of the coatings were obviously deteriorated.

  5. Influence of voltage waveform on anodic film of AZ91 Mg alloy via plasma electrolytic oxidation: Microstructural characteristics and electrochemical responses

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Young Gun [School of Materials Science and Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Lee, Eung Seok [Department of Metallurgy and Materials Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Shin, Dong Hyuk, E-mail: dhshin@hanyang.ac.kr [Department of Metallurgy and Materials Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of)

    2014-02-15

    Highlights: • The effect of voltage waveform on the anodic film structure is significant. • The anodic film by asymmetric-sine wave is denser than that by half-sine wave. • Asymmetric-sine wave results in excellent electrochemical properties. -- Abstract: The present study investigated how the voltage waveform influenced the microstructural characteristics and electrochemical responses of the anodic film on AZ91 Mg alloy coated by plasma electrolytic oxidation (PEO). PEO coatings of AZ91 Mg alloy were performed for 600 s in an alkaline silicate electrolyte with respect to the voltage waveform such as half-sine and asymmetric-sine waveforms. Microstructural observations on cross section of the anodic film utilizing scanning electron microscope revealed that the anodic film formed via asymmetric-sine wave was much denser in structure than that via half-sine counterpart since the occurrence of the cathodic breakdown between the anodic pulses could effectively suppress the formation of the micro-pores and discharge channels in the anodic films. Thereby, the hardness and corrosion properties of the anodic film formed by asymmetric-sine wave were found to be superior to those by half-sine wave. In addition, electrochemical responses were interpreted in relation to the equivalent circuit model consisting of resistor and capacitor elements within an electrical cell.

  6. 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.

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

    Science.gov (United States)

    Tanaka, Hidetatsu; Mori, Yu; Noro, Atsushi; Kogure, Atsushi; Kamimura, Masayuki; Yamada, Norikazu; Hanada, Shuji; Masahashi, Naoya; Itoi, Eiji

    2016-01-01

    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. PMID:26914329

  8. 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.

  9. 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.

  10. 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.

  11. First-principles study of interphase Ni3Sn in Sn-Ni alloy for anode of lithium ion battery

    Institute of Scientific and Technical Information of China (English)

    Hou Xian-Hua; Hu She-Jun; Li Wei-Shan; Ru Qiang; Yu Hong-Wen; Huang Zhao-Wen

    2008-01-01

    This paper investigates the mechanism of Li insertion into interphase NiaSn in Ni-Sn alloy for the anode of lithium ion battery by means of the first-principles plane-wave pseudopotential.Compared with other phases,it is found that the Ni3Sn has larger relative expansion ratio and lower electrochemical potential,with its specific plateaus voltage around 0.3 eV when lithium atoms are filled in all octahedral interstitial sites.and the relative expansion ratio increasing dramatically when the lithiated phase transits from octahedral interstitial sites to tetrahedral interstitial sites.So this phase is a devastating phase for whole alloy electrode materials.

  12. Effect of Solution Temperature for Al Alloy Anodizing on Cavitation Characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung-Jun [Kunsan National University, Kunsan (Korea, Republic of); Lee, Jung Hyung; Kim, Seong Jong [Mokpo National Maritime University, Haeyangdaehak-ro 91, Mokpo (Korea, Republic of)

    2015-06-15

    The commercialization of aluminum had been delayed than other metals because of its high oxygen affinity. Anodizing is a process in which oxide film is formed on the surface of a valve metal in an electrolyte solution by anodic oxidation reaction. Aluminum has thin oxide film on surface but the oxide film is inhomogeneous having a thickness only in the range of several nanometers. Anodizing process increases the thickness of the oxide film significantly. In this study, porous type oxide film was produced on the surface of aluminum in sulfuric acid as a function of electrolyte temperature, and the optimum condition were determined for anodizing film to exhibit excellent cavitation resistance in seawater environment. The result revealed that the oxide film formed at 10 ℃ represented the highest cavitation resistance, while the oxide film formed at 15 ℃ showed the lowest resistance to cavitation in spite of its high hardness.

  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. 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.

  15. 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...

  16. 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.

  17. 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.

  18. Studies on anodic oxide coating with low absorptance and high emittance on aluminum alloy 2024

    Energy Technology Data Exchange (ETDEWEB)

    Siva Kumar, C. [Department of Post-graduate studies in Chemistry, Central College, Bangalore (India); Sharma, A.K. [Thermal Process Section, ISRO Satellite Centre, Vimanapura Post, Bangalore (India); Mahendra, K.N.; Mayanna, S.M. [Department of Post-graduate studies in Chemistry, Central College, Bangalore (India)

    2000-01-01

    Anodization of AA 2024 in sulfuric acid bath containing glycerol, lactic acid and ammonium metavenadate has been studied to develop white anodic oxide coating. Investigation on the influence of various operating parameters - coating thickness, current density and ammonium metavenadate concentration on the optical properties was carried out to optimize the process. Infrared, atomic absorption spectroscopic techniques and scanning electron micrograph were used to characterize the coating. The obtained oxide coating provides a ratio of solar absorptance ({alpha}) to infrared emittance ({epsilon}), as low as 0.2. The optical properties and hardness values measured under optimum experimental conditions support its use as a thermal control coating.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. High-performance core-shell PdPt@Pt/C catalysts via decorating PdPt alloy cores with Pt

    Science.gov (United States)

    Wu, Yan-Ni; Liao, Shi-Jun; Liang, Zhen-Xing; Yang, Li-Jun; Wang, Rong-Fang

    A core-shell structured low-Pt catalyst, PdPt@Pt/C, with high performance towards both methanol anodic oxidation and oxygen cathodic reduction, as well as in a single hydrogen/air fuel cell, is prepared by a novel two-step colloidal approach. For the anodic oxidation of methanol, the catalyst shows three times higher activity than commercial Tanaka 50 wt% Pt/C catalyst; furthermore, the ratio of forward current I f to backward current I b is high up to 1.04, whereas for general platinum catalysts the ratio is only ca. 0.70, indicating that this PdPt@Pt/C catalyst has high activity towards methanol anodic oxidation and good tolerance to the intermediates of methanol oxidation. The catalyst is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The core-shell structure of the catalyst is revealed by XRD and TEM, and is also supported by underpotential deposition of hydrogen (UPDH). The high performance of the PdPt@Pt/C catalyst may make it a promising and competitive low-Pt catalyst for hydrogen fueled polymer electrolyte membrane fuel cell (PEMFC) or direct methanol fuel cell (DMFC) applications.

  12. 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.

  13. Effect of the Pd/MWCNTs anode catalysts preparation methods on their morphology and activity in a direct formic acid fuel cell

    Science.gov (United States)

    Lesiak, B.; Mazurkiewicz, M.; Malolepszy, A.; Stobinski, L.; Mierzwa, B.; Mikolajczuk-Zychora, A.; Juchniewicz, K.; Borodzinski, A.; Zemek, J.; Jiricek, P.

    2016-11-01

    Impact of Pd/MWCNTs catalysts preparation method on the catalysts morphology and activity in a formic acid electrooxidation reaction was investigated. Three reduction methods of Pd precursor involving reduction in a high pressure microwave reactor (Pd1), reduction with NaBH4 (Pd2) and microwave-assisted polyol method (Pd3) were used in this paper. Crystallites size and morphology were studied using the scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), whereas elemental composition, Pd chemical state and functional groups content by the X-ray photoelectron spectroscopy (XPS). The prepared catalysts were tested in a direct formic acid fuel cell (DFAFC) as an anode material. The catalytic activity was correlated with a mean fraction of the total Pd atoms exposed at the surface (FE). The value of FE was calculated from the crystallites size distribution determined by the STEM measurements. Non-linear dependence of a current density versus FE, approaching the maximum at FE≈0.25 suggests that the catalytic process proceeded at Pd nanocrystallites faces, with inactive edges and corners. Pd2 catalyst exhibited highest activity due to its smallest Pd crystallites (3.2 nm), however the absence of Pd crystallites aggregation and low content of carbon in PdCx phase, i.e. x = 4 at.% may also affect the observed.

  14. 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.

  15. 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) .

  16. 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

  17. Pd-Au bimetallic catalysts: understanding alloy effects from planar models and (supported) nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Feng; Goodman, Wayne D.

    2012-12-21

    Pd-Au bimetallic catalysts often display enhanced catalytic activities and selectivities compared with Pd-alone catalysts. This enhancement is often caused by two alloy effects, i.e., ensemble and ligand effects. The ensemble effect is dilution of surface Pd by Au. With increasing surface Au coverages, contiguous Pd ensembles disappear and isolated Pd ensembles form. For certain reactions, for example vinyl acetate synthesis, this effect is responsible for reaction rate enhancement via the formation of highly active surface sites, e.g., isolated Pd pairs. The disappearance of contiguous Pd ensembles also switches off side reactions catalyzed by these sites. This explains selectivity increase of certain reactions, for example direct H2O2 synthesis. The ligand effect is electronic perturbation of Au to Pd. By direct charge transfer or affecting bond length, the ligand effect causes the Pd d band to be more filled and the d-band center away from the Fermi level. Both changes make Pd more "atomic like" therefore binding reactants and products weaker. For certain reactions, this eliminates the so-called "self poisoning" and enhances activity/selectivity.

  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. 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.

  20. 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.

  1. 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

  2. Enhancing the power generation in microbial fuel cells with effective utilization of goethite recovered from mining mud as anodic catalyst.

    Science.gov (United States)

    Jadhav, Dipak A; Ghadge, Anil N; Ghangrekar, Makarand M

    2015-09-01

    Catalytic effect of goethite recovered from iron-ore mining mud was studied in microbial fuel cells (MFCs). Characterization of material recovered from mining mud confirms the recovery of iron oxide as goethite. Heat treated goethite (550 °C) and untreated raw goethite were coated on stainless-steel anode of MFC-1 and MFC-2, respectively; whereas, unmodified stainless-steel anode was used in MFC-3 (control). Fivefold increment in power was obtained in MFC-1 (17.1 W/m(3) at 20 Ω) than MFC-3 (3.5 W/m(3)). MFC with raw goethite coated anode also showed enhanced power (11 W/m(3)). Higher Coulombic efficiency (34%) was achieved in MFC-1 than control MFC-3 (13%). Decrease in mass-transport losses and higher redox current during electrochemical analyses support improved electron transfer with the use of goethite on anode. Cheaper goethite coating kinetically accelerates the electron transfer between bacteria and anode, proving to be a novel approach for enhancing the electricity generation along with organic matter removal in MFC.

  3. Self-Organizing Evolution of Anodized Oxide Films on Ti-25Nb-3Mo-2Sn-3Zr Alloy and Hydrophilicity

    Institute of Scientific and Technical Information of China (English)

    何芳; 李立军; 陈利霞; 李凤娇; 黄远

    2014-01-01

    In the present work, hierarchical nanostructured titanium dioxide (TiO2) films were fabricated on Ti-25Nb-3Mo-2Sn-3Zr (TLM) alloy for biomedical applications via one-step anodization process in ethylene glycol-based electrolyte containing 0.5wt%NH4F. The nanostructured TiO2 films exhibited three distinct types depending on the anodization time:top irregular nanopores (INP)/beneath regular nanopores (RNP), top INP/middle regular nano-tubes (RNT)/bottom RNP and top RNT with underlying RNP. The evolution of the nanostructured TiO2 films with anodization time demonstrated that self-organizing nanopores formed at the very beginning and individual nanotubes originated from underlying nanopore dissolution. Furthermore, a modified two-stage self-organizing mechanism was introduced to illustrate the growth of the nanostructured TiO2 films. Compared with TLM titanium alloy matrix, the TiO2 films with special nano-structure hold better hydrophilicity and higher specific surface area, which lays the foun-dation for their biomedical applications.

  4. Reversible conversion-alloying of Sb2O3 as a high-capacity, high-rate, and durable anode for sodium ion batteries.

    Science.gov (United States)

    Hu, Meijuan; Jiang, Yinzhu; Sun, Wenping; Wang, Hongtao; Jin, Chuanhong; Yan, Mi

    2014-11-12

    Sodium ion batteries are attracting ever-increasing attention for the applications in large/grid scale energy storage systems. However, the research on novel Na-storage electrode materials is still in its infancy, and the cycling stability, specific capacity, and rate capability of the reported electrode materials cannot satisfy the demands of practical applications. Herein, a high performance Sb(2)O(3) anode electrochemically reacted via the reversible conversion-alloying mechanism is demonstrated for the first time. The Sb(2)O(3) anode exhibits a high capacity of 550 mAh g(-1) at 0.05 A g(-1) and 265 mAh g(-1) at 5 A g(-1). A reversible capacity of 414 mAh g(-1) at 0.5 A g(-1) is achieved after 200 stable cycles. The synergistic effect involving conversion and alloying reactions promotes stabilizing the structure of the active material and accelerating the kinetics of the reaction. The mechanism may offer a well-balanced approach for sodium storage to create high capacity and cycle-stable anode materials.

  5. 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

  6. 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.

  7. 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)

  8. 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.

  9. Electrochemical Partial Reforming of Ethanol into Ethyl Acetate Using Ultrathin Co3O4 Nanosheets as a Highly Selective Anode Catalyst.

    Science.gov (United States)

    Dai, Lei; Qin, Qing; Zhao, Xiaojing; Xu, Chaofa; Hu, Chengyi; Mo, Shiguang; Wang, Yu Olivia; Lin, Shuichao; Tang, Zichao; Zheng, Nanfeng

    2016-08-24

    Electrochemical partial reforming of organics provides an alternative strategy to produce valuable organic compounds while generating H2 under mild conditions. In this work, highly selective electrochemical reforming of ethanol into ethyl acetate is successfully achieved by using ultrathin Co3O4 nanosheets with exposed (111) facets as an anode catalyst. Those nanosheets were synthesized by a one-pot, templateless hydrothermal method with the use of ammonia. NH3 was demonstrated critical to the overall formation of ultrathin Co3O4 nanosheets. With abundant active sites on Co3O4 (111), the as-synthesized ultrathin Co3O4 nanosheets exhibited enhanced electrocatalytic activities toward water and ethanol oxidations in alkaline media. More importantly, over the Co3O4 nanosheets, the electrooxidation from ethanol to ethyl acetate was so selective that no other oxidation products were yielded. With such a high selectivity, an electrolyzer cell using Co3O4 nanosheets as the anode electrocatalyst and Ni-Mo nanopowders as the cathode electrocatalyst has been successfully built for ethanol reforming. The electrolyzer cell was readily driven by a 1.5 V battery to achieve the effective production of both H2 and ethyl acetate. After the bulk electrolysis, about 95% of ethanol was electrochemically reformed into ethyl acetate. This work opens up new opportunities in designing a material system for building unique devices to generate both hydrogen and high-value organics at room temperature by utilizing electric energy from renewable sources. PMID:27610415

  10. 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.

  11. 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

  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. Novel silicon and tin alloy nano-particulate materials via spark erosion for high performance and high capacity anodes in lithium ion batteries

    Science.gov (United States)

    White, Emma Marie Hamilton

    The advent and popularity of portable electronics, as well as the need to reduce carbon-based fuel dependence for environmental and economic reasons, has led to the search for higher energy density portable power storage methods. Lithium ion batteries offer the highest energy density of any portable energy storage technology, but their potential is limited by the currently used materials. Theoretical capacities of silicon (3580 mAh/g) and tin (990 mAh/g) are significantly higher than existing graphitic anodes (372 mAh/g). However, silicon and tin must be scaled down to the nano-level to mitigate the pulverization from drastic volume changes in the anode structure during lithium ion insertion/extraction. The available synthesis techniques for silicon and tin nano-particles are complicated and scale-up is costly. A unique one-step process for synthesizing Si-Sn alloy and Sn nano-particles via spark plasma erosion has been developed to achieve the ideal nano-particulate size and carbon coating architecture. Spark erosion produces crystalline and amorphous spherical nano-particles, averaging 5-500nm in diameter. Several tin and silicon alloys have been spark eroded and thoroughly characterized using SEM, TEM, EDS, XPS, Auger spectroscopy, NMR spectroscopy and TGA. The resulting nano-particles show improved performance as anodes over commercialized materials. In particular, pure sparked Sn particles show stable reversible capacity at ˜460 mAh/g with >99.5% coulombic efficiency for over 100 cycles. These particles are drop-in ready for existing commercial anode processing techniques and by only adding 10% of the sparked Sn particles the total current cell capacity will increase by ˜13%.

  14. Formation of Sn-M (M=Fe, Al, Ni) alloy nanoparticles by DC arc-discharge and their electrochemical properties as anodes for Li-ion batteries

    Science.gov (United States)

    Gao, Song; Huang, Hao; Wu, Aimin; Yu, Jieyi; Gao, Jian; Dong, Xinglong; Liu, Chunjing; Cao, Guozhong

    2016-10-01

    A direct current arc-discharge method was applied to prepare the Sn-M (M=Fe, Al, Ni) bi-alloy nanoparticles. Thermodynamic is introduced to analyze the energy circumstances for the formation of the nanoparticles during the physical condensation process. The electrochemical properties of as-prepared Sn-M alloy nanoparticles are systematically investigated as anodes of Li-ion batteries. Among them, Sn-Fe nanoparticles electrode exhibits high Coulomb efficiency (about 71.2%) in the initial charge/discharge (257.9 mA h g-1/366.6 mA h g-1) and optimal cycle stability (a specific reversible capacity of 240 mA h g-1 maintained after 20 cycles) compared with others. Large differences in the electrochemical behaviors indicate that the chemical composition and microstructure of the nanoparticles determine the lithium-ion storage properties and the long-term cyclic stability during the charge/discharge process.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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 pr......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 Zn...... 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...

  20. 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 pro......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 Zn...... 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...

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Preparation of low-platinum-content platinum-nickel, platinum-cobalt binary alloy and platinum-nickel-cobalt ternary alloy catalysts for oxygen reduction reaction in polymer electrolyte fuel cells

    Science.gov (United States)

    Li, Mu; Lei, Yanhua; Sheng, Nan; Ohtsuka, Toshiaki

    2015-10-01

    A series of low-platinum-content platinum-nickel (Pt-Ni), platinum-cobalt (Pt-Co) binary alloys and platinum-nickel-cobalt (Pt-Ni-Co) ternary alloys electrocatalysts were successfully prepared by a three-step process based on electrodeposition technique and studied as electrocatalysts for oxygen reduction reaction (ORR) in polymer-electrolyte fuel cells. Kinetics of ORR was studied in 0.5 M H2SO4 solution on the Pt-Ni, Pt-Co and Pt-Ni-Co alloys catalysts using rotating disk electrode technique. Both the series of Pt-Ni, Pt-Co binary alloys and the Pt-Ni-Co ternary alloys catalysts exhibited an obvious enhancement of ORR activity in comparison with pure Pt. The significant promotion of ORR activities of Pt-Ni and Pt-Co binary alloys was attributed to the enhancement of the first electron-transfer step, whereas, Pt-Ni-Co ternary alloys presented a more complicated mechanism during the electrocatalysis process but a much more efficient ORR activities than the binary alloys.

  6. Performance of metal alloys as hydrogen evolution reaction catalysts in a microbial electrolysis cell

    NARCIS (Netherlands)

    Jeremiasse, A.W.; Bergsma, J.; Kleijn, J.M.; Saakes, M.; Buisman, C.J.N.; Cohen Stuart, M.A.; Hamelers, H.V.M.

    2011-01-01

    H2 can be produced from organic matter with a microbial electrolysis cell (MEC). To decrease the energy input and increase the H2 production rate of an MEC, a catalyst is used at the cathode. Platinum is an effective catalyst, but its high costs stimulate searching for alternatives, such as non-nobl

  7. 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.;

    2010-01-01

    . The 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...

  8. 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).

  9. 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.

  10. 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  

  11. 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.

  12. 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.

  13. L-S mass transfer in G-L-S countercurrent magnetically stabilized bed with amorphous alloy SRNA-4 catalyst

    Institute of Scientific and Technical Information of China (English)

    Wei; Li; Baoning; Zong; Xiaofang; Li; Xiangkun; Meng; Jinli; Zhang

    2007-01-01

    Liquid-solid (L-S) mass transfer coefficients (Ks) were characterized in a gas-liquid-solid (G-L-S) three-phase countercurrent magnetically stabilized bed (MSB) using amorphous alloy SRNA-4 as the solid phase. Effects of superficial liquid velocity, superficial gas velocity, magnetic field strength, liquid viscosity and surface tension were investigated. Experimental results indicated that the external magnetic field increased Ks in three-phase MSB, as compared to those in conventional G-L-S fluidized beds; that Ks increased with magnetic field strength, superficial gas and liquid velocities and decreased with liquid viscosity and surface tension; and that Ks showed uniform axial and radial distributions except for small increases close to the wall. Dimensionless correlations were established to estimate Ks of the G-L-S countercurrent MSB using SRNA-4catalyst, with an average error of 3.6%.

  14. 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.

  15. 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...

  16. 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.

  17. 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

  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. Reducing the Cost and Preserving the Reactivity in Noble-Metal-Based Catalysts: Oxidation of CO by Pt and Al-Pt Alloy Clusters Supported on Graphene.

    Science.gov (United States)

    Koizumi, Kenichi; Nobusada, Katsuyuki; Boero, Mauro

    2016-04-01

    The oxidation mechanisms of CO to CO2 on graphene-supported Pt and Pt-Al alloy clusters are elucidated by reactive dynamical simulations. The general mechanism evidenced is a Langmuir-Hinshelwood (LH) pathway in which O2 is adsorbed on the cluster prior to the CO oxidation. The adsorbed O2 dissociates into two atomic oxygen atoms thus promoting the CO oxidation. Auxiliary simulations on alloy clusters in which other metals (Al, Co, Cr, Cu, Fe, Ni) replace a Pt atom have pointed to the aluminum doped cluster as a special case. In the nanoalloy, the reaction mechanism for CO oxidation is still a LH pathway with an activation barrier sufficiently low to be overcome at room temperature, thus preserving the catalyst efficiency. This provides a generalizable strategy for the design of efficient, yet sustainable, Pt-based catalysts at reduced cost. PMID:26878836

  20. 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.

  1. 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.

  2. A durable PtRu/C catalyst with a thin protective layer for direct methanol fuel cells.

    Science.gov (United States)

    Shimazaki, Yuzuru; Hayasaka, Sho; Koyama, Tsubasa; Nagao, Daisuke; Kobayashi, Yoshio; Konno, Mikio

    2010-11-15

    A methanol oxidation catalyst with improved durability in acidic environments is reported. The catalyst consists of PtRu alloy nanoparticles on a carbon support that were stabilized with a silane-coupling agent. The catalyst was prepared by reducing ions of Pt and Ru in the presence of a carbon support and the silane-coupling agent. The careful choice of preparatory conditions such as the concentration of the silane-coupling agent and solution pH resulted in the preparation of catalyst in which the PtRu nanoparticles were dispersively adsorbed onto the carbon support. The catalytic activity was similar to that of a commercial catalyst and was unchanged after immersion in sulfuric acid solution for 1000 h, suggesting the high durability of the PtRu catalyst for the anode of direct methanol fuel cells.

  3. 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.

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

    DEFF Research Database (Denmark)

    Karamad, Mohammadreza; Tripkovic, Vladimir; Rossmeisl, Jan

    2014-01-01

    One of the main challenges associated with the electrochemical CO or CO2 reduction is poor selectivity toward energetically rich products. In order to promote selectivity toward hydrocarbons and alcohols, most notably, the hydrogen evolution reaction (HER) should be suppressed. To achieve this goal...... 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...

  5. 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.

  6. 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

  7. Alternative alloys for catalysts and platinum jewelry? New structures in Pt-Hf and Pt-Mo

    Science.gov (United States)

    Gilmartin, Erin; Corbitt, Jacqueline; Hart, Gus

    2009-03-01

    The only known intermetallic structure with an 8:1 stoichiometry is that of Pt8Ti. It is intriguing that an ordered phase would occur at such low concentrations of the minority atom, but this structure occurs in about a dozen binary intermetallic systems. The formation of an ordered phase in an alloy can significantly enhance the performance of the material, particularly the hardness. We have taken a broad look at possible systems where this phase forms. Using first-principles, we calculated the stability of this structure relative to experimentally known phases for more than 80 Pt/Pd binary systems. We find the Pt8Ti structure is a possible ground state in more than 20 cases. Our experimental collaborators have verified our prediction in Pt-Mo and observed order-hardening in Pt-Hf. We discuss the discovery of new ground states that are likely to be verified experimentally and their impact on materials for Pt- and Pd-based catalysts and jewelry.

  8. 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.

  9. 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...

  10. 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....... Powder conductivity measurements were also performed, which showed the influence of the support particles in the packing of IrO2 particles, perhaps favouring the formation of channels and pores between particles, thus increasing the catalyst utilisation....... of the IrO2 particles, affecting the IrO2 particle size. The prepared catalysts were electrochemically characterised by cyclic voltammetry experiments at 25,80,120 and 150 °C. In accordance with the observed variation in particle size, a support loading of up to 20% improved the activity of the catalyst...

  11. Bifunctional Pt-Si Alloys for Small Organic Molecule Electro-oxidation

    DEFF Research Database (Denmark)

    Permyakova, Anastasia Aleksandrovna; Suntivich, Jin; Han, Binghong;

    Designing highly active catalysts for electro-oxidation of small organic molecules can help to reduce the anodic overpotential for more efficient utilization of hydrocarbon fuels. The challenge in developing more active electrocatalysts for electro-oxidation reactions is to satisfy the stringent...... adsorption site. We will discuss the enhanced activity of Pt-Si alloys for small organic molecule oxidation, which can be attributed to the improved CO electro-oxidation kinetics on Pt-Si....

  12. 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

  13. Nano-molybdenum carbide/carbon nanotubes composite as bifunctional anode catalyst for high-performance Escherichia coli-based microbial fuel cell.

    Science.gov (United States)

    Wang, Yaqiong; Li, Bin; Cui, Dan; Xiang, Xingde; Li, Weishan

    2014-01-15

    A novel electrode, carbon felt-supported nano-molybdenum carbide (Mo2C)/carbon nanotubes (CNTs) composite, was developed as platinum-free anode of high performance microbial fuel cell (MFC). The Mo2C/CNTs composite was synthesized by using the microwave-assisted method with Mo(CO)6 as a single source precursor and characterized by using X-ray diffraction and transmission electron microscopy. The activity of the composite as anode electrocatalyst of MFC based on Escherichia coli (E. coli) was investigated with cyclic voltammetry, chronoamperometry, and cell discharge test. It is found that the carbon felt electrode with 16.7 wt% Mo Mo2C/CNTs composite exhibits a comparable electrocatalytic activity to that with 20 wt% platinum as anode electrocatalyst. The superior performance of the developed platinum-free electrode can be ascribed to the bifunctional electrocatalysis of Mo2C/CNTs for the conversion of organic substrates into electricity through bacteria. The composite facilitates the formation of biofilm, which is necessary for the electron transfer via c-type cytochrome and nanowires. On the other hand, the composite exhibits the electrocatalytic activity towards the oxidation of hydrogen, which is the common metabolite of E. coli.

  14. 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

  15. 环境温度对Zn合金牺牲阳极性能的影响%Influence of Environmental Temperature on Electrochemical Properties of Zn Alloy Sacrificial Anode

    Institute of Scientific and Technical Information of China (English)

    华建社; 韩巍; 刘长瑞

    2011-01-01

    研究了Zn系合金阳极材料在不同环境介质中其电化学性能的变化,通过分析Zn系合金在3.5%NaCl溶液中的不同温度极化曲线,获得了环境温度对牺牲阳极材料性能影响的基本规律.结果表明,Zn-Al-Cd系合金在常温、50℃时,工作情况基本稳定,但当温度高于70℃时,Zn-Al-Cd电位比钢铁还高,钢铁腐蚀速率加快,即电位发生逆转,Zn-Al-Cd无法对钢铁再起到保护作用.%The changes of electrochemical properties of Zn alloy anode materials in different environmental media were studied. By analyzing the different temperature polarization curves of Zn department alloy in 3.5%NaCl solution, the basic law of the influence of environmental temperature on Zn alloy sacrificial anode materials was obtained. The results show that Zn-Al-Cd alloy performance at room temperature and 50 ℃ is stable basically. However, when temperature is above 70 ℃, the potential of Zn-Al-Cd is higher than that of the steel. The corrosion rate of the steel is accelerated, so Zn-Al-Cd can't play a protective effect on the steel.

  16. Noble metals on anodic TiO2 nanotubes mouths: Thermal dewetting of minimal Pt co-catalyst loading leads to significantly enhanced photocatalytic H2 generation

    CERN Document Server

    Nguyen, Nhat Truong; Yoo, JeongEun; Taccardi, Nicola; Schmuki, Patrik

    2016-01-01

    The least is the best. We introduce a technique to strongly reduce Pt use for photocatalytic hydrogen generation from TiO2 nanotubes. By site-selectively depositing thin layers of Pt only at the mouth of the nanotubes and by a subsequent thermal dewetting step, we achieve an outstanding photocatalytic improvement with minimal amounts of co-catalyst.

  17. 铝合金氧化膜的铝溶胶封孔工艺研究%Aluminium Sols Sealing of Al Alloy Anodized Film

    Institute of Scientific and Technical Information of China (English)

    孙玉凤; 周琦; 赫先醒; 才庆魁

    2011-01-01

    用铝溶胶对铝合金阳极氧化膜进行封孔处理是无铬、无氟并且无重金属的绿色环保新技术.通过双因素的方差分析和极差分析研究了异丙醇铝溶胶封闭膜耐酸性溶液腐蚀、耐盐雾和封闭膜的染色性能.通过正交试验研究了硝酸铝溶胶的染色性和耐酸性点滴液腐蚀的性能.试验在室温下,用低浓度且pH小于5的能稳定保存的两种铝溶胶进行的,封闭后膜层未经水洗,该工艺具有耗能小,封闭工艺简单的优点.试验结果表明,异丙醇铝溶胶的封闭膜性能优于硝酸铝溶胶膜,两种溶胶封闭膜耐酸性介质的腐蚀性能都优于蒸馏水封孔.%Chromium-free, fluorin-free and heavy metal-free aluminium sols sealing a new environmental-friendly green technology was used for sealing Al alloy anodized film. Corrosion resistance in acid solution and in salt spray and dyeing property of the film sealed by aluminium isopropoxide sol were studied by range and variance analyses. Corrosion resistance in acidic dropping test and dyeing property of the film sealed by aluminium nitrate sol were also studied by orthogonal test. All the experiments were carried out at room temperature and in lower concentration,lower pH sols( <5 for keeping the sols stable) ,and the sealed film neednt water rinsing, so this technology was simple and with lower energy consumption. Comparing the two sols,properties of the film sealed by aluminium isopropoxide sol is better than that by aluminium nitrate sol, and corrosion resistance of the film sealed by aluminium sols was superior to that by distilled water.

  18. 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

  19. 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.

  20. 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).

  1. Sodium citrate assisted facile synthesis of AuPd alloy networks for ethanol electrooxidation with high activity and durability

    Science.gov (United States)

    Zhai, Yanling; Zhu, Zhijun; Lu, Xiaolin; Zhou, H. Susan

    2016-10-01

    The direct ethanol fuel cell is an emerging energy conversion device for which palladium is considered as the one of the most effective components for anode catalyst, however, its widespread application has been still limited by the activity and durability of the anode catalyst. In this work, AuPd alloy networks (NWs) are synthesized using H2PdCl4 and HAuCl4 as precursors reduced by NaBH4 in the presence of sodium citrate (SC). The results reveal that SC plays significant role in network structure, resulting in the enhanced electrocatalytic activity of the catalyst. This self-supported AuPd NWs catalyst exhibits much higher electrochemical catalytic activity than commercial Pd/C catalyst toward ethanol electrooxidation in alkaline solution. Significantly, AuPd NWs catalyst shows extremely high durability at the beginning of the chronoamperometry test, and as high as 49% of the mass current density (1.41 A/mgPd) remains after 4000 s current-time test at -0.3 V (vs. Ag/AgCl) in N2-saturated KOH-ethanol solution. This strategy provides a facile method for the preparation of alloy networks with high electrochemical activity, and can be potentially expanded to a variety of electrochemical applications.

  2. Investigation of nano Pt and Pt-based alloys electrocatalysts for direct methanol fuel cells and their properties

    Directory of Open Access Journals (Sweden)

    Chunguang Suo

    2014-03-01

    Full Text Available The electrocatalysts used in micro direct methanol fuel cell (μDMFC, such as Pt/C and Pt alloy/C, prepared by liquid-phase NaBH4 reduction method have been investigated. XC-72 (Cobalt corp. Company, U.S.A is chosen as the activated carrier for the electrocatalysts to keep the catalysts powder in the range of several nanometers. The XRD, SEM, EDX analyses indicated that the catalysts had small particle size in several nanometers, in excellent dispersed phase and the molar ratio of the precious metals was found to be optimal. The performances of the DMFCs using cathodic catalyst with Pt percentage of 30wt% and different anodic catalysts (Pt-Ru, Pt-Ru-Mo were tested. The polarization curves and power density curves of the cells were measured to determine the optimal alloy composition and condition for the electrocatalysts. The results showed that the micro direct methanol fuel cell with 30wt% Pt/C as the cathodic catalyst and n(Pt:n(Ru:n(Mo = 3:2:2 PtRuMo/C as the anodic catalyst at room temperature using 2.0mol/L methanol solution has the best performances.

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

    Science.gov (United States)

    Sin, A.; Kopnin, E.; Dubitsky, Y.; Zaopo, A.; Aricò, A. S.; La Rosa, D.; Gullo, L. R.; Antonucci, V.

    An anodic cermet of NiCu alloy and gadolinia doped ceria has been investigated for CH 4 electro-oxidation in IT-SOFCs. Polarization curves have been recorded in the temperature range from 650 to 800 °C. A maximum power density of 320 mW cm -2 at 800 °C has been obtained in the presence of dry methane in an electrolyte-supported cell. The electrochemical behaviour during 1300 h operation in dry methane and in the presence of redox-cycles has been investigated at 750 °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.

  4. 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)

  5. 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

  6. 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.

  7. 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.

  8. 可溶性阳极电刷镀纳米晶Ni-Fe合金镀层的退火再强化%Annealing hardening of nanocrystalline Ni-Fe alloy coatings synthesized by brush plating using soluble anode

    Institute of Scientific and Technical Information of China (English)

    戴品强; 陈晓文; 项忠楠; 许伟长

    2009-01-01

    Nanocrystalline Ni-Fe alloy coatings were synthesized by brush plating using soluble anode. Microhardness test and techniques of XRD, SEM and TEM were applied to characterize the microstructures and mechanical properties of Ni-Fe alloy coatings. The results show that the microhardness of Ni-Fe alloy coatings increases with increasing annealing temperature and reaches a peak value at 200 ℃, showing a significant hardening during annealing. With further increasing annealing temperature, the microhardness decreases gradually, but the microhardness of the coating after being annealed at 400 ℃ is still as high as that of the as-deposited sample. The abnormal grain growth is not observed during annealing of Ni-Fe alloy coatings, which indicates a better thermal stability.%采用可溶性Ni阳极电刷镀方法制备纳米晶Ni-Fe合金镀层,利用XRD、SEM、TEM、显微硬度计等测试方法分析低温退火对镀层结构和性能的影响.结果表明:纳米晶Ni-Fe合金镀层的硬度随退火温度的升高而提高,在200 ℃时达到最大值,存在明显的退火再强化;继续提高退火温度导致镀层硬度降低;400 ℃退火后的镀层硬度与镀态的接近;纳米晶Ni-Fe合金镀层退火过程没有出现晶粒异常长大,表现出比纯Ni镀层更高的热稳定性.

  9. 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.

  10. 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.

  11. Near-surface alloys for hydrogen fuel cell applications

    DEFF Research Database (Denmark)

    Greeley, Jeffrey Philip; Mavrikakis, Manos

    2006-01-01

    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...... 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...

  12. 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.

  13. 镁合金阳极氧化膜腐蚀特性的红外显微成像分析%Studies on Corrosion Property of the Anodic Coating on the Mg Alloy by Micro-FTIR Mapping

    Institute of Scientific and Technical Information of China (English)

    李美超; 易景苗; 卢金金; 李静; 赵卫娟

    2014-01-01

    采用显微红外成像技术对镁合金阳极氧化膜表面的腐蚀特性进行了研究。镁合金在7.3 Wt%Na2 SO4溶液中浸泡后,表面氧化层中的部分M gO逐渐转化为M g (O H )2,进而发生溶解和脱落,使得镁合金失去保护作用。当浸泡时间达到2 h时,显微红外成像结果表明阳极氧化膜中Mg(OH)2的红外吸收信号最强,Mg(OH)2的含量最多。而4 h后Mg(OH)2的红外吸收信号开始减弱,Mg(OH)2开始减少,镁合金不断被腐蚀。氧化膜中另一成分Al2 O3随浸泡时间的显微红外成像信息与Mg(OH)2的变化规律相同。采用电化学阻抗谱技术对阳极氧化膜的阻抗进行测试,其阻抗随时间的变化特点基本符合氧化膜腐蚀规律。本研究对于镁合金阳极氧化膜的表征具有很好的指导作用和推广应用价值。%Micro-FTIR mapping technology was used to monitor the amount and distribution of Mg (OH)2 on the anodic coating of magnesium alloy which was immersed in the 7 .3 Wt% Na2 SO4 solution for different time .In the solution ,part of the MgO on the surface of the Mg alloy could gradually transform into Mg (OH)2 which could be detached from the Mg alloy surface and dis-solved into the solution .With immersion time of 2 h in 7 .3 Wt% Na2 SO4 solution 2h ,FTIR mapping results showed that FTIR absorption signal of Mg(OH)2 was strongest and Mg(OH)2 was most on the surface of the anodic coating .After 4 hours ,the content of Mg(OH)2 began to decrease ,and the Mg alloy was etched gradually .The FTIR mapping results of another compo-nent Al2O3 with immersion time were almost similar to those of Mg(OH)2 .The impedance of the oxide film was also analyzed using electrochemical impedance spectroscopy .It showed that the impedance changed with the immersion time and conformed to the corrosion law of the oxide coating .This research has a good guidance and application value for characterization of the anodic coating on

  14. 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.

  15. 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。

  16. 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

  17. 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)

  18. Effects of cerium on performance of Al-Zn-Sn sacrificial anode alloy%Ce对Al-Zn-Sn牺牲阳极合金性能的影响

    Institute of Scientific and Technical Information of China (English)

    贺俊光; 文九巴; 孙乐民; 高军伟; 李登辉

    2015-01-01

    采用扫描电镜(SEM)、X射线衍射(XRD)、动电位极化、电化学阻抗等方法研究了Ce含量对Al-7Zn-0.1Sn(质量分数,%)合金显微组织和电化学性能的影响。结果表明:Ce可明显细化晶粒,使Al-7Zn-0.1Sn合金从粗大枝状晶向细小等轴晶转变;适量的Ce可有效改善Al-7Zn-0.1Sn合金的电化学性能;随着Ce含量增加,合金电位负移、电流效率逐步提高;当 Ce 含量(质量分数)为0.5%时,合金具有最好的电化学性能,其电流效率相比Al-7Zn-0.1Sn 合金的提高10%。%The effects of cerium content on the microstructure and electrochemical performance of Al-7Zn-0.1Sn (mass fraction, %) alloy were investigated by scanning electron microscopy (SEM), X-ray diffractometry (XRD), potentiodynamic polarization and electrochemical impedance spectra measurements. The results show that cerium can refine the crystalline structure and make the microstructure of Al-7Zn-0.1Sn alloy transform from bulky dendrite grain to fine equiaxed grain. Proper cerium addition is effective on improving the electrochemical properties of Al-7Zn-0.1Sn alloy. The corrosion potential shifts negatively and the current efficiency increases with increasing the cerium content. The optimal electrochemical performance can be obtained when the Ce content in the alloy is 0.5%. The current efficiency of the Al-7Zn-0.1Sn-0.5Ce alloy increases by 10% than that of Al-7Zn-0.1Sn alloy.

  19. One-step synthesis of PtPdAu ternary alloy nanoparticles on graphene with superior methanol electrooxidation activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yuzhen; Gu Yonge; Lin Shaoxiong; Wei Jinping; Wang Zaihua [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Wang Chunming, E-mail: wangcm@lzu.edu.cn [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Du Yongling; Ye Weichun [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China)

    2011-10-01

    Highlights: > PtPdAu nanoparticles were synthesized on graphene sheets via chemical reduction method. > The prepared PtPdAu nanoparticles were ternary alloy with fcc structure. > The catalyst exhibited superior catalytic activity and stability for MOR in alkaline. - Abstract: Well-dispersed PtPdAu ternary alloy nanoparticles were synthesized on graphene sheets via a simple one-step chemical reduction method in ethylene glycol (EG) and water system, in which EG served as both reductive and dispersing agent. The electrocatalytic activity of PtPdAu/G was tested by methanol oxidation reaction (MOR). The catalyst was further characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), which indicated that the as-synthesized PtPdAu nanoparticles with alloy structures were successfully dispersed on the graphene sheets. Electrocatalytic properties of the catalyst for MOR in alkaline have been investigated by cyclic voltammetry (CV), chronoamperometry and Tafel curves. The electrocatalytic activity and stability of PtPdAu/G were superior to PtPd/G, PtAu/G and Pt/G. In addition, the anodic peak current on PtPdAu/G catalyst was proportional to the concentration of methanol in the range of 0.05-1.00 M. This study implies that the prepared catalyst have great potential applications in fuel cells.

  20. 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

  1. 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

  2. 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...

  3. 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.

  4. Palladium-Based Catalysts as Electrodes for Direct Methanol Fuel Cells: A Last Ten Years Review

    Directory of Open Access Journals (Sweden)

    Juan Carlos Calderón Gómez

    2016-08-01

    Full Text Available Platinum-based materials are accepted as the suitable electrocatalysts for anodes and cathodes in direct methanol fuel cells (DMFCs. Nonetheless, the increased demand and scarce world reserves of Pt, as well as some technical problems associated with its use, have motivated a wide research focused to design Pd-based catalysts, considering the similar properties between this metal and Pt. In this review, we present the most recent advancements about Pd-based catalysts, considering Pd, Pd alloys with different transition metals and non-carbon supported nanoparticles, as possible electrodes in DMFCs. In the case of the anode, different reported works have highlighted the capacity of these new materials for overcoming the CO poisoning and promote the oxidation of other intermediates generated during the methanol oxidation. Regarding the cathode, the studies have showed more positive onset potentials, as fundamental parameter for determining the mechanism of the oxygen reduction reaction (ORR and thus, making them able for achieving high efficiencies, with less production of hydrogen peroxide as collateral product. This revision suggests that it is possible to replace the conventional Pt catalysts by Pd-based materials, although several efforts must be made in order to improve their performance in DMFCs.

  5. 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.

  6. 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

  7. Oxidation catalyst

    Science.gov (United States)

    Ceyer, Sylvia T.; Lahr, David L.

    2010-11-09

    The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

  8. 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...

  9. Modeling of the anode side of a direct methanol fuel cell with analytical solutions

    CERN Document Server

    Mosquera, Martín A

    2010-01-01

    In this work, analytical solutions were derived (for any methanol oxidation reaction order) for the profiles of methanol concentration and proton current density by assuming diffusion mass transport mechanism, Tafel kinetics, and fast proton transport in the anodic catalyst layer of a direct methanol fuel cell. An expression for the Thiele modulus that allows to express the anodic overpotential as a function of the cell current, and kinetic and mass transfer parameters was obtained. For high cell current densities, it was found that the Thiele modulus ($\\phi^2$) varies quadratically with cell current density; yielding a simple correlation between anodic overpotential and cell current density. Analytical solutions were derived for the profiles of both local methanol concentration in the catalyst layer and local anodic current density in the catalyst layer. Under the assumptions of the model presented here, in general, the local methanol concentration in the catalyst layer cannot be expressed as an explicit fun...

  10. 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.

  11. 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...

  12. 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.

  13. Cu-Ni-Fe anodes having improved microstructure

    Science.gov (United States)

    Bergsma, S. Craig; Brown, Craig W.

    2004-04-20

    A method of producing aluminum in a low temperature electrolytic cell containing alumina dissolved in an electrolyte. The method comprises the steps of providing a molten electrolyte having alumina dissolved therein in an electrolytic cell containing the electrolyte. A non-consumable anode and cathode is disposed in the electrolyte, the anode comprised of Cu--Ni--Fe alloys having single metallurgical phase. Electric current is passed from the anode, through the electrolyte to the cathode thereby depositing aluminum on the cathode, and molten aluminum is collected from the cathode.

  14. 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.

  15. 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...

  16. 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.

  17. Releasing metal catalysts via phase transition: (NiO)0.05-(SrTi0.8Nb0.2O3)0.95 as a redox stable anode material for solid oxide fuel cells.

    Science.gov (United States)

    Xiao, Guoliang; Wang, Siwei; Lin, Ye; Zhang, Yanxiang; An, Ke; Chen, Fanglin

    2014-11-26

    Donor-doped perovskite-type SrTiO3 experiences stoichiometric changes at high temperatures in different Po2 involving the formation of Sr or Ti-rich impurities. NiO is incorporated into the stoichiometric strontium titanate, SrTi0.8Nb0.2O3-δ (STN), to form an A-site deficient perovskite material, (NiO)0.05-(SrTi0.8Nb0.2O3)0.95 (Ni-STN), for balancing the phase transition. Metallic Ni nanoparticles can be released upon reduction instead of forming undesired secondary phases. This material design introduces a simple catalytic modification method with good compositional control of the ceramic backbones, by which transport property and durability of solid oxide fuel cell anodes are largely determined. Using Ni-STN as anodes for solid oxide fuel cells, enhanced catalytic activity and remarkable stability in redox cycling have been achieved. Electrolyte-supported cells with the cell configuration of Ni-STN-SDC anode, La0.8Sr0.2Ga0.87Mg0.13O3 (LSGM) electrolyte, and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode produce peak power densities of 612, 794, and 922 mW cm(-2) at 800, 850, and 900 °C, respectively, using H2 as the fuel and air as the oxidant. Minor degradation in fuel cell performance resulted from redox cycling can be recovered upon operating the fuel cells in H2. Such property makes Ni-STN a promising regenerative anode candidate for solid oxide fuel cells.

  18. Effect of heat treatment on the activity and stability of carbon supported PtMo alloy electrocatalysts for hydrogen oxidation in proton exchange membrane fuel cells

    Science.gov (United States)

    Hassan, Ayaz; Carreras, Alejo; Trincavelli, Jorge; Ticianelli, Edson Antonio

    2014-02-01

    The effect of heat treatment on the activity, stability and CO tolerance of PtMo/C catalysts was studied, due to their applicability in the anode of proton exchange membrane fuel cells (PEMFCs). To this purpose, a carbon supported PtMo (60:40) alloy electrocatalyst was synthesized by the formic acid reduction method, and samples of this catalyst were heat-treated at various temperatures ranging between 400 and 700 °C. The samples were characterized by temperature programmed reduction (TPR), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), cyclic voltammetry (CV), scanning electron microscopy (SEM) and wavelength dispersive X-ray spectroscopy (WDS). Cyclic voltammetry was used to study the stability, and polarization curves were used to investigate the performance of all materials as CO tolerant anode on a PEM single cell text fixture. The catalyst treated at 600 °C, for which the average crystallite size was 16.7 nm, showed the highest hydrogen oxidation activity in the presence of CO, giving an overpotential induced by CO contamination of 100 mV at 1 Acm-2. This catalyst also showed a better stability up to 5000 potential cycles of cyclic voltammetry, as compared to the untreated catalyst. CV, SEM and WDS results indicated that a partial dissolution of Mo and its migration/diffusion from the anode to the cathode occurs during the single cell cycling. Polarization results showed that the catalytic activity and the stability can be improved by a heat treatment, in spite of a growth of the catalyst particles.

  19. 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

  20. 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...

  1. 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...

  2. 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...

  3. 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......, 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....

  4. Microstructure and optical appearance of anodized friction stir processed Al - Metal oxide surface composites

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Jensen, Flemming; Bordo, Kirill;

    2014-01-01

    Multiple-pass friction stir processing (FSP) was employed to impregnate Ti, Y and Ce oxide powders into the surface of an Aluminium alloy. The FSP processed surface composite was subsequently anodized with an aim to develop optical effects in the anodized layer owing to the presence of incorporated...

  5. 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...

  6. 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

  7. 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.

  8. 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.

  9. In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

    Science.gov (United States)

    Bertram, F.; Zhang, F.; Evertsson, J.; Carlà, F.; Pan, J.; Messing, M. E.; Mikkelsen, A.; Nilsson, J.-O.; Lundgren, E.

    2014-07-01

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  10. In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bertram, F., E-mail: florian.bertram@sljus.lu.se; Evertsson, J.; Messing, M. E.; Mikkelsen, A.; Lundgren, E. [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Zhang, F.; Pan, J. [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas väg 51, 10044 Stockholm (Sweden); Carlà, F. [ESRF, B. P. 220, 38043 Grenoble (France); Nilsson, J.-O. [Sapa Technology, Kanalgatan 1, 612 31 Finspång (Sweden)

    2014-07-21

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  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. Catalysts for oxidation of mercury in flue gas

    Science.gov (United States)

    Granite, Evan J.; Pennline, Henry W.

    2010-08-17

    Two new classes of catalysts for the removal of heavy metal contaminants, especially mercury (Hg) from effluent gases. Both of these classes of catalysts are excellent absorbers of HCl and Cl.sub.2 present in effluent gases. This adsorption of oxidizing agents aids in the oxidation of heavy metal contaminants. The catalysts remove mercury by oxidizing the Hg into mercury (II) moieties. For one class of catalysts, the active component is selected from the group consisting of iridium (Ir) and iridum-platinum (Ir/Pt) alloys. The Ir and Ir/Pt alloy catalysts are especially corrosion resistant. For the other class of catalyst, the active component is partially combusted coal or "Thief" carbon impregnated with Cl.sub.2. Untreated Thief carbon catalyst can be self-activating in the presence of effluent gas streams. The Thief carbon catalyst is disposable by means of capture from the effluent gas stream in a particulate collection device (PCD).

  13. 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%.

  14. 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.% ...

  15. 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...

  16. 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

  17. 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

  18. Evaluation of anode (electro)catalytic materials for the direct borohydride fuel cell: Methods and benchmarks

    Science.gov (United States)

    Olu, Pierre-Yves; Job, Nathalie; Chatenet, Marian

    2016-09-01

    In this paper, different methods are discussed for the evaluation of the potential of a given catalyst, in view of an application as a direct borohydride fuel cell DBFC anode material. Characterizations results in DBFC configuration are notably analyzed at the light of important experimental variables which influence the performances of the DBFC. However, in many practical DBFC-oriented studies, these various experimental variables prevent one to isolate the influence of the anode catalyst on the cell performances. Thus, the electrochemical three-electrode cell is a widely-employed and useful tool to isolate the DBFC anode catalyst and to investigate its electrocatalytic activity towards the borohydride oxidation reaction (BOR) in the absence of other limitations. This article reviews selected results for different types of catalysts in electrochemical cell containing a sodium borohydride alkaline electrolyte. In particular, propositions of common experimental conditions and benchmarks are given for practical evaluation of the electrocatalytic activity towards the BOR in three-electrode cell configuration. The major issue of gaseous hydrogen generation and escape upon DBFC operation is also addressed through a comprehensive review of various results depending on the anode composition. At last, preliminary concerns are raised about the stability of potential anode catalysts upon DBFC operation.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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…

  11. Anodes for Solid Oxide Fuel Cells Operating at Low Temperatures

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain

    . 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......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......, an investigation on the effect of application of cathodic polarization on Ni-YSZ anodes is described....

  12. 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.

  13. 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.

  14. 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.

  15. Combined high-pressure cell-ultrahigh vacuum system for fast testing of model metal alloy catalysts using scanning mass spectrometry

    DEFF Research Database (Denmark)

    Johansson, Martin; Jørgensen, Jan Hoffmann; Chorkendorff, Ib

    2004-01-01

    and gas sampling device over the sample surface. The gas sampled is analyzed with mass spectrometry. Experiments can be made at pressures up to 1 bar and temperatures up to 500 °C. It is shown that the lateral resolution is better than 0.2 mm and that up to 20 circular spots, 1 mm in diameter, can...... techniques available are scanning electron microscopy, x-ray photoemission spectroscopy, ion scattering spectroscopy, Auger electron spectroscopy, sputter profiling, and temperature programmed desorption. The catalytic activity of the model catalysts is tested individually by scanning a combined gas delivery...... be studied on a substrate 10 mm in diameter. A high pressure cell with an all-metal sealed ultrahigh vacuum lock is also described as part of the work. ©2004 American Institute of Physics....

  16. 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...

  17. 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).

  18. 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.

  19. 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)

  20. 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.

  1. 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)

  2. 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.

  3. 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.

  4. Urchin-Like Amorphous Ni2B Alloys: Efficient Antibacterial Materials and Catalysts for Hydrous Hydrazine Decomposition to Produce H2.

    Science.gov (United States)

    Deng, Miao; Fu, Shi Yan; Yang, Fan; Wu, Ping; Tong, Dong Ge

    2016-03-01

    Urchin-like amorphous Ni2B alloys were successfully prepared for the first time from a mixture of Ni(NH3)6(2+) and polyvinyl alcohol (PVA) via a solution plasma process (SPP). The as-synthesized samples were characterized by X-ray powder diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES) X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), selected-area electron diffraction patterns (SAED) and nitrogen adsorption-desorption isotherms. In the performance test, the obtained Ni-B urchins showed great antibacterial activities, comparable with those of amikacin and kanamycin, especially towards Pseudomonas aeruginosa (P. aeruginosa). Meanwhile, the magnetic properties of Ni-B urchins are enhanced in comparison with those of conventional Ni-B. During hydrous hydrazine (N2H4) decomposition, the dehydrogenation performance of Ni-B urchins is superior to those of Raney Ni and conventional Ni-B. The enhanced catalytic performance of Ni-B urchins is attributed to their high surface area of active species nickel and the enhanced intrinsic activity resulting from their unique structure. PMID:27455647

  5. 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.

  6. 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.

  7. Friction coefficient and microhardness of anodized aluminum alloys under different elaboration conditions%不同加工条件下阳极化铝合金的摩擦因数和显微硬度

    Institute of Scientific and Technical Information of China (English)

    M GUEZMIL; W BENSALAH; A KHALLADI; K ELLEUCH; M DEPETRIS-WERY; HF AYEDI

    2015-01-01

    研究电解液、电流密度和温度等阳极化条件对在Al 5745和Al 1050A基质上形成的氧化膜层摩擦因数和维氏硬度的影响。采用DELTALAB HVS−1000维氏硬度计和旋转销盘摩擦试验机测量样品的硬度和摩擦性能。结果表明:当草酸浓度为10 g/L、电流密度为3 A/dm2及温度为5°C时,样品获得最高的维氏硬度(>HV 400)和最低的摩擦因数(HV 400) and the lowest friction coefficient (<0.4) were obtained with the oxalic acid addition of 10 g/L at high current density of 3 A/dm2 and low temperature of 5 °C. The presence of oxidized Mg through the anodic oxide layer formed on Al 5754 was examined using glow-discharge optical emission spectroscopy (GDOES). The MgO was found to act negatively on the mechanical property of the layer. Finally, the scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and atomic force microscopy (AFM) were used to characterize the anodic layer before and after friction tests. It is found that the wear mechanism is related to many aspects of the initial morphology, chemical composition of the layer (C, S and Mg), porosity and internal stress.

  8. 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 ...

  9. 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

  10. Studies on black anodic coatings for spacecraft thermal control applications

    Energy Technology Data Exchange (ETDEWEB)

    Uma Rani, R.; Subba Rao, Y.; Sharma, A.K. [ISRO Satellite Centre, Bangalore (India). Thermal Systems Group

    2011-10-15

    An inorganic black colouring process using nickel sulphate and sodium sulphide was investigated on anodized aluminium alloy 6061 to provide a flat absorber black coating for spacecraft thermal control applications. Influence of colouring process parameters (concentration, pH) on the physico-optical properties of black anodic film was investigated. The nature of black anodic film was evaluated by the measurement of film thickness, micro hardness and scanning electron microscopy (SEM). Energy dispersive X-ray spectroscopy studies confirmed the presence of nickel and sulphur in the black anodic coating. Electrochemical impedance spectroscopy (EIS) was used to evaluate the corrosion resistance of the coating. The environmental tests, namely, humidity, corrosion resistance, thermal cycling and thermo vacuum performance tests were used to evaluate the space worthiness of the coating. Optical properties of the film were measured before and after each environmental test to ascertain its stability in harsh space environment. The black anodic films provide higher thermal emittance ({proportional_to} 0.90) and solar absorptance ({proportional_to} 0.96) and their high stability during the environmental tests indicated their suitability for space and allied applications. (orig.)

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. Assembly of a Cost-Effective Anode Using Palladium Nanoparticles for Alkaline Fuel Cell Applications

    Science.gov (United States)

    Feliciano-Ramos, Ileana; Casan~as-Montes, Barbara; García-Maldonado, María M.; Menendez, Christian L.; Mayol, Ana R.; Díaz-Vazquez, Liz M.; Cabrera, Carlos R.

    2015-01-01

    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…

  1. Catalyst composition

    Energy Technology Data Exchange (ETDEWEB)

    Onodera, T.; Sakai, T.; Sumitani, K.; Yamasaki, Y.

    1984-11-27

    A catalyst composition comprising a crystalline aluminosilicate selected from the group consisting of zeolite ZSM-5, zeolite ZSM-11, zeolite ZSM-12, zeolite ZSM-35 and zeolite ZSM-38 and having a silica/alumina mole ratio of 20 to 1,000; and at least two metals which are platinum and at least one other metal selected from the group consisting of titanium, chromium, zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, palladium, tin, barium, cerium, tungsten, osmium, lead, cadmium, mercury, indium, lanthanum and beryllium. This catalyst composition is useful particularly for the isomerization of aromatic hydrocarbons and reforming of naphtha.

  2. 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.

  3. 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.

  4. 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.

  5. 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...

  6. 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.

  7. 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.

  8. 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

  9. Biocorrosion study of titanium-nickel alloys.

    Science.gov (United States)

    Chern Lin, J H; Lo, S J; Ju, C P

    1996-02-01

    The present study provides results of the corrosion behaviour in Hank's physiological solution and some other properties of three Ti-Ni alloys with 18, 25 and 28.4 wt% Ni, respectively. Results indicate that alpha-titanium and Ti2Ni were the two major phases in all three Ti-Ni alloys. The relative amount of the Ti2Ni phase increased with additional Ni content. Hardness of the Ti-Ni alloys also increased with added nickel content, ranging from 310 to 390 VHN, similar to the hardness of enamel. Melting temperatures of the Ti-Ni alloys were all lower than that of pure titanium by least 600 degrees C. The three Ti-Ni alloys behaved almost identically when potentiodynamically polarized in Hank's solution at 37 degrees C. The critical anodic current densities of the alloys were nearly 30 microA/cm2 and the breakdown potentials were all above 1100 mV (SCE).

  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. 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.

  12. 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

  13. 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.

  14. 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...

  15. 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.

  16. Reduced Graphene Oxide/Tin-Antimony Nanocomposites as Anode Materials for Advanced Sodium-Ion Batteries.

    Science.gov (United States)

    Ji, Liwen; Zhou, Weidong; Chabot, Victor; Yu, Aiping; Xiao, Xingcheng

    2015-11-11

    Reduced graphene oxides loaded with tin-antimony alloy (RGO-SnSb) nanocomposites were synthesized through a hydrothermal reaction and the subsequent thermal reduction treatments. Transmission electron microscope images confirm that SnSb nanoparticles with an average size of about 20-30 nm are uniformly dispersed on the RGO surfaces. When they were used as anodes for rechargeable sodium (Na)-ion batteries, these as-synthesized RGO-SnSb nanocomposite anodes delivered a high initial reversible capacity of 407 mAh g(-1), stable cyclic retention for more than 80 cycles and excellent cycle stability at ultra high charge/discharge rates up to 30C. The significantly improved performance of the synthesized RGO-SnSb nanocomposites as Na-ion battery anodes can be attributed to the synergetic effects of RGO-based flexible framework and the nanoscale dimension of the SnSb alloy particles (batteries.

  17. 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

  18. 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.

  19. 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.

  20. Alternate Anodes for the Electrolytic Reduction of UO2

    Science.gov (United States)

    Merwin, Augustus; Chidambaram, Dev

    2015-01-01

    The electrolytic reduction process of UO2 employs a platinum anode and a stainless steel cathode in molten LiCl-LiO2 maintained at 973 K (700 °C). The degradation of platinum under the severely oxidizing conditions encountered during the process is an issue of concern. In this study, Inconel 600 and 718, stainless steel alloy 316, tungsten, nickel, molybdenum, and titanium, were investigated though electrochemical polarization techniques, electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy to serve as potential anode materials. Of the various materials investigated, only tungsten exhibited sufficient stability at the required potential in the molten electrolyte. Tungsten anodes were further studied in molten LiCl-LiO2 electrolyte containing 2, 4, and 6 wt pct of Li2O. In LiCl-2 wt pct Li2O tungsten was found to be sufficiently stable to both oxidation and microstructural changes and the stability is attributed to the formation of a lithium-intercalated tungsten oxide surface film. Increase in the concentration of Li2O was found to lead to accelerated corrosion of the anode, in conjunction with the formation of a peroxotungstate oxide film.

  1. 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)

  2. Multi-anode ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Bolotnikov, Aleksey E. (South Setauket, NY); Smith, Graham (Port Jefferson, NY); Mahler, George J. (Rocky Point, NY); Vanier, Peter E. (Setauket, NY)

    2010-12-28

    The present invention includes a high-energy detector having a cathode chamber, a support member, and anode segments. The cathode chamber extends along a longitudinal axis. The support member is fixed within the cathode chamber and extends from the first end of the cathode chamber to the second end of the cathode chamber. The anode segments are supported by the support member and are spaced along the longitudinal surface of the support member. The anode segments are configured to generate at least a first electrical signal in response to electrons impinging thereon.

  3. 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 combinatio...... meaningful for everyone. The exhibited works are designed by SANAA, Diller Scofidio + Renfro, James Corner Field Operation, JBMC Arquitetura e Urbanismo, Atelier Bow-Wow, Ateliers Jean Nouvel, COBE, Transform, BIG, Topotek1, Superflex, and by visual artist Jane Maria Petersen....

  4. Environmental friendly plasma electrolytic oxidation of AM60 magnesium alloy and its corrosion resistance

    Institute of Scientific and Technical Information of China (English)

    CAO Fa-he; LIN Long-yong; ZHANG Zhao; ZHANG Jian-qing; CAO Chu-nan

    2008-01-01

    Plasma electrolytic oxidation of Mg-based AM60 alloys was investigated using 50 Hz AC anodizing technique in an alkaline borate solution, which contained a new kind of organic. The anodic film is relatively smooth with some micro pores and cracks, while the anodic film consists of MgO, MgAl2O4 and MgSiO3. The electrochemical behavior of anodic film was studied by electrochemical impedance spectroscopy and potentiodynamic polarization. Polarization results indicate the PEO treatment can decrease corrosion current by 3-4 magnitude compared with blank AM60 alloy. The anodic film presents a good level of corrosion protection for AM60 magnesium alloy, over 272 h of the salt spray test based on ASTM B117. The effect of micro-structure and composition on corrosion protection efficiency was also investigated.

  5. 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)

  6. Galvanic corrosion of selected dental alloys.

    Science.gov (United States)

    Karov, J; Hinberg, I

    2001-03-01

    Samples prepared from three different amalgam brands were coupled to two gold alloys and orthodontic brackets. In the resulting galvanic cells, the amalgam coupled to gold were anodic, exhibiting galvanic current densities about one order of magnitude higher than the uncoupled corrosion current densities of 0.2-0.5 microA. Coupling amalgams to orthodontic brackets resulted in galvanic current densities of the same magnitude as the uncoupled samples. Corrosion current densities at the anode were found to be up to six times higher than the measured galvanic current densities. Brushing caused transient increases in galvanic current densities that decayed within 100 s to the previous steady state levels. Brushing of amalgam/bracket couples, caused an anodic peak followed by brief polarization reversal during which the brackets were anodic.

  7. 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)

  8. 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.

  9. Preparation and Properties of Anode Electrophoresis Extinction Coatings for Aluminum Alloy%铝型材阳极电泳消光涂料的合成与性能

    Institute of Scientific and Technical Information of China (English)

    区菊花; 张敏; 杨永; 干建群; 哈成勇

    2013-01-01

    An acrylic-polyurethane resin was prepared by an emulsion polymerization using potassium persulfate as initiator. The results show that emulsion has best properties under the condition of semi-continuous addition, 0.6% initiator potassium persulfate of the total monomer, reaction temperature of 353K. Fourier transform infrared spectroscopy (FT-IR) indicates that the polymer presents a copolymer structure. The transmission electron microscopy (TEM) images show that the composite latex particles obtained by semi-continuous dropping polymerization have a clear core-shell structure. After neutralized by N,N-dimethyl ethanolamine, composite latex particles are found to show micro-phase separation. The gloss of the coating on aluminum alloy by electrophoresis is below 10 (60°). The heat resistance, impact resistance and adhesion performance of the acrylic-polyurethane resin reach industry standards, which can be applied to the matting field of electrophoresis.%以丙烯酸酯和聚氨酯为原料,过硫酸钾为引发剂进行乳液聚合得到一种阴离子消光电泳涂料,研究了合成工艺、引发剂用量、反应温度对合成的影响.结果显示,采用半连续滴加法,引发剂过硫酸钾的用量为单体总量的0.6%,反应温度353K得到的乳液性能最优.通过红外光谱确认产物呈现共聚结构,透射电子显微镜结果显示,采用半连续滴加法制备的复合物呈现清晰的核壳结构,加入N,N-二甲基乙醇胺中和丙烯酸树脂上的羧基后,复合乳胶粒出现一定的微相分离.利用所得到的涂料进行电泳后涂膜光泽10(60°)以下,耐热性、耐冲击、附着力等性能达到行业标准,可应用于消光电泳涂料领域.

  10. 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.

  11. 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)

  12. 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.

  13. 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.

  14. PROPERTIES OF POLYMER SUPPORTED Ni-Cu BIMETALLIC CATALYSTS PREPARED BY SOLVATED METAL ATOM IMPREGNATION

    Institute of Scientific and Technical Information of China (English)

    WU Shihua; ZHU Changying; HUANG Wenqiang

    1996-01-01

    D-72 resin supported nickel-copper catalysts prepared by solvated metal atom impregnation (SMAI) were studied by magnetic measurements and X-ray photoelectron spectroscopy (XPS). The Ni particles on the catalysts are very highly dispersed and display superparamagnetic behaviour. Ni-Cu alloy clusters were found to be formed. The surface compositions are different from the bulk concentrations. In contrast with the surface enrichment in copper generally observed on conventional Ni-Cu catalysts, the surfaces of these catalysts are enriched in nickel. The nickel is in both zero and valent states, while copper is mainly in metallic state. Catalytic data show that the formation of Ni-Cu alloy clusters has a profound effect on the catalytic activities of the catalysts in the hydrogenation of furfural. The activity of the Ni:Cu ratio of one bimetallic catalysts is much higher than that of the Ni or Cu monometallic catalyst.

  15. 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.

  16. High capacity anode materials for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. 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.

  18. 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.

  19. 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 ...

  20. 微波辅助雷尼镍-铝合金催化剂催化1,4-二氯苯快速脱氯反应动力学研究%In-situ Rapid Dechlorination by Microwave-assisted Catalytic Reduction of Chlorobenzene and 1,4-dichlorobenzene on Raney Ni-Al alloy Catalyst

    Institute of Scientific and Technical Information of China (English)

    陈志明; 莫招育; 吕保樱; 谢鸿; 唐丽; 林华

    2013-01-01

    Microwave-assisted catalytic rednctive dechlorination on Raney Ni-Al alloy catalyst is an efficient method for chlorobenzene (CB) and 1,4-dichlorobenzene (1,4-DCB) treatment. The result showed that the Raney Ni-Al alloy catalyst retains its high activity in this in-situ reductive dechlorination reaction. This reductive dechlorination reaction was in accordance of the psendo-second-order reaction kinetics under microwave irradiation. The activation energy (Ea) was 76.24 kj/mol. And the constant of 1,4-DCB dechlorination was 0.037 6 (35 ℃ ) and 0.151 mol/(L · min) (50 ℃) , and the activation energy (Ea) was 76. 66 kj/mol. Rapid and complete dechlorination which was achieved for CB and 1,4-DCB was obtained at close to ambient conditions. And it was showed that microwave-assisted catalytic in-situ reductive dechlorination on Raney Ni-Al alloy catalyst was an effective method to rapid and complete dechlorination for polychlorinated organic compounds.%利用雷尼镍-铝合金催化剂的高催化活性,提出了使用微波辅助雷尼镍-铝合金催化1,4-二氯苯还原脱氯的方法.结果表明,在微波辅助雷尼镍-铝合金催化剂条件下,1,4-二氯苯还原脱氯的反应符合二级反应动力学方程.1,4-二氯苯脱氯的反应速率常数k1在35和50℃下分别为0.037 6和0.151 mol/(L·min),反应活化能为76.66 kJ/mol.研究还表明,在微波辅助雷尼镍-铝合金催化剂的条件下,35℃时,1,4-二氯苯10 min脱氯率达到90%,并且反应同时脱掉两个氯,能达到高效脱氯的目的.由此可知,微波辅助雷尼镍-铝合金催化脱氯的方法应用于多氯苯类物质脱氯取得良好的效果.

  1. Study of localized corrosion in aluminum alloys by the scanning reference electrode technique

    Science.gov (United States)

    Danford, M. D.

    1995-01-01

    Localized corrosion in 2219-T87 aluminum (Al) alloy, 2195 aluminum-lithium (Al-Li) alloy, and welded 2195 Al-Li alloy (4043 filler) have been investigated using the relatively new scanning reference electrode technique (SRET). Anodic sites are more frequent and of greater strength in the 2195 Al-Li alloy than in the 2219-T87 Al alloy, indicating a greater tendency toward pitting for the latter. However, the overall corrosion rates are about the same for these two alloys, as determined using the polarization resistance technique. In the welded 2195 Al-Li alloy, the weld bean is entirely cathodic, with rather strongly anodic heat affected zones (HAZ) bordering both sides, indicating a high probability of corrosion in the HAZ parallel to the weld bead.

  2. Research Update: Nickel filling in nanofeatures using supercritical fluid and its application to fabricating a novel catalyst structure for continuous growth of nanocarbon fibers

    Directory of Open Access Journals (Sweden)

    Mitsuhiro Watanabe

    2014-10-01

    Full Text Available A novel catalyst structure for continuous growth of nanocarbon fibers is proposed. In this structure, catalyst nanofibers are embedded in a membrane that separates the growth ambient into carbon-supplying and carbon-precipitating environments. The catalyst nanofibers pierce through the membrane so that carbon source gas is supplied only to one end of the catalyst fibers and nanocarbon fibers grow continuously at the other end. To realize this structure, self-supporting anodized alumina was used as a membrane, and its nano-through-holes were filled with catalyst Ni in supercritical CO2 fluid. Direct carbon growth from the Ni nanofibers was confirmed using this catalyst structure.

  3. 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.

  4. 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.;

    2010-01-01

    -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....

  5. Porous Anodic Aluminum Oxide with Serrated Nanochannels

    Science.gov (United States)

    Li, Dongdong; Zhao, Liang; Lu, Jia G.

    2010-03-01

    Self-assembled nanoporous anodic aluminum oxide (AAO) membrane with straight channels has long been an important tool in synthesizing highly ordered and vertically aligned quasi-1D nanostructures for various applications. Recently shape-selective nanomaterials have been achieved using AAO as a template. It is envisioned that nanowires with multi-branches will significantly increase the active functional sites for applications as sensors, catalysts, chemical cells, etc. Here AAO membranes with serrated nanochannels have been successfully fabricated via a two-step annodization method. The serrated channels with periodic intervals are aligned at an angle of ˜25^circ along the stem channels. The formation of the serrated channels is attributed to the evolution of oxygen gas bubbles and the resulted plastic deformation in oxide membrane. In order to reveal the inside channel structure, Platinum are electrodeposited into the AAO template. The as-synthesized serrated Pt nanowires demonstrate a superior electrocatalytic activity. This is attributed to the enhanced electric field strength around serrated tips as shown in the electric field simulation by COMOSL. Moreover, hierarchical serrated/straight hybrid structures can be constructed using this simple and novel self assembly technique.

  6. Effect of Oxide Inclusions on Electrochemical Properties of Aluminium Sacrificial Anodes

    Institute of Scientific and Technical Information of China (English)

    M. Emamy; A. Keyvani; M. Mahta; J. Campbell

    2009-01-01

    Oxide films are incorporated into melts by an entrainment process, and are expected to be present in most metals, but particularly cast Al alloys. The oxides are necessarily present as folded-over double films (bifilms) that are effectively cracks. Their effect on the electrochemical behaviour of cast Al-5Zn-0.02ln sacrificial anodes was studied in 3 wt pct sodium chloride solution using the NACE efficiency evaluation. Three methods were employed to entrain progressive amounts of oxide in the alloy, including the addition of Al-Zn-ln maching chips to the charge, increasing the pouring height, and agitating the melt. The introduction of oxide bifilms in the cast alloy resulted in the deterioration of the electrochemical properties of the sacrificial anodes, such as current capacity and anode efficiency, and introduced increasing variability in these properties. The results suggest that corrosion behaviour is strongly related to the presence of bifilms suspended in the liquid alloy because bifilms provide crack paths allowing the corrodant to penetrate deeply into the metal matrix, and simultaneously provide localized galvanic cells because of the precipitation of Fe rich intermetallic compounds on their outer surfaces.

  7. 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.

  8. Electrochemical catalyst recovery method

    Science.gov (United States)

    Silva, Laura J.; Bray, Lane A.

    1995-01-01

    A method of recovering catalyst material from latent catalyst material solids includes: a) combining latent catalyst material solids with a liquid acid anolyte solution and a redox material which is soluble in the acid anolyte solution to form a mixture; b) electrochemically oxidizing the redox material within the mixture into a dissolved oxidant, the oxidant having a potential for oxidation which is effectively higher than that of the latent catalyst material; c) reacting the oxidant with the latent catalyst material to oxidize the latent catalyst material into at least one oxidized catalyst species which is soluble within the mixture and to reduce the oxidant back into dissolved redox material; and d) recovering catalyst material from the oxidized catalyst species of the mixture. The invention is expected to be particularly useful in recovering spent catalyst material from petroleum hydroprocessing reaction waste products having adhered sulfides, carbon, hydrocarbons, and undesired metals, and as well as in other industrial applications.

  9. 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

  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. 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.

  13. Platinum and Palladium Alloys Suitable as Fuel Cell Electrodes

    DEFF Research Database (Denmark)

    2011-01-01

    and innovative catalyst compositions in fuel cell electrodes. The novel electrode catalysts of the invention comprise a noble metal selected from Pt, Pd and mixtures thereof alloyed with a further element selected from Sc, Y and La as well as any mixtures thereof, wherein said alloy is supported on a conductive......The present invention concerns electrode catalysts used in fuel cells, such as proton exchange membrane (PEM) fuel cells. The invention is related to the reduction of the noble metal content and the improvement of the catalytic efficiency by low level substitution of the noble metal to provide new...

  14. Determination of platinum in Adam's catalyst

    Directory of Open Access Journals (Sweden)

    Anđelić Brankica Č.

    2003-01-01

    Full Text Available Adams's catalyst PtO2 x H2O has an important application in the chemical industry. The method for determination of platinum in Adam's catalyst has been elaborated. It includes the combination of cupellation and gravimetry methods. Considering that platinum oxide is practically insolvent in mineral acids, the sample is alloyed with lead by cupellation method and the separated balls solution procedure has been tested. The ball, platinum and lead alloy, is soluble in mineral acid. The platinum was settled by amonium chloride from solution, and obtained deposit treated by amonium acetate with addition of ethanol for lead removing. The retained platinum was determined by atomic absorption spctrophotometry method in the filtrate (after the platinum separation and the final result of platinum content corrected. It was shown how the combined gravimetric and AAS-Pt determination methods might be used for solving determination of Pt content in practically unsoluble sample of catalyst. Applied procedure enables testing the catalyst quality and proving its characteristics required for chemical industry.

  15. 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.

  16. 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

  17. 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

  18. DIRECT METHANOL FUEL CELLS AT REDUCED CATALYST LOADINGS

    Energy Technology Data Exchange (ETDEWEB)

    P. ZELENAY; F. GUYON; SM. GOTTESFELD

    2001-05-01

    We focus in this paper on the reduction of catalyst loading in direct methanol fuel cells currently under development at Los Alamos National Laboratory. Based on single-cell DMFC testing, we discuss performance vs. catalyst loading trade-offs and demonstrate optimization of the anode performance. We also show test data for a short five-cell DMFC stack with the average total platinum loading of 0.53 mg cm{sup {minus}2} and compare performance of this stack with the performance of a single direct methanol fuel cell using similar total amount of precious metal.

  19. Direct methanol fuel cells at reduced catalyst loadings

    Energy Technology Data Exchange (ETDEWEB)

    Zelenay, P. (Piotr); Guyon, F. (Francois); Gottesfeld, Shimshon

    2001-01-01

    We focus in this paper on the reduction of catalyst loading in direct methanol fuel cells currently under development at Los Alamos National Laboratory. Based on single-cell DMFC testing, we discuss performance vs. catalyst loading trade-offs and demonstrate optimization of the anode performance. We also show test data for a short five-cell DMFC stack with the average total platinum loading of 0.53 mg cm{sup -2} and compare performance of this stack with the performance of a single direct methanol fuel cell using similar total amount of precious metal.

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. Development of biologically modified anodes for energy harvesting using microbial fuel cells

    Science.gov (United States)

    Sumner, James J.; Ganguli, Rahul; Chmelka, Brad

    2012-06-01

    Biological fuel cells hold promise as an alternative energy source to batteries for unattended ground sensor applications due to the fact that they can be extremely long lived. This lifetime can be extended over batteries by scavenging fuel from the deployed environment. Microbial fuel cells (MFC) are one class of such sources that produce usable energy from small organic compounds (i.e. sugars, alcohols, organic acids, and biopolymers) which can be easily containerized or scavenged from the environment. The use of microorganisms as the anodic catalysts is what makes these systems unique from other biofuel cell designs. One of the main drawbacks of engineering a sensor system powered by an MFC is that power densities and current flux are extremely low in currently reported systems. The power density is limited by the mass transfer of the fuel source to the catalyst, the metabolism of the microbial catalysts and the electron transfer from the organism to the anode. This presentation will focus on the development of a new style of microbially-modified anodes which will increase power density to a level where a practical power source can be engineered. This is being achieved by developing a three dimensional matrix as an artificial, conductive biofilm. These artificial biofilms will allow the capture of a consortium of microbes designed for efficient metabolism of the available fuel source. Also it will keep the microbes close to the electrode allowing ready access by fuel and providing a low resistance passage of the liberated electrons from fuel oxidation.

  5. 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.

  6. 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

  7. [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

  8. 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...

  9. 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

  10. 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.

  11. Effect of Micro Arc Oxidation Coatings on Corrosion Resistance of 6061-Al Alloy

    Science.gov (United States)

    Wasekar, Nitin P.; Jyothirmayi, A.; Rama Krishna, L.; Sundararajan, G.

    2008-10-01

    In the present study, the corrosion behavior of micro arc oxidation (MAO) coatings deposited at two current densities on 6061-Al alloy has been investigated. Corrosion in particular, simple immersion, and potentiodynamic polarization tests have been carried out in 3.5% NaCl in order to evaluate the corrosion resistance of MAO coatings. The long duration (up to 600 h) immersion tests of coated samples illustrated negligible change in weight as compared to uncoated alloy. The anodic polarization curves were found to exhibit substantially lower corrosion current and more positive corrosion potential for MAO-coated specimens as compared to the uncoated alloy. The electrochemical response was also compared with SS-316 and the hard anodized coatings. The results indicate that the overall corrosion resistance of the MAO coatings is significantly superior as compared to SS316 and comparable to hard anodized coating deposited on 6061 Al alloy.

  12. Interfacial phenomena in electric field-assisted anodic bonding of Kovar/Al film-glass

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Anodic bonding of glass to Kovar alloy coated with Al film (Glass-Al film/Kovar) was performed in the temperature range of 513~713?K under the static electric voltage of 500?V in order to investigate the interfacial phenomena of Al-glass joint. The results reveal that Na and K ions within the glass are displaced by the applied field from the anode-side surface of the glass to form depletion layers of them. The K ion depletion layer is narrow and followed by a K pile-up layer, and both the two layers are formed within the Na depletion layer. The width of the Na and K depletion layers is increased with increasing bonding temperature and time. The activation energies for the growth of both depletion layers were close to that for Na diffusion in the glass. TEM observations reveal that Al film coated at the surface of Kovar alloy is oxidized to amorphous Al2O3 containing a few of Fe, Ni and Co by oxygen ions from the glass drifted by high electric field during bonding. The amount of Fe ions diffusing into the glass adjacent to the anode is significantly low due to the presence of Al film between Kovar alloy and the glass. As a result, the amorphous reaction layer of Fe-Si-O in the glass near the interface is avoided which is formed in Kovar-glass joints.

  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. Reactions on carbon anodes in aluminium electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Eidet, Trygve

    1997-12-31

    The consumption of carbon anodes and energy in aluminium electrolysis is higher than what is required theoretically. This thesis studies the most important of the reactions that consume anode materials. These reactions are the electrochemical anode reaction and the airburn and carboxy reactions. The first part of the thesis deals with the kinetics and mechanism of the electrochemical anode reaction using electrochemical impedance spectroscopy. The second part deals with air and carboxy reactivity of carbon anodes and studies the effects of inorganic impurities on the reactivity of carbon anodes in the aluminium industry. Special attention is given to sulphur since its effect on the carbon gasification is not well understood. Sulphur is always present in anodes, and it is expected that the sulphur content of available anode cokes will increase in the future. It has also been suggested that sulphur poisons catalyzing impurities in the anodes. Other impurities that were investigated are iron, nickel and vanadium, which are common impurities in anodes which have been reported to catalyze carbon gasification. 88 refs., 92 figs., 24 tabs.

  15. 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.

  16. 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.

  17. 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)

  18. Effect of anodization and alkali-heat treatment on the bioactivity of titanium implant material (an in vitro study)

    Science.gov (United States)

    Abdelrahim, Ramy A.; Badr, Nadia A.; Baroudi, Kusai

    2016-01-01

    Objective: This study was aimed to assess the effect of anodized and alkali-heat surface treatment on the bioactivity of titanium alloy (Ti-6Al-4V) after immersion in Hank's solution for 7 days. Materials and Methods: Fifteen titanium alloy samples were used in this study. The samples were divided into three groups (five for each), five samples were anodized in 1M H3PO4 at constant voltage value of 20 v and another five samples were alkali-treated in 5 M NaOH solution for 25 min at temperature 60°C followed by heat treatment at 600°C for 1 h. All samples were then immersed in Hank's solution for 7 days to assess the effect of surface modifications on the bioactivity of titanium alloy. The different treated surfaces and control one were characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transformation infra-red spectroscopy. Statistical analysis was performed with PASW Statistics 18.0® (Predictive Analytics Software). Results: Anodization of Ti-alloy samples (Group B) led to the formation of bioactive titanium oxide anatase phase and PO43− group on the surface. The alkali-heat treatment of titanium alloy samples (Group C) leads to the formation of bioactive titania hydrogel and supplied sodium ions. The reaction between the Ti sample and NaOH alkaline solution resulted in the formation of a layer of amorphous sodium titania on the Ti surface, and this layer can induce apatite deposition. Conclusions: The surface roughness and surface chemistry had an excellent ability to induce bioactivity of titanium alloy. The anodization in H3PO4 produced anatase titanium oxide on the surface with phosphate originated from electrolytes changed the surface topography and allowed formation of calcium-phosphate. PMID:27382532

  19. Anode materials for sour natural gas solid oxide fuel cells

    Science.gov (United States)

    Danilovic, Nemanja

    Novel anode catalysts have been developed for sour natural gas solid oxide fuel cell (SOFC) applications. Sour natural gas comprises light hydrocarbons, and typically also contains H2S. An alternative fuel SOFC that operates directly on sour natural gas would reduce the overall cost of plant construction and operation for fuel cell power generation. The anode for such a fuel cell must have good catalytic and electrocatalytic activity for hydrocarbon conversion, sulfur-tolerance, resistance to coking, and good electronic and ionic conductivity. The catalytic activity and stability of ABO3 (A= La, Ce and/or Sr, B=Cr and one or more of Ti, V, Cr, Fe, Mn, or Co) perovskites as SOFC anode materials depends on both A and B, and are modified by substituents. The materials have been prepared by both solid state and wet-chemical methods. The physical and chemical characteristics of the materials have been fully characterized using electron microscopy, XRD, calorimetry, dilatometry, particle size and area, using XPS and TGA-DSC-MS. Electrochemical performance was determined using potentiodynamic and potentiostatic cell testing, electrochemical impedance analysis, and conductivity measurements. Neither Ce0.9Sr0.1VO3 nor Ce0.9 Sr0.1Cr0.5V0.5O3 was an active anode for oxidation of H2 and CH4 fuels. However, active catalysts comprising Ce0:9Sr0:1V(O,S)3 and Ce0.9Sr 0.1Cr0.5V0.5(O,S)3 were formed when small concentrations of H2S were present in the fuels. The oxysulfides formed in-situ were very active for conversion of H2S. The maximum performance improved from 50 mW cm-2 to 85 mW cm -2 in 0.5% H2S/CH4 at 850°C with partial substitution of V by Cr in Ce0.9Sr0.1V(O,S)3. Selective conversion of H2S offers potential for sweetening of sour gas without affecting the hydrocarbons. Perovskites La0.75Sr0.25Cr0.5X 0.5O3--delta, (henceforth referred to as LSCX, X=Ti, Mn, Fe, Co) are active for conversion of H2, CH4 and 0.5% H2S/CH4. The order of activity in the different fuels depends on

  20. 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.

  1. 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…

  2. Electrophoretic deposition of PTFE particles on porous anodic aluminum oxide film and its tribological properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dongya; Dong, Guangneng, E-mail: donggn@mail.xjtu.edu.cn; Chen, Yinjuan; Zeng, Qunfeng

    2014-01-30

    Polytetrafluoroethylene (PTFE) composite film was successfully fabricated by depositing PTFE particles into porous anodic aluminum oxide film using electrophoretic deposition (EPD) process. Firstly, porous anodic aluminum oxide film was synthesized by anodic oxidation process in sulphuric acid electrolyte. Then, PTFE particles in suspension were directionally deposited into the porous substrate. Finally, a heat treatment at 300 °C for 1 h was utilized to enhance PTFE particles adhesion to the substrate. The influence of anodic oxidation parameters on the morphology and micro-hardness of the porous anodic aluminum oxide film was studied and the PTFE particles deposited into the pores were authenticated using energy-dispersive spectrometer (EDS) and scanning electron microscopy (SEM). Tribological properties of the PTFE composite film were investigated under dry sliding. The experimental results showed that the composite film exhibit remarkable low friction. The composite film had friction coefficient of 0.20 which deposited in 15% PTFE emulsion at temperature of 15 °C and current density of 3 A/dm{sup 2} for 35 min. In addition, a control specimen of porous anodic aluminum oxide film and the PTFE composite film were carried out under the same test condition, friction coefficient of the PTFE composite film was reduced by 60% comparing with the control specimen at 380 MPa and 100 mm/s. The lubricating mechanism was that PTFE particles embedded in porous anodic aluminum oxide film smeared a transfer film on the sliding path and the micro-pores could support the supplement of solid lubricant during the sliding, which prolonged the lubrication life of the aluminum alloys.

  3. Electrophoretic deposition of PTFE particles on porous anodic aluminum oxide film and its tribological properties

    Science.gov (United States)

    Zhang, Dongya; Dong, Guangneng; Chen, Yinjuan; Zeng, Qunfeng

    2014-01-01

    Polytetrafluoroethylene (PTFE) composite film was successfully fabricated by depositing PTFE particles into porous anodic aluminum oxide film using electrophoretic deposition (EPD) process. Firstly, porous anodic aluminum oxide film was synthesized by anodic oxidation process in sulphuric acid electrolyte. Then, PTFE particles in suspension were directionally deposited into the porous substrate. Finally, a heat treatment at 300 °C for 1 h was utilized to enhance PTFE particles adhesion to the substrate. The influence of anodic oxidation parameters on the morphology and micro-hardness of the porous anodic aluminum oxide film was studied and the PTFE particles deposited into the pores were authenticated using energy-dispersive spectrometer (EDS) and scanning electron microscopy (SEM). Tribological properties of the PTFE composite film were investigated under dry sliding. The experimental results showed that the composite film exhibit remarkable low friction. The composite film had friction coefficient of 0.20 which deposited in 15% PTFE emulsion at temperature of 15 °C and current density of 3 A/dm2 for 35 min. In addition, a control specimen of porous anodic aluminum oxide film and the PTFE composite film were carried out under the same test condition, friction coefficient of the PTFE composite film was reduced by 60% comparing with the control specimen at 380 MPa and 100 mm/s. The lubricating mechanism was that PTFE particles embedded in porous anodic aluminum oxide film smeared a transfer film on the sliding path and the micro-pores could support the supplement of solid lubricant during the sliding, which prolonged the lubrication life of the aluminum alloys.

  4. Effect of hydrogen on aluminium and aluminium alloys: A review

    DEFF Research Database (Denmark)

    Ambat, Rajan; Dwarakadasa, E.S.

    1996-01-01

    Susceptibility of aluminium and its alloys towards hydrogen embrittlement has been well established. Still a lot of confusion exists on the question of transport of hydrogen and its possible role in stress corrosion cracking. This paper reviews some of the fundamental properties of hydrogen...... in aluminium and its alloys and its effect on mechanical properties. The importance of hydrogen embrittlement over anodic dissolution to explain the stress corrosion cracking mechanism of these alloys is also examined in considerable detail. The various experimental findings concerning the link between...

  5. 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.

  6. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    International Nuclear Information System (INIS)

    The anode ablation rate is investigated as a function of anode diameter for a carbon nanotube arc plasma. It is found that anomalously high ablation occurs for small anode diameters. This result is explained by the formation of a positive anode sheath. The increased ablation rate due to this positive anode sheath could imply greater production rate for carbon nanotubes.

  7. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Abe Fetterman, Yevgeny Raitses, and Michael Keidar

    2008-04-08

    The anode ablation rate is investigated as a function of anode diameter for a carbon nanotube arc plasma. It is found that anomalously high ablation occurs for small anode diameters. This result is explained by the formation of a positive anode sheath. The increased ablation rate due to this positive anode sheath could imply greater production rate for carbon nanotubes.

  8. Anodic Materials for Electrocatalytic Ozone Generation

    OpenAIRE

    Yun-Hai Wang; Qing-Yun Chen

    2013-01-01

    Ozone has wide applications in various fields. Electrocatalytic ozone generation technology as an alternative method to produce ozone is attractive. Anodic materials have significant effect on the ozone generation efficiency. The research progress on anodic materials for electrocatalytic ozone generation including the cell configuration and mechanism is addressed in this review. The lead dioxide and nickel-antimony-doped tin dioxide anode materials are introduced in detail, including their st...

  9. Fabrication and evaluation of nickel cobalt alloy electrocatalysts for alkaline water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Hoon [School of Integrative Engineering, Chung-Ang University, Heukseokno 84, Dongjak-gu, Seoul 156-756 (Korea, Republic of); Ahn, Sang Hyun; Choi, Insoo [Fuel Cell Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Pyo, Sung Gyu [School of Integrative Engineering, Chung-Ang University, Heukseokno 84, Dongjak-gu, Seoul 156-756 (Korea, Republic of); Kim, Hyoung-Juhn; Jang, Jong Hyun [Fuel Cell Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Kim, Soo-Kil, E-mail: sookilkim@cau.ac.kr [School of Integrative Engineering, Chung-Ang University, Heukseokno 84, Dongjak-gu, Seoul 156-756 (Korea, Republic of)

    2014-07-01

    As a catalyst for the hydrogen evolution reaction (HER) in alkaline water splitting, NiCo alloys of various compositions were prepared through electrodeposition onto Cu substrates. The composition of each alloy catalyst was varied by controlling the molar ratio of Co{sup 2+} ions in the electrolyte. With an increase in the Co content, the morphologies of the NiCo alloys were progressively changed from a round to polygonal shape. The NiCo alloys all exhibited a Ni rich surface, as confirmed by the bulk-to-surface compositional ratio and degree of alloying. The catalytic activities of the NiCo alloys toward the HER of water splitting were electrochemically tested in a KOH electrolyte, and the specific activities were characterized by considering the electrochemical surface areas of Ni and Co. The effect of alloying was demonstrated to be a significant enhancement of HER activity, resulting from a change in the electronic structures of Ni and Co.

  10. Synthesis and characterization of hybrid micro/nano-structured NiTi surfaces by a combination of etching and anodizing

    International Nuclear Information System (INIS)

    The purpose of this study was to generate hybrid micro/nano-structures on biomedical nickel–titanium alloy (NiTi). To achieve this, NiTi surfaces were firstly electrochemically etched and then anodized in fluoride-containing electrolyte. With the etching process, the NiTi surface was micro-roughened through the formation of micropits uniformly distributed over the entire surface. Following the subsequent anodizing process, self-organized nanotube structures enriched in TiO2 could be superimposed on the etched surface under specific conditions. Furthermore, the anodizing treatment significantly reduced water contact angles and increased the surface free energy compared to the surfaces prior to anodizing. The results of this study show for the first time that it is possible to create hybrid micro/nano-structures on biomedical NiTi alloys by combining electrochemical etching and anodizing under controlled conditions. These novel structures are expected to significantly enhance the surface biofunctionality of the material when compared to conventional implant devices with either micro- or nano-structured surfaces. (paper)

  11. Synthesis and characterization of hybrid micro/nano-structured NiTi surfaces by a combination of etching and anodizing

    Science.gov (United States)

    Huan, Z.; Fratila-Apachitei, L. E.; Apachitei, I.; Duszczyk, J.

    2014-02-01

    The purpose of this study was to generate hybrid micro/nano-structures on biomedical nickel-titanium alloy (NiTi). To achieve this, NiTi surfaces were firstly electrochemically etched and then anodized in fluoride-containing electrolyte. With the etching process, the NiTi surface was micro-roughened through the formation of micropits uniformly distributed over the entire surface. Following the subsequent anodizing process, self-organized nanotube structures enriched in TiO2 could be superimposed on the etched surface under specific conditions. Furthermore, the anodizing treatment significantly reduced water contact angles and increased the surface free energy compared to the surfaces prior to anodizing. The results of this study show for the first time that it is possible to create hybrid micro/nano-structures on biomedical NiTi alloys by combining electrochemical etching and anodizing under controlled conditions. These novel structures are expected to significantly enhance the surface biofunctionality of the material when compared to conventional implant devices with either micro- or nano-structured surfaces.

  12. Alternative anode materials for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Goodenough, John B.; Huang, Yun-Hui [Texas Materials Institute, ETC 9.102, 1 University Station, C2200, The University of Texas at Austin, Austin, TX 78712 (United States)

    2007-11-08

    The electrolyte of a solid oxide fuel cell (SOFC) is an O{sup 2-}-ion conductor. The anode must oxidize the fuel with O{sup 2-} ions received from the electrolyte and it must deliver electrons of the fuel chemisorption reaction to a current collector. Cells operating on H{sub 2} and CO generally use a porous Ni/electrolyte cermet that supports a thin, dense electrolyte. Ni acts as both the electronic conductor and the catalyst for splitting the H{sub 2} bond; the oxidation of H{sub 2} to H{sub 2}O occurs at the Ni/electrolyte/H{sub 2} triple-phase boundary (TPB). The CO is oxidized at the oxide component of the cermet, which may be the electrolyte, yttria-stabilized zirconia, or a mixed oxide-ion/electron conductor (MIEC). The MIEC is commonly a Gd-doped ceria. The design and fabrication of these anodes are evaluated. Use of natural gas as the fuel requires another strategy, and MIECs are being explored for this application. The several constraints on these MIECs are outlined, and preliminary results of this on-going investigation are reviewed. (author)

  13. Modulation of Transmission Spectra of Anodized Alumina Membrane Distributed Bragg Reflector by Controlling Anodization Temperature

    OpenAIRE

    Zheng WenJun; Fei GuangTao; Wang Biao; Zhang Li

    2009-01-01

    Abstract We have successfully prepared anodized alumina membrane distributed Bragg reflector (DBR) using electrochemical anodization method. The transmission peak of this distributed Bragg reflector could be easily and effectively modulated to cover almost any wavelength range of the whole visible spectrum by adjusting anodization temperature.

  14. Modulation of Transmission Spectra of Anodized Alumina Membrane Distributed Bragg Reflector by Controlling Anodization Temperature

    Directory of Open Access Journals (Sweden)

    Zheng WenJun

    2009-01-01

    Full Text Available Abstract We have successfully prepared anodized alumina membrane distributed Bragg reflector (DBR using electrochemical anodization method. The transmission peak of this distributed Bragg reflector could be easily and effectively modulated to cover almost any wavelength range of the whole visible spectrum by adjusting anodization temperature.

  15. Polyol synthesis of highly active PtRu/C catalyst with high metal loading

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Shiyou; Sun, Gongquan; Tian, Juan; Jiang, Luhua; Qi, Jing; Xin, Qin [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian (China)

    2006-12-01

    Highly loaded PtRu/C catalyst with high activity toward methanol electrooxidation was synthesized via a modified polyol process. XRD patterns indicated that the prepared catalyst was highly alloyed and TEM results showed that the metal nanoparticles were small and uniformly distributed on the carbon support despite the high metal loading. EDX results suggested that the two metals distributed uniformly in the catalyst. Electrochemical characterization and single cell test jointly showed that the prepared 40-20wt.%PtRu/C catalyst possessed high activity toward methanol electrooxidation. (author)

  16. Development of highly active and stable hybrid cathode catalyst for PEMFCs

    Science.gov (United States)

    Jung, Won Suk

    Polymer electrolyte membrane fuel cells (PEMFCs) are attractive power sources of the future for a variety of applications including portable electronics, stationary power, and automobile application. However, sluggish cathode kinetics, high Pt cost, and durability issues inhibit the commercialization of PEMFCs. To overcome these drawbacks, research has been focused on alloying Pt with transition metals since alloy catalysts show significantly improved catalytic properties like high activity, selectivity, and durability. However, Pt-alloy catalysts synthesized using the conventional impregnation method exhibit uneven particle size and poor particle distribution resulting in poor performance and/or durability in PEMFCs. In this dissertation, a novel catalyst synthesis methodology is developed and compared with catalysts prepared using impregnation method and commercial catalysts. Two approaches are investigated for the catalyst development. The catalyst durability was studied under U. S. DRIVE Fuel Cell Tech Team suggested protocols. In the first approach, the carbon composite catalyst (CCC) having active sites for oxygen reduction reaction (ORR) is employed as a support for the synthesis of Pt/CCC catalyst. The structural and electrochemical properties of Pt/CCC catalyst are investigated using high-resolution transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, while RDE and fuel cell testing are carried out to study the electrochemical properties. The synergistic effect of CCC and Pt is confirmed by the observed high activity towards ORR for the Pt/CCC catalyst. The second approach is the synthesis of Co-doped hybrid cathode catalysts (Co-doped Pt/CCC) by diffusing the Co metal present within the CCC support into the Pt nanoparticles during heat-treatment. The optimized Co-doped Pt/CCC catalyst performed better than the commercial catalysts and the catalyst prepared using the impregnation method in PEMFCs and showed high

  17. Design of Pd-Based Bimetallic Catalysts for ORR: A DFT Calculation Study

    Directory of Open Access Journals (Sweden)

    Lihui Ou

    2015-01-01

    Full Text Available Developing Pd-lean catalysts for oxygen reduction reaction (ORR is the key for large-scale application of proton exchange membrane fuel cells (PEMFCs. In the present paper, we have proposed a multiple-descriptor strategy for designing efficient and durable ORR Pd-based alloy catalysts. We demonstrated that an ideal Pd-based bimetallic alloy catalyst for ORR should possess simultaneously negative alloy formation energy, negative surface segregation energy of Pd, and a lower oxygen binding ability than pure Pt. By performing detailed DFT calculations on the thermodynamics, surface chemistry and electronic properties of Pd-M alloys, Pd-V, Pd-Fe, Pd-Zn, Pd-Nb, and Pd-Ta, are identified theoretically to have stable Pd segregated surface and improved ORR activity. Factors affecting these properties are analyzed. The alloy formation energy of Pd with transition metals M can be mainly determined by their electron interaction. This may be the origin of the negative alloy formation energy for Pd-M alloys. The surface segregation energy of Pd is primarily determined by the surface energy and the atomic radius of M. The metals M which have smaller atomic radius and higher surface energy would tend to favor the surface segregation of Pd in corresponding Pd-M alloys.

  18. Robust CoAl Alloy: Highly Active, Reusable and Green Catalyst in the Hydrogenolysis of Glycerol%Robust CoAl Alloy: Highly Active, Reusable and Green Catalyst in the Hydrogenolysis of Glycerol

    Institute of Scientific and Technical Information of China (English)

    郭晓洋; 尹安远; 郭晓东; 郭秀英; 戴维林; 范康年

    2011-01-01

    CoAl alloy catalyst is found, for the first time, to be highly active, selective and reusable for the synthesis of diols via the hydrogenolysis of glycerol under mild conditions. The products and the catalyst could be self-separated from the reaction system through a simple reactor.

  19. Influence of Alloying Element Nd on the Electrochemical Behavior of Pb-Ag Anode in H2SO4 Solution%合金元素Nd对Pb-Ag阳极在H2SO4溶液中电化学行为的影响

    Institute of Scientific and Technical Information of China (English)

    钟晓聪; 桂俊峰; 于枭影; 刘芳洋; 蒋良兴; 赖延清; 李劼; 刘业翔

    2014-01-01

    Anodic layers and oxygen evolution reaction (OER) of Pb-Ag and Pb-Ag-Nd anodes were investigated by cyclic voltammetry, linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and environmental scanning electron microscopy (ESEM). Al oying with Nd promoted the formation of Pb/PbOn/PbSO4 (1≤n<2). Nd facilitated the transformation of PbOn and PbSO4 toα-PbO2 andβ-PbO2, at potential above 1.2 V vs Hg/Hg2SO4 (saturated K2SO4 solution). ESEM and LSV indicated that the anodic layer formed on the Pb-Ag-Nd anode was thicker and more compact than that formed on the Pb-Ag anode. Consequently, the anodic layer on the Pb-Ag-Nd anode could provide better protection for metal ic substrates. EIS indicated that the OER was determined by the formation and adsorption of intermediates. Nd enhanced the OER reactivity, because of a smal er adsorption resistance and larger coverage of intermediates at the anodic layer/electrolyte interface. In summary, al oying with Nd can enhance the corrosion resistance and reduce the energy consumption of Pb-Ag anode due to lower anodic potential.%采用循环伏安、线性扫描、电化学阻抗和环境扫描电镜对比研究了Pb-Ag和Pb-Ag-Nd阳极的阳极膜和析氧反应.结果表明,合金元素Nd促进了Pb/PbOn/PbSO4(1≤n<2)膜层的生长.在高极化电位区间(高于1.20 V (vs Hg/Hg2SO4/饱和K2SO4溶液)), Nd有利于低价铅的化合物(PbOn, PbSO4)向α-PbO2和β-PbO2转变.此外,环境扫描电镜形貌和线性扫描分析证明Pb-Ag-Nd表面生成的阳极膜较Pb-Ag的阳极膜更厚且更致密.因此, Pb-Ag-Nd阳极表面的阳极膜可以给合金基底提供更好的保护.另一方面,电化学阻抗测试揭示了两种阳极的析氧反应均受中间产物的形成和吸附控制. Nd可以降低阳极膜/电解液界面处中间产物的吸附阻抗且增加中间产物的覆盖率,从而提高析氧反应活性.综上所述,合金元素Nd可提高Pb-Ag阳极的耐腐蚀性,降低阳极电

  20. Anodic Fabrication of Ti-Nb-Zr-O Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    2014-01-01

    Full Text Available Highly ordered Ti-Nb-Zr-O nanotube arrays were fabricated through pulse anodic oxidation of Ti-Nb-Zr alloy in 1 M NaH2PO4 containing 0.5 wt% HF electrolytes. The effect of anodization parameters and Zr content on the microstructure and composition of Ti-Nb-Zr-O nanotubes was investigated using a scanning electron microscope equipped with energy dispersive X-ray analysis. It was found that length of the Ti-Nb-Zr-O nanotubes increased with increase of Zr contents. The diameter and the length of Ti-Nb-Zr-O nanotubes could be controlled by pulse voltage. XRD analysis of Ti-Nb-Zr-O samples annealed at 500°C in air indicated that the (101 diffraction peaks shifted from 25.78° to 25.05° for annealed Ti-Nb-Zr-O samples with different Zr contents because of larger lattice parameter of Ti-Nb-Zr-O compared to that of undoped TiO2.

  1. Effect of the synthesis method of SnSb anode materials on their electrochemical properties

    Institute of Scientific and Technical Information of China (English)

    Chaoli Yin; Hailei Zhao; Hong Guo; Xianliang Huang; Weihua Qiu

    2007-01-01

    SnSb alloy powders for the anode of Li-ion batteries were synthesized by two kinds of reduction precipitation methods:solution titration and rapid mixing. Two kinds of SnSb alloy powders showed different phase compositions and particle morphologies although the same starting materials were used. The SnSb alloy electrode synthesized by titration exhibits high reversible specific capacity and good cycling stability, whereas the rapid-mixing sample shows high irreversible capacity and fast capacity fade. The broad particle size distribution of SnSb powders synthesized by titration is considered to be responsible for the improvement of cycling stability. The initial charge-discharge efficiency exceeding 80% has been obtained for the titration sample. The electrochemical reaction process of two kinds of synthesized SnSb composite electrodes was characterized by cyclic voltammetry and AC impedance techniques.

  2. Passivity of polycrystalline NiMnGa alloys for magnetic shape memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Gebert, A. [Leibniz Institute for Solid State and Materials Research IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany)], E-mail: a.gebert@ifw-dresden.de; Roth, S.; Oswald, S. [Leibniz Institute for Solid State and Materials Research IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Schultz, L. [Leibniz Institute for Solid State and Materials Research IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Dresden University of Technology, Department of Mechanical Engineering, Institute for Materials Science, 01062 Dresden (Germany)

    2009-05-15

    The corrosion and passivation behaviour of bulk polycrystalline martensite Ni{sub 50}Mn{sub 30}Ga{sub 20} and austenite Ni{sub 48}Mn{sub 30}Ga{sub 22} alloys was compared in electrolytes with different pH values. Linear anodic and cyclic potentiodynamic polarisation methods and anodic current transient measurements have been conducted for the alloys and their constituents to analyze free corrosion, anodic dissolution and passive layer formation processes. Electrochemically treated alloy surfaces were characterized with scanning electron microscopy (SEM) and angle-resolved x-ray photoelectron spectroscopy (XPS). The electrochemical response of both alloys is in principal similar and is dominated by the Ni oxidation. In acidic solutions (pH 0.5 and 5) a slightly higher reactivity is detectable for the martensitic alloy which is mainly attributed to enhanced dissolution processes at the multiple twin boundaries. In weakly acidic to strongly alkaline solutions (pH 5-11) both alloys exhibit a low corrosion rate and a stable anodic passivity. While air-formed films comprise NiOOH, Ga{sub 2}O{sub 3} and MnO{sub 2}, passive films formed in near neutral media (pH 5-8.4) are composed of Ni(OH){sub 2}, NiOOH and Ga{sub 2}O{sub 3} in the outer region and of NiO, MnO{sub 2} and MnO in the metal-near region.

  3. Ternary alloy nanocatalysts for hydrogen evolution reaction

    Indian Academy of Sciences (India)

    SOUMEN SAHA; SONALIKA VAIDYA; KANDALAM V RAMANUJACHARY; SAMUEL E LOFLAND; ASHOK K GANGULI

    2016-04-01

    Cu–Fe–Ni ternary alloys (size ∼55–80 nm) with varying compositions viz. CuFeNi (A1), CuFe2Ni (A2) and CuFeNi2 (A3) were successfully synthesized using microemulsion. It is to be noted that synthesis of nanocrystallineternary alloys with precise composition is a big challenge which can be overcome by choosing an appropriate microemulsion system. High electrocatalytic activity towards HER in alkaline medium was achieved by the formation of alloys of metals with low and high binding energies. A high value of current density (228 mA cm$^2$) at an overpotential of 545 mV was obtained for CuFeNi (A1), which is significantly high as compared to the previously reported Ni$_{59}$Cu$_{41}$ alloy catalyst.

  4. EFFECT OF TEFLON AND NAFION LOADING AT ANODE IN DIRECT FORMIC ACID FUEL CELL (DFAFC

    Directory of Open Access Journals (Sweden)

    M. S. MASDAR

    2016-08-01

    Full Text Available DFAFC has extensive hydrophilic nature and will cause problems in a limited mass transport in the anode side of electrode. Thus, the microporous layer (MPL of DFAFC needs a different in structure and morphology compared with that of PEMFC and DMFC because it will directly affect the performance. Therefore, in this study, the formulation of anode’s MPL has been investigated by varying the amount of Teflon and Nafion. Different loading of Teflon in MPL and Nafion in catalyst layer, i.e., 0 to 40% in weight, were used to fabricate the anode’s DFAFC. The characteristic of MPLs and anode (MPL with catalyst layer such as surface morphologies and resistivity, i.e., electrical impedance, have been analyzed using field emission scanning electron microscopy (FESEM and contact angle measurements as well as electrochemical impedance spectra (EIS. Meanwhile, the performance of fabricated anode was measured using cyclic voltammetry (CV technique with a half cell of DFAFC. From the result, it was obtained that the optimum content for both Teflon and Nafion on anode’s DFAFC was 20 wt% as shown in a highest electro-activity in electrode. The single cell DFAFC with optimum MEA formulation showed a good performance and hence, it is possible to apply the electricity power for electronic devices.

  5. Towards the Rational Design of Nanoparticle Catalysts

    Science.gov (United States)

    Dash, Priyabrat

    stabilization in BMIMPF6 IL is described, and have shown that nanoparticle stability and catalytic activity of nanoparticles is dependent on the overall stability of the nanoparticles towards aggregation (manuscript submitted). The second major project is focused on synthesizing structurally well-defined supported catalysts by incorporating the nanoparticle precursors (both alloy and core shell) into oxide frameworks (TiO2 and Al2O 3), and examining their structure-property relationships and catalytic activity. a full article has been published on this project (Journal of Physical Chemistry C, 2009, 113, 12719) in which a route to rationally design supported catalysts from structured nanoparticle precursors with precise control over size, composition, and internal structure of the nanoparticles has been shown. In a continuation of this methodology for the synthesis of heterogeneous catalysts, efforts were carried out to apply the same methodology in imidazolium-based ILs as a one-pot media for the synthesis of supported-nanoparticle heterogeneous catalysts via the trapping of pre-synthesized nanoparticles into porous inorganic oxide materials. Nanoparticle catalysts in highly porous titania supports were synthesized using this methodology (manuscript to be submitted).

  6. Synergetic effects leading to coke-resistant NiCo bimetallic catalysts for dry reforming of methane

    KAUST Repository

    Li, Lidong

    2015-01-08

    A new dry reforming of methane catalyst comprised of NiCo bimetallic nanoparticles and a Mgx(Al)O support that exhibits high coke resistance and long-term on-stream stability is reported. The structural characterization by XRD, TEM, temperature-programmed reduction, and BET analysis demonstrates that the excellent performance of this catalyst is ascribed to the synergy of various parameters, including metal-nanoparticle size, metal-support interaction, catalyst structure, ensemble size, and alloy effects.

  7. Nanostructured Ir-supported on Ti4O7 as cost effective anode for proton exchange membrane (PEM) electrolyzers

    OpenAIRE

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

    2015-01-01

    PEM water electrolysis has recently emerged as one of the most promising technologies for large H2 production from temporal surplus of renewable electricity, yet it is expensive partly due to the use of large amounts of Ir present in the anode. Here we report the development and characterization of a cost effective catalyst, which consists of metallic Ir nanoparticles supported on commercial Ti4O7. The catalyst is synthetized by reducing IrCl3 with NaBH4 in a suspension containing Ti4O7, cety...

  8. Resin Catalyst Hybrids

    Institute of Scientific and Technical Information of China (English)

    S. Asaoka

    2005-01-01

    @@ 1Introduction: What are resin catalyst hybrids? There are typically two types of resin catalyst. One is acidic resin which representative is polystyrene sulfonic acid. The other is basic resin which is availed as metal complex support. The objective items of this study on resin catalyst are consisting of pellet hybrid, equilibrium hybrid and function hybrid of acid and base,as shown in Fig. 1[1-5].

  9. Manufacture of Raney Ni catalyst with metastable Ni2Al3 by high-energy milling

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The Ni-Al alloy containing Cr, Fe additives were prepared as Raney Ni catalyst by high energy milling. The size and surface state of Ni-Al alloy powder were studied by particle size analyzer and sanning electron microscopy, the structure was analyzed by XRD and Mossbauer methods. The results showed that after a high-energy milling (HEM), the Ni-Al alloy transforms to a nano-scale NiAl structure with rich Al. Byannealing the alloy, a metastable Ni2Al3 phase can be obtained.

  10. Manufacture of Raney Ni catalyst with metastable Ni2Al3 by high—energy milling

    Institute of Scientific and Technical Information of China (English)

    滕荣厚; 马如璋; 等

    1999-01-01

    The Ni-Al alloy containing Cr,Fe additives were prepared as Raney Ni Catalyst by high energy milling.The size and surface state of Ni-Al alloy powder were studied by particle size analyzer and sanning electron microscopy.the Structure was analyzed by XRD and Moessbauer methods.The results showed that after a high-energy milling(HEM).the Ni-Al alloy transforms to a nano-scale NiAl structure with rich Al.By annealing the alloy,a metastable Ni2Al3 phase can be obtained.

  11. 以非晶态合金催化剂SRNA-4为固相的气液固磁稳定床的界面传质研究%Interphase Mass Transfer in G-L-S Magnetically Stabilized Bed with Amorphous Alloy SRNA-4 Catalyst

    Institute of Scientific and Technical Information of China (English)

    李(韦华); 宗保守; 李晓芳; 孟祥坤; 张金利

    2006-01-01

    Gas-liquid (G-L) and liquid-solid (L-S) mass transfer coefficients were characterized in a gas-liquid-solid(G-L-S) three-phase magnetically stabilized bed (MSB) using amorphous alloy SRNA-4 as the solid phase. Effects such as superficial liquid velocity, superficial gas velocity, magnetic strength, liquid viscosity, and particle size were investigated. Experimental results indicated that the G-L volumetric mass transfer coefficients (KLa) increased along with the magnetic strength, superficial gas and liquid velocities. Proper increase of liquid viscosity promoted KLa only in the range of lower liquid viscosity. The external magnetic field made L-S mass transfer coefficients (Ks)in the G-L-S MSB lower than those of conventional fluidized beds. Ks in the MSB almost kept constant as the superficial liquid velocity and superficial gas velocity increased and decreased with the liquid viscosity and surface tension, while increased with the particle size Ks showed uniform axial and radial distributions except of small decreases close to the wall. Dimensionless correlations were established to estimate KLa and Ks of the MSB with SRNA-4 catalysts, which showed the average error of 5.4% and 2.5% respectively.

  12. PARAMETRIC STUDY FOR THE PREPARATION OF ALIGNED SINGLE-WALLED CARBON NANOTUBES BY ANODE-ARC DISCHARGE METHOD

    Institute of Scientific and Technical Information of China (English)

    J.F. Dai; Q. Wang; W.X. Li; Z.Q. Wei; G.J. Xu

    2005-01-01

    Well aligned quasi-straight single-walled carbon nanotubes (SWCNTs) and straight SWCNTs bundle have been prepared in large scale by anode-arc vaporization of graphite with metallic catalysts. Various parameters such as the catalyst preparation, the kinds and pressure of the buffer gases, the quantity of anode-arc current intensity, and the method of purification have been examined. The influence of these parameters on the deposited carbon yield is reported, together with observations of the produced material. Improvement in synthetic techniques has resulted in the optimal conditions for the production of large quantities of high quality SWCNTs in our semi-continuous synthesis method. The formation of carbon nanotubes (CNTs) was studied briefly in this paper. Owing to the magnetic pinching effect of arc current, the CNTs arrange in parallel lines along the arc current direction.

  13. Quantum Mechanics Studies of Fuel Cell Catalysts and Proton Conducting Ceramics with Validation by Experiment

    Science.gov (United States)

    Tsai, Ho-Cheng

    We carried out quantum mechanics (QM) studies aimed at improving the performance of hydrogen fuel cells. In part I, The challenge was to find a replacement for the Pt cathode that would lead to improved performance for the Oxygen Reduction Reaction (ORR) while remaining stable under operational conditions and decreasing cost. Our design strategy was to find an alloy with composition Pt3M that would lead to surface segregation such that the top layer would be pure Pt, with the second and subsequent layers richer in M. Under operating conditions we expect the surface to have significant O and/or OH chemisorbed on the surface; we searched for M that would remain segregated under these conditions. Using QM we examined surface segregation for 28 Pt3M alloys, where M is a transition metal. We found that only Pt3Os and Pt3Ir showed significant surface segregation when O and OH are chemisorbed on the catalyst surfaces. This result indicates that Pt3Os and Pt 3Ir favor formation of a Pt-skin surface layer structure that would resist the acidic electrolyte corrosion during fuel cell operation environments. We chose to focus on Os because the phase diagram for Pt-Ir indicated that Pt-Ir could not form a homogeneous alloy at lower temperature. To determine the performance for ORR, we used QM to examine intermediates, reaction pathways, and reaction barriers involved in the processes for which protons from the anode reactions react with O2 to form H2O. These QM calculations used our Poisson-Boltzmann implicit solvation model include the effects of the solvent (water with dielectric constant 78 with pH 7 at 298K). We also carried out similar QM studies followed by experimental validation for the Os/Pt core-shell catalyst fabricated by the underpotential deposition (UPD) method. The QM results indicated that the RDS for ORR is a compromise between the OOH formation step (0.37 eV for Pt, 0.23 eV for Pt2ML/Os core-shell) and H2O formation steps (0.32 eV for Pt, 0.22 eV for Pt2ML

  14. One pot aqueous synthesis of nanoporous Au85Pt15 material with surface bound Pt islands: an efficient methanol tolerant ORR catalyst

    Science.gov (United States)

    Anandha Ganesh, P.; Jeyakumar, D.

    2014-10-01

    For the first time, we are reporting the synthesis of Au100-xPtx nanoporous materials in the size range of 7-10 nm through the galvanic replacement of Ag by Pt from Au100-xAg2x spherical nano-alloys (x = 20, 15, 10 and 5) in an aqueous medium. The galvanic replacement reaction follows the `Volmer-Weber' growth mode, resulting in the formation of surface bound platinum islands on a nanoporous gold surface. The high angle annular dark field image and low angle X-ray diffraction studies confirm the presence of nanoporous Au100-xPtx NPs. The electrochemical studies using the Au85Pt15/C catalyst show excellent methanol tolerance behaviour and better performance towards oxygen reduction reaction (ORR) in terms of high mass activity, mass-specific activity and figure of merit (FOM) when compared to HiSPEC Pt/C commercial catalyst. Preliminary studies on a full cell using nanoporous Au85Pt15/C (loading 1.0 mg cm-2) as the cathode material and Pt-Ru/C (loading: 0.5 mg cm-2) as the anode material performed better (38 mW cm-2) than the HiSPEC Pt/C cathode material (16 mW cm-2).For the first time, we are reporting the synthesis of Au100-xPtx nanoporous materials in the size range of 7-10 nm through the galvanic replacement of Ag by Pt from Au100-xAg2x spherical nano-alloys (x = 20, 15, 10 and 5) in an aqueous medium. The galvanic replacement reaction follows the `Volmer-Weber' growth mode, resulting in the formation of surface bound platinum islands on a nanoporous gold surface. The high angle annular dark field image and low angle X-ray diffraction studies confirm the presence of nanoporous Au100-xPtx NPs. The electrochemical studies using the Au85Pt15/C catalyst show excellent methanol tolerance behaviour and better performance towards oxygen reduction reaction (ORR) in terms of high mass activity, mass-specific activity and figure of merit (FOM) when compared to HiSPEC Pt/C commercial catalyst. Preliminary studies on a full cell using nanoporous Au85Pt15/C (loading 1.0 mg

  15. The Capabilities of the Foamed Amorphous Alloy Catalyst for th e Hydrogenation of Benzene%发泡非晶态合金对苯加氢的催化性能

    Institute of Scientific and Technical Information of China (English)

    牛玉舒; 李保山; 全明秀; 胡壮麒

    2001-01-01

    采用新型发泡非晶态Ni-P合金催化剂,在微型固定床连续反应器上进行了苯加氢制 备环己烷的实验研究。结果表明:这种新型发泡非晶态合金催化剂具有较好的加氢催化活性 和很好的选择性,在体系氢压为2.0 MPa、反应温度为300 ℃,苯的进料速率为3 mL/h的条 件下 ,环己烷的单程收率为33.28%。试验考察了该催化剂的稳定性,结果表明,在360 h内,其 催化 活性没有显著变化。另外,该催化剂具有很好的通透性,催化剂层前、后几乎无压差。试验 还发现,该催化剂没有明显的诱导期,无需经过预处理就有很好的加氢催化活性。因此,发 泡非晶态Ni-P催化剂有希望成为工业催化剂。%Using the novel foamed amorphous alloy-fo amed Ni-P alloy-as catal yst, the hydrogenation of benzene to cyclohexane was carried out in a minisize c atena fix-bed reactor. The products were analyzed by gas chromatograph. Through t he experiments, the suitable processing conditions were obtained as the followi ng:the re action temperature 300 ℃, the feed rate 3 mL/h and the pressure of the system 2 .0 MPa. Under these conditions, the selectivity of hexamethylene alkyl was nearl y 1 00 % and the yield was about 33.28%. The results of the research on the stability indicated that the activity didn't change much in 360 h. In addition, the catal y st has no obvious inducement time. It has a good hydrogenation activity dispense with pretreatment. So the foamed Ni-P amorphous alloy can be used as industry cata lyst.

  16. Synthesis of Au/C and Au/Pani for anode electrodes in glucose microfluidic fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Guerra-Balcazar, M.; Morales-Acosta, D.; Castaneda, F.; Arriaga, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, 76703 Queretaro (Mexico); Ledesma-Garcia, J. [Division de Investigacion y Posgrado, Facultad de Ingenieria, Universidad Autonoma de Queretaro, 76010 Queretaro (Mexico)

    2010-06-15

    Gold nanoparticles have been prepared by two methods: chemical (ex-situ, Au/C) by two phase protocol, and electrochemical (in-situ, Au/Pani) by electroreduction of gold ions on a polyaniline film and compared as anode catalysts in a glucose microfluidic fuel cell. In this paper the structural characteristics and electrocatalytic properties were investigated by X-ray diffraction and electrochemical measurements. The catalytic behavior of both anodes was tested in a microfluidic fuel cell with a reference electrode incorporated, by means of linear sweep voltammetry (LSV), showing a cathodic shift in the glucose oxidation peak for Au/Pani. Results show a higher power density (0.5 mW cm{sup -} {sup 2}) for Au/C anode compared with an already reported value, where a glucose microfluidic fuel cell was used in similar conditions. (author)

  17. Oxidation of H2 and CO in a fuel cell with a Platinum-tin Anode

    Directory of Open Access Journals (Sweden)

    Javier González

    2010-06-01

    Full Text Available This report describes the construction and evolution of a fuel cell with a bi-metallic anode of Pt-Sn supported on carbon, as catalysts for oxidation of pure hydrogen, pure CO and a 2% CO in H2 mixture. Both, cathode and anode were made with a structure composed by a diffusive layer and a catalytic layer. The diffusive layer was made with a carbon cloth while the catalytic layer contained the platinum and tin supported on carbon. To test the performance of the catalytic mixture, a proton exchange membrane fuel cell (PEMFC was developed with an original design for the gas distributation plates. The reactants were feed to ambient temperature and 3 psig in the anode side, while 5 psig pure oxygen was used in the cathode. The anode catalytic load was 0.57 mg/cm2 of platinum and 0.08 mg/cm2 of tin. The catalytic load in cathode was 0.85 mg/cm2 of pure platinum. It was found that this caralytic mixture is tolerant to CO presence.

  18. Iridium-Doped Ruthenium Oxide Catalyst for Oxygen Evolution

    Science.gov (United States)

    Valdez, Thomas I.; Narayan, Sri R.; Billings, Keith J.

    2011-01-01

    NASA requires a durable and efficient catalyst for the electrolysis of water in a polymer-electrolyte-membrane (PEM) cell. Ruthenium oxide in a slightly reduced form is known to be a very efficient catalyst for the anodic oxidation of water to oxygen, but it degrades rapidly, reducing efficiency. To combat this tendency of ruthenium oxide to change oxidation states, it is combined with iridium, which has a tendency to stabilize ruthenium oxide at oxygen evolution potentials. The novel oxygen evolution catalyst was fabricated under flowing argon in order to allow the iridium to preferentially react with oxygen from the ruthenium oxide, and not oxygen from the environment. Nanoparticulate iridium black and anhydrous ruthenium oxide are weighed out and mixed to 5 18 atomic percent. They are then heat treated at 300 C under flowing argon (in order to create an inert environment) for a minimum of 14 hours. This temperature was chosen because it is approximately the creep temperature of ruthenium oxide, and is below the sintering temperature of both materials. In general, the temperature should always be below the sintering temperature of both materials. The iridium- doped ruthenium oxide catalyst is then fabricated into a PEM-based membrane- electrode assembly (MEA), and then mounted into test cells. The result is an electrolyzer system that can sustain electrolysis at twice the current density, and at the same efficiency as commercial catalysts in the range of 100-200 mA/sq cm. At 200 mA/sq cm, this new system operates at an efficiency of 85 percent, which is 2 percent greater than commercially available catalysts. Testing has shown that this material is as stable as commercially available oxygen evolution catalysts. This means that this new catalyst can be used to regenerate fuel cell systems in space, and as a hydrogen generator on Earth.

  19. Review on recent progress of nanostructured anode materials for Li-ion batteries

    KAUST Repository

    Goriparti, Subrahmanyam

    2014-07-01

    This review highlights the recent research advances in active nanostructured anode materials for the next generation of Li-ion batteries (LIBs). In fact, in order to address both energy and power demands of secondary LIBs for future energy storage applications, it is required the development of innovative kinds of electrodes. Nanostructured materials based on carbon, metal/semiconductor, metal oxides and metal phosphides/nitrides/sulfides show a variety of admirable properties for LIBs applications such as high surface area, low diffusion distance, high electrical and ionic conductivity. Therefore, nanosized active materials are extremely promising for bridging the gap towards the realization of the next generation of LIBs with high reversible capacities, increased power capability, long cycling stability and free from safety concerns. In this review, anode materials are classified, depending on their electrochemical reaction with lithium, into three groups: intercalation/de-intercalation, alloy/de-alloy and conversion materials. Furthermore, the effect of nanoscale size and morphology on the electrochemical performance is presented. Synthesis of the nanostructures, lithium battery performance and electrode reaction mechanisms are also discussed. To conclude, the main aim of this review is to provide an organic outline of the wide range of recent research progresses and perspectives on nanosized active anode materials for future LIBs.

  20. The Nitrogen-Nitride Anode.

    Energy Technology Data Exchange (ETDEWEB)

    Delnick, Frank M.

    2014-10-01

    Nitrogen gas N 2 can be reduced to nitride N -3 in molten LiCl-KCl eutectic salt electrolyte. However, the direct oxidation of N -3 back to N 2 is kinetically slow and only occurs at high overvoltage. The overvoltage for N -3 oxidation can be eliminated by coordinating the N -3 with BN to form the dinitridoborate (BN 2 -3 ) anion which forms a 1-D conjugated linear inorganic polymer with -Li-N-B-N- repeating units. This polymer precipitates out of solution as Li 3 BN 2 which becomes a metallic conductor upon delithiation. Li 3 BN 2 is oxidized to Li + + N 2 + BN at about the N 2 /N -3 redox potential with very little overvoltage. In this report we evaluate the N 2 /N -3 redox couple as a battery anode for energy storage.

  1. Titania Supported Pt and Pt/Pd Nano-particle Catalysts for the Oxidation of Sulfur Dioxide

    DEFF Research Database (Denmark)

    Koutsopoulos, Sotiris; Johannessen, Tue; Eriksen, Kim Michael;

    2006-01-01

    Several types of titania (anatase) were used as supports for pure platinum and Pt–Pd bimetallic alloy catalysts. The preparation methods, normal wet impregnation technique and flame aerosol synthesis, obtained metal loadings of 2% by weight. The prepared catalysts were tested for SO2 oxidation...... activity at atmospheric pressure in the temperature range 250–600 °C. The SO2 to SO3 conversion efficiency of the Pt–Pd alloy was significantly higher than that of the individual metals. The effects of the preparation method and the titania type used on the properties and activity of the resulting catalyst...

  2. High-Strength Low-Alloy (HSLA) Mg-Zn-Ca Alloys with Excellent Biodegradation Performance

    Science.gov (United States)

    Hofstetter, J.; Becker, M.; Martinelli, E.; Weinberg, A. M.; Mingler, B.; Kilian, H.; Pogatscher, S.; Uggowitzer, P. J.; Löffler, J. F.

    2014-04-01

    This article deals with the development of fine-grained high-strength low-alloy (HSLA) magnesium alloys intended for use as biodegradable implant material. The alloys contain solely low amounts of Zn and Ca as alloying elements. We illustrate the development path starting from the high-Zn-containing ZX50 (MgZn5Ca0.25) alloy with conventional purity, to an ultrahigh-purity ZX50 modification, and further to the ultrahigh-purity Zn-lean alloy ZX10 (MgZn1Ca0.3). It is shown that alloys with high Zn-content are prone to biocorrosion in various environments, most probably because of the presence of the intermetallic phase Mg6Zn3Ca2. A reduction of the Zn content results in (Mg,Zn)2Ca phase formation. This phase is less noble than the Mg-matrix and therefore, in contrast to Mg6Zn3Ca2, does not act as cathodic site. A fine-grained microstructure is achieved by the controlled formation of fine and homogeneously distributed (Mg,Zn)2Ca precipitates, which influence dynamic recrystallization and grain growth during hot forming. Such design scheme is comparable to that of HSLA steels, where low amounts of alloying elements are intended to produce a very fine dispersion of particles to increase the material's strength by refining the grain size. Consequently our new, ultrapure ZX10 alloy exhibits high strength (yield strength R p = 240 MPa, ultimate tensile strength R m = 255 MPa) and simultaneously high ductility (elongation to fracture A = 27%), as well as low mechanical anisotropy. Because of the anodic nature of the (Mg,Zn)2Ca particles used in the HSLA concept, the in vivo degradation in a rat femur implantation study is very slow and homogeneous without clinically observable hydrogen evolution, making the ZX10 alloy a promising material for biodegradable implants.

  3. Effects of Cu over Pd based catalysts supported on silica or niobia

    Directory of Open Access Journals (Sweden)

    Roma M.N.S.C.

    2000-01-01

    Full Text Available Palladium and palladium-copper catalysts supported on silica and niobia were characterized by H2 chemisorption and H2-O2 titration. Systems over silica were also analyzed by transmission electron microscopy and EXAFS. The metallic dispersion decreased from 20% to 7% when the content of Pd was increased from 0.5wt.-% to 3wt.-% in monometallic catalysts. The addition of 3 wt.-% Cu to obtain Pd-Cu catalysts caused a remarkable capacity loss of hydrogen chemisorption. TPR analysis suggested an interaction between the two metals and EXAFS characterization of the catalyst supported on silica confirmed the formation of Pd-Cu alloy. Pd/Nb2O5 catalysts showed turnover numbers higher than those obtained with the Pd/SiO2 systems in the cyclohexane dehydrogenation. However, the bimetallic catalysts showed very low turnover numbers.

  4. Conductive Anodic Filament (CAF) Formation

    Science.gov (United States)

    Caputo, Antonio

    Conductive anodic filament (CAF) is a failure mode in printed wiring boards (PWBs) which occurs under high humidity and high voltage gradient conditions. The filament, a copper salt, grows from anode to cathode along the epoxy-glass interface. Ready and Turbini (2000) identified this copper salt as the Cu 2(OH)3Cl, atacamite compound. This work has investigated the influence of polyethylene glycol (PEG) and polyethylene propylene glycol (PEPG) fluxing agents on the chemical nature of CAF. For coupons processed with PEPG flux, with and without chloride, a copper-chloride containing compound was formed in the polymer matrix. This compound was characterized using x-ray photoelectron spectroscopy (XPS) as CuCl and an electrochemical mechanism for the formation of the chloride-containing CAF has been proposed. For PEG flux, with and without chloride, it has been shown that CAF only formed, but no copper containing compound formed in the matrix. It appears for PEG fluxed coupons, a PEG-Cu-Cl complex forms, binds the available Cu and acts as a barrier to the formation of CuCl in the polymer matrix. Meeker and Lu Valle (1995) have previously proposed that CAF failure is best represented by two competing reactions -- the formation of a copper chloride corrosion compound (now identified as Cu2(OH)3Cl) and the formation of innocuous trapped chlorine compounds. Since no evidence of any trapped chloride compounds has been found, we propose that the formation of CAF is best represented by a single non-reversible reaction. For coupons processed with a high bromide-containing flux, bromide containing CAF was created and characterized using transmission electron microscopy (TEM) to be Cu2(OH)3Br. In addition, a copper-containing compound was formed in the polymer matrix and characterized using XPS as CuBr. An electrochemical mechanism for the formation of bromide-containing CAF has been proposed based on the XPS data.

  5. Studies on PEM Fuel Cell Noble Metal Catalyst Dissolution

    DEFF Research Database (Denmark)

    Ma, Shuang; Skou, Eivind Morten

    Incredibly vast advance has been achieved in fuel cell technology regarding to catalyst efficiency, improvement of electrolyte conductivity and optimization of cell system. With breathtakingly accelerating progress, Proton Exchange Membrane Fuel Cells (PEMFC) is the most promising and most widely....... 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...

  6. Galvanic Corrosion between Alloy 690 and Magnetite in Alkaline Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Soon-Hyeok Jeon

    2015-12-01

    Full Text Available The galvanic corrosion behavior of Alloy 690 coupled with magnetite has been investigated in an alkaline solution at 30 °C and 60 °C using a potentiodynamic polarization method and a zero resistance ammeter. The positive current values were recorded in the galvanic couple and the corrosion potential of Alloy 690 was relatively lower. These results indicate that Alloy 690 behaves as the anode of the pair. The galvanic coupling between Alloy 690 and magnetite increased the corrosion rate of Alloy 690. The temperature increase led to an increase in the extent of galvanic effect and a decrease in the stability of passive film. Galvanic effect between Alloy 690 and magnetite is proposed as an additional factor accelerating the corrosion rate of Alloy 690 steam generator tubing in secondary water.

  7. Corrosion behavior of alloy 600 coupled with electrodeposited magnetite in simulated secondary water of PWRs

    International Nuclear Information System (INIS)

    The corrosion behavior of Alloy 600 coupled with magnetite was investigated in simulated secondary water of pressurized water reactors using a potentiodynamic polarization test and zero-resistance ammeter. Passive film formed on the surface of Alloy 600 was also analyzed using X-ray photoelectron spectroscopy. Alloy 600 was the anodic element of the galvanic pair since its corrosion potential was less noble than that of the magnetite. Galvanic coupling increased the corrosion current density of Alloy 600 due to the shifting of the potential of Alloy 600 to the positive value. The passive film of coupled Alloy 600 was more slowly stabilized and was thinner and less protective than that of non-coupled Alloy 600. (author)

  8. Stereometry specification of anodised and PVD coated surface of aluminium alloy

    Directory of Open Access Journals (Sweden)

    J. Konieczny

    2009-08-01

    Full Text Available Purpose: The aim of the work is to present the influence of casting method and anodic treatment parameters on properties, thickness and structure of an anodic layer with (PVD physical vapour deposition method achieved TiN layer formed on aluminum casting alloys.Design/methodology/approach: Investigations were carried out on the laser profile measurement gauge MicroProf from company FRT, abrasive wear test was made with using ABR-8251 equipment delivered by TCD Teknologi ApS and microstructure investigations were made with using a light microscope equipped with an electronic camera configured with a computer on two casting aluminum alloys which both were founding by pressure die casting and gravity casting.Findings: The researches included analyze of the influence of geometry, roughness and abrasive wear resistant of anodic layer obtained on aluminum casts. The studied PVD coating deposited by cathodic arc evaporation method demonstrates high hardness, adhesion and wear resistance.Research limitations/implications: Contributes to research on anodic and PVD layer for aluminum casting alloys.Practical implications: Conducted investigations lay out the areas of later researches, especially in the direction of the possible, next optimization anodization process of aluminum casting alloys, e.g. in the range of raising resistance on corrosion.Originality/value: The range of possible applications increases staidly for example for materials used on working building constructions, elements in electronics and construction parts in air and motorization industry in the aggressive environment.

  9. Improving the Performance of SOFC Anodes by Decorating Perovskite with Ni Nanoparticles

    KAUST Repository

    Boulfrad, S.

    2013-10-07

    In this work (La0.75Sr0.25)0.97Cr0.5Mn0.5O3 (LSCM) perovskite powders were pre-coated with 5 wt% nickel and mixed with different amounts of CGO for testing as anode materials under 3% wet H2. By using scanning transmission electron microscopy (STEM) with X-ray energy dispersive spectroscopy (EDS), we demonstrated that Ni forms a solid solution in the perovkite phase under oxidizing atmosphere and exsolves in form of nanoparticles under reducing atmospheres. The presence of the catalyst nanoparticles led to a decrease in the anodic activation energy by half and thus the polarization resistance was dropped by 60% at 800¢ªC. The effect of CGO amount will be also discussed.

  10. Electrochemical Impedance Spectroscopy Investigation of the Anodic Functionalities and Processes in LSCM-CGO-Ni Systems

    KAUST Repository

    Boulfrad, Samir

    2015-07-17

    Electrochemical impedance spectroscopy was used to characterize anode compositions made of (La0.75Sr0.25)0.97Cr0.5Mn0.5O3 (LSCM) and gadolinia doped ceria (CGO) with and without additional submicron Ni, or exsoluted Ni nanoparticles. In addition, the effects of the anode gas flow rate and the working temperature were investigated. Higher content of the ionic conductor leads to a decrease of the impedance in the frequency range from 100 Hz to 10 Hz. The effect of the catalyst component was investigated while keeping the electronic conductivity unchanged in the tested materials. Enhanced catalytic activity was demonstrated to considerably decrease the impedance especially in the frequency range between 100 Hz to 1 Hz. The change in the gas flow rate affects mainly the impedance bellow 1 Hz. © The Electrochemical Society.

  11. Hydrogen absorption induced metal deposition on palladium and palladium-alloy particles

    Science.gov (United States)

    Wang, Jia X.; Adzic, Radoslav R.

    2009-03-24

    The present invention relates to methods for producing metal-coated palladium or palladium-alloy particles. The method includes contacting hydrogen-absorbed palladium or palladium-alloy particles with one or more metal salts to produce a sub-monoatomic or monoatomic metal- or metal-alloy coating on the surface of the hydrogen-absorbed palladium or palladium-alloy particles. The invention also relates to methods for producing catalysts and methods for producing electrical energy using the metal-coated palladium or palladium-alloy particles of the present invention.

  12. Magnetic catalyst bodies

    NARCIS (Netherlands)

    Teunissen, Wendy; Bol, A.A.; Geus, John W.

    2001-01-01

    After a discussion about the importance of the size of the catalyst bodies with reactions in the liquid-phase with a suspended catalyst, the possibilities of magnetic separation are dealt with. Deficiencies of the usual ferromagnetic particles are the reactivity and the clustering of the particles.

  13. Catalyst for Ammonia Oxidation

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a bimetallic catalyst for ammonia oxidation, a method for producing a bimetallic catalyst for ammonia oxidation and a method for tuning the catalytic activity of a transition metal. By depositing an overlayer of less catalytic active metal onto a more catalytic...

  14. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

    The article gives an overview of electrical resistance alloys and alloys with low thermal expansion. The electrical resistance alloys comprise resistance alloys, heating alloys and thermostat alloys. The low expansion alloys comprise alloys with very low expansion coefficients, alloys with very low...

  15. Galvanic compatibility of corrosion protective coatings with AA7075 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lodhi, Z.F.; Hamer, W.J. [Netherlands Institute for Metals Research (NIMR), Mekelweg 2, 2628 CD Delft (Netherlands); Mol, J.M.C.; Wit, J.H.W. de [Delft University of Technology, Department of Materials Science and Engineering, Mekelweg 2, 2628 CD Delft (Netherlands); Terryn, H. [Netherlands Institute for Metals Research (NIMR), Mekelweg 2, 2628 CD Delft (Netherlands); Department of Metallurgy, Electrochemistry and Materials Science, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels (Belgium)

    2008-04-15

    The galvanic compatibility of aerospace aluminum alloy AA7075 with cadmium (Cd), zinc (Zn), and zinc-cobalt-iron (Zn-Co-Fe, 32-37%Co and 1%Fe) alloys was investigated. A comparison of open circuit potential [OCP vs. saturated calomel electrode (SCE)] measurements in 0.6 mM NaCl showed that all coatings would act anodically to AA7075 with an exception of Zn-Co-Fe (37%Co + 1%Fe) alloy which was electropositive to AA7075. During the zero resistance ammetry (ZRA) measurement in 0.6 M NaCl electrolyte the coupled OCP and current density were measured during 7 days of immersion and both Zn and Cd acted anodic and thus sacrificial to AA7075. Galvanic coupling of AA7075 with (37%Co + 1%Fe) Zn-Co-Fe alloy resulted in the consequent dissolution of the AA7075 aluminum alloy. In contrast, Zn-Co-Fe (32%Co + 1%Fe) alloy was found to be anodic to AA7075 during the first 26 h of immersion but after dezincification and cobalt enrichment at the surface became cathodic to the AA7075 aluminum alloy. During coupling with Zn, some pitting was also observed on AA7075. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  16. Inorganic Glue Enabling High Performance of Silicon Particles as Lithium Ion Battery Anode

    KAUST Repository

    Cui, Li-Feng

    2011-01-01

    Silicon, as an alloy-type anode material, has recently attracted lots of attention because of its highest known Li+ storage capacity (4200 mAh/g). But lithium insertion into and extraction from silicon are accompanied by a huge volume change, up to 300, which induces a strong strain on silicon and causes pulverization and rapid capacity fading due to the loss of the electrical contact between part of silicon and current collector. Silicon nanostructures such as nanowires and nanotubes can overcome the pulverization problem, however these nano-engineered silicon anodes usually involve very expensive processes and have difficulty being applied in commercial lithium ion batteries. In this study, we report a novel method using amorphous silicon as inorganic glue replacing conventional polymer binder. This inorganic glue method can solve the loss of contact issue in conventional silicon particle anode and enables successful cycling of various sizes of silicon particles, both nano-particles and micron particles. With a limited capacity of 800 mAh/g, relatively large silicon micron-particles can be stably cycled over 200 cycles. The very cheap production of these silicon particle anodes makes our method promising and competitive in lithium ion battery industry. © 2011 The Electrochemical Society.

  17. Heterogeneous hydrogenation catalysts

    International Nuclear Information System (INIS)

    The main types of heterogeneous catalysts used for hydrogenation, the methods for their preparation, and the structure and chemistry of their surfaces are considered, as well as the catalytic activity and the mechanism of action in the hydrogenation of unsaturated and aromatic compounds, of CO, and of carbonyl compounds and in the hydrorefining of fuels. Chief attention is paid to supported Ni catalysts, to the methods for their preparation and physicochemical studies, and to the development of novel catalytic systems through modification. A novel type of catalyst for hydrogenation, viz. metal carbides, is described. Some aspects of the mechanochemical treatment of hydrogenation catalysts, including in situ methods, are discussed. Sulfide catalysts for hydrotreating are also discussed in detail. The bibliography includes 340 references.

  18. Design of heterogeneous catalysts

    DEFF Research Database (Denmark)

    Frey, Anne Mette

    . Previously it has been shown that calcination of cobalt catalyst in a NO/He mixture resulted in improved catalytic activity compared to standard air calcined samples, since more homogenous cobalt particles with a narrow particle size distribution were formed. Unfortunately the C5+ selectivity decreased....... Since Mn is known to improve C5+ selectivity the addition of this promoter, combined with NO calcination, was studied. The influence of parameters such as Co:Mn ratio, drying conditions, and reduction temperatures on the catalytic performance were investigated. The promotion strategy 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 vanadium-based catalyst...

  19. Conversion Coatings Produced on AZ61 Magnesium Alloy by Low-Voltage Process

    Directory of Open Access Journals (Sweden)

    Nowak M.

    2016-03-01

    Full Text Available The resultes of anodic oxide conversion coatings on wrought AZ61 magnesium alloy production are describe. The studies were conducted in a solution containing: KOH (80 g/l and KF (300 g/l using anodic current densities of 3, 5 and 10 A/dm2 and different process durations. The obtained coatings were examined under a microscope and corrosion tests were performed by electrochemical method. Based on these results, it was found that the low-voltage process produces coatings conferring improved corrosion resistance to the tested magnesium alloy.

  20. Method for forming gold-containing catalyst with porous structure

    Energy Technology Data Exchange (ETDEWEB)

    Biener, Juergen; Hamza, Alex V; Baeumer, Marcus; Schulz, Christian; Jurgens, Birte; Biener, Monika M.

    2014-07-22

    A method for forming a gold-containing catalyst with porous structure according to one embodiment of the present invention includes producing a starting alloy by melting together of gold and at least one less noble metal that is selected from the group consisting of silver, copper, rhodium, palladium, and platinum; and a dealloying step comprising at least partial removal of the less noble metal by dissolving the at least one less noble metal out of the starting alloy. Additional methods and products thereof are also presented.

  1. The Electrochemical Behavior of Al Alloys Containing Tin and Gallium in Alkaline Electrolytes%含镓、锡的铝合金在碱性溶液中的阳极行为

    Institute of Scientific and Technical Information of China (English)

    李振亚; 秦学; 余远彬; 陈艳英; 易玲; 杨林

    1999-01-01

    The major reason of Al anode activation is that Ga can plate out on the aluminum surface and form activated points.The Al-Sn,Al-Ga binary alloys can′ t be activated in alkaline medium.During the dissolution of the Al-Sn-Ga ternary anode,Sn and Ga dissolove solution aions as ions.After Sn ions deposit on the surface of Al anode,Ga ions will underpotentially deposit on Sn.The higher activation of the polycomponent alloy anode is caused by much more new activated points being continually formed.The activation mechanism for the polycomponent Al-alloy anode in alkaline medium is abided by the "dissolution-deposition".

  2. Confinement dependence of electro-catalysts for hydrogen evolution from water splitting

    Directory of Open Access Journals (Sweden)

    Mikaela Lindgren

    2014-02-01

    Full Text Available Density functional theory is utilized to articulate a particular generic deconstruction of the electrode/electro-catalyst assembly for the cathode process during water splitting. A computational model was designed to determine how alloying elements control the fraction of H2 released during zirconium oxidation by water relative to the amount of hydrogen picked up by the corroding alloy. This model is utilized to determine the efficiencies of transition metals decorated with hydroxide interfaces in facilitating the electro-catalytic hydrogen evolution reaction. A computational strategy is developed to select an electro-catalyst for hydrogen evolution (HE, where the choice of a transition metal catalyst is guided by the confining environment. The latter may be recast into a nominal pressure experienced by the evolving H2 molecule. We arrived at a novel perspective on the uniqueness of oxide supported atomic Pt as a HE catalyst under ambient conditions.

  3. Organic dyestuffs as catalysts for fuel cells.

    Science.gov (United States)

    Jahnke, H; Schönborn, M; Zimmermann, G

    1976-01-01

    Electrocatalysis in fuel cells requires as well substances capable of catalyzing the anodic oxidation of fuels as catalysts for the cathodic reduction of oxygen. Several dyestuffs that catalyze oxygen reduction are known, but up to now only one has been described as active in anodic reactions. All these dyestuffs are N4-chelates. Comparative studies have shown that chelates with other types of coordination, in particular N202-, 04-, N2S2- and S4-chelates, are able to catalyze the reduction of oxygen, though they are considerably less active than the N4-compounds. With a given type of coordination, the nature of the central atom has a decisive influence on the catalytic activity of the dyestuff, whereas substitution on the organic skeleton has only a slight effect. Thermal pretreatment of the N4-chelates can considerably increase their stability in electrolytes containing sulfuric acid. All the experimental results point to the conclusion that, with electrocatalysts, as with natural oxygen carriers, the interaction essential for catalysis takes place between the oxygen and the central metal ion. Various assumptions may be made as to the nature of the rate-determining step. The cathodic reduction of oxygen can be regarded as redox catalysis, or it can be considered from the standpoint of molecular orbital theory. The models hitherto suggested for the mechanism of oxygen reduction are tested against the experimental results and a modified model based on MO theory is put forward. PMID:7032

  4. Localized corrosion mechanism associated with precipitates containing Mg in Al alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    To clarify the localized corrosion mechanism associated with precipitates containing Mg in Al alloys, the simulated bulk precipitates of S and β were synthesized through melting and casting. Their electrochemical behaviors and coupling behaviors with α(Al) in NaCl solution were measured. Meanwhile, simulated Al alloys containing S and β particles were prepared and their corrosion morphologies were observed. It's found that there exist two kinds of corrosion mechanisms associated with precipitates containing Mg. The precipitate of β is anodic to the alloy base, resulting in its anodic dissolution and corrosion during the whole corrosion process. While, there exists a corrosion conversion mechanism associated with the S precipitate, which contains active element Mg and noble element Cu simultaneously. At an initial stage, S is anodic to the alloy matrix at its periphery and the corrosion occurs on its surface. However, during its corrosion process, Mg is preferentially dissolved and noble Cu is enriched in the remnants.This makes S become cathodic to α(Al) and leads to anodic dissolution and corrosion on the alloy base at its periphery at a later stage.

  5. Catalysts, methods of making catalysts, and methods of use

    KAUST Repository

    Renard, Laetitia

    2014-03-06

    Embodiments of the present disclosure provide for catalysts, methods of making catalysts, methods of using catalysts, and the like. In an embodiment, the method of making the catalysts can be performed in a single step with a metal nanoparticle precursor and a metal oxide precursor, where a separate stabilizing agent is not needed.

  6. Mechanochemical approaches to employ silicon as a lithium-ion battery anode

    Directory of Open Access Journals (Sweden)

    Norihiro Shimoi

    2015-05-01

    Full Text Available Silicon is essential as an active material in lithium-ion batteries because it provides both high-charge and optimal cycle characteristics. The authors attempted to realize a composite by a simple mechanochemical grinding approach of individual silicon (Si particles and copper monoxide (CuO particles to serve as an active material in the anode and optimize the charge-discharge characteristics of a lithium-ion battery. The composite with Si and CuO allowed for a homogenous dispersion with nano-scale Si grains, nano-scale copper-silicon alloy grains and silicon monoxide oxidized the oxide from CuO. The authors successfully achieved the synthesis of an active composite unites the structural features of an active material based on silicon composite as an anode in Li-ion battery with high capacity and cyclic reversible charge properties of 3256 mAh g−1 after 200 cycles.

  7. Mechanochemical approaches to employ silicon as a lithium-ion battery anode

    International Nuclear Information System (INIS)

    Silicon is essential as an active material in lithium-ion batteries because it provides both high-charge and optimal cycle characteristics. The authors attempted to realize a composite by a simple mechanochemical grinding approach of individual silicon (Si) particles and copper monoxide (CuO) particles to serve as an active material in the anode and optimize the charge-discharge characteristics of a lithium-ion battery. The composite with Si and CuO allowed for a homogenous dispersion with nano-scale Si grains, nano-scale copper-silicon alloy grains and silicon monoxide oxidized the oxide from CuO. The authors successfully achieved the synthesis of an active composite unites the structural features of an active material based on silicon composite as an anode in Li-ion battery with high capacity and cyclic reversible charge properties of 3256 mAh g−1 after 200 cycles

  8. Anodic dissolution of gold in alkaline solutions containing thiourea, thiosulfate and sulfite ions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Gold dissolves electrochemically in alkaline solutions containing ligands to form complex ions with gold ion. Therefore, selective leaching of noble metals is expected without dissolution of base metals such as steels, aluminum alloys in scrap treatment. Gold electrodes were investigated using linear sweep voltammetry, EQCM method and potentiostatic electrolysis in alkaline solutions containing thiourea, Na2SO3 and Na2S2O3. The solution composition, electrode potential affect gold dissolution rate and current efficiency. The gold dissolved from anode electrode forms complex ions, suspension particles as compound precipitates and deposits on cathode electrode as a metal. Anodic efficiency for gold dissolution is between 10% and 22%. This is caused by the oxidation decomposition of sulfite ions and thiourea. The stability of the alkaline solution containing these elements was also estimated by capillary electrophoresis technique.

  9. Synthesis of nano Sb-encapsulated pyrolytic polyacrylonitrile composite for anode material in lithium secondary batteries

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiangming; Pu, Weihua; Wang, Li; Ren, Jianguo; Jiang, Changyin; Wan, Chunrong [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)

    2007-03-01

    A novel process was proposed to synthesize nano Sb-encapsulated pyrolytic polyacrylonitrile composite for anode material in lithium secondary batteries. The preparation started with the dissolution of SbCl{sub 3} and polyacrylonitrile (PAN) in dimethylformamide (DMF) solution, followed by the addition of KBH{sub 4} to reduce Sb{sup 3+} in the solution. The Sb composite was obtained by pyrolysis of the Sb/PAN mixture that precipitated out when the DMF solution was added by plentiful water. The TEM analysis showed that about 100-200 nm Sb particles were embedded by the pyrolyzed PAN, which provided a conductive matrix to relieve the morphological change of Sb during electrochemical cycling. As-prepared composite presented good cycleability for lithium storage. The proposed process paves an effective way to prepare high performance alloy based composite anode materials for high performance lithium-ion batteries. (author)

  10. Micro thermal shear stress sensor based on vacuum anodic bonding and bulk-micromachining

    Institute of Scientific and Technical Information of China (English)

    Yi Liang; Ou Yi; Shi Sha-Li; Ma Jin; Chen Da-Peng; Ye Tian-Chun

    2008-01-01

    This paper describes a micro thermal shear stress sensor with a cavity underneath, based on vacuum anodic bonding and bulk micromachined technology. A Ti/Pt alloy strip, 2μmx100μm, is deposited on the top of a thin silicon nitride diaphragm and functioned as the thermal sensor element. By using vacuum anodic bonding and bulk-si anisotropic wet etching process instead of the sacrificial-layer technique, a cavity, functioned as the adiabatic vacuum chamber, 200μm×200μm×400μm, is placed between the silicon nitride diaphragm and glass (Corning 7740). This method totally avoid adhesion problem which is a major issue of the sacrificial-layer technique.

  11. Mechanochemical approaches to employ silicon as a lithium-ion battery anode

    Energy Technology Data Exchange (ETDEWEB)

    Shimoi, Norihiro, E-mail: shimoi@mail.kankyo.tohoku.ac.jp; Bahena-Garrido, Sharon; Tanaka, Yasumitsu [Graduate School of Environmental Studies, Tohoku University 6-6-20 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Qiwu, Zhang [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2015-05-15

    Silicon is essential as an active material in lithium-ion batteries because it provides both high-charge and optimal cycle characteristics. The authors attempted to realize a composite by a simple mechanochemical grinding approach of individual silicon (Si) particles and copper monoxide (CuO) particles to serve as an active material in the anode and optimize the charge-discharge characteristics of a lithium-ion battery. The composite with Si and CuO allowed for a homogenous dispersion with nano-scale Si grains, nano-scale copper-silicon alloy grains and silicon monoxide oxidized the oxide from CuO. The authors successfully achieved the synthesis of an active composite unites the structural features of an active material based on silicon composite as an anode in Li-ion battery with high capacity and cyclic reversible charge properties of 3256 mAh g{sup −1} after 200 cycles.

  12. Integration of robust fluidic interconnects using metal to glass anodic bonding

    Science.gov (United States)

    Briand, Danick; Weber, Patrick; de Rooij, Nicolaas F.

    2005-09-01

    This paper reports on the encapsulation of a piezoresistive silicon/Pyrex liquid flow sensor using metal to glass anodic bonding. The bonding technique allowed integrating robust metallic microfluidic interconnects and eliminating the use of glue and O-rings. The bonding parameters of a silicon/Pyrex/metal triple stack were chosen to minimize the residual stress and to obtain a strong and liquid tight bonding interface. The silicon/Pyrex liquid flow sensor was successfully bonded to metallic plates of Kovar and Alloy 42, on which tubes were fixed and a printed circuit board (PCB) was integrated. A post-bonding annealing procedure was developed to reduce the residual bonding stress. The characteristics of the encapsulated liquid flow sensor, such as the temperature coefficient of sensitivity, fulfilled the specifications. Wafer level packaging using metal to glass anodic bonding was considered to reduce the packaging size and cost.

  13. Chemo-mechanical softening during in situ nanoindentation of anodic porous alumina with anodization processing

    OpenAIRE

    Cheng, C; Ngan, AHW

    2013-01-01

    Simultaneous application of mechanical stresses on a material as it undergoes an electrochemical reaction can result in interesting coupling effects between the chemical and mechanical responses of the material. In this work, anodic porous alumina supported on Al is found to exhibit significant softening during in situ nanoindentation with anodization processing. Compared with ex situ nanoindentation without anodization processing, the in situ hardness measured on the alumina is found to be m...

  14. Corrosion behavior of an Al-6Mg-Sc-Zr alloy

    Institute of Scientific and Technical Information of China (English)

    XU Guangxing; TAO Binwu; LIU Jianhua; LI Songmei

    2005-01-01

    The corrosion behavior of an Al-6Mg-Sc-Zr alloy was studied and compared with that of an Al-6Mg-Zr alloy.The addition of scandium into the Al-6Mg-Zr alloy reduced the susceptibility to exfoliation corrosion. By using the constant load tensile method in a 3.5 wt.% NaCl solution, the resistance to SCC of the Al-6Mg-Sc-Zr alloy was higher than that of the Al-6Mg-Zr alloy. When the specimens were not applied with an anodic current, the Al-6Mg-Sc-Zr alloy was resistance to SCC and no brittle cracking was found on the fracture surface. When an anodic current was applied, the Al-6Mg-Sc-Zr alloy specimens failed as a result of accelerated corrosion rather than SCC. It was believed that the addition of scandium resulted in (Al3Sc, Zr) particles that greatly refmed grains and promoted the formation of homogeneous discontinuous distribution of β-phase in the alloy base, which much contributed to good corrosion resistance of the Al-6Mg-Sc-Zr alloy.

  15. Formation of upper rim acylated calix[4]arenes using a sacrifici al zinc anode

    OpenAIRE

    Louati, Alain; Vataj, Rame; Gabelica, Valérie; Lejeune, Manuel; MATT, DOMINIQUE

    2005-01-01

    A straightforward electrosynthetic method is described, which allows upper rim acylation of non-p-halogenated calix[4]-arenes. For example, a solution of tetrapropoxycalix[4]arene 4 was electrolysed in the presence of ZnBr2, in an undivided cell fitted with a sacrificial zinc anode using pure acetonitrile as solvent, yielding an organozinc species, which was then treated with acetyl chloride in the presence of a palladium catalyst to afford 5,11-diacety1-25,26,27,28-tetrapropoxycalix[4]arene ...

  16. Improved electrical properties of silicon-incorporated anodic niobium oxide formed on porous Nb-Si substrate

    International Nuclear Information System (INIS)

    In the present study, porous Nb-Si alloy films with isolated nano-column morphology have been successfully developed by oblique angle magnetron sputtering on to aluminum substrate with concave cell structure. The deposited films are amorphous with the 15 at% silicon supersaturated into niobium. The porous Nb-15 at% Si films, as well as niobium films with similar morphology, are anodized at several voltages up to 50 V in 0.1 mol dm-3 ammonium pentaborate electrolyte. Due to the presence of sufficient gaps between neighboring columns, the gaps are not filled with anodic oxide, despite the large Pilling-Bedworth ratio (for instance, 2.6 for Nb/Nb2O5) and hence, a linear correlation between the reciprocal of capacitance and formation voltage is obtained for the Nb-15 at% Si. From the comparison with the anodic films formed on porous niobium films, it has been found that silicon addition improves the thermal stability of anodic niobium oxide; the change in capacitance and increase in leakage current become small for the Nb-Si. The findings indicate the potential of oblique angle deposition to tailor porous non-equilibrium niobium alloy films for high performance niobium-base capacitor.

  17. Electroplating and corrosion behavior of tin-zinc alloy

    Science.gov (United States)

    Wang, Kai

    Due to the toxicity of cadmium and its electroplating processes, a replacement to this widely used coating is desired. Electroplated tin-zinc alloy is a good candidate. In this thesis the electroplating of tin-zinc alloy and its corrosion behavior have been studied. Tin-zinc alloy was plated from a commercial, neutral, non-cyanide and non-toxic bath. To get an alloy deposit with a composition of 70%Sn-30%Zn, a plating current density of 5 mA/cm2 should be applied. When plating without agitation, the consumption of the H+ ions by the accompanying hydrogen evolution reaction on the cathode surface caused a local pH increase and then the formation of a hydroxide layer on the outer surface. This can be prevented by agitating the solution with nitrogen gas bubbling during plating. The alloy deposit is a fine mixture of pure zinc and tin phases. The plating current efficiency was calculated to be 71% at the plating current density of 5 mA/cm2. The tin-zinc electrodeposits have both a sacrificial property provided by zinc and a barrier property provided by tin. The open circuit potential (OCP) of the alloy coating is very close to that of zinc, so it acts as a sacrificial anode and provides a cathodic protection to the steel substrate. On the other hand, the anodic polarization current density keeps very small before the potential reaches the OCP of tin. This is because the presence of the tin on the surface forms a barrier layer which retarded the dissolution of zinc and enhanced the durability of the alloy deposit. The OCP of the tin-zinc alloys increases with corrosion duration. It is perhaps due to an IR-drop mechanism. As zinc dissolves into the solution, cavities appear on the surface. Further zinc dissolution only occurs at the bottom of the pores, while the hydrogen evolution reaction mainly occurs on the outer surface. The separation of the anodic and cathodic sites causes an IR drop. An equivalent circuit is devised and the values of the circuit elements are

  18. Supported Pt-based nanoparticulate catalysts for the electro-oxidation of methanol: An experimental protocol for quantifying its activity

    DEFF Research Database (Denmark)

    Hernandez-Fernandez, Patricia; Lund, Peter Brilner; Kallesøe, Christian;

    2014-01-01

    in the literature. We recommend analyzing the catalytic activity in the methanol oxidation reaction by chronoamperometry. This is because it is the only way to account poisoning effects on the catalytic surface, which will determine the performance of the catalyst as anode in a direct methanol fuel cell....

  19. Macrokinetic relationships between anodic processes in chlorine electrolysis on ruthenium-titanium oxide anodes

    International Nuclear Information System (INIS)

    Effect of porosity on kinetics of the main (chlorine evolution) and side (oxygen evolution and anodic dissolution of ruthenium dioxide) reactions for chlorine electrolysis conditions has been analyzed. Making allowance for chlorine hydrolysis secondary reaction, the distribution of chlorine concentration, solution pH and current densities of the main and side processes over the porous anode depth, have been found. It is shown that solution acidification in the anode pores due to chlorine hydrolysis can bring about replacement of oxygen evolution and ruthenium dioxide dissolution side reactions toward the porous anode external sides thus affecting its selectivity and corrosion resistance

  20. Catalyst in Basic Oleochemicals

    Directory of Open Access Journals (Sweden)

    Eva Suyenty

    2007-10-01

    Full Text Available Currently Indonesia is the world largest palm oil producer with production volume reaching 16 million tones per annum. The high crude oil and ethylene prices in the last 3 – 4 years contribute to the healthy demand growth for basic oleochemicals: fatty acids and fatty alcohols. Oleochemicals are starting to replace crude oil derived products in various applications. As widely practiced in petrochemical industry, catalyst plays a very important role in the production of basic oleochemicals. Catalytic reactions are abound in the production of oleochemicals: Nickel based catalysts are used in the hydrogenation of unsaturated fatty acids; sodium methylate catalyst in the transesterification of triglycerides; sulfonic based polystyrene resin catalyst in esterification of fatty acids; and copper chromite/copper zinc catalyst in the high pressure hydrogenation of methyl esters or fatty acids to produce fatty alcohols. To maintain long catalyst life, it is crucial to ensure the absence of catalyst poisons and inhibitors in the feed. The preparation methods of nickel and copper chromite catalysts are as follows: precipitation, filtration, drying, and calcinations. Sodium methylate is derived from direct reaction of sodium metal and methanol under inert gas. The sulfonic based polystyrene resin is derived from sulfonation of polystyrene crosslinked with di-vinyl-benzene. © 2007 BCREC UNDIP. All rights reserved.[Presented at Symposium and Congress of MKICS 2007, 18-19 April 2007, Semarang, Indonesia][How to Cite: E. Suyenty, H. Sentosa, M. Agustine, S. Anwar, A. Lie, E. Sutanto. (2007. Catalyst in Basic Oleochemicals. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 22-31.  doi:10.9767/bcrec.2.2-3.6.22-31][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.2-3.6.22-31 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/6