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Sample records for ru electrocatalysts prepared

  1. Carbon supported nanoparticles Pt Ru (Pt Ru/C electrocatalysts) prepared using electron beam irradiation; Preparacao de nanoparticulas de PtRu suportadas em carbono (eletrocatalisadores PtRu/C) utilizando feixe de eletrons

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio F. da; Oliveira Neto, Almir; Pino, Eddy S.; Linardi, Marcelo; Spinace, Estevam V. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Programa de Celulas a Combustivel], e-mail: espinace@ipen.br, e-mail: dfsilva@ipen.br

    2006-07-01

    Carbon-supported Pt Ru (electrocatalysts PtRu/C nanoparticles) were prepared submitting a water/ethylene glycol mixture containing Pt(IV) and Ru(III) ions and the carbon support to electron beam irradiation. The PtRu/C electrocatalysts were characterized by EDX, XRD and cyclic voltammetry and tested for methanol electro-oxidation aiming fuel cell application. The obtained PtRu/C electrocatalysts were more active for methanol electro-oxidation than the commercial PtRu/C ETEK electrocatalyst at ambient temperature. (author)

  2. Preparation of PtRu/C anode electrocatalysts using gamma radiation for methanol electro-oxidation

    International Nuclear Information System (INIS)

    Silva, Dionisio Fortunato da

    2006-01-01

    Pt Ru/C (carbon-supported Pt Ru nanoparticles) anode electrocatalysts were prepared using radiolytic process (gamma radiation) and tested for methanol electro-oxidation. In this process, water/2-propanol and water/ethylene glycol solutions containing the metallic ions and the carbon support were submitted to gamma radiation under stirring. The water/alcohol ratio (v/v) and the total dose (kGy) were studied. A nominal Pt Ru atomic ratio of 50:50 were used in all experiments. The electrocatalysts were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry (CV). The electro-oxidation of methanol was studied by cyclic voltammetry using the thin porous coating technique. The electrocatalysts prepared in water/2-propanol showed crystallite size in the range of 3-5 nm and Pt Ru atomic ratio of 50:50. The electrocatalysts prepared in water/ethylene glycol showed crystallite size (2-3 nm) smaller than the ones obtained in water/2-propanol, however, the Pt Ru atomic ratios obtained were approximately 80:20, showing that only part of ruthenium ions were reduced. For methanol oxidation the electrocatalytic activity depends on the water/2-propanol and water/ethylene glycol ratio used in the reaction medium. The electrocatalysts prepared in water/2-propanol showed inferior performance to the ones prepared in water/ethylene glycol, which showed similar or superior performances (amperes per gram of platinum) to the commercial electrocatalyst from E-TEK. (author)

  3. PtRu/C and PtRuBi/C electrocatalysts prepared by two different methodologies of borohydride reduction process for ethanol electro-oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Brandalise, Michele; Tusi, Marcelo Marques; Piasentin, Ricardo Marcelo; Correa, Olandir Vercino; Linardi, Marcelo; Spinace, Estevam Vitorio; Oliveira Neto, Almir, E-mail: brandalise@usp.br, E-mail: mmtusi@usp.br, E-mail: rmpiasen@ipen.br, E-mail: ovcorrea@ipen.br, E-mail: mlinardi@ipen.br, E-mail: espinace@ipen.br, E-mail: aolivei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    PtRu/C (50:50) and PtRuBi/C (50:40:10) electrocatalysts were prepared by borohydride reduction using H{sub 2}PtCl{sub 6.6}H{sub 2}O, RuCl{sub 3.x}H{sub 2}O and Bi(NO{sub 3}){sub 3.5}H{sub 2}O as metals sources and Vulcan XC72 as support. The borohydride solution was added in two different ways: drop by drop and rapid addition of all the solution. The obtained electrocatalysts were characterized by EDX, XRD and cyclic voltammetry. The electro-oxidation of ethanol was studied by cyclic voltammetry and chronoamperometry at room temperature and on a single cell of a direct ethanol fuel cell (DEFC) at 100 deg C. PtRuBi/C electrocatalysts showed superior performance for ethanol electro-oxidation than PtRu/C electrocatalysts prepared in a similar way. However, PtRuBi/C electrocatalyst prepared by rapid addition of the borohydride solution showed superior performance for ethanol electro oxidation at room temperature, while PtRuBi/C electrocatalyst prepared by addition drop by drop of borohydride solution showed superior performance on DEFC at 100 deg C. (author)

  4. PtRu/C and PtRuBi/C electrocatalysts prepared by two different methodologies of borohydride reduction process for ethanol electro-oxidation

    International Nuclear Information System (INIS)

    Brandalise, Michele; Tusi, Marcelo Marques; Piasentin, Ricardo Marcelo; Correa, Olandir Vercino; Linardi, Marcelo; Spinace, Estevam Vitorio; Oliveira Neto, Almir

    2009-01-01

    PtRu/C (50:50) and PtRuBi/C (50:40:10) electrocatalysts were prepared by borohydride reduction using H 2 PtCl 6.6 H 2 O, RuCl 3.x H 2 O and Bi(NO 3 ) 3.5 H 2 O as metals sources and Vulcan XC72 as support. The borohydride solution was added in two different ways: drop by drop and rapid addition of all the solution. The obtained electrocatalysts were characterized by EDX, XRD and cyclic voltammetry. The electro-oxidation of ethanol was studied by cyclic voltammetry and chronoamperometry at room temperature and on a single cell of a direct ethanol fuel cell (DEFC) at 100 deg C. PtRuBi/C electrocatalysts showed superior performance for ethanol electro-oxidation than PtRu/C electrocatalysts prepared in a similar way. However, PtRuBi/C electrocatalyst prepared by rapid addition of the borohydride solution showed superior performance for ethanol electro oxidation at room temperature, while PtRuBi/C electrocatalyst prepared by addition drop by drop of borohydride solution showed superior performance on DEFC at 100 deg C. (author)

  5. Preparation of Pt Ru/C electrocatalysts using gamma radiation for application as anode in direct methanol fuel cell

    International Nuclear Information System (INIS)

    Spinace, Estevam V.; Silva, Dionisio F. da; Cruz, Victor A. da; Oliveira Neto, Almir; Machado, Luci D.B.; Pino, Eddy S.; Linardi, Marcelo

    2005-01-01

    PtRu nanoparticles supported on carbon (PtRu/C electrocatalysts) were prepared submitting a water/2-propanol mixture containing the metal ions and the carbon support to gamma radiation. The water/2-propanol (v/v) and the total dose (kGy) were studied. The electrocatalysts were characterized by EDX, XRD and cyclic voltammetry. The methanol electro-oxidation was studied by cyclic voltammetry using the thin porous coating. In the studied conditions, the electrocatalytic activity of the prepared electrocatalysts depend on the water/2-propanol ratio used in the reaction medium. (author)

  6. Electro-oxidation of methanol and ethanol using PtRu/C, PtSn/C and PtSnRu/C electrocatalysts prepared by an alcohol-reduction process

    Energy Technology Data Exchange (ETDEWEB)

    Neto, Almir Oliveira; Dias, Ricardo R.; Tusi, Marcelo M.; Linardi, Marcelo; Spinace, Estevam V. [Instituto de Pesquisas Energeticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, Cidade Universitaria, CEP 05508-900 Sao Paulo, SP (Brazil)

    2007-03-30

    PtRu/C, PtSn/C and PtSnRu/C electrocatalysts were prepared by the alcohol reduction process using ethylene glycol as the solvent and reduction agent and Vulcan Carbon XC72 as the support. The electrocatalysts were characterized by EDX, XRD and cyclic voltammetry. The electrochemical oxidation of methanol and ethanol were studied by chronoamperometry using a thin porous coating technique. The PtSn/C electrocatalyst prepared by this methodology showed superior performance compared to the PtRu/C and PtSnRu/C electrocatalysts for methanol and ethanol oxidation at room temperature. (author)

  7. Electro-oxidation of methanol and ethanol using PtRu/C, PtSn/C and PtSnRu/C electrocatalysts prepared by an alcohol-reduction process

    Science.gov (United States)

    Neto, Almir Oliveira; Dias, Ricardo R.; Tusi, Marcelo M.; Linardi, Marcelo; Spinacé, Estevam V.

    PtRu/C, PtSn/C and PtSnRu/C electrocatalysts were prepared by the alcohol reduction process using ethylene glycol as the solvent and reduction agent and Vulcan Carbon XC72 as the support. The electrocatalysts were characterized by EDX, XRD and cyclic voltammetry. The electrochemical oxidation of methanol and ethanol were studied by chronoamperometry using a thin porous coating technique. The PtSn/C electrocatalyst prepared by this methodology showed superior performance compared to the PtRu/C and PtSnRu/C electrocatalysts for methanol and ethanol oxidation at room temperature.

  8. Preparation of PtRu/C and PtSn/C electrocatalysts using electron beam irradiation for direct and ethanol fuel cell

    International Nuclear Information System (INIS)

    Silva, Dionisio Furtunato da

    2009-01-01

    PtRu/C and PtSn/C electrocatalysts were prepared using electron beam irradiation. The metal ions were dissolved in water/2-propanol and water/ethylene glycol solutions and the carbon support was added. The resulting mixtures were irradiated under stirring. The effect of water/ethylene glycol and water/2-propanol (v/v) ratio, Pt:Ru and Pt:Sn atomic ratios, the irradiation time and dose rate were studied. The obtained materials were characterized by Energy dispersive analysis of X-rays (EDX), X-ray diffraction (XRD), cyclic voltammetry (CV) and Moessbauer spectroscopy. The electro-oxidation of methanol and ethanol were studied by cyclic voltammetry and chronoamperometry using the thin porous coating technique. The electrocatalysts were also tested on the Direct Methanol and Ethanol Fuel Cells. PtRu/C electrocatalysts prepared in water/ethylene glycol showed Pt:Ru atomic ratios different from the nominal ones. The results suggested that part of the Ru(III) ions were not reduced. The obtained materials showed the face-centered cubic (fcc) structure of Pt and Pt alloys with crystallite sizes of 2-3 nm. PtRu/C electrocatalysts prepared in water/2-propanol showed Pt:Ru atomic ratios similar to the nominal ones. The obtained materials also showed the fcc structure of platinum and platinum alloys with crystallite sizes of 3-4 nm. PtSn/C electrocatalysts prepared in water/ethylene glycol and water/2-propanol showed Pt:Sn atomic ratios similar to the nominal ones. The obtained materials showed the platinum (fcc) phase with crystallite sizes in the range of 2 - 4 nm and a SnO 2 (cassiterite) phase. The obtained PtRu/C and PtSn/C electrocatalysts showed similar or superior performance for methanol and ethanol electro-oxidation compared to commercial PtRu/C (E-TEK) and PtSn/C (BASF) electrocatalysts. (author)

  9. Preparation of supported PtRu/C electrocatalyst for direct methanol fuel cells

    International Nuclear Information System (INIS)

    Jiang Luhua; Sun Gongquan; Zhao Xinsheng; Zhou Zhenhua; Yan Shiyou; Tang Shuihua; Wang Guoxiong; Zhou Bing; Xin Qin

    2005-01-01

    In this work, high-surface supported PtRu/C were prepared with Ru(NO)(NO 3 ) 3 and [Pt(H 2 NCH 2 CH 2 NH 2 ) 2 ]Cl 2 as the precursors and hydrogen as a reducing agent. XRD and TEM analyses showed that the PtRu/C catalysts with different loadings possessed small and homogeneous metal particles. Even at high metal loading (40 wt.% Pt, 20 wt.% Ru) the mean metal particle size is less than 4 nm. Meanwhile, the calculated Pt crystalline lattice parameter and Pt (2 2 0) peak position indicated that the geometric structure of Pt was modified by Ru atoms. Among the prepared catalysts, the lattice parameter of 40-20 wt.% PtRu/C contract most. Cyclic voltammetry (CV), chronoamperometry (CA), CO stripping and single direct methanol fuel cell tests jointly suggested that the 40-20 wt.% PtRu/C catalyst has the highest electrochemical activity for methanol oxidation

  10. Preparation of PtRu/C anode electrocatalysts using gamma radiation for methanol electro-oxidation; Preparacao de eletrocatalisadores PtRu/C utilizando radiacao gama para aplicacao como anodo na oxidacao direta de metanol

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio Fortunato da

    2006-07-01

    Pt Ru/C (carbon-supported Pt Ru nanoparticles) anode electrocatalysts were prepared using radiolytic process (gamma radiation) and tested for methanol electro-oxidation. In this process, water/2-propanol and water/ethylene glycol solutions containing the metallic ions and the carbon support were submitted to gamma radiation under stirring. The water/alcohol ratio (v/v) and the total dose (kGy) were studied. A nominal Pt Ru atomic ratio of 50:50 were used in all experiments. The electrocatalysts were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry (CV). The electro-oxidation of methanol was studied by cyclic voltammetry using the thin porous coating technique. The electrocatalysts prepared in water/2-propanol showed crystallite size in the range of 3-5 nm and Pt Ru atomic ratio of 50:50. The electrocatalysts prepared in water/ethylene glycol showed crystallite size (2-3 nm) smaller than the ones obtained in water/2-propanol, however, the Pt Ru atomic ratios obtained were approximately 80:20, showing that only part of ruthenium ions were reduced. For methanol oxidation the electrocatalytic activity depends on the water/2-propanol and water/ethylene glycol ratio used in the reaction medium. The electrocatalysts prepared in water/2-propanol showed inferior performance to the ones prepared in water/ethylene glycol, which showed similar or superior performances (amperes per gram of platinum) to the commercial electrocatalyst from E-TEK. (author)

  11. Preparation and characterization of PtRu/C, PtBi/C, PtRuBi/C electrocatalysts for direct electro-oxidation of ethanol in PEM fuels cells using the method of reduction by sodium borohydride

    International Nuclear Information System (INIS)

    Brandalise, Michele

    2010-01-01

    Pt/C, PtBi/C, PtRu/C and PtRuBi/C electrocatalysts were prepared by a borohydride reduction methodology and tested for ethanol oxidation. This methodology consists in mix a solution with sodium hydroxide and sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. It was studied the addition method of borohydride (drop by drop addition or rapid addition). The obtained electrocatalysts were characterized by energy dispersive X ray spectroscopy (EDX), thermogravimetric analysis (TGA), X ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry. The ethanol electro-oxidation was studied by cyclic voltammetry and chronoamperometry using the thin porous coating technique. The electrocatalysts were tested in real conditions of operation by unit cell tests. The stability of PtRuBi/C electrocatalysts was evaluated by cyclic voltammetry, chronoamperometry using the ultra-thin porous coating technique and ring-disk electrode. The PtRuBi/C electro catalyst apparently presented a good performance for ethanol electro-oxidation but experimental evidences showed accentuated bismuth dissolution. (author)

  12. Preparation of PtSn/C, PtRu/C, PtRh/C, PtRuRh/C and PtSnRh/C electrocatalysts using an alcohol-reduction process for methanol and ethanol oxidation

    International Nuclear Information System (INIS)

    Dias, Ricardo Rodrigues

    2009-01-01

    In this work, Pt/C, PtRh (90:10), PtRh/C (50:50), PtSn/C (50:50), PtRu (50:50)/C, PtRuRh/C (50:40:10) and PtSnRh/C (50:40:10) were prepared by an alcohol-reduction process with metal loading of 20 wt.% using H 2 PtCl 6 .6H 2 O (Aldrich), SnCl 2 .2H 2 O (Aldrich),and RhCl 2 .XH 2 O (Aldrich) as metals sources and Vulcan XC72 as support. The electrocatalysts were characterized by EDX, XRD and cyclic voltammetry (CV). The electro-oxidation of ethanol was studied by CV, chronoamperomety at room temperature in acid medium and tests at 100 deg C on a single cell of a direct methanol or ethanol fuel cell. The EDX analysis showed that the metal atomic ratios of the obtained electrocatalysts were similar to the nominal atomic ratios used in the preparation. The diffractograms of electrocatalysts prepared showed four peaks at approximately 2θ = 40 0 , 47 0 , 67 0 and 82 0 , which are associated with the (111), (200), (220) and (311) planes, respectively, of a face cubic-centered (fcc) structure characteristic of platinum and platinum alloys. The average crystallite sizes using the Scherrer equation and the calculated values were in the range of 2–3 nm. For PtSn/C and PtSnRh/C two additional peaks were observed at 2θ = 34 0 and 52 0 that were identified as a SnO 2 phase. PtSn/C (50:50) and PtSnRh/C (50:40:10) electrocatalyst showed the best performance for ethanol oxidation at room temperature. For methanol oxidation at room temperature PtRu/C, PtSn/C and PtRuRh/C electrocatalysts showed the best performance. Tests at 100 deg C on a single cell of a direct ethanol fuel cell PtSnRh/C showed the best performance, for methanol oxidation PtRuRh/C showed the best performance. (author)

  13. Preparation and characterization of Pt/C and Pt sbnd Ru/C electrocatalysts for direct ethanol fuel cells

    Science.gov (United States)

    Liu, Zhaolin; Ling, Xing Yi; Su, Xiaodi; Lee, Jim Yang; Gan, Leong Ming

    Nano-sized Pt and Pt sbnd Ru colloids are prepared by a microwave-assisted polyol process, and transferred to a toluene solution of decanthiol. Vulcan XC-72 is then added to the toluene solution to adsorb the thiolated Pt and Pt sbnd Ru colloids. Transmission electron microscopy examinations show nearly spherical particles and narrow size distributions for both supported and unsupported metals. The carbon-supported Pt and Pt sbnd Ru nanoparticles are activated by thermal treatment to remove the thiol stabilizing shell. All Pt and Pt sbnd Ru catalysts (except Pt 23sbnd Ru 77) give the X-ray diffraction pattern of a face-centered cubic (fcc) crystal structure, whereas the Pt 23sbnd Ru 77 alloy is more typical of the hexagonal close packed (hcp) structure. The electro-oxidation of liquid ethanol on these catalysts is investigated at room temperature by cyclic voltammetry. The results demonstrate that the alloy catalyst is catalytically more active than pure platinum. Preliminary tests on a single cell of a direct ethanol fuel cell (DEFC) indicate that a Pt 52sbnd Ru 48/C anode catalyst gives the best electrocatalytic performance among all the carbon-supported Pt and Pt sbnd Ru catalysts.

  14. Preparation and characterization of Pt/C and Pt-Ru/C electrocatalysts for direct ethanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhaolin; Ling, Xing Yi; Su, Xiaodi; Lee, Jim Yang; Gan, Leong Ming [Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602 (Singapore)

    2005-09-26

    Nano-sized Pt and Pt-Ru colloids are prepared by a microwave-assisted polyol process, and transferred to a toluene solution of decanthiol. Vulcan XC-72 is then added to the toluene solution to adsorb the thiolated Pt and Pt-Ru colloids. Transmission electron microscopy examinations show nearly spherical particles and narrow size distributions for both supported and unsupported metals. The carbon-supported Pt and Pt-Ru nanoparticles are activated by thermal treatment to remove the thiol stabilizing shell. All Pt and Pt-Ru catalysts (except Pt{sub 23}-Ru{sub 77}) give the X-ray diffraction pattern of a face-centered cubic (fcc) crystal structure, whereas the Pt{sub 23}-Ru{sub 77} alloy is more typical of the hexagonal close packed (hcp) structure. The electro-oxidation of liquid ethanol on these catalysts is investigated at room temperature by cyclic voltammetry. The results demonstrate that the alloy catalyst is catalytically more active than pure platinum. Preliminary tests on a single cell of a direct ethanol fuel cell (DEFC) indicate that a Pt{sub 52}-Ru{sub 48}/C anode catalyst gives the best electrocatalytic performance among all the carbon-supported Pt and Pt-Ru catalysts. (author)

  15. Chemometric study of the effects of PtRu:BH4-molar ratio and solvent used in the preparation of PtRu/C electrocatalysts for for direct methanol fuel cell anodes

    Energy Technology Data Exchange (ETDEWEB)

    Polanco, N.S.O.; Neto, A.O.; Spinace, E.V. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Tusi, M.M. [Universidade Regional Integrada do Alto Uruguai e das Missoes (URI), Santiago, RS (Brazil); Brandalise, M. [Instituto Federal Fluminense (IFF), Campos dos Goyracazes, RJ (Brazil)

    2014-07-01

    PtRu/C electrocatalysts were prepared by borohydride reduction method and a chemometric study was performed to evaluate the influence of the solvent (water and isopropyl alcohol) and amount of reducing agent (PtRu:BH4- molar ratios of 5 and 15) in maximum power density. In borohydride reduction method, a solution containing sodium hydroxide and sodium borohydride (NaBH4) is added to a mixture containing water, isopropyl alcohol, metallic precursors and the carbon support Vulcan XC72. The obtained materials were characterized by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Membrane Electrode Assemblies (MEA's) were produced and tests in single direct methanol fuel cells were performed. The amount of sodium borohydride used in the reduction showed more influence on the maximum power density than the change of solvent of the reaction. (author)

  16. Influence of method of preparation of Pt Ru/C electrocatalysts on the catalytic activity for the ethanol oxidation reaction in acidic medium; Influencia do metodo de preparacao de eletrocatalisadores PtRu/C sobre a atividade catalitica frente a reacao de oxidacao de etanol em meio acido

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Walber dos Santos; Silva, Uriel Lean Valente; Souza, Jose Pio Iudice de, E-mail: jpio@ufpa.br [Universidade Federal do Para, (UFPA), Belem, PA (Brazil). Instituto de Ciencias Exatas e Naturais. Faculdade de Quimica

    2013-09-01

    In this work the influence of variations in the borohydrate reduction method on the properties of Pt Ru/C electrocatalysts was investigated. The electrocatalysts were prepared using 1:1 ; 2:1; 5:1; 50:1 and 250:1 molar ratios of NaBH{sub 4} to metals. The reduction was also performed by dripping or by fast addition of the solution. The results showed that Pt Ru nanoparticles obtained by fast addition had the smallest crystallite sizes. It was also noted that the catalytic activity increased as the borohydrate:metal molar ratio increased. The Pt Ru/C electrocatalysts (50:1) obtained by fast addition presented the best catalytic activity for ethanol electro-oxidation. (author)

  17. Pt-Ru nanoparticles supported on functionalized carbon as electrocatalysts for the methanol oxidation

    International Nuclear Information System (INIS)

    Salgado, J.R.C.; Fernandes, J.C.S.; Botelho do Rego, A.M.; Ferraria, A.M.; Duarte, R.G.; Ferreira, M.G.S.

    2011-01-01

    Highlights: → The functionalized carbon using acid solutions contains surface oxygenated groups. → Uniform dispersion of PtRu nanoparticles on the carbon surface was achieved. → Physical analysis showed the formation of PtRu alloy catalysts on functionalized carbon. → PtRu alloy catalysts on functionalized carbon enhanced the methanol oxidation rate. - Abstract: Platinum-ruthenium alloy electrocatalysts, for methanol oxidation reaction, were prepared on carbons thermally treated in helium atmosphere or chemically functionalized in H 2 O 2 , or in HNO 3 + H 2 SO 4 or in HNO 3 solutions. The functionalized carbon that is produced using acid solutions contains more surface oxygenated functional groups than carbon treated with H 2 O 2 solution or HeTT. The XRD/HR-TEM analysis have showed the existence of a higher alloying degree for Pt-Ru electrocatalysts supported on functionalized carbon, which present superior electrocatalytic performance, assessed by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy, as compared to electrocatalysts on unfunctionalized carbon. It also was found that Pt-Ru alloy electrocatalysts on functionalized carbon improve the reaction rate compared to Pt-Ru on carbons treated with H 2 O 2 solution and thermally. A mechanism is discussed, where oxygenated groups generated from acid functionalization of carbon and adsorbed on Pt-Ru electrocatalysts are considered to enhance the electrocatalytic activity of the methanol oxidation reaction.

  18. Preparation of PtSn/C, PtRu/C, PtRh/C, PtRuRh/C and PtSnRh/C electrocatalysts using an alcohol-reduction process for methanol and ethanol oxidation; Preparacao e caracterizacao de eletrocatalisadores PtRu, PtSn, PtRh, PtRuRh e PtSnRh para oxidacao direta de alcoois em celulas a combustivel tipo PEM utilizando a metodologia da reducao por alcool

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Ricardo Rodrigues

    2009-07-01

    In this work, Pt/C, PtRh (90:10), PtRh/C (50:50), PtSn/C (50:50), PtRu (50:50)/C, PtRuRh/C (50:40:10) and PtSnRh/C (50:40:10) were prepared by an alcohol-reduction process with metal loading of 20 wt.% using H{sub 2}PtCl{sub 6}.6H{sub 2}O (Aldrich), SnCl{sub 2}.2H{sub 2}O (Aldrich),and RhCl{sub 2}.XH{sub 2}O (Aldrich) as metals sources and Vulcan XC72 as support. The electrocatalysts were characterized by EDX, XRD and cyclic voltammetry (CV). The electro-oxidation of ethanol was studied by CV, chronoamperomety at room temperature in acid medium and tests at 100 deg C on a single cell of a direct methanol or ethanol fuel cell. The EDX analysis showed that the metal atomic ratios of the obtained electrocatalysts were similar to the nominal atomic ratios used in the preparation. The diffractograms of electrocatalysts prepared showed four peaks at approximately 2θ = 40{sup 0}, 47{sup 0}, 67{sup 0} and 82{sup 0}, which are associated with the (111), (200), (220) and (311) planes, respectively, of a face cubic-centered (fcc) structure characteristic of platinum and platinum alloys. The average crystallite sizes using the Scherrer equation and the calculated values were in the range of 2–3 nm. For PtSn/C and PtSnRh/C two additional peaks were observed at 2θ = 34{sup 0} and 52{sup 0} that were identified as a SnO{sub 2} phase. PtSn/C (50:50) and PtSnRh/C (50:40:10) electrocatalyst showed the best performance for ethanol oxidation at room temperature. For methanol oxidation at room temperature PtRu/C, PtSn/C and PtRuRh/C electrocatalysts showed the best performance. Tests at 100 deg C on a single cell of a direct ethanol fuel cell PtSnRh/C showed the best performance, for methanol oxidation PtRuRh/C showed the best performance. (author)

  19. Preparation of PtSn/C, PtRu/C, PtRh/C, PtRuRh/C and PtSnRh/C electrocatalysts using an alcohol-reduction process for methanol and ethanol oxidation; Preparacao e caracterizacao de eletrocatalisadores PtRu, PtSn, PtRh, PtRuRh e PtSnRh para oxidacao direta de alcoois em celulas a combustivel tipo PEM utilizando a metodologia da reducao por alcool

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Ricardo Rodrigues

    2009-07-01

    In this work, Pt/C, PtRh (90:10), PtRh/C (50:50), PtSn/C (50:50), PtRu (50:50)/C, PtRuRh/C (50:40:10) and PtSnRh/C (50:40:10) were prepared by an alcohol-reduction process with metal loading of 20 wt.% using H{sub 2}PtCl{sub 6}.6H{sub 2}O (Aldrich), SnCl{sub 2}.2H{sub 2}O (Aldrich),and RhCl{sub 2}.XH{sub 2}O (Aldrich) as metals sources and Vulcan XC72 as support. The electrocatalysts were characterized by EDX, XRD and cyclic voltammetry (CV). The electro-oxidation of ethanol was studied by CV, chronoamperomety at room temperature in acid medium and tests at 100 deg C on a single cell of a direct methanol or ethanol fuel cell. The EDX analysis showed that the metal atomic ratios of the obtained electrocatalysts were similar to the nominal atomic ratios used in the preparation. The diffractograms of electrocatalysts prepared showed four peaks at approximately 2{theta} =40 deg, 47 deg, 67 deg and 82 deg, which are associated with the (111), (200), (220) and (311) planes, respectively, of a face cubic-centered (fcc) structure characteristic of platinum and platinum alloys. The average crystallite sizes using the Scherrer equation and the calculated values were in the range of 2-3 nm. For Pt Sn/C and PtSnRh/C two additional peaks were observed at 2 = 34 deg and 52 deg that were identified as a SnO{sub 2} phase. Pt Sn/C (50:50) and PtSnRh/C (50:40:10) electro catalyst showed the best performance for ethanol oxidation at room temperature. For methanol oxidation at room temperature Pt Ru/C, Pt Sn/C and PtRuRh/C electrocatalysts showed the best performance. Tests at 100 deg C on a single cell of a direct ethanol fuel cell PtSnRh/C showed the best performance, for methanol oxidation PtRuRh/C showed the best performance. (author)

  20. Preparation of Pt Ru/C + rare earths by the method of reduction by alcohol for the electro-oxidation of ethanol

    International Nuclear Information System (INIS)

    Tusi, M.M.; Rodrigues, R.M.S.; Spinace, E.V.; Oliveira Neto, A.

    2010-01-01

    PtRu/C electrocatalyst was prepared in a single step, while that PtRu/85%C-15%Ce, PtRu/85%C-15%La, PtRu/85%C-15%Nd and PtRu/85%C-15%Er electrocatalyst were prepared in a two step. In the first step a Carbon Vulcan XC72 + rare earth supports were prepared. In the second step PtRu electrocatalyst were prepared by an alcohol-reduction process using ethylene glycol as solvent and reducing agent and supported on Vulcan XC72 + earth rare. The obtained electrocatalysts were characterized by EDAX, XRD and chronoamperometry. The electro-oxidation of ethanol was studied by chronoamperometry at room temperature. PtRu/85%C- 15%Ce electrocatalyst showed a significant increase of performance for ethanol oxidation compared to PtRu/C electrocatalyst. (author)

  1. Co-catalytic effect of nickel in Pt-Ru/C and Pt-Sn/C electrocatalysts for ethanol electrooxidation

    OpenAIRE

    Ribadeneira, R. E.; Hoyos, B. A.

    2010-01-01

    In the present study, we examined the effect of adding nickel to Pt-Ru and Pt-Sn catalysts for ethanol electrooxidation. The alcohol-reduction process with ethylene glycol was used to prepare ten electrocatalysts. These were microchemically and physically characterized by EDX and XRD analysis. The electrocatalysts were evaluated at mini-electrodes with cyclic voltammetry at 25 and 50 °C in sulfuric acid and ethanol solutions, and as anodes in fuel cell tests. Nickel addition to Pt-Ru mixtures...

  2. Pt-Ru/CeO2/carbon nanotube nanocomposites: an efficient electrocatalyst for direct methanol fuel cells.

    Science.gov (United States)

    Sun, Zhenyu; Wang, Xiang; Liu, Zhimin; Zhang, Hongye; Yu, Ping; Mao, Lanqun

    2010-07-20

    Pt-Ru/CeO(2)/multiwalled carbon nanotube (MWNT) electrocatalysts were prepared using a rapid sonication-facilitated deposition method and were characterized by X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), and voltammetry. Morphological characterization by TEM revealed that CeO(2) nanoparticles (NPs) were in intimate contact with Pt-Ru NPs, and both were highly dispersed on the exteriors of nanotubes with a small size and a very narrow size distribution. Compared with the Pt-Ru/MWNT and Pt/MWNT electrocatalysts, the as-prepared Pt-Ru/CeO(2)/MWNT exhibited a significantly improved electrochemically active surface area (ECSA) and a remarkably enhanced activity toward methanol oxidation. The effects of the Pt-Ru loading and the Pt-to-Ru molar ratio on the electrocatalytic activity of Pt-Ru/CeO(2)/MWNT for methanol oxidation were investigated. We found that a maximum activity toward methanol oxidation reached at the 10 wt % of Pt-Ru loading and 1:1 of Pt-to-Ru ratio. Moreover, the role of CeO(2) in the catalysts for the enhancement of methanol oxidation was discussed in terms of both bifunctional mechanism and electronic effects.

  3. Preparation of Pt Ru/C + rare earths by the method of reduction by alcohol for the electro-oxidation of ethanol; Preparacao de eletrocatalisadores PtRu/C + terras raras pelo metodo da reducao por alcool para a eletro-oxidacao do etanol

    Energy Technology Data Exchange (ETDEWEB)

    Tusi, M M; Rodrigues, R M.S.; Spinace, E V; Oliveira Neto, A., E-mail: aolivei@ipen.b, E-mail: espinace@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2010-07-01

    PtRu/C electrocatalyst was prepared in a single step, while that PtRu/85%C-15%Ce, PtRu/85%C-15%La, PtRu/85%C-15%Nd and PtRu/85%C-15%Er electrocatalyst were prepared in a two step. In the first step a Carbon Vulcan XC72 + rare earth supports were prepared. In the second step PtRu electrocatalyst were prepared by an alcohol-reduction process using ethylene glycol as solvent and reducing agent and supported on Vulcan XC72 + earth rare. The obtained electrocatalysts were characterized by EDAX, XRD and chronoamperometry. The electro-oxidation of ethanol was studied by chronoamperometry at room temperature. PtRu/85%C- 15%Ce electrocatalyst showed a significant increase of performance for ethanol oxidation compared to PtRu/C electrocatalyst. (author)

  4. Electrocatalysts using porous polymers and method of preparation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Di-Jia; Yuan, Shengwen; Goenaga, Gabriel A.

    2016-08-02

    A method of producing an electrocatalyst article using porous polymers. The method creates a porous polymer designed to receive transition metal groups disposed at ligation sites and activating the transition metals to form an electrocatalyst which can be used in a fuel cell. Electrocatalysts prepared by this method are also provided. A fuel cell which includes the electrocatalyst is also provided.

  5. Electrocatalysts using porous polymers and method of preparation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Di-Jia; Yuan, Shengwen; Goenaga, Gabriel A.

    2015-04-21

    A method of producing an electrocatalyst article using porous polymers. The method creates a porous polymer designed to receive transition metal groups disposed at ligation sites and activating the transition metals to form an electrocatalyst which can be used in a fuel cell. Electrocatalysts prepared by this method are also provided. A fuel cell which includes the electrocatalyst is also provided.

  6. Synthesis and characterization of PtRuMo/C nanoparticle electrocatalyst for direct ethanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhen-Bo; Yin, Ge-Ping [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Lin, Yong-Ge [Department of Chemistry, University of Puerto Rico, Rio Piedras Campus, San Juan, PR 00931 (United States)

    2007-07-10

    This research aims at enhancement of the performance of anodic catalysts for the direct ethanol fuel cell (DEFC). Two distinct DEFC nanoparticle electrocatalysts, PtRuMo/C and PtRu/C, were prepared and characterized, and one glassy carbon working electrode for each was employed to evaluate the catalytic performance. The cyclic-voltammetric, chronoamperometric, and amperometric current-time measurements were done in the solution 0.5 mol L{sup -1} CH{sub 3}CH{sub 2}OH and 0.5 mol L{sup -1} H{sub 2}SO{sub 4}. The composition, particle sizes, lattice parameters, morphology, and the oxidation states of the metals on nanoparticle catalyst surfaces were determined by energy dispersive analysis of X-ray (EDAX), X-ray diffraction (XRD), transmission electron micrographs (TEM) and X-ray photoelectron spectrometer (XPS), respectively. The results of XRD analysis showed that both PtRuMo/C and PtRu/C had a face-centered cubic (fcc) structure with smaller lattice parameters than that of pure platinum. The typical particle sizes were only about 2.5 nm. Both electrodes showed essentially the same onset potential as shown in the CV for ethanol electrooxidation. Despite their comparable active specific areas, PtRuMo/C was superior to PtRu/C in respect of the catalytic activity, durability and CO-tolerance. The effect of Mo in the PtRuMo/C nanoparticle catalyst was illustrated with a bifunctional mechanism, hydrogen-spillover effect and the modification on the Pt electronic states. (author)

  7. Pt and PtRu nanoparticles supported on N-doped carbons as electrocatalysts for methanol electro oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Viviane Santos; Silva, Julio Cesar Martins; Oliveira Neto, Almir; Spinace, Estevam Vitorio, E-mail: viviane_sp_saopaulo@yahoo.com.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2016-07-01

    Full text: Methanol is a liquid transportation fuel that can be produced from fossil or renewable resources. Fuel cells employing methanol directly as fuel (Direct Methanol Fuel Cell - DMFC) are very attractive as power source for portable, mobile and stationary applications [1]. PtRu/C electrocatalyst has been considered the best electrocatalyst for methanol electro-oxidation, however, its performance is strongly dependent on the method of preparation and on the characteristics of the carbon support. N-doped carbons with different N contents (1, 2 and 5 wt%) were prepared by thermal treatment of carbon with urea at 800 deg C. Pt and PtRu nanoparticles were supported on N-doped carbons by coreduction of Pt(IV) and Ru(III) ions using an alcohol-reduction process [2]. The obtained materials were characterized by Energy Dispersive X-ray spectroscopy, X-ray diffraction, Transmission electron microscopy and Cyclic Voltammetry. Pt and PtRu nanoparticles supported on N-doped carbons showed superior performance for methanol electro-oxidation when compared to the materials supported on non-modified carbon and to Pt/C and PtRu/C commercial electrocatalysts. Pt/C and PtRu/C prepared with the carbon modified with 2.5 wt% of N content showed the best activities. (author) [1] Y. Zhou, K. Neyerlin, T.S. Olson, S. Pylypenko, J. Bult, H.N. Dinh, T. Gennett, Z. Shao and R. O'Hayre, Energy Environ. Sci. 3, 1437 (2010); [2] E.V. Spinace, A.Oliveira Neto, T.R.R. Vasconcellos, M. Linardi, J. Power Sources 137, 17 (2004)

  8. Functional separation of oxidation–reduction reactions and electron transport in PtRu/ND and conductive additive hybrid electrocatalysts during methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan; Wang, Yanhui [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Bian, Linyan [College of Physics and Chemistry, Henan Polytechnic University, Jiaozuo, Henan 454000 (China); Lu, Rui [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Zang, Jianbing, E-mail: jbzang@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2016-02-28

    Graphical abstract: - Highlights: • Functional separation of reactions and electron transport in PtRu/ND + AB (or CNT). • A conductive network was formed after the addition of AB or CNT. • PtRu/ND + AB (or CNT) exhibited enhanced activity and stability than PtRu/ND. - Abstract: Undoped nanodiamond (ND) supported PtRu (PtRu/ND) electrocatalyst for methanol oxidation reactions (MOR) in direct methanol fuel cells was prepared by a microwave-assisted polyol reduction method. Sp{sup 3}-bonded ND possesses high electrochemical stability but low conductivity, while sp{sup 2}-bonded carbon nanomaterials with high conductivity are prone to oxidation. Therefore, the functions of the supporting material were separated in this study. ND (sp{sup 3}), as a support, and AB or CNTs (sp{sup 2}), as a conductive additive, were combined to form the hybrid electrocatalysts PtRu/ND + AB and PtRu/ND + CNT for MOR. The morphology of the electrocatalysts was characterized by scanning electron microscopy and electrochemical measurements were performed using an electrochemical workstation. The results indicated that the electrocatalytic activity of PtRu/ND for MOR was improved with the addition of AB or CNTs as a conductive additive. Moreover, adding CNTs to PtRu/ND as a conductive additive showed better electrocatalytic activities than adding AB, which can be ascribed to the better electron-transfer ability of CNTs.

  9. Ru-decorated Pt surfaces as model fuel cell electrocatalysts for CO electrooxidation.

    Science.gov (United States)

    Maillard, F; Lu, G-Q; Wieckowski, A; Stimming, U

    2005-09-01

    This feature article concerns Pt surfaces modified (decorated) by ruthenium as model fuel cell electrocatalysts for electrooxidation processes. This work reveals the role of ruthenium promoters in enhancing electrocatalytic activity toward organic fuels for fuel cells, and it particularly concerns the methanol decomposition product, surface CO. A special focus is on surface mobility of the CO as it is catalytically oxidized to CO(2). Different methods used to prepare Ru-decorated Pt single crystal surfaces as well as Ru-decorated Pt nanoparticles are reviewed, and the methods of characterization and testing of their activity are discussed. The focus is on the origin of peak splitting involved in the voltammetric electrooxidation of CO on Ru-decorated Pt surfaces, and on the interpretative consequences of the splitting for single crystal and nanoparticle Pt/Ru bimetallic surfaces. Apparently, screening through the literature allows formulating several models of the CO stripping reaction, and the validity of these models is discussed. Major efforts are made in this article to compare the results reported by the Urbana-Champaign group and the Munich group, but also by other groups. As electrocatalysis is progressively more and more driven by theory, our review of the experimental findings may serve to summarize the state of the art and clarify the roads ahead. Future studies will deal with highly dispersed and reactive nanoscale surfaces and other more advanced catalytic materials for fuel cell catalysis and related energy applications. It is expected that the metal/metal and metal/substrate interactions will be increasingly investigated on atomic and electronic levels, with likewise increasing participation of theory, and the structure and reactivity of various monolayer catalytic systems involving more than two metals (that is ternary and quaternary systems) will be interrogated.

  10. Electrocatalysts Prepared by Galvanic Replacement

    Directory of Open Access Journals (Sweden)

    Athanasios Papaderakis

    2017-03-01

    Full Text Available Galvanic replacement is the spontaneous replacement of surface layers of a metal, M, by a more noble metal, Mnoble, when the former is treated with a solution containing the latter in ionic form, according to the general replacement reaction: nM + mMnoblen+ → nMm+ + mMnoble. The reaction is driven by the difference in the equilibrium potential of the two metal/metal ion redox couples and, to avoid parasitic cathodic processes such as oxygen reduction and (in some cases hydrogen evolution too, both oxygen levels and the pH must be optimized. The resulting bimetallic material can in principle have a Mnoble-rich shell and M-rich core (denoted as Mnoble(M leading to a possible decrease in noble metal loading and the modification of its properties by the underlying metal M. This paper reviews a number of bimetallic or ternary electrocatalytic materials prepared by galvanic replacement for fuel cell, electrolysis and electrosynthesis reactions. These include oxygen reduction, methanol, formic acid and ethanol oxidation, hydrogen evolution and oxidation, oxygen evolution, borohydride oxidation, and halide reduction. Methods for depositing the precursor metal M on the support material (electrodeposition, electroless deposition, photodeposition as well as the various options for the support are also reviewed.

  11. Investigation of Novel Electrocatalysts for Metal Supported Solid Oxide Fuel Cells - Ru:GDC

    DEFF Research Database (Denmark)

    Sudireddy, Bhaskar Reddy; Nielsen, Jimmi; Thydén, Karl Tor Sune

    2015-01-01

    Even though solid oxide fuel cells (SOFCs) have a high potential with respect to efficiency and fuel flexibility they are not yet competitive in terms of cost and durability with conventional chemical energy conversion technologies. The potential cost reduction can be achieved through...... in tolerating the vibrations, transient loads, thermal and redox cycling [1-2]. The DTU MS-SOFC design based on ferritic stainless steel requires incorporation of electrocatalyst into the anode functional layer by infiltration methods [3]. Previously, the preferred electrocatalyst has been gadolinium doped...... and microstructure of the infiltrated electrocatalyst layer was characterized using high-resolution electron microscopy. The electrochemical characterization involved polarization curves and electrochemical impedance spectroscopy (EIS) in the temperature range of 650-750ºC. The polarization curve for Ru...

  12. Combinatorial investigation of Pt-Ru-Sn alloys as an anode electrocatalysts for direct alcohol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Young Hwan [Department of New Energy.Resource Engineering, College of Science and Engineering, Sangji University, 124, Sangjidae-gil, Wonju-si, Gangwon-Do 220-702 (Korea); Shul, Yong Gun [Department of Chemical and Biomolecular Engineering, Yonsei University, 134, Shinchon-Dong, Seodaemun-Gu, Seoul 120-749 (Korea)

    2010-10-15

    Low-temperature direct alcohol fuel cells fed with different kinds of alcohol (methanol, ethanol and 2-propanol) have been investigated by employing ternary electrocatalysts (Pt-Ru-Sn) as anode catalysts. Combinatorial chemistry has been applied to screen the 66-PtRuSn-anode arrays at the same time to reduce cost, time, and effort when we select the optimum composition of electrocatalysts for DAFCs (Direct Alcohol Fuel Cells). PtRuSn (80:20:0) showed the lowest onset potential for methanol electro-oxidation, PtRuSn (50:0:50) for ethanol, and PtRuSn (20:70:10) for 2-propanol in CV results respectively, and single cell performance test indicated that Ru is more suitable for direct methanol fuel cell system, Sn for direct ethanol fuel cell system, and 2-propanol could be applied as fuel with low platinum composition anode electrocatalyst. The single cell performance results and electrochemical results (CV) were well matched with the combinatorial electrochemical results. As a result, we could verify the availability of combinatorial chemistry by comparing the results of each extreme electrocatalysts compositions as follows: PtRuSn (80:20:0) for methanol, PtRuSn (50:0:50) for ethanol and PtRuSn (20:70:10) for 2-propanol. (author)

  13. Carbon-Supported PtRuMo Electrocatalysts for Direct Alcohol Fuel Cells

    Directory of Open Access Journals (Sweden)

    José L.G. Fierro

    2013-10-01

    Full Text Available The review article discusses the current status and recent findings of our investigations on the synthesis and characterization of carbon-supported PtRuMo electrocatalysts for direct alcohol fuel cells. In particular, the effect of the carbon support and the composition on the structure, stability and the activity of the PtRuMo nanoparticles for the electrooxidation of CO, methanol and ethanol have been studied. Different physicochemical techniques have been employed for the analysis of the catalysts structures: X-ray analytical methods (XRD, XPS, TXRF, thermogravimetry (TGA and transmission electron microscopy (TEM, as well as a number of electrochemical techniques like CO adsorption studies, current-time curves and cyclic voltammetry measurements. Furthermore, spectroscopic methods adapted to the electrochemical systems for in situ studies, such as Fourier transform infrared spectroscopy (FTIRS and differential electrochemical mass spectrometry (DEMS, have been used to evaluate the oxidation process of CO, methanol and ethanol over the carbon-supported PtRuMo electrocatalysts.

  14. In Situ Synthesis and Characterization of Polyethyleneimine-Modified Carbon Nanotubes Supported PtRu Electrocatalyst for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Xi Geng

    2015-01-01

    Full Text Available PtRu bimetallic nanoparticles were successfully synthesized on polyethyleneimine- (PEI- functionalized multiwalled carbon nanotubes (MWCNTs via an effective and facile polyol reduction approach. Noncovalent surface modification of MWCNTs with PEI was confirmed by FTIR and zeta potential measurements. The morphology, crystalline structure, and composition of the hybrid material were characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray powder diffraction (XRD, and energy dispersive X-ray spectroscopy (EDX, respectively. According to SEM and TEM observations, PtRu nanoparticles with narrow size distribution were homogeneously deposited on PEI-MWCNTs. Cyclic voltammetry tests demonstrated that the as-prepared PtRu/PEI-MWCNTs nanocomposite had a large electrochemical surface area and exhibited enhanced electrocatalytic activity towards methanol oxidation in comparison with oxidized MWCNTs as catalyst support. PEI-functionalized CNTs, as useful building blocks for the assembly of Pt-based electrocatalyst, may have great potential for applications such as direct methanol fuel cell (DMFC.

  15. Kinetic study of methanol oxidation on carbon-supported PtRu electrocatalyst

    International Nuclear Information System (INIS)

    Gojkovic, S.Lj.; Vidakovic, T.R.; Durovic, D.R.

    2003-01-01

    Methanol electrooxidation was investigated on the carbon-supported PtRu electrocatalyst (1:1 atomic ratio) in acid media. X-ray diffraction measurement indicated alloying of Pt and Ru. Cyclic voltammetry of the sample reflects the amount of Ru in the catalyst and its ability to adsorb OH radicals. Tafel plots for the oxidation of 0.02-3 M methanol in the solutions containing 0.05-1 M HClO 4 and in the temperature range 27-40 deg. C showed reasonably well-defined linear region with the slope of about 115 mV dec -1 at the low currents, irrespective of the experimental conditions employed. Reaction order with respect to methanol was found to be 0.5. A correlation between methanol oxidation rate and pseudocapacitive current of OH adsorption on Ru sites was established. It was proposed that bifunctional mechanism is operative with the reaction between methanol residues adsorbed on Pt sites and OH radicals adsorbed on Ru sites as the rate-determining step

  16. Mesoporous Pt and Pt/Ru alloy electrocatalysts for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, Esteban A. [Grupo de Celdas de Combustible, Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Planes, Gabriel A. [Departamento de Quimica, Facultad de Ciencias Exactas, Fisicoquimicas y Naturales, Universidad Nacional de Rio Cuarto, Agencia Postal No 3, 5800, Rio Cuarto (Argentina); Williams, Federico J. [Departamento de Quimica Inorganica, Analitica y Quimica-Fisica, INQUIMAE CONICET, Facultad Ciencias Exactas y Naturales, Pabellon 2, Ciudad Universitaria, Buenos Aires (Argentina); Soler-Illia, Galo J.A.A. [Gerencia de Quimica, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Corti, Horacio R. [Grupo de Celdas de Combustible, Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Departamento de Quimica Inorganica, Analitica y Quimica-Fisica, INQUIMAE CONICET, Facultad Ciencias Exactas y Naturales, Pabellon 2, Ciudad Universitaria, Buenos Aires (Argentina)

    2011-02-15

    Mesoporous Pt and Pt/Ru catalysts with 2D-hexagonal mesostructure were synthesized using a triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer (Pluronic F127 {sup registered}) template, on a gold support. Large electrochemical surface areas were observed for the catalysts prepared at high overpotentials. Compared to the Pt catalyst, the Pt/Ru alloy containing 3 at% of Ru exhibited lower onset potential and more than three times the limit mass activity for methanol oxidation. This behavior is assigned to the larger pore size of the mesoporous Pt and Pt/Ru catalysts obtained with this template that seems to improve the methanol accessibility to the active sites compared to those obtained using lyotropic liquid crystals. (author)

  17. Optimum Pt and Ru atomic composition of carbon-supported Pt-Ru alloy electrocatalyst for methanol oxidation studied by the polygonal barrel-sputtering method

    International Nuclear Information System (INIS)

    Hiromi, Chikako; Inoue, Mitsuhiro; Taguchi, Akira; Abe, Takayuki

    2011-01-01

    Highlights: → The sputtered Pt and Ru form the Pt-Ru alloy nanoparticles on the carbon support. → The deposited Pt-Ru alloy particles have uniform Pt:Ru atomic ratios. → The optimum Pt:Ru ratio of the Pt-Ru/C for methanol oxidation is 58:42 at.% at 25 deg. C. → The optimum Pt:Ru ratio of 58:42 shifts to 50:50 at.% at 40 and 60 deg. C. → The polygonal barrel-sputtering method is useful to prepare the DMFC anode catalyst. - Abstract: The optimum Pt and Ru atomic composition of a carbon-supported Pt-Ru alloy (Pt-Ru/C) used in a practical direct methanol fuel cell (DMFC) anode was investigated. The samples were prepared by the polygonal barrel-sputtering method. Based on the physical properties of the prepared Pt-Ru/C samples, the Pt-Ru alloy was found to be deposited on a carbon support. The microscopic characterization showed that the deposited alloy forms nanoparticles, of which the atomic ratios of Pt and Ru (Pt:Ru ratios) are uniform and are in accordance with the overall Pt:Ru ratios of the samples. The formation of the Pt-Ru alloy is also supported by the electrochemical characterization. Based on these results, methanol oxidation on the Pt-Ru/C samples was measured by cyclic voltammetry and chronoamperometry. The results indicated that the methanol oxidation activities of the prepared samples depended on the Pt:Ru ratios, of which the optimum Pt:Ru ratio is 58:42 at.% at 25 deg. C and 50:50 at.% at 40 and 60 deg. C. This temperature dependence of the optimum Pt:Ru ratio is well explained by the relationship between the methanol oxidation reaction process and the temperature, which is reflected in the rate-determining steps considered from the activation energies. It should be noted that at 25-60 deg. C, the Pt-Ru/C with Pt:Ru = 50:50 at.% prepared by our sputtering method has the higher methanol oxidation activity than that of a commercially available sample with the identical overall Pt:Ru ratio. Consequently, the polygonal barrel-sputtering method

  18. Methanol resistant ruthenium electrocatalysts for oxygen reduction synthesized by pyrolysis of Ru{sub 3}(CO){sub 12} in different atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Altamirano-Gutierrez, A.; Jimenez-Sandoval, O.; Uribe-Godinez, J.; Borja-Arco, E. [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional (Cinvestav), Unidad Queretaro, Apartado Postal 1-798, Queretaro, Qro. 76001 (Mexico); Castellanos, R.H. [Universidad del Papaloapan, Campus Tuxtepec, Circuito Central No. 200, Col. Parque Industrial, Tuxtepec, Oax. 68301 (Mexico); Olivares-Ramirez, J.M. [Universidad Tecnologica de San Juan del Rio, Av. La Palma No. 125, Col. Vista Hermosa, San Juan del Rio, Qro. 76800 (Mexico)

    2009-10-15

    Novel ruthenium electrocatalysts for the oxygen reduction reaction (ORR) were prepared by pyrolysis of Ru{sub 3}(CO){sub 12} in three atmospheres: neutral (N{sub 2}), partially oxidative (air) and partially reductive (70:30 N{sub 2}/H{sub 2}), at temperatures in the 80-700 C range. The materials were characterized by FT-IR spectroscopy, X-ray diffraction and scanning electron microscopy. A thermogravimetric analysis of the Ru{sub 3}(CO){sub 12} precursor in the three atmospheres was also performed. The electrocatalytic properties of the materials were evaluated by rotating disk electrode measurements in 0.5 mol L{sup -1} H{sub 2}SO{sub 4}. The kinetic parameters, such as the Tafel slope, exchange current density and charge transfer coefficient, are reported. The catalysts prepared in N{sub 2} and N{sub 2}/H{sub 2}, in general, show a higher performance than those synthesized in air. In the two nitrogen containing atmospheres, a pyrolysis temperature of 360 C seems to lead to better electrocatalytic properties for the ORR. The new electrocatalysts are also tolerant to methanol concentrations as high as 2.0 mol L{sup -1}. (author)

  19. SiO2 decoration dramatically enhanced the stability of PtRu electrocatalysts with undetectable deterioration in fuel cell performance

    Science.gov (United States)

    Yu, Xinxin; Xu, Zejun; Yang, Zehui; Xu, Sen; Zhang, Quan; Ling, Ying; Zhang, Yunfeng; Cai, Weiwei

    2018-06-01

    Prevention of Ru dissolution is essential for steady CO tolerance of anodic electrocatalysts in direct methanol fuel cells. Here, we demonstrate a facile way to stabilize Ru atoms by decorating commercial CB/PtRu with SiO2, which shows a six-fold higher stability and similar activity toward a methanol oxidation reaction leading to no discernible degradation in fuel cell performance compared to commercial CB/PtRu electrocatalysts. The higher stability and stable CO tolerance of SiO2-decorated electrocatalysts originate from the SiO2 coating, since Ru atoms are partially ionized during SiO2 decorating, resulting in difficulties in dissolution; while, in the case of commercial CB/PtRu, the dissolved Ru offers active sites for Pt coalescences and CO species resulting in the rapid decay of the electrochemical surface area and fuel cell performance. To the best of our knowledge, this is the first study about the stabilization of Ru atoms by SiO2. The highest stability is obtained for a PtRu electrocatalyst with negligible effect on the electrochemical properties.

  20. Novel Pt-Ru nanoparticles formed by vapour deposition as efficient electrocatalyst for methanol oxidation

    International Nuclear Information System (INIS)

    Sivakumar, Pasupathi; Tricoli, Vincenzo

    2006-01-01

    The methods developed and described in paper-part I are employed to prepare nanometer size Pt-Ru particles on a Vulcan[reg] XC72R substrate with controlled metal loading. Transmission Electron Microscopy (TEM) confirmed uniform particles size (average diameter 2 nm) and homogeneous dispersion of the particles over the substrate. Energy Dispersive X-ray absorption (EDX) analysis confirmed the compositional homogeneity. The catalytic activity of these supported nanoparticles with regard to methanol electrooxidation is investigated using cyclic voltammetry (CV), chronoamperometry (CA) and CO-stripping voltammetry techniques at temperatures between 25 and 60 deg. C. Such investigation concerns supported catalysts prepared with ca. 10 and 18 wt.% overall metal loading (Pt + Ru) onto the Vulca[reg] XC72R substrate. Comparative testing of our catalysts and a commercial Pt-Ru/Vulcan reveals markedly superior activity for our catalysts. In fact, we observe for the latter a five-fold increase of the oxidation current as compared to a commercial Pt-Ru/Vulcan with equal metal loading. One of the reasons for the greater activity is found to be the very high dispersion of the metals over the substrate, i.e. the large surface area of the active phase. Other reasons are plausibly ascribable to the varied Pt/Ru composition and/or reduced presence of contaminants at the catalyst surface

  1. Preparation of supported electrocatalyst comprising multiwalled carbon nanotubes

    Science.gov (United States)

    Wu, Gang; Zelenay, Piotr

    2013-08-27

    A process for preparing a durable non-precious metal oxygen reduction electrocatalyst involves heat treatment of a ball-milled mixture of polyaniline and multiwalled carbon nanotubes in the presence of a Fe species. The catalyst is more durable than catalysts that use carbon black supports. Performance degradation was minimal or absent after 500 hours of operation at constant cell voltage of 0.40 V.

  2. Novel Pt-Ru nanoparticles formed by vapour deposition as efficient electrocatalyst for methanol oxidation

    International Nuclear Information System (INIS)

    Sivakumar, Pasupathi; Ishak, Randa; Tricoli, Vincenzo

    2005-01-01

    Bimetallic Pt-Ru nanoparticles supported on carbon substrates have been prepared reproducibly by a simple method that utilizes commercially available metal-organic precursors at low temperature in vacuum. Particles morphology, composition and structure have been investigated using HRTEM, EDX, selected area electron diffraction (SAED) and powder XRD analysis. TEM shows that the obtained nanoparticles are homogeneously dispersed on the substrate surface and exhibit narrow size distribution, the average diameter being ca. 2 nm. Point resolved EDX analysis demonstrates co-presence of both Pt and Ru in each particle, thereby indicating that truly bimetallic nanoparticles have been obtained. Moreover, EDX performed on several areas of the sample evidences uniform particles composition. The latter can be controlled very easily and effectively by regulating the operation temperature during particles preparation. HRTEM imaging shows that the particles possess crystalline structure. Both SAED and XRD analyses indicate presence of nanoparticles exhibiting structure consistent with that of an f.c.c. Pt-Ru alloy. Besides the f.c.c. alloy, an additional crystalline phase might also be present as noticed by SAED. These nanoparticles display electrocatalytic activity with regard to methanol oxidation as evidenced by cyclic voltammetry (CV)

  3. Preparation and characterization of Pt Sn / C-rare earth and PtRu / C-rare earth using an alcohol reduction process for ethanol electron-oxidation

    International Nuclear Information System (INIS)

    Rodrigues, Rita Maria de Sousa

    2011-01-01

    The electro catalyst PtRu / C-rare earth and PtSn/C-rare earth (20 wt%) were prepared by alcohol reduction method using H 2 PtCl 6 .6H 2 O Ru Cl xH 2 O, SnCl 2 .2H 2 O as a source of metals 85 % Vulcan - 15 % rare earth as a support and, finally, ethylene glycol as reducing agent. The electrocatalysts were characterized physically by X-ray diffraction (XRD), energy dispersive X-ray (EDX), and transmission electron microscopy (TEM). Analyses by EDX showed that the atomic ratios of different electrocatalysts, prepared by alcohol reduction method are similar to the nominal starting compositions indicating that this methodology is promising for the preparation of electrocatalysts. In all the XRD patterns for the prepared electrocatalysts there is a broad peak at about 2θ = 25 o , which is associated with the carbon support and four additional diffraction peaks at approximately 2θ = 40 o , 47 o , 67 o e 82 o , which in turn are associated with the plans (111), (200), (220) e (311), respectively, of face-centered cubic structure (FCC) platinum. The results of X-ray diffraction also showed average crystallite sizes between 2.0 and 4.0 nm for PtSn e 2,0 a 3,0 para PtRu. The studies for the electrochemical oxidation of ethanol in acid medium were carried out using the technique of chronoamperometry in a solution 0,5 mol.L-1 H 2 SO 4 , + 1,0 mol.L-1 de C 2 H 5 OH. The polarization curves obtained in the fuel cell unit, powered directly by ethanol, are in agreement with the results of voltammetry and chronoamperometry noting the beneficial effect of rare earths in the preparation of electrocatalysts and attesting that the electrocatalysts PtSn/C are more effective than PtRu/C for the oxidation of ethanol.

  4. Optimization of Ru{sub x}Se{sub y} electrocatalyst loading for oxygen reduction in a PEMFC

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Huerta, R.G. [Instituto Politecnico Nacional, Laboratorio de Electroquimica y Corrosion ESIQIE, UPALP, 07738 Mexico, D.F., Mexico (Mexico); Guzman-Guzman, A.; Solorza-Feria, O. [Depto. Quimica, Centro de Investigacion y de Estudios Avanzados del IPN, A. Postal 14-740, 07360 Mexico D.F., Mexico (Mexico)

    2010-11-15

    The synthesis, characterization and optimization of Ru{sub x}Se{sub y} catalyst loading as a cathode electrode for a single polymer electrolyte membrane fuel cell, PEMFC were investigated. Ru{sub x}Se{sub y} catalyst was synthesized via a decarbonylation of Ru{sub 3}(CO){sub 12} and elemental selenium in 1,6-hexanediol under refluxing conditions for 2 h. The powder electrocatalyst was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and examined for the oxygen reduction reaction (ORR) in 0.5M H{sub 2}SO{sub 4} by rotating disk electrode (RDE) and in membrane-electrode assemblies, MEAs for a single PEMFC. Results indicate the formation of agglomerates of crystalline particles with nanometric size embedded in an amorphous phase. The catalyst exhibited high current density and lower overpotential for the ORR compared to that of Ru{sub x} cluster catalyst. Dispersed Ru{sub x}Se{sub y} catalyst loading on Vulcan carbon was optimized as a cathode electrode by performance testing in a single H{sub 2}-O{sub 2} fuel cell. (author)

  5. In situ EXAFS study of Ru-containing electrocatalysts of oxygen reduction

    International Nuclear Information System (INIS)

    Malakhov, I.V.; Nikitenko, S.G.; Savinova, E.R.; Kochubey, D.I.; Alonso-Vante, N.

    2000-01-01

    The series of Ru chalcogenide compounds is obtained by varying the nature of the chalcogen with the transition metal (Ru) matrix. The EXAFS technique reveals that the electrocatalytic centre is Ru in a cluster matrix. Furthermore, a reversible change in the structure of the active centre as a function of the applied electrode potential appears

  6. Investigation of Novel Electrocatalysts for Metal Supported Solid Oxide Fuel Cells - Ru:GDC

    DEFF Research Database (Denmark)

    Sudireddy, Bhaskar Reddy; Nielsen, Jimmy; Thydén, Karl Tor Sune

    2015-01-01

    The electrochemical performance and stability of the planar metal supported solid oxide fuel cells (MS-SOFC) with two different electrocatalytically active materials, namely, Ni:GDC and Ru:GDC were investigated. Ru:GDC with an ASR of 0.322 Ωcm2 performed better than Ni:GDC with an ASR of 0.453 Ωc...

  7. Nanostructured Carbon Materials as Supports in the Preparation of Direct Methanol Fuel Cell Electrocatalysts

    Directory of Open Access Journals (Sweden)

    María Jesús Lázaro

    2013-08-01

    Full Text Available Different advanced nanostructured carbon materials, such as carbon nanocoils, carbon nanofibers, graphitized ordered mesoporous carbons and carbon xerogels, presenting interesting features such as high electrical conductivity and extensively developed porous structure were synthesized and used as supports in the preparation of electrocatalysts for direct methanol fuel cells (DMFCs. The main advantage of these supports is that their physical properties and surface chemistry can be tailored to adapt the carbonaceous material to the catalytic requirements. Moreover, all of them present a highly mesoporous structure, diminishing diffusion problems, and both graphitic character and surface area can be conveniently modified. In the present work, the influence of the particular features of each material on the catalytic activity and stability was analyzed. Results have been compared with those obtained for commercial catalysts supported on Vulcan XC-72R, Pt/C and PtRu/C (ETEK. Both a highly ordered graphitic and mesopore-enriched structure of these advanced nanostructured materials resulted in an improved electrochemical performance in comparison to the commercial catalysts assayed, both towards CO and alcohol oxidation.

  8. Highly effective and CO-tolerant PtRu electrocatalysts supported on poly(ethyleneimine) functionalized carbon nanotubes for direct methanol fuel cells

    International Nuclear Information System (INIS)

    Cheng, Yi; Jiang, San Ping

    2013-01-01

    A highly efficient and CO tolerant PtRu electrocatalysts supported on amino-rich, cationic poly(ethyleneimine) polyelectrolyte functionalized multi-walled carbon nanotubes (PtRu/PEI-MWCNTs) has been developed. The catalysts were characterized by thermogravimetric analysis, Raman spectroscopy, cyclic voltammograms, CO stripping, chronoamperometry, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The PtRu particles with average size ∼2.5 nm are well dispersed on PEI-MWCNTs. The peak current for the methanol oxidation reaction on 40% PtRu/PEI-MWCNTs is 636mAmg Pt −1 , 5.7 times higher than 112mA mg Pt −1 measured on the 40% PtRu supported on acid treated MWCNTs (PtRu/AO-MWCNTs) under identical conditions. PtRu/PEI-MWCNTs catalysts exhibit a superior electrocatalytic activity and stability for the methanol oxidation reaction due to its high tolerance toward CO poisoning as compared with PtRu/AO-MWCNTs for direct methanol fuel cells

  9. Structure and composition of single Pt–Ru electrocatalyst nanoparticles supported on multiwall carbon nanotubes

    International Nuclear Information System (INIS)

    Paraguay-Delgado, Francisco; Malac, Marek; Alonso-Nuñez, Gabriel

    2014-01-01

    Individual Pt-Ru nanoparticles (NPs) supported on multiwall carbon nanotubes (MWCNTs) synthesized by microemulsion method were characterized by nano beam diffraction (NBD) and high resolution imaging in transmission electron microscopy (TEM). Comparing the TEM images and NBD to simulations provided insight into particle composition, structure and morphology in three dimensions. In particular, the NBD allowed us to detect various components of the individual NPs that would be difficult to observe otherwise. We find that the NPs contain four different components: Pt–RuO 2 , Pt–Ru, RuO 2 and metallic Pt. Often an individual NP is composed of more than one component. The most frequently encountered external morphology is close to a spherical shape and ∼3.7 nm in diameter. The collective properties of NPs’ assemblies were studied by thermogravimetry, differential thermal analysis and x-ray diffraction. The results allowed us to gain some insight into the relation of the NPs’ structure and composition with their catalytic performance, and revealed the presence of components not detectable by bulk methods. The electrocatalytic properties were evaluated by CO stripping, methanol oxidation and oxygen reduction. Bulk characterization methods miss many properties and structures present in the sample due to low volume fraction and due to overlap of reflections. Single NPs should be analyzed to obtain reliable indication of sample composition. (paper)

  10. Preparation and characterization of PT-rare earth/C electrocatalysts for PEM fuel cells

    International Nuclear Information System (INIS)

    Santoro, Thais Aranha de Barros

    2009-01-01

    Pt-rare earth/C electrocatalysts (rare earth = La, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Tm, and Lu) were prepared (20 wt.% and Pt-to-RE atomic ratio of 50:50) by an alcohol reduction process using H 2 PtCl 6 .6H 2 O (Aldrich) and rare earth (III) chlorides (Aldrich) as metal sources, ethylene glycol as solvent and reducing agent, and Vulcan XC72 as support. The electrocatalysts were characterized by Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffractometry (XRD) and Transmission Electron Microscopy (TEM). The energy dispersive x-ray spectroscopy analysis showed that the Pt-Rare Earth atomic ratios obtained for all electrocatalysts were similar to those used in the preparations. In all diffractograms, it was observed a broad peak at about 25 degree which was associated to the Vulcan XC72 support material and four peaks at approximately 28=40 degree, 47 degree, 67 degree and 82 degree, which were associated to the (111), (200), (220), (311), and (222) planes, respectively, of the face-centered cubic (fcc) structure characteristic of platinum and platinum alloys. For the Pt-Rare Earth/C electrocatalysts, it was also observed peaks related to the rare earth oxides on the X ray diffractograms. PtLa/C electrocatalysts were prepared at different atomic ratio. Transmission electronic microscopy micrographs of electrocatalysts showed a reasonable distribution of the Pt particles on the carbon support with some agglomerations, which is in agreement with x-ray diffractometry result. The performance for CO, methanol and ethanol oxidation was investigated by cyclic voltammetry, chronoamperometry and Fourier transform infrared spectroscopy spectroscopy. The electrocatalytic activity of the Pt-Rare Earth/C electro catalyst, specially PtLa/C, were higher than that of the Pt/C electrocatalyst. Fourier transform infrared spectroscopy studies for ethanol oxidation on Pt-Rare Earth/C electrocatalyst showed that acetaldehyde and acetic acid were the main products. The PtLa/C (30

  11. Comparison of different promotion effect of PtRu/C and PtSn/C electrocatalysts for ethanol electro-oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Huanqiao; Cao, Lei [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate School of the Chinese Academy Sciences, Beijing 100039 (China); Sun, Gongquan; Jiang, Luhua [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Xin, Qin [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2007-08-01

    Well dispersed PtSn/C, PtRu/C and Pt/C electrocatalysts were synthesized by a modified polyol process and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and inductively coupled plasma-atomic emission spectrometry techniques. XRD patterns show that Ru induces the contraction of Pt lattice parameter while Sn makes the Pt crystal lattice extended. Ethanol oxidation activities on the catalysts were studied via cyclic voltammetry (CV) and chronoamperometry (CA) methods at room temperature. It is found that the electrode potential plays an important role in the electrochemical behavior of ethanol oxidation on PtRu/C and PtSn/C catalysts. In the lower potential region, PtSn/C possesses higher performance for ethanol oxidation, while in the higher potential region PtRu/C is more active. The different promotion effects of PtSn/C and PtRu/C to ethanol oxidation can be explained by the structural effect and modified bi-functional mechanism in different potential region. Single cell test of a direct ethanol fuel cell (DEFC) was also carried out to elucidate the promotion effect of PtRu/C and PtSn/C catalysts on the ethanol oxidation at 90 C. (author)

  12. Comparison of different promotion effect of PtRu/C and PtSn/C electrocatalysts for ethanol electro-oxidation

    International Nuclear Information System (INIS)

    Li, Huanqiao; Sun, Gongquan; Cao, Lei; Jiang, Luhua; Xin, Qin

    2007-01-01

    Well dispersed PtSn/C, PtRu/C and Pt/C electrocatalysts were synthesized by a modified polyol process and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and inductively coupled plasma-atomic emission spectrometry techniques. XRD patterns show that Ru induces the contraction of Pt lattice parameter while Sn makes the Pt crystal lattice extended. Ethanol oxidation activities on the catalysts were studied via cyclic voltammetry (CV) and chronoamperometry (CA) methods at room temperature. It is found that the electrode potential plays an important role in the electrochemical behavior of ethanol oxidation on PtRu/C and PtSn/C catalysts. In the lower potential region, PtSn/C possesses higher performance for ethanol oxidation, while in the higher potential region PtRu/C is more active. The different promotion effects of PtSn/C and PtRu/C to ethanol oxidation can be explained by the structural effect and modified bi-functional mechanism in different potential region. Single cell test of a direct ethanol fuel cell (DEFC) was also carried out to elucidate the promotion effect of PtRu/C and PtSn/C catalysts on the ethanol oxidation at 90 o C

  13. PtRu nanoparticles dispersed on nitrogen-doped carbon nanohorns as an efficient electrocatalyst for methanol oxidation reaction

    International Nuclear Information System (INIS)

    Zhang, Linwei; Gao, Ang; Liu, Yan; Wang, Yuan; Ma, Jiantai

    2014-01-01

    Highlights: • A novel anode catalyst is synthesized using N-doped carbon nanohorns as support. • PtRu/NCNHs exhibits an excellent activity for MOR relative to PtRu/C catalysts. • The enhancement is due to the electronic interaction between NCNHs and PtRu NPs. - Abstract: A novel anode catalyst (PtRu/NCNHs) assembled with nitrogen-doped carbon nanohorns (NCNHs) and PtRu nanoparticles (1.9 nm) exhibits an obvious enhancement in the tolerance to carbonaceous intermediates and the electocatalytic activity for methanol oxidation reaction (MOR) in comparison to a commercial PtRu/C-JM catalyst and a home-made PtRu/Vulcan catalyst. The MOR mass activity of PtRu/NCNHs (850 mA mg −1 PtRu ) is 2.5 times as high as that of PtRu/C-JM (341 mA mg −1 PtRu ). The MOR specific activity of PtRu/NCNHs is 1.8 times as high as that of PtRu/Vulcan having similar Pt/Ru atomic ratios, specific electrochemical surface areas and particle sizes of PtRu NPs. The electronic interaction between PtRu NPs and NCNHs is responsible for the enhancement in the MOR activity of PtRu/NCNHs

  14. A facile preparation of Pt–Ru nanoparticles supported on polyaniline modified fullerene [60] for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Zhengyu, E-mail: baizhengyu2000@163.com; Shi, Min; Niu, Lu; Li, Zhichao; Jiang, Libin; Yang, Lin, E-mail: yanglin1819@163.com [School of Chemistry and Chemical Engineering, Henan Normal University, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education (China)

    2013-11-15

    The use of fullerene [60] (C{sub 60}) as carbon support material for the dispersion of catalysts, which provides new ways to develop the advanced electrocatalyst materials for its distorted structure. In this article, polyaniline (PANI)-modified C{sub 60} (abbreviated as PANI-C{sub 60}) is introduced, and the platinum–ruthenium alloy nanoparticles are successfully supported on PANI-C{sub 60.} According to the transmission electron microscopy measurements, the average particle size of the as-prepared nanoparticles dispersed on PANI-C{sub 60} is 2.4 nm. Electrochemical studies reveal that the Pt-Ru/PANI-C{sub 60} nanocomposites show excellent electrocatalytic activity toward methanol oxidation, showing that the PANI-C{sub 60} may be a better potential candidate to be used as the supports of catalyst for electrochemical oxidation.

  15. Electrocatalysts with platinum, cobalt and nickel preparations by mechanical alloyed and CVD for the reaction of oxygen reduction

    International Nuclear Information System (INIS)

    Garcia C, M. A.

    2008-01-01

    In this research, the molecular oxygen reduction reaction (ORR) was investigated on electrocatalysts of Co, Ni, Pt and their alloys CoNi, PtCo, PtNi and PtCoNi by using H 2 SO 4 0.5 and KOH 0.5 M solutions as electrolytes. The electrocatalysts were synthesized by Mechanical Alloying (MA) and Chemical Vapor Deposition (CVD) processes. For MA, metallic powders were processed during 20 h of milling in a high energy SPEX 8000 mill. For CVD, a hot-wall reactor was utilized and Co, Ni and Pt acetilactetonates were used as precursors. Films were deposited at a total pressure of 1 torr and temperatures of 400-450 C. Electrocatalysts were characterized by X-Ray Diffraction (XRD). Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-Ray Spectroscopy (EDS). Electrocatalysts prepared by mechanical alloying showed a homogeneously dispersed agglomeration of particles with nano metric size. Electrocatalysts obtained by CVD showed, in some cases, non uniform films, with particles of nano metric size, as well. The electrocatalytic performance was evaluated by using the Rotating Disk Electrode technique (RDE). Electrocatalysts prepared by MA showed higher activity than those obtained by CVD. All electrocatalysts were evaluated in alkaline media. Only electrocatalysts containing Pt were evaluated in acid media, because those materials with Co, Ni and their alloys showed instability in acidic media. Most electrocatalysts followed a mechanism for the ORR producing a certain proportion of H 2 O 2 . All electrocatalysts, exhibited a fair or good electrocatalytic activity in comparison with other similar reported materials. It was found that MA and CVD are appropriate processes to prepare electrocatalysts for the ORR with particles of nano metric size and performing with an acceptable catalytic activity. PtCoNi 70-23-7% by MA and PtCoNi-CVD electrocatalysts showed the highest activity in alkaline media, while in acidic electrolyte PtCoNi 70

  16. Preparation of PtRu/Carbon hybrid materials by hydrothermal carbonization: A study of the Pt:Ru atomic ratio

    International Nuclear Information System (INIS)

    Tusi, Marcelo Marques; Brandalise, Michele; Correa, Olandir Vercino; Oliveira Neto, Almir; Linardi, Marcelo; Spinace, Estevam Vitorio; Villalba, Juan Carlo

    2009-01-01

    PtRu/Carbon materials with different Pt:Ru atomic ratios (30:70, 50:50, 60:40, 80:20 and 90:10) and 5 wt% of nominal metal load were prepared by hydrothermal carbonization using H 2 PtCl 6.6 H 2 O and RuCl 3. xH 2 O as metals sources and catalysts of the carbonization process and starch as carbon source and reducing agent. The obtained materials were treated at 900 deg C under argon and characterized by EDX, XRD and cyclic voltammetry. The electro-oxidation of methanol was studied by cyclic voltammetry and chronoamperometry using thin porous coating technique. The PtRu/Carbon materials showed Pt:Ru atomic ratios obtained by EDX similar to the nominal ones. XRD analysis showed that Pt face-cubic centered (FCC) and Ru hexagonal close-packed (HCP) phases coexist in the obtained materials. The average crystallite sizes of the Pt (FCC) phase were in the range of 8-12 nm. The material prepared with Pt:Ru atomic ratio of 50:50 showed the best performance for methanol electro-oxidation. (author)

  17. Raman Spectroscopy and Electrochemical Investigations of Pt Electrocatalyst Supported on Carbon Prepared through Plasma Pyrolysis of Natural Gas

    Directory of Open Access Journals (Sweden)

    Tereza Cristina Santos Evangelista

    2015-01-01

    Full Text Available Physicochemical and electrochemical characterisations of Pt-based electrocatalysts supported on carbon (Vulcan carbon, C1, and carbon produced by plasma pyrolysis of natural gas, C2 toward ethanol electrooxidation were investigated. The Pt20/C180 and Pt20/C280 electrocatalysts were prepared by thermal decomposition of polymeric precursors at 350°C. The electrochemical and physicochemical characterisations of the electrocatalysts were performed by means of X-ray diffraction (XRD, transmission electron microscope (TEM, Raman scattering, cyclic voltammetry, and chronoamperometry tests. The XRD results show that the Pt-based electrocatalysts present platinum metallic which is face-centered cubic structure. The results indicate that the Pt20/C180 electrocatalyst has a smaller particle size (10.1–6.9 nm compared with the Pt20/C280 electrocatalyst; however, the Pt20/C280 particle sizes are similar (12.8–10.4 nm and almost independent of the reflection planes, which suggests that the Pt crystallites grow with a radial shape. Raman results reveal that both Vulcan carbon and plasma carbon are graphite-like materials consisting mostly of sp2 carbon. Cyclic voltammetry and chronoamperometry data obtained in this study indicate that the deposition of Pt on plasma carbon increases its electrocatalytic activity toward ethanol oxidation reaction.

  18. Effects of the Electrodeposition Time in the Synthesis of Carbon-Supported Pt(Cu and Pt-Ru(Cu Core-Shell Electrocatalysts for Polymer Electrolye Fuel Cells

    Directory of Open Access Journals (Sweden)

    Griselda Caballero-Manrique

    2016-08-01

    Full Text Available Pt(Cu/C and Pt-Ru(Cu/C electrocatalysts with core-shell structure supported on Vulcan Carbon XC72R have been synthesized by potentiostatic deposition of Cu nanoparticles on the support, galvanic exchange with Pt and spontaneous deposition of Ru species. The duration of the electrodeposition time of the different species has been modified and the obtained electrocatalysts have been characterized using electrochemical and structural techniques. The High Resolution Transmission Electron Microscopy (HRTEM, Fast Fourier Transform (FFT and Energy Dispersive X-ray (EDX microanalyses allowed the determining of the effects of the electrodeposition time on the nanoparticle size and composition. The best conditions identified from Cyclic Voltammetry (CV corresponded to onset potentials for CO and methanol oxidation on Pt-Ru(Cu/C of 0.41 and 0.32 V vs. the Reversible Hydrogen Electrode (RHE, respectively, which were smaller by about 0.05 V than those determined for Ru-decorated commercial Pt/C. The CO oxidation peak potentials were about 0.1 V smaller when compared to commercial Pt/C and Pt-Ru/C. The positive effect of Cu was related to its electronic effect on the Pt shells and also to the generation of new active sites for CO oxidation. The synthesis conditions to obtain the best performance for CO and methanol oxidation on the core-shell Pt-Ru(Cu/C electrocatalysts were identified. When compared to previous results in literature for methanol, ethanol and formic acid oxidation on Pt(Cu/C catalysts, the present results suggest an additional positive effect of the deposited Ru species due to the introduction of the bifunctional mechanism for CO oxidation.

  19. Development of plurimetallic electrocatalysts prepared by decomposition of polymeric precursors for EtOH/O{sub 2} fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Palma, Livia M.; Almeida, Thiago S.; Andrade, Adalgisa R. de, E-mail: ardandra@ffclrp.usp.br [Departamento de Quimica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, SP (Brazil)

    2012-03-15

    This work aimed to develop plurimetallic electrocatalysts composed of Pt, Ru, Ni, and Sn supported on C by decomposition of polymeric precursors (DPP), at a constant metal:carbon ratio of 40:60 wt.%, for application in direct ethanol fuel cell (DEFC). The obtained nanoparticles were physico-chemically characterized by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). XRD results revealed a face-centered cubic crystalline Pt with evidence that Ni, Ru, and Sn atoms were incorporated into the Pt structure. Electrochemical characterization of the nanoparticles was accomplished by cyclic voltammetry (CV) and chronoamperometry (CA) in slightly acidic medium (0.05 mol L{sup -1}H{sub 2}SO{sub 4}), in the absence and presence of ethanol. Addition of Sn to PtRuNi/C catalysts significantly shifted the ethanol and CO onset potentials toward lower values, thus increasing the catalytic activity, especially for the quaternary composition Pt{sub 64}Sn{sub 15}Ru{sub 13}Ni{sub 8}/C. Electrolysis of ethanol solutions at 0.4 V vs. RHE allowed determination of acetaldehyde and acetic acid as the main reaction products. The presence of Ru in alloys promoted formation of acetic acid as the main product of ethanol oxidation. The Pt{sub 64}Sn{sub 15}Ru{sub 13}Ni{sub 8}/C catalyst displayed the best performance for DEFC. (author)

  20. Development of plurimetallic electrocatalysts prepared by decomposition of polymeric precursors for EtOH/O2 fuel cell

    International Nuclear Information System (INIS)

    Palma, Livia M.; Almeida, Thiago S.; Andrade, Adalgisa R. de

    2012-01-01

    This work aimed to develop plurimetallic electrocatalysts composed of Pt, Ru, Ni, and Sn supported on C by decomposition of polymeric precursors (DPP), at a constant metal:carbon ratio of 40:60 wt.%, for application in direct ethanol fuel cell (DEFC). The obtained nanoparticles were physico-chemically characterized by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). XRD results revealed a face-centered cubic crystalline Pt with evidence that Ni, Ru, and Sn atoms were incorporated into the Pt structure. Electrochemical characterization of the nanoparticles was accomplished by cyclic voltammetry (CV) and chronoamperometry (CA) in slightly acidic medium (0.05 mol L -1 H 2 SO 4 ), in the absence and presence of ethanol. Addition of Sn to PtRuNi/C catalysts significantly shifted the ethanol and CO onset potentials toward lower values, thus increasing the catalytic activity, especially for the quaternary composition Pt 64 Sn 15 Ru 13 Ni 8 /C. Electrolysis of ethanol solutions at 0.4 V vs. RHE allowed determination of acetaldehyde and acetic acid as the main reaction products. The presence of Ru in alloys promoted formation of acetic acid as the main product of ethanol oxidation. The Pt 64 Sn 15 Ru 13 Ni 8 /C catalyst displayed the best performance for DEFC. (author)

  1. Effect of Pt:Sn atomic ratio on the preparation of PtSn/C electrocatalysts using electron beam irradiation

    International Nuclear Information System (INIS)

    Silva, Dionisio F.; Oliveira Neto, Almir; Pino, Eddy S.; Linardi, Marcelo; Spinace, Estevam V.

    2009-01-01

    PtSn/C electrocatalysts were prepared with Pt:Sn atomic ratios of 3:1, 1:1 and 1:3 in water/2-propanol using electron beam irradiation. The obtained materials were characterized by EDX, XRD and cyclic voltammetry. The ethanol electro-oxidation was studied by chronoamperometry. The XRD diffractograms of the PtSn/C electrocatalysts showed typical face-centered cubic (fcc) structure of platinum and the presence of a SnO 2 phase (cassiterite). The mean crystallite sizes of Pt fcc phase was in the range of 3.0-3.5 nm. The PtSn/C electrocatalysts were active for ethanol electro-oxidation at room temperature and the material prepared with Pt:Sn atomic ratio of 1:1 showed the best activity. (author)

  2. Effect of Pt:Sn atomic ratio on the preparation of PtSn/C electrocatalysts using electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio F.; Oliveira Neto, Almir; Pino, Eddy S.; Linardi, Marcelo; Spinace, Estevam V., E-mail: dfsilva@ipen.b, E-mail: espinace@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    PtSn/C electrocatalysts were prepared with Pt:Sn atomic ratios of 3:1, 1:1 and 1:3 in water/2-propanol using electron beam irradiation. The obtained materials were characterized by EDX, XRD and cyclic voltammetry. The ethanol electro-oxidation was studied by chronoamperometry. The XRD diffractograms of the PtSn/C electrocatalysts showed typical face-centered cubic (fcc) structure of platinum and the presence of a SnO{sub 2} phase (cassiterite). The mean crystallite sizes of Pt fcc phase was in the range of 3.0-3.5 nm. The PtSn/C electrocatalysts were active for ethanol electro-oxidation at room temperature and the material prepared with Pt:Sn atomic ratio of 1:1 showed the best activity. (author)

  3. RuO 2 nanoparticles supported on MnO 2 nanorods as high efficient bifunctional electrocatalyst of lithium-oxygen battery

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yue-Feng; Chen, Yuan; Xu, Gui-Liang; Zhang, Xiao-Ru; Chen, Zonghai; Li, Jun-Tao; Huang, Ling; Amine, Khalil; Sun, Shi-Gang

    2016-10-01

    RuO2 nanoparticles supported on MnO2 nanorods (denoted as np-RuO2/nr-MnO2) were synthesized via a two-step hydrothermal reaction. SEM and TEM images both illustrated that RuO2 nanoparticles are well dispersed on the surface of MnO2 nanorods in the as-prepared np-RuO2/nr-MnO2 material. Electrochemical results demonstrated that the np-RuO2/nr-MnO2 as oxygen cathode of Li-O-2 batteries could maintain a reversible capacity of 500 mA h g(-1) within 75 cycles at a rate of 50 mA g(-1), and a higher capacity of 4000 mA h g(-1) within 20 cycles at a rate as high as 200 mA g(-1). Moreover, the cell with the np-RuO2/nr-MnO2 catalyst presented much lower voltage polarization (about 0.58 V at a rate of 50 mA g(-1)) than that measured with only MnO2 nanorods during charge/discharge processes. The catalytic property of the np-RuO2/nr-MnO2 and MnO2 nanorods were further compared by conducting studies of using rotating disk electrode (RDE), chronoamperommetry and linear sweep voltammetry. The results illustrated that the np-RuO2/nr-MnO2 exhibited excellent bifunctional electrocatalytic activities towards both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Furthermore, in-situ high-energy X-ray diffraction was employed to trace evolution of species on the np-RuO2/nr-MnO2 cathode during the discharge processes. In-situ XRD patterns demonstrated the formation process of the discharge products that consisted of mainly Li2O2. Ex-situ SEM images were recorded to investigate the morphology and decomposition of the sphere-like Li2O2, which could be observed clearly after discharge process, while are decomposed almost after charge process. The excellent electrochemical performances of the np-RuO2/nr-MnO2 as cathode of Li-O-2 battery could be contributed to the excellent bifunctional electrocatalytic activities for both the ORR and OER, and to the one-dimensional structure which would benefit the diffusion of oxygen and the storage of Li2O2 in the discharge process of

  4. Ethanol oxidation on a nichrome-supported spherical platinum microparticle electrocatalyst prepared by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhen-Hui; Li, Jing; Dong, Xiaoya; Wang, Dong; Chen, Tiwei; Qiao, Haiyan; Huang, Aiping [College of Chemistry and Environmental Science, Henan Key Laboratory for Environmental Pollution Control, Henan Normal University, Jianshe Road, Xinxiang 453007 (China)

    2008-11-15

    A novel electrode was rapidly prepared by depositing microparticle platinum onto a nichrome substrate in dilute chloroplatinic acid solution by cyclic voltammetry. The SEM results revealed that the deposits were composed of spherical Pt microparticles. Cyclic voltammetry and chronoamperometry were used for the characterization of the electrodes. Results of the electrochemical measurements showed that the spherical Pt microparticle electrodes retained the properties of metal platinum, increased the catalytic activity and promoted the electrocatalytic oxidation of ethanol. Moreover, the deposited Pt microparticles improved the electrochemical properties of the support material and reduced the dosage of noble metal platinum remarkably. The cost could be reduced dramatically by decreasing the contents of platinum. The spherical Pt microparticles deposited on the nichrome supports are likely a potential electrocatalyst for ethanol electrooxidation. (author)

  5. Preparation and characterization of electrocatalysts based on palladium for electro-oxidation of alcohols in alkaline medium

    International Nuclear Information System (INIS)

    Brandalise, Michele

    2012-01-01

    In this study Pd/C, Au/C, PdAu/C, PdAuPt/C, PdAuBi/C and PdAuIr/C electrocatalysts were prepared by the sodium borohydride reduction method for the electrochemical oxidation of methanol, ethanol and ethylene glycol. This methodology consists in mix an alkaline solution of sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. The electrocatalysts were characterized by energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry. The electrochemical oxidation of the alcohols was studied by chronoamperometry using a thin porous coating technique. The mechanism of ethanol electro-oxidation was studied by Fourier Transformed Infrared (FTIR) in situ. The most effective electrocatalysts were tested in alkaline single cells directly fed with methanol, ethanol or ethylene glycol. Preliminary studies showed that the most suitable atomic composition for preparing the ternary catalysts is 50:45:05. Electrochemical data in alkaline medium show that the electrocatalysts PdAuPt/C (50:45:05) showed the better activity for methanol electro oxidation, while PdAuIr/C was the most active for ethanol oxidation and PdAuBi/C (50:45:05) was the most effective for ethylene glycol oxidation in alkaline medium. These results show that the addition of gold in the composition of electrocatalysts increases their catalytic activities. The spectroelectrochemical FTIR in situ data permitted to conclude that C-C bond is not broken and the acetate is formed. (author)

  6. Ternary Pt-Ru-Ni catalytic layers for methanol electrooxidation prepared by electrodeposition and galvanic replacement

    Directory of Open Access Journals (Sweden)

    Athanasios ePapaderakis

    2014-06-01

    Full Text Available Ternary Pt-Ru-Ni deposits on glassy carbon substrates, Pt-Ru(Ni/GC, have been formed by initial electrodeposition of Ni layers onto glassy carbon electrodes, followed by their partial exchange for Pt and Ru, upon their immersion into equimolar solutions containing complex ions of the precious metals. The overall morphology and composition of the deposits has been studied by SEM microscopy and EDS spectroscopy. Continuous but nodular films have been confirmed, with a Pt÷Ru÷Ni % bulk atomic composition ratio of 37÷12÷51 (and for binary Pt-Ni control systems of 47÷53. Fine topographical details as well as film thickness have been directly recorded using AFM microscopy. The composition of the outer layers as well as the interactions of the three metals present have been studied by XPS spectroscopy and a Pt÷Ru÷Ni % surface atomic composition ratio of 61÷12÷27 (and for binary Pt-Ni control systems of 85÷15 has been found, indicating the enrichment of the outer layers in Pt; a shift of the Pt binding energy peaks to higher values was only observed in the presence of Ru and points to an electronic effect of Ru on Pt. The surface electrochemistry of the thus prepared Pt-Ru(Ni/GC and Pt(Ni/GC electrodes in deaerated acid solutions (studied by cyclic voltammetry proves the existence of a shell consisting exclusively of Pt-Ru or Pt. The activity of the Pt-Ru(Ni deposits towards methanol oxidation (studied by slow potential sweep voltammetry is higher from that of the Pt(Ni deposit and of pure Pt; this enhancement is attributed both to the well-known Ru synergistic effect due to the presence of its oxides but also (based on the XPS findings to a modification effect of Pt electronic properties.

  7. Preparation and characterization of RuO2/polypyrrole electrodes for supercapacitors

    Science.gov (United States)

    Li, Xiang; Wu, Yujiao; Zheng, Feng; Ling, Min; Lu, Fanghai

    2014-11-01

    Polypyrrole (PPy) embedded RuO2 electrodes were prepared by the composite method. Precursor solution of RuO2 was coated on tantalum sheet and annealed at 260 °C for 2.5 h to develop a thin film. PPy particles were deposited on RuO2 films and dried at 80 °C for 12 h to form composite electrode. Microstructure and morphology of RuO2/PPy electrode were characterized using Fourier transform infrared spectrometer, X-ray diffraction and scanning electron microscopy, respectively. Our results confirmed that counter ions are incorporated into RuO2 matrix. Structure of the composite with amorphous phase was verified by X-ray diffraction. Analysis by scanning electron microscopy reveals that during grain growth of RuO2/PPy, PPy particle size sharply increases as deposition time is over 20 min. Electrochemical properties of RuO2/PPy electrode were calculated using cyclic voltammetry. As deposition times of PPy are 10, 20, 25 and 30 min, specific capacitances of composite electrodes reach 657, 553, 471 and 396 F g-1, respectively. Cyclic behaviors of RuO2/PPy composite electrodes are stable.

  8. Preparation of Pt–Ru bimetallic catalyst supported on carbon

    Indian Academy of Sciences (India)

    The template carbonization of polyphenyl acetylene yields hollow, uniform cylindrical carbon nanotubes with outer diameter almost equal to pore diameter of the template used. High resolution transmission electron microscopic investigation reveals that Pt–Ru nanoparticles are highly dispersed inside the tube with an ...

  9. Spray pyrolysed Ru:TiO2 thin film electrodes prepared for electrochemical supercapacitor

    Science.gov (United States)

    Fugare, B. Y.; Thakur, A. V.; Kore, R. M.; Lokhande, B. J.

    2018-04-01

    Ru doped TiO2 thin films are prepared by using 0.06 M aqueous solution of potassium titanium oxalate (pto), and 0.005 M aqueous solution of ruthenium tri chloride (RuCl3) precursors. The deposition was carried on stainless steel (SS) by using well known ultrasonic spray pyrolysis technique (USPT) at 723° K by maintaining the spray rate 12 cc/min and compressed air flow rate 10 Lmin-1. Prepared Ru:TiO2 thin films were characterized by structurally, morphologically and electrochemically. Deposited RuO2 shows amorphous structure and TiO2 shows tetragonal crystal structure with rutile as prominent phase at very low decomposition temperature. SEM micrographs of RuO2 exhibits porous, interconnected, spherical grains type morphology and TiO2 shows porous, nanorods and nanoplates like morphology and also Ru doped TiO2 shows porous, spherical, granular and nanorods type morphology. The electrochemical cyclic voltammetery shows mixed capacitive behavior. The achieved highest value of specific capacitance 2692 F/g was Ru doped TiO2 electrode in 0.5 M H2SO4.

  10. Nano-composite of PtRu alloy electrocatalyst and electronically conducting polymer for use as the anode in a direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Jongho Choi; Kyungwon Park; Hyekyung Lee; Youngmin Kim; Jaesuk Lee; Yungeun Sung [Kwangju Inst. of Science and Technology, Dept. of Materials Science and Engineering, Gwangju (Korea)

    2003-08-15

    Nano-composites comprised of PtRu alloy nanoparticles and an electronically conducting polymer for the anode electrode in direct methanol fuel cell (DMFC) were prepared. Two conducting polymers of poly(N-vinyl carbazole) and poly(9-(4-vinyl-phenyl)carbazole) were used for the nano-composite electrodes. Structural analyses were carried out using Fourier transform nuclear magnetic resonance spectroscopy, AC impedance spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Electrocatalytic activities were investigated by voltammetry and chronoamperometry in a 2 M CH{sub 3}OH/{sub 0.5} M H{sub 2}SO{sub 4} solution and the data compared with a carbon-supported PtRu electrode. XRD patterns indicated good alloy formation and nano-composite formation was confirmed by TEM. Electrochemical measurements and DMFC unit-cell tests indicate that the nano-composites could be useful in a DMFC, but its performance would be slightly lower than that of a carbon-supported electrode. The interfacial property between the PtRu-polymer nano-composite anode and the polymer electrolyte was good, as evidenced by scanning electron microscopy. For better performance in a DMFC, a higher electric conductivity of the polymer and a lower catalyst loss are needed in nano-composite electrodes. (Author)

  11. PREPARATION AND PROPERTY OF POLYMERIC PENDANT Ru(bpy)32+ COMPLEXES

    Institute of Scientific and Technical Information of China (English)

    HOU Xiaohuai; Masao Kaneko; Akira Yamada

    1984-01-01

    Polymeric pendant Ru(bpy)32+ complexes were prepared from homopolymer and copolymers of 4-methyl-4'-vinyl-2,2'-bipyridine (Vbpy). Vbpy was prepared from 4-methylpyridine. The comonomers were styrene (St), acrylic acid (AA), N-vinylpyrrolidone (Pyr), 4-vinylpyridine (Vpy), methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), acrylonitrile (AN) and N-ethyl-4-vinylpyridium bromide (EQ-Vpy). The fraction of the pendant Ru(bpy)32+ repeating unit in the polymeric complex was 0.022 to 0.052. Absorption maximum, molar extinction coefficient, emission maximum and relative emission intensity of the polymeric complexes were studied.

  12. Glycerol electro-oxidation in alkaline medium using Pd/C and PdSn/C electrocatalysts prepared by electron beam irradiation

    International Nuclear Information System (INIS)

    Geraldes, Adriana Napoleao; Silva, Dionisio Fortunato da; Pino, Eddy Segura; Spinace, Estevan Vitorio; Oliveira Neto, Almir; Linardi, Marcelo; Santos, Mauro Coelhos dos

    2013-01-01

    Carbon-supported metal nanoparticles were prepared for fuel cell applications by radiation-induced reduction of metal ions precursors. Pd/C and PdSn/C electrocatalysts (Pd:Sn atomic ratio 90:10), prepared by using electron beam irradiation, were tested for glycerol electro-oxidation in single alkaline direct glycerol fuel cell (ADGFC). EDX analysis showed that the Pd:Sn atomic ratio is very similar to the nominal one. X-ray diffractograms of PdSn/C electrocatalyst showed the presence of Pd (fcc) phase. Cyclic voltammetry (CV) indicated that Pd/C and PdSn/C electrocatalysts have good activity for glycerol electro-oxidation, at room temperature. Experiments with single ADGFC were carried out from 60 to 90 deg C, using Pd/C and PdSn/C electrocatalysts and glycerol 2.0 mol.L -1 , as fuel. The best performance was obtained at 85 deg C, for both electrocatalysts. The Pd/C and PdSn/C electrocatalysts showed similar performance (34 mW cm -2 ), at 85 deg C. (author)

  13. Ethanol electro-oxidation in alkaline medium using Pd/MWCNT and PdAuSn/MWCNT electrocatalysts prepared by electron beam irradiation

    International Nuclear Information System (INIS)

    Geraldes, Adriana Napoleao; Silva, Dionisio Furtunato da; Andrade e Silva, Leonardo Gondin de; Spinace, Estevam Vitorio; Oliveira Neto, Almir; Santos, Mauro Coelho dos

    2015-01-01

    Environmental problems and the world growing demand for energy has mobilized the scientific community in finding of clean and renewable energy sources. In this context, fuel cells appear as appropriate technology for generating electricity through alcohols electro-oxidation. Multi Wall Carbon Nanotubes (MWCNT)-supported Pd and trimetallic PdAuSn (Pd:Au:Sn 50:10:40 atomic ratio) electrocatalysts were prepared using electron beam irradiation. The obtained materials were characterized by VC, Chronoamperometry, EDX, TEM and XRD. The catalytic activities of electrocatalysts toward ethanol electro-oxidation were evaluated in alkaline medium in a single alkaline direct ethanol fuel cell (ADEFC) in a range temperature 60 to 90 deg C. The best performances were obtained at 85 deg C: 33 mW.cm -2 and 31 mW.cm -2 for Pd/ MWCNT and PdAuSn/MWCNT electrocatalysts, respectively. X-ray diffractograms of electrocatalysts showed the presence of Pd-rich (fcc) and Au-rich (fcc) phases. Cyclic voltammetry and chronoamperometry experiments showed that PdAuSn/MWCNT electrocatalyst demonstrated similar activity toward ethanol electro-oxidation at room temperature, compared to electrocatalyst Pd/MWCNT. (author)

  14. Ethanol electro-oxidation in alkaline medium using Pd/c and PdRh/C electrocatalysts prepared by electron beam irradiation

    International Nuclear Information System (INIS)

    Silva, Dionisio Furtunato da; Geraldes, Adriana Napoleao; Pino, Eddy Segura; Spinace, Estevam Vitorio; Oliveira Neto, Almir; Linardi, Marcelo

    2013-01-01

    In this study, carbon-supported Pd (Pd/C) and bimetallic PdRh (Pd:Rh 90:10 atomic ratio) (PdRh/C) electrocatalysts were prepared using electron beam irradiation. The morphology and composition of the obtained materials were characterized by Cyclic voltammetry (VC), Chronoamperometry (CA), Energy dispersive X-ray (EDX), X-ray Diffraction (XRD) and Thermo-gravimetric analysis (TGA). The catalytic activities of the electrocatalysts toward the ethanol electro-oxidation were evaluated in alkaline medium in a single alkaline direct ethanol fuel cell (ADEFC), in a range temperature of 50 to 85 deg C. The best performances were obtained at 85 deg C (25 mW.cm -2 ) and 75 deg C (38 mW.cm -2 ) for Pd/C and PdRh/C electrocatalysts, respectively. The XRD of the PdRh/C electrocatalyst showed the presence of Pd-rich (fcc) phase. CV and CA experiments showed that PdRh/C electrocatalyst demonstrated superior activity toward ethanol electro-oxidation at room temperature, compared to Pd/C electrocatalyst. (author)

  15. Ethanol electro-oxidation in alkaline medium using Pd/c and PdRh/C electrocatalysts prepared by electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio Furtunato da; Geraldes, Adriana Napoleao; Pino, Eddy Segura; Spinace, Estevam Vitorio; Oliveira Neto, Almir; Linardi, Marcelo, E-mail: dfsilva@ipen.br, E-mail: drinager@ig.com.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    In this study, carbon-supported Pd (Pd/C) and bimetallic PdRh (Pd:Rh 90:10 atomic ratio) (PdRh/C) electrocatalysts were prepared using electron beam irradiation. The morphology and composition of the obtained materials were characterized by Cyclic voltammetry (VC), Chronoamperometry (CA), Energy dispersive X-ray (EDX), X-ray Diffraction (XRD) and Thermo-gravimetric analysis (TGA). The catalytic activities of the electrocatalysts toward the ethanol electro-oxidation were evaluated in alkaline medium in a single alkaline direct ethanol fuel cell (ADEFC), in a range temperature of 50 to 85 deg C. The best performances were obtained at 85 deg C (25 mW.cm{sup -2}) and 75 deg C (38 mW.cm{sup -2}) for Pd/C and PdRh/C electrocatalysts, respectively. The XRD of the PdRh/C electrocatalyst showed the presence of Pd-rich (fcc) phase. CV and CA experiments showed that PdRh/C electrocatalyst demonstrated superior activity toward ethanol electro-oxidation at room temperature, compared to Pd/C electrocatalyst. (author)

  16. Ethanol electro-oxidation in alkaline medium using Pd/MWCNT and PdAuSn/MWCNT electrocatalysts prepared by electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Geraldes, Adriana Napoleao; Silva, Dionisio Furtunato da; Andrade e Silva, Leonardo Gondin de; Spinace, Estevam Vitorio; Oliveira Neto, Almir, E-mail: drinager@ig.com.br, E-mail: dfsilva@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Santos, Mauro Coelho dos [Universidade Federal do ABC (LEMN/CCNH/UFABC), Santo Andre, SP (Brazil)

    2015-07-01

    Environmental problems and the world growing demand for energy has mobilized the scientific community in finding of clean and renewable energy sources. In this context, fuel cells appear as appropriate technology for generating electricity through alcohols electro-oxidation. Multi Wall Carbon Nanotubes (MWCNT)-supported Pd and trimetallic PdAuSn (Pd:Au:Sn 50:10:40 atomic ratio) electrocatalysts were prepared using electron beam irradiation. The obtained materials were characterized by VC, Chronoamperometry, EDX, TEM and XRD. The catalytic activities of electrocatalysts toward ethanol electro-oxidation were evaluated in alkaline medium in a single alkaline direct ethanol fuel cell (ADEFC) in a range temperature 60 to 90 deg C. The best performances were obtained at 85 deg C: 33 mW.cm{sup -2} and 31 mW.cm{sup -2} for Pd/ MWCNT and PdAuSn/MWCNT electrocatalysts, respectively. X-ray diffractograms of electrocatalysts showed the presence of Pd-rich (fcc) and Au-rich (fcc) phases. Cyclic voltammetry and chronoamperometry experiments showed that PdAuSn/MWCNT electrocatalyst demonstrated similar activity toward ethanol electro-oxidation at room temperature, compared to electrocatalyst Pd/MWCNT. (author)

  17. Preparation and characterization of multi-walled carbon nanotube (MWCNTs)-supported Pt-Ru catalyst for methanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Yang Chunwei [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: cw.yang@hit.edu.cn; Wang Dianlong; Hu Xinguo; Dai Changsong [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Zhang Liang [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

    2008-01-10

    Multi-walled carbon nanotubes (MWCNTs) as a support of PtRu catalyst nanocomposites were prepared by colloid method in this work. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) all indicate that ultrasonic treatment can effectively functionalize MWCNTs, endowing them with groups that can act as nucleation sites which can favor well-dispersed deposition of PtRu clusters on their surface. The PtRu/MWCNTs catalysts have a high and homogeneous dispersion of spherical PtRu metal particles with a narrow particle-size distribution. From XPS tests, in PtRu/MWCNTs catalysts Ru can weaken the out-shell electrons of Pt because a part of Ru form alloy with Pt. The remnant Ru exists in oxidation and provides abundant oxygen to nearby Pt, as accelerated desorption and oxidation of intermediate products of methanol oxidation at surface of Pt. By a series of electrochemistry measurements, the PtRu/MWCNTs catalysts display significantly higher performance than the PtRu/XC-72 catalysts. Finally, schematic procedures for the oxidation of MWCNTs and synthesis of PtRu/MWCNTs catalysts were given.

  18. Preparation and characterization of multi-walled carbon nanotube (MWCNTs)-supported Pt-Ru catalyst for methanol electrooxidation

    International Nuclear Information System (INIS)

    Yang Chunwei; Wang Dianlong; Hu Xinguo; Dai Changsong; Zhang Liang

    2008-01-01

    Multi-walled carbon nanotubes (MWCNTs) as a support of PtRu catalyst nanocomposites were prepared by colloid method in this work. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) all indicate that ultrasonic treatment can effectively functionalize MWCNTs, endowing them with groups that can act as nucleation sites which can favor well-dispersed deposition of PtRu clusters on their surface. The PtRu/MWCNTs catalysts have a high and homogeneous dispersion of spherical PtRu metal particles with a narrow particle-size distribution. From XPS tests, in PtRu/MWCNTs catalysts Ru can weaken the out-shell electrons of Pt because a part of Ru form alloy with Pt. The remnant Ru exists in oxidation and provides abundant oxygen to nearby Pt, as accelerated desorption and oxidation of intermediate products of methanol oxidation at surface of Pt. By a series of electrochemistry measurements, the PtRu/MWCNTs catalysts display significantly higher performance than the PtRu/XC-72 catalysts. Finally, schematic procedures for the oxidation of MWCNTs and synthesis of PtRu/MWCNTs catalysts were given

  19. Preparation of Pt–Ru bimetallic catalyst supported on carbon ...

    Indian Academy of Sciences (India)

    Unknown

    of carbon nanotube (Iijima 1991) was first based on the carbon-arc method, though the carbon nanotube prepared by this method are more graphitic, the low yield and rela- tively small length (< 1 m) make the production cost very high. The template synthesis method (Martin 1994) and catalytic production methods (Jose et ...

  20. Radiolytic Preparation of Electrocatalysts with Pt-Co and Pt-Sn Nanoparticles for a Proton Exchange Membrane Fuel Cell

    Directory of Open Access Journals (Sweden)

    Sang Kyum Kim

    2014-01-01

    Full Text Available Nanosized Pt-Sn/VC and Pt-Co/VC electrocatalysts were prepared by a one-step radiation-induced reduction (30 kGy process using distilled water as the solvent and Vulcan XC72 as the supporting material. While the Pt-Co/VC electrodes were compared with Pt/VC (40 wt%, HiSpec 4000, in terms of their electrocatalytic activity towards the oxidation of H2, the Pt-Co/VC electrodes were evaluated in terms of their activity towards the hydrogen oxidation reaction (HOR and compared with Pt/VC (40 wt%, HiSpec 4000, Pt-Co/VC, and Pt-Sn/VC in a single cell. Additionally, the prepared electrocatalyst samples (Pt-Co/VC and Pt-Sn/VC were characterized by transmission electron microscopy (TEM, scanning electron microscope (SEM, thermogravimetric analysis (TGA, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, electrochemical surface area (ECSA, and fuel cell polarization performance.

  1. Preparation of highly dispersed Ru-Sn bimetallic supported catalysts from the single source precursors Cp(PPh32Ru-SnX3 (X = Cl or Br

    Directory of Open Access Journals (Sweden)

    Ana Cláudia Bernardes Silva

    2003-06-01

    Full Text Available In this work highly dispersed Ru-Sn bimetallic catalysts have been prepared from organobimetallic Cp(PPh32Ru-SnX3 (X = Cl or Br complexes. These single source precursors can be easily impregnated in high surface area supports, such as activated carbon and sol-gel SiO2, and upon controlled thermal treatment the ligands are released as volatile products resulting in the formation of the bimetallic system Ru-Sn. Catalytic reactions, such as hydrodechlorination of CCl4 and chlorobenzene and TPR (Temperature Programmed Reduction experiments carried out with these RuSn catalysts suggested a strong interaction between Ruthenium and Tin. Mössbauer measurements showed that these materials when exposed to air are immediately oxidized to form Sn (IV. It was shown that upon controlled reduction conditions with H2 it is possible to reduce selectively Sn to different oxidation states and different phases. The Sn oxidation state showed significant effect on the catalytic hydrogenation of 1,5-cyclooctadiene. The use of these single source precursors with a controlled decomposition/reduction procedure allows the preparation of unique catalysts with an intimate interaction between the components ruthenium and tin and the possibility of varying the Sn oxidation state around the Ru metal.

  2. Enhanced electro-oxidation of ethanol using PtSn/CeO{sub 2}-C electrocatalyst prepared by an alcohol-reduction process

    Energy Technology Data Exchange (ETDEWEB)

    Neto, Almir Oliveira; Farias, Luciana A.; Dias, Ricardo R.; Brandalise, Michelle; Linardi, Marcelo; Spinace, Estevam V. [Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP, Av. Prof. Lineu Prestes, 2242 - Cidade Universitaria, CEP 05508-900 Sao Paulo-SP (Brazil)

    2008-09-15

    PtSn/CeO{sub 2}-C electrocatalysts were prepared by an alcohol-reduction process using ethylene glycol as solvent and reduction agent and CeO{sub 2} and Vulcan Carbon XC72 as supports. The electrocatalysts were characterized by EDX and XRD. The electro-oxidation of ethanol was studied at room temperature by chronoamperometry. PtSn/CeO{sub 2}-C electrocatalyst with 15 wt% of CeO{sub 2} showed a significant increase of performance for ethanol oxidation compared to PtSn/C catalyst. Preliminary tests at 100C on a single cell of a direct ethanol fuel cell (DEFC) also confirm the results obtained by chronoamperometry. (author)

  3. Preparation of Pt Au/C and Pt Au Bi/C electrocatalysts using electron beam irradiation for ethanol electro-oxidation in alkaline medium

    International Nuclear Information System (INIS)

    Silva, Dionisio F.; Geraldes, Adriana N.; Cardoso, Elisangela S.Z.; Gomes, Thiago B.; Linardi, Marcelo; Oliveira Neto, Almir; Spinace, Estevam V.

    2011-01-01

    Pt Au/C (50:50) and PtAuBi/C electrocatalysts with Pt:Au:Bi atomic ratios of 50:40:10, 50:30:20 and 50:10:40 were prepared in water/2-propanol using electron beam irradiation. The materials were characterized by X-ray diffraction (XRD) and the electro-oxidation of ethanol was studied by chronoamperometry at room temperature. The X-ray diffraction measurements for all electrocatalysts prepared showed four peaks, which are associated with the planes of the face-centered cubic (fcc) structure characteristic of Pt and Pt alloys. For PtAuBi/C it was also observed the presence of a mixture of BiPt alloys and bismuth phases. The average crystallite sizes for Pt/C, PtAu/C, PtAuBi/C (50:40:10), PtAuBi/C (50:30:20) and PtAuBi/C (50:10:40) were in the range of 2.0 - 4.0 nm. The activity of the electrocatalysts for ethanol oxidation in alkaline medium showed that PtAuBi/C (50:40:10) had a higher performance for ethanol oxidation compared to others electrocatalysts prepared. (author)

  4. Preparation of Pt Au/C and Pt Au Bi/C electrocatalysts using electron beam irradiation for ethanol electro-oxidation in alkaline medium

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio F.; Geraldes, Adriana N.; Cardoso, Elisangela S.Z.; Gomes, Thiago B.; Linardi, Marcelo; Oliveira Neto, Almir; Spinace, Estevam V., E-mail: dfsilva@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Pt Au/C (50:50) and PtAuBi/C electrocatalysts with Pt:Au:Bi atomic ratios of 50:40:10, 50:30:20 and 50:10:40 were prepared in water/2-propanol using electron beam irradiation. The materials were characterized by X-ray diffraction (XRD) and the electro-oxidation of ethanol was studied by chronoamperometry at room temperature. The X-ray diffraction measurements for all electrocatalysts prepared showed four peaks, which are associated with the planes of the face-centered cubic (fcc) structure characteristic of Pt and Pt alloys. For PtAuBi/C it was also observed the presence of a mixture of BiPt alloys and bismuth phases. The average crystallite sizes for Pt/C, PtAu/C, PtAuBi/C (50:40:10), PtAuBi/C (50:30:20) and PtAuBi/C (50:10:40) were in the range of 2.0 - 4.0 nm. The activity of the electrocatalysts for ethanol oxidation in alkaline medium showed that PtAuBi/C (50:40:10) had a higher performance for ethanol oxidation compared to others electrocatalysts prepared. (author)

  5. Platinum monolayer electrocatalysts for oxygen reduction: effect of substrates, and long-term stability

    Directory of Open Access Journals (Sweden)

    J. ZHANG

    2005-03-01

    Full Text Available We describe a novel concept for a Ptmonolayer electrocatalyst and present the results of our electrochemical, X-ray absorption spectroscopy, and scanning tunneling microscopy studies. The electrocatalysts were prepared by a new method for depositing Pt monolayers involving the galvanic displacement by Pt of an underpotentially deposited Cu monolayer on substrates of Au (111, Ir(111, Pd(111, Rh(111 and Ru(0001 single crylstals, and Pd nanoparticles. The kinetics of O2 reduction showed significant enhancement with Pt monolayers on Pd(111 and Pd nanoparticle surfaces in comparisonwith the reaction on Pt(111 and Pt nanoparticles, respectively. This increase in catalytic activity is attributed partly to the decreased formation of PtOH, as shown by in situ X-ray absorption spectroscopy. The results illustrate that placing a Pt monolayer on a suitable substrate of metal nanoparticles is an attractive way of designing better O2 reduction electrocatalysts with very low Pt contents.

  6. Scalable preparation of sized-controlled Co-N-C electrocatalyst for efficient oxygen reduction reaction

    Science.gov (United States)

    Ai, Kelong; Li, Zelun; Cui, Xiaoqiang

    2017-11-01

    Heat-treated metal-nitrogen-carbon (M-N-C) materials are emerging as promising non-precious catalysts to replace expensive Pt-based materials for oxygen reduction reaction (ORR) in energy conversion and storage devices. Despite recent progress, their activity and durability are still far from satisfactory. The activity site and particle size are among the most important factors for the ORR activity of M-N-C catalysts. Extensive efforts have been made to reveal the correlation of active site and activity. However, it remains unclear to what extent the particle size will influence the ORR activity of M-N-C materials. Moreover, to the best of our knowledge, controllable synthesis of M-N-C catalysts with high-density activity sites remains elusive. Herein, we develop a straightforward method to produce a monodisperse and size-controlled Co-N-C (Nano-P-ZIF-67) electrocatalyst, and systemically investigate its catalytic mechanisms. Only by optimizing the particle size, Nano-P-ZIF-67 outperforms the commercial 20 wt% Pt/C regarding all evaluating indicators for ORR catalysts in alkaline media including higher catalytic activity, durability, and stronger methanol tolerance. Nano-P-ZIF-67 is assembled into a cell, and the cell shows a power density of 45.5 mW/cm2, which is the highest value among currently studied cathode catalysts. We expect Nano-P-ZIF-67 to be a highly interesting candidate for the next generation of ORR catalysts.

  7. Method of preparing Ru-immobilized polymer-supported catalyst for hydrogen generation from NaBH{sub 4} solution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ching-Wen; Chen, Chuh-Yung; Huang, Yao-Hui [Department of Chemical Engineering, National Cheng Kung University, No.1, University Road, Tainan City 70101 (China)

    2009-03-15

    A method of preparing a polymer-supported catalyst for hydrogen generation is introduced in this article. This polymer-supported catalyst is the structure of ruthenium (Ru) nanoparticle immobilized on a monodisperse polystyrene (PSt) microsphere. The diameter of the Ru nanoparticle is around 16 nm, and the diameter of the PSt microsphere is 2.65 um. This preparation method is accomplished by two unique techniques: one is sodium lauryl sulfate/sodium formaldehyde sulfoxylate (SLS/SFS) interface-initiated system, the other is 2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester (GMA-IDA) chelating monomer. By taking advantage of these two techniques, Ru{sup 3+} ion will be chelated and then reduced to Ru{sup (0)} nanoparticle over PSt surface predominantly. The hydrolysis of alkaline sodium borohydride (NaBH{sub 4}) solution catalyzed by this Ru-immobilized polymer-supported catalyst is also examined in this article. It reveals that the hydrogen generation rate is 215.9 ml/min g-cat. in a diluted solution containing 1 wt.% NaBH{sub 4} and 1 wt.% NaOH, and this Ru-immobilized polymer-supported catalyst could be recycled during the reaction. (author)

  8. Fuel cell testing of Pt–Ru catalysts supported on differently prepared and pretreated carbon nanotubes

    International Nuclear Information System (INIS)

    Tokarz, Wojciech; Lota, Grzegorz; Frackowiak, Elzbieta; Czerwiński, Andrzej; Piela, Piotr

    2013-01-01

    Proton-exchange membrane fuel cell (PEMFC) testing of Pt–Ru catalysts supported on differently prepared multiwall carbon nanotube (MCNT) supports was performed to elucidate the influence of the different supports on the operating characteristics of the catalysts under real direct methanol fuel cell (DMFC) anode and H 2 -PEMFC anode conditions. The MCNTs were either thin, entangled or thick, disentangled. Pretreatment of the MCNTs was also done and it was either high-temperature KOH etching or annealing (graphitization). The performance of the catalysts was compared against the performance of a commercial Pt–Ru catalyst supported on a high-surface-area carbon black. Among the different MCNT supports, the graphitized, entangled support offered the best performance in all tests, which was equal to the performance of the commercial catalyst, despite the MCNT catalyst layer was ca. 2.2 times thicker than the carbon black catalyst layer. Even for an MCNT catalyst layer, which was almost 7 times thicker than the carbon black catalyst layer, the transport limitations were not prohibitive. This confirmed the expected potential of nanotube supports for providing superior reactant transport properties of the PEMFC catalyst layers

  9. Electrocatalysts with platinum, cobalt and nickel preparations by mechanical alloyed and CVD for the reaction of oxygen reduction; Electrocatalizadores a base de platino, cobalto y niquel preparados por aleado mecanico y CVD para la reaccion de reduccion de oxigeno

    Energy Technology Data Exchange (ETDEWEB)

    Garcia C, M A [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)

    2008-07-01

    In this research, the molecular oxygen reduction reaction (ORR) was investigated on electrocatalysts of Co, Ni, Pt and their alloys CoNi, PtCo, PtNi and PtCoNi by using H{sub 2}SO{sub 4} 0.5 and KOH 0.5 M solutions as electrolytes. The electrocatalysts were synthesized by Mechanical Alloying (MA) and Chemical Vapor Deposition (CVD) processes. For MA, metallic powders were processed during 20 h of milling in a high energy SPEX 8000 mill. For CVD, a hot-wall reactor was utilized and Co, Ni and Pt acetilactetonates were used as precursors. Films were deposited at a total pressure of 1 torr and temperatures of 400-450 C. Electrocatalysts were characterized by X-Ray Diffraction (XRD). Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-Ray Spectroscopy (EDS). Electrocatalysts prepared by mechanical alloying showed a homogeneously dispersed agglomeration of particles with nano metric size. Electrocatalysts obtained by CVD showed, in some cases, non uniform films, with particles of nano metric size, as well. The electrocatalytic performance was evaluated by using the Rotating Disk Electrode technique (RDE). Electrocatalysts prepared by MA showed higher activity than those obtained by CVD. All electrocatalysts were evaluated in alkaline media. Only electrocatalysts containing Pt were evaluated in acid media, because those materials with Co, Ni and their alloys showed instability in acidic media. Most electrocatalysts followed a mechanism for the ORR producing a certain proportion of H{sub 2}O{sub 2}. All electrocatalysts, exhibited a fair or good electrocatalytic activity in comparison with other similar reported materials. It was found that MA and CVD are appropriate processes to prepare electrocatalysts for the ORR with particles of nano metric size and performing with an acceptable catalytic activity. PtCoNi 70-23-7% by MA and PtCoNi-CVD electrocatalysts showed the highest activity in alkaline media, while in acidic

  10. Influence of alcohol additives in the preparation of electrodeposited Pt-Ru catalysts on oxidized graphite cloths

    International Nuclear Information System (INIS)

    Sieben, Juan Manuel; Duarte, Marta M.E.; Mayer, Carlos E.

    2011-01-01

    Research highlights: → Pt-Ru catalysts were prepared by potential pulse electrodeposition from solutions containing EtOH or EG at pH 2 and 5. → The catalyst particle size, loading and dispersion were influenced by solution pH and alcohol addition. → The deposits prepared at pH 2 exhibited large irregular agglomerates while those prepared at pH 5 presented smaller globular particles. → Pt-Ru system prepared using EG at pH 5 exhibited the best performance for CH 3 OH oxidation. - Abstract: Carbon supported Pt-Ru catalysts were prepared by multiple cycles of potentiostatic pulses from aqueous diluted chloroplatinic acid and ruthenium chloride solutions in the presence of ethanol or ethylene glycol at pH 2 and 5. SEM images showed that the metallic deposit prepared at pH 2 consisted of large irregular agglomerates, whereas smaller globular particles were obtained at pH 5. In addition, the average particle size was considerably decreased in the presence of the stabilizers. The supported Pt-Ru alloys were tested as catalysts for methanol electro-oxidation in acid media. Electrocatalytic activity measurements indicated that the most active electrode was obtained with ethylene glycol as additive at pH 5.

  11. Synthesis, spectroscopic, structural and optical studies of Ru2S3 nanoparticles prepared from single-source molecular precursors

    Science.gov (United States)

    Mbese, Johannes Z.; Ajibade, Peter A.

    2017-09-01

    Homonuclear tris-dithiocarbamato ruthenium(III) complexes, [Ru(S2CNR2)3] were prepared and characterized by spectroscopic techniques and thermogravimetric analyses. The thermogravimetric analyses (TGA) of the ruthenium complexes showed that the complexes decompose to ruthenium(III) sulfide nanoparticles. The ruthenium(III) complexes were dispersed in oleic acid and thermolysed in hexadecylamine to prepared oleic acid/hexadecylamine capped Ru2S3 nanoparticles. FTIR revealed that Ru2S3 nanoparticles are capped through the interaction of the -NH2 group of hexadecylamine HDA adsorbed on the surfaces of nanoparticles and it also showed that oleic acid (OA) is acting as both coordinating stabilizing surfactant and capping agent. EDS spectra revealed that the prepared nanoparticles are mainly composed of Ru and S, confirming the formation of Ru2S3 nanoparticles. Powder XRD confirms that the nanoparticles are in cubic phase. The inner morphology of nanoparticles obtained from transmission electron microscopy (TEM) showed nanoparticles with narrow particle size distributions characterized by an average diameter of 8.45 nm with a standard deviation of 1.6 nm. The optical band gap (Eg) determined from Tauc plot are in the range 3.44-4.18 eV.

  12. 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.

  13. Highly dispersed TaOx nanoparticles prepared by electrodeposition as oxygen reduction electrocatalysts for polymer electrolyte fuel cells

    KAUST Repository

    Seo, Jeongsuk

    2013-06-06

    Based on the chemical stability of group IV and V elements in acidic solutions, TaOx nanoparticles prepared by electrodeposition in an ethanol-based Ta plating bath at room temperature were investigated as novel nonplatinum electrocatalysts for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs). Electrodeposition conditions of Ta complexes and subsequent various heat treatments for the deposited TaOx were examined for the best performance of the ORR. TaOx particles on carbon black (CB), electrodeposited at a constant potential of -0.5 V Ag/AgCl for 10 s and then heat-treated by pure H2 flow at 523 K for 1 h, showed excellent catalytic activity with an onset potential of 0.93 VRHE (for 2 μA cm-2) for the ORR. Surface characterizations of the catalysts were performed by scanning transmission electron microscopy (STEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). The loading amounts of the electrodeposited material on the CB were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). All the physical results suggested that high dispersion of TaOx particles on the CB surface with 2-3 nm size was critical and key for high activity. The chemical identity and modified surface structure for the deposited TaOx catalysts before and after H 2 heat treatment were analyzed by X-ray photoelectron spectroscopy (XPS). The formation of more exposed active sites on the electrode surface and enhanced electroconductivity of the tantalum oxide promoted from the H 2 treatment greatly improved the ORR performance of the electrodeposited TaOx nanoparticles on CB. Finally, the highly retained ORR activity after an accelerated durability test in an acidic solution confirmed and proved the chemical stability of the oxide nanoparticles. The high utilization of the electrodeposited TaOx nanoparticles uniformly dispersed on CB for the ORR was comparable to that of commercial Pt/CB catalysts

  14. Ethanol electrooxidation using Ti/(RuO2)(x) Pt(1-x) electrodes prepared by the polymeric precursor method

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, R.G.; Marchesi, L.F.Q.P.; Forim, M.R.; Pereira, E.C. [Departamento de Quimica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil); Bulhoes, L.O.S [CENIP, Centro Universitario Central Paulista, Sao Carlos, SP (Brazil); Santos, M.C. [LEMN, Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC, Santo Andre, SP (Brazil); Oliveira, R.T.S., E-mail: robson@icbn.uftm.edu.br [Instituto de Ciencias Biologicas e Naturais, Universidade Federal do Triangulo Mineiro, Uberaba, MG (Brazil)

    2011-09-15

    This work describes a detailed study of the ethanol electrooxidation on Ti/(RuO{sub 2}){sub (x)}Pt{sub (1-x)} electrodes using several compositions prepared by the polymeric precursor method. The results obtained using cyclic voltammetry and chronoamperometry showed that the best composition of Ti/(RuO{sub 2}){sub (x)}Pt{sub (1-x)} electrodes for CO and ethanol oxidation processes is Ti/(RuO{sub 2}){sub 0.50}Pt{sub 0.50}. On this electrode composition the onset of CO and the ethanol oxidation occurred at 380 mV and 220 mV more negative than on Ti/Pt, respectively. Besides, there was an increase of 2.5-fold in the current density for ethanol electrooxidation under constant potential polarization. The Ti/(RuO{sub 2}){sub 0.50}Pt{sub 0.50}. electrodes produced lower amount of acetic acid compared to Ti/Pt and polycrystalline Pt electrodes using in situ HPLC spectrometric analysis. Also, a non common product from ethanol oxidation could be observed on higher RuO{sub 2} loads: ethyl acetate. Finally, the impedance data showed that Ti/(RuO{sub 2}){sub 0.50}Pt{sub 0.50}. electrode composition had the smallest charge transfer resistance for ethanol oxidation among those compositions investigated. (author)

  15. Preparation and characterization of Pt–CeO{sub 2}/C and Pt–TiO{sub 2}/C electrocatalysts with improved electrocatalytic activity for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Hameed, R.M. Abdel [Chemistry Department, Faculty of Science, Cairo University, Giza (Egypt); Amin, R.S. [Chemical Engineering Department, National Research Center, Dokki, Giza (Egypt); El-Khatib, K.M., E-mail: Kamelced@hotmail.com [Chemical Engineering Department, National Research Center, Dokki, Giza (Egypt); Fetohi, Amani E. [Chemical Engineering Department, National Research Center, Dokki, Giza (Egypt)

    2016-03-30

    Graphical abstract: - Highlights: • Adding TiO{sub 2} or CeO{sub 2} to Pt/C reduced its Pt particle size. • Methanol oxidation current density decreased as Pt–CeO{sub 2}/C > Pt–TiO{sub 2}/C > Pt/C. • Decreased R{sub ct} values were observed at Pt–TiO{sub 2}/C and Pt–CeO{sub 2}/C. - Abstract: Pt–TiO{sub 2}/C and Pt–CeO{sub 2}/C electrocatalysts were synthesized by solid state reaction of TiO{sub 2}/C and CeO{sub 2}/C powders using intermittent microwave heating, followed by chemical reduction of platinum ions using mixed reducing agents of ethylene glycol and sodium borohydride. The crystal structure, surface morphology and chemical composition of prepared electrocatalysts were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The phase angle values of different Pt diffraction planes in Pt–TiO{sub 2}/C and Pt–CeO{sub 2}/C were shifted in the positive direction relative to those in Pt/C. Pt particles with diameter values of 3.06 and 2.78 nm were formed in Pt–TiO{sub 2}/C and Pt–CeO{sub 2}/C, respectively. The electrochemical performance of prepared electrocatalysts was examined using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Pt–CeO{sub 2}/C showed an enhanced oxidation current density when compared to Pt/C. Long time oxidation test at Pt–TiO{sub 2}/C and Pt–CeO{sub 2}/C revealed their improved stability. Lower charge transfer resistance values were estimated at Pt–metal oxide/C electrocatalysts.

  16. Effect of heat treatment on stability of gold particle modified carbon supported Pt-Ru anode catalysts for a direct methanol fuel cell

    International Nuclear Information System (INIS)

    Li Xiaowei; Liu Juanying; Huang Qinghong; Vogel, Walter; Akins, Daniel L.; Yang Hui

    2010-01-01

    Carbon supported Au-PtRu (Au-PtRu/C) catalysts were prepared as the anodic catalysts for the direct methanol fuel cell (DMFC). The procedure involved simple deposition of Au particles on a commercial Pt-Ru/C catalyst, followed by heat treatment of the resultant composite catalyst at 125, 175 and 200 o C in a N 2 atmosphere. High-resolution transmission electron microscopy (HR-TEM) measurements indicated that the Au nanoparticles were attached to the surface of the Pt-Ru nanoparticles. We found that the electrocatalytic activity and stability of the Au-PtRu/C catalysts for methanol oxidation is better than that of the PtRu/C catalyst. An enhanced stability of the electrocatalyst is observed and attributable to the promotion of CO oxidation by the Au nanoparticles adsorbed onto the Pt-Ru particles, by weakening the adsorption of CO, which can strongly adsorb to and poison Pt catalyst. XPS results show that Au-PtRu/C catalysts with heat treatment lead to surface segregation of Pt metal and an increase in the oxidation state of Ru, which militates against the dissolution of Ru. We additionally find that Au-PtRu/C catalysts heat-treated at 175 o C exhibit the highest electrocatalytic stability among the catalysts prepared by heat treatment: this observation is explained as due to the attainment of the highest relative concentration of gold and the highest oxidation state of Ru oxides for the catalyst pretreated at this temperature.

  17. Preparation of PtSnCu/C and PtSn/C electrocatalysts and activation by dealloying processes for ethanol electrooxidation

    International Nuclear Information System (INIS)

    Crisafulli, Rudy

    2013-01-01

    PtSnCu/C (with different Pt:Sn:Cu atomic ratios) and PtSn/C (50:50) electrocatalysts were prepared by borohydride (BR) and alcohol-reduction (AR) processes using H 2 PtCl 6 .6H 2 O, SnCl 2 .2H 2 O and CuCl 2 .2H 2 O as metal sources, NaBH 4 and ethylene glycol as reducing agents, 2-propanol and ethylene glycol/water as solvents and carbon black as support. In a further step, these electrocatalysts were activated by chemical (CD) and electrochemical (ED) dealloying processes through acid treatment and thin porous coating technique, respectively. These materials were characterized by energy dispersive X-ray, Xray diffraction, transmission electron microscopy, line scan energy dispersive Xray and cyclic voltammetry. Electrochemical studies for ethanol electro-oxidation were performed by cyclic voltammetry, chronoamperometry and in single Direct Ethanol Fuel Cell using Membrane Electrode Assembly (MEA). The anodic effluents were analysed by gas chromatography. The X-ray diffractograms of the as-synthesized electrocatalysts showed the typical face-centered cubic structure (FCC) of platinum and its alloys. After dealloying, the X-ray diffractograms showed that the Pt FCC structure was preserved. The crystallite sizes of the assynthesized electrocatalysts were in the range of PtSnCu/C (50:40:10) AR/ED > PtSnCu/C (50:10:40) BR/CD. PtSn/C (50:50) BR/CD, PtSnCu/C (50:10:40) BR/CD, PtSnCu/C (50:40:10) AR/CD electrocatalysts and Pt/C BASF, PtSn/C (75:25) BASF commercial electrocatalysts were tested in single Direct Ethanol Fuel Cell. The results showed the following performance for ethanol electro-oxidation: PtSn/C (50:50) BR/CD > PtSnCu/C (50:40:10) AR/CD > PtSnCu/C > PtSn/C (75:25) BASF > PtSnCu/C (50:10:40) BR/CD > Pt/C BASF. (author)

  18. Use of Dendrimers during the Synthesis of Pt-Ru Electrocatalysts for PEM Fuel Cells: Effects on the Physical and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    J. C. Calderón

    2011-01-01

    Full Text Available In this work, Pt-Ru catalysts were synthesized by a novel methodology which includes the use as encapsulating molecules of dendrimers of different generation: zero (DN-0, one (DN-1, two (DN-2, and three (DN-3. Synthesized catalysts were heat-treated at 350°C, and the effects of this treatment was established from the physical (X-ray dispersive energy (XDE and X-ray diffraction (XRD and electrochemical characterization (cyclic voltammetry and chronoamperometry. Results showed that the heat-treatment benefits the catalytic properties of synthesized materials in terms of CO and methanol electrochemical oxidation. The curves for CO stripping were more defined for heat-treated catalysts, and methanol oxidation current densities were higher for these materials. These changes are principally explained from the removal of organic residues remaining on the surface of the Pt-Ru nanoparticles after the synthesis procedure. After the activation of the catalysts by heating at 350°C, the real importance of the use of these encapsulating molecules and the effect of the generation of the dendrimer become visible. From these results, it can be concluded that synthesized catalysts are good catalytic anodes for direct methanol fuel cells (DMFCs.

  19. Study the Polyol Process of Preparing the ru Doped FePt Nanoparticles

    Science.gov (United States)

    Lee, Chih-Hao; Hsu, Jen-Ho; Su, Hui-Chia; Huang, Tzu Wen

    The structure of Ru doped FePt nanoparticles using polyol process was studied. The particle size grown is around 5 nm, and a shell structure might be formed. By selecting the time and temperature of adding the Ru precursors into solution, three different processes to synthesize the FePtRu particles were studied resulting in different growing mechanics. The possible models during the reaction process are also discussed. The phase transition temperature for the as-grown FCC FePt nanoparticle to transform into L10 FePt nanoparticle is about 823 K which is about the same as the one without doping Ru atoms. From the XAS study of each element, the possible scenario is that: although Ru atoms with the size close to the Pt, they do not totally replace the Pt sites in the FePt alloy. Instead, most of Ru formed a shell outside the FePt nanoparticles and Fe atoms are replaced.

  20. Electrocatalytic Activity for CO, MeOH, and EtOH Oxidation on the Surface of Pt-Ru Nanoparticles Supported by Metal Oxide

    Directory of Open Access Journals (Sweden)

    Kwang-Sik Sim

    2011-01-01

    Full Text Available This paper describes the electrocatalytic activity for CO, MeOH, and EtOH oxidation on the surface of Pt-Ru nanoparticles supported by metal oxide (Nb-TiO2-H prepared for use in a fuel cell. To prepare Nb-TiO2-supported Pt-Ru nanoparticles, first, the Nb-TiO2 supports were prepared by sol-gel reaction of titanium tetraisopropoxide with a small amount of the niobium ethoxide in polystyrene (PS colloids. Second, Pt-Ru nanoparticles were then deposited by chemical reduction of the Pt4+ and Ru3+ ions onto Nb-TiO2 supports (Pt-Ru@Nb-TiO2-CS. Nb element was used to reduce electrical resistance to facilitate electron transport during the electrochemical reactions on a fuel cell electrode. Finally, the Pt-Ru@Nb-TiO2-H catalysts were formed by the removal of core-polystyrene ball from Pt-Ru@TiO2-CS at 500∘C. The successfully prepared Pt-Ru electrocatalysts were confirmed via TEM, XPS, and ICP analysis. The electrocatalytic efficiency of Pt-Ru nanoparticles was evaluated via CO, MeOH, and EtOH oxidation for use in a direct methanol fuel cell (DMFC. As a result, the Pt-Ru@Nb-TiO2-H electrodes showed high electrocatalytic activity for the electrooxidation of CO, MeOH, and EtOH.

  1. Ni@Ru and NiCo@Ru Core-Shell Hexagonal Nanosandwiches with a Compositionally Tunable Core and a Regioselectively Grown Shell.

    Science.gov (United States)

    Hwang, Hyeyoun; Kwon, Taehyun; Kim, Ho Young; Park, Jongsik; Oh, Aram; Kim, Byeongyoon; Baik, Hionsuck; Joo, Sang Hoon; Lee, Kwangyeol

    2018-01-01

    The development of highly active electrocatalysts is crucial for the advancement of renewable energy conversion devices. The design of core-shell nanoparticle catalysts represents a promising approach to boost catalytic activity as well as save the use of expensive precious metals. Here, a simple, one-step synthetic route is reported to prepare hexagonal nanosandwich-shaped Ni@Ru core-shell nanoparticles (Ni@Ru HNS), in which Ru shell layers are overgrown in a regioselective manner on the top and bottom, and around the center section of a hexagonal Ni nanoplate core. Notably, the synthesis can be extended to NiCo@Ru core-shell nanoparticles with tunable core compositions (Ni 3 Co x @Ru HNS). Core-shell HNS structures show superior electrocatalytic activity for the oxygen evolution reaction (OER) to a commercial RuO 2 black catalyst, with their OER activity being dependent on their core compositions. The observed trend in OER activity is correlated to the population of Ru oxide (Ru 4+ ) species, which can be modulated by the core compositions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Methanol oxidation at carbon paste electrodes modified with (Pt–Ru)/carbon aerogels nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Fort, Carmen I., E-mail: iladiu@chem.ubbcluj.ro [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania); Cotet, Liviu C. [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania); Vasiliu, Florin [The National Institute of Materials Physics, Atomistilor str. 105 bis, PO Box MG. 7, Magurele, RO 077125, Bucharest (Romania); Marginean, Petre [National Institute for Research and Development of Isotopic and Molecular Technologies, RO 400293, Cluj-Napoca (Romania); Danciu, Virginia; Popescu, Ionel C. [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania)

    2016-04-01

    Mesoporous carbon aerogels (CAs) impregnated with (Pt–Ru) nanoparticles were prepared, incorporated into carbon paste electrodes (CPEs) and investigated as electrocatalysts for CH{sub 3}OH electro-oxidation. The sol–gel method, followed by supercritical drying with liquid CO{sub 2} and thermal pyrolysis in an inert atmosphere, was used to obtain high mesoporous CAs. (Pt–Ru)/CAs nanocomposites with various (Pt–Ru) loading were prepared by using Ru(AcAc){sub 3} and H{sub 2}PtCl{sub 6} as metal precursors and the impregnation method. The morpho-structural peculiarities of the so prepared (Pt–Ru)/CAs electrocatalysts were examined by using elemental analysis, N{sub 2} adsorption-desorption isotherms, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) and selected area electron diffraction (SAED). Cyclic voltammetry measurements, carried out at (Pt–Ru)/CA-CPEs incorporating nanocomposites with various Pt–Ru loading and different specific surface areas, showed that CA with the highest specific surface area (843 m{sup 2}/g) and impregnated with 6% (w/w) (Pt–Ru) nanoparticles exhibit the best CH{sub 3}OH electro-oxidation efficiency. The Michaelis–Menten formalism was used to describe the dependence of the oxidation peak current on the CH{sub 3}OH concentration, allowing the estimation of the modified electrodes sensitivities. Thus, for (Pt–Ru, 10%)/CA{sub 535}-CPE was observed the highest sensitivity (12.5 ± 0.8 mA/M) and, at the same time, the highest maximum current density ever reported (153.1 mA/cm{sup 2} for 2 M CH{sub 3}OH and an applied potential of 600 mV vs. SHE). - Highlights: • (Pt–Ru) nanoparticles were deposited on high mesoporous carbon aerogels (CAs). • (Pt–Ru)/CAs were characterized by TEM, EDX, SAED and N{sub 2} adsorption-desorption. • Carbon paste electrodes modified with (Pt–Ru)/CA were used for CH{sub 3}OH oxidation. • (Pt–Ru, 10

  3. Application of green chemistry techniques to prepare electrocatalysts for direct methanol fuel cells.

    Science.gov (United States)

    Shimizu, Kenichi; Wang, Joanna S; Wai, Chien M

    2010-03-25

    A series of green techniques for synthesizing carbon nanotube-supported platinum nanoparticles and their high electrocatalytic activity toward methanol fuel cell applications are reported. The techniques utilize either the supercritical fluid carbon dioxide or water as a medium for depositing platinum nanoparticles on surfaces of multiwalled or single-walled carbon nanotubes. The catalytic properties of the carbon nanotubes-supported Pt nanoparticle catalysts prepared by four different techniques are compared for anodic oxidation of methanol and cathodic reduction of oxygen using cyclic voltammetry. One technique using galvanic exchange of Pt(2+) in water with zerovalent iron present on the surfaces of as-grown single-walled carbon nanotubes produces a Pt catalyst that shows an unusually high catalytic activity for reduction of oxygen but a negligible activity for oxidation of methanol. This fuel-selective catalyst may have a unique application as a cathode catalyst in methanol fuel cells to alleviate the problems caused by crossover of methanol through the polymer electrolyte membrane.

  4. Preparation of nitrogen-doped graphitic carboncages as electrocatalyst for oxygen reduction reaction

    International Nuclear Information System (INIS)

    Yan, Jing; Meng, Hui; Yu, Wendan; Yuan, Xiaoli; Lin, Worong; Ouyang, Wenpeng; Yuan, Dingsheng

    2014-01-01

    Nitrogen-doped carbon nanomaterials have been attracted increasing research interests in lithium-O 2 and Zinc-O 2 batteries, ultracapacitors and fuel cells. Herein, nitrogen-doped graphitic carboncages (N-GCs) have been prepared by mesoporous Fe 2 O 3 as a catalyst and lysine as a nitrogen doped carbon source. Due to the catalysis of Fe 2 O 3 , the N-GCs have a high graphitization degree at a low temperature, which is detected by X-ray diffraction and Raman spectrometer. Simultaneously, the heteroatom nitrogen is in-situ doped into carbon network. Therefore, the excellent electrocatalysis performance for oxygen reduction reaction is expected. The electrochemical measurement indicates that The N-GCs for oxygen reduction reaction in O 2 -saturated 0.1 mol L −1 KOH show a four-electron transfer process and exhibit excellent electrocatalytic activity (E ORR = -0.05 V vs. Ag/AgCl) and good stability (i/i 0 = 90% at -0.35 V after 4000 s with a rotation rate of 1600 rpm)

  5. A dielectric barrier discharge (DBD) plasma reactor: an efficient tool to prepare novel RuO2 nanorods

    International Nuclear Information System (INIS)

    Ananth, Antony; Gandhi, Mani Sanjeeva; Mok, Young Sun

    2013-01-01

    One-dimensional (1D) nanostructured materials have attracted a great deal of interest owing to their potential applications in various industries. Due to the limitations and cost associated with conventional low-pressure plasma systems, atmospheric-pressure plasma techniques such as dielectric barrier discharges (DBDs) are investigated as an alternative approach for inducing specific chemical reactions. RuO 2 nanomaterials are widely used as supercapacitor electrodes, in field-emission devices and for catalytic applications. In such applications, size and shape dependent properties of nanomaterials play critical roles in improving the performance. In this paper, an attempt is made to prepare 1D RuO 2 nanostructured materials using a DBD plasma. It is reported here that the composition of feed gas is an important factor in determining the final morphology. For example, an Ar + H 2 plasma yields aggregated RuO 2 nanostructures, whereas ‘nanopillar’ and ‘nanorod’ morphologies are obtained when using Ar + O 2 and Ar, respectively. Possible mechanisms behind the morphological differences are elucidated on the basis of the temperature variations inside the plasma reactor and the chemistry of the gaseous reactive species. The application of a DBD plasma to the synthesis of RuO 2 nanorods is reported for the first time in this paper. (paper)

  6. Facile preparation of efficient electrocatalysts for oxygen reduction reaction: One-dimensional meso/macroporous cobalt and nitrogen Co-doped carbon nanofibers

    Science.gov (United States)

    Yoon, Ki Ro; Choi, Jinho; Cho, Su-Ho; Jung, Ji-Won; Kim, Chanhoon; Cheong, Jun Young; Kim, Il-Doo

    2018-03-01

    Efficient electrocatalyst for oxygen reduction reaction (ORR) is an essential component for stable operation of various sustainable energy conversion and storage systems such as fuel cells and metal-air batteries. Herein, we report a facile preparation of meso/macroporous Co and N co-doped carbon nanofibers (Co-Nx@CNFs) as a high performance and cost-effective electrocatalyst toward ORR. Co-Nx@CNFs are simply obtained from electrospinning of Co precursor and bicomponent polymers (PVP/PAN) followed by temperature controlled carbonization and further activation step. The prepared Co-Nx@CNF catalyst carbonized at 700 °C (Co-Nx@CNF700) shows outstanding ORR performance, i.e., a low onset potential (0.941 V) and half wave potential (0.814 V) with almost four-electron transfer pathways (n= 3.9). In addition, Co-Nx@CNF700 exhibits a superior methanol tolerance and higher stability (>70 h) in Zn-air battery in comparison with Pt/C catalyst (∼30 h). The outstanding performance of Co-Nx@CNF700 catalysts is attributed to i) enlarged surface area with bimodal porosity achieved by leaching of inactive species, ii) increase of exposed ORR active Co-Nx moieties and graphitic edge sites, and iii) enhanced electrical conductivity and corrosion resistance due to the existence of numerous graphitic flakes in carbon matrix.

  7. Preparation and characterization of PdxAgy/C electrocatalysts for ethanol electrooxidation reaction in alkaline media

    International Nuclear Information System (INIS)

    Li Guanglan; Jiang Luhua; Jiang Qian; Wang Suli; Sun Gongquan

    2011-01-01

    Highlights: · The effects of Pd or PdAg particle size and PdAg alloy degrees on the EOR activity are investigated. · The Pd lattice constant of the PdAg increases with increasing the Ag content. · The EOR activity of the PdAg/C presents a 'volcano' plot with increasing the Pd lattice constant. · The optimal Pd/Ag atomic ratio locates between 2/1 and 3/1. · The EOR activity of the PdAg/C increases with increasing the PdAg particle size from 3.4 to 5.2 nm. - Abstract: Carbon-supported bimetallic PdAg catalysts with Pd/Ag atomic ratios varying from 4/1 to 1/2 were prepared by an impregnation-reduction method. The impregnated black mixture was treated in H 2 /N 2 atmosphere at a temperature varying from 180 to 500 deg. C. The obtained Pd x Ag y /C catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV) and chronoamperometry (CA). XRD results show that the lattice constant of Pd is dilated, suggesting the formation of PdAg alloy. The lattice constant of Pd for the Pd x Ag y /C-500 (reduced at 500 deg. C by H 2 ) increases linearly and the average metal particle size decreases slightly from 6.8 to 5.1 nm with increasing Ag fractions from 20% to 67% in the PdAg composition. For Pd x Ag y /C catalysts with a certain specific Pd/Ag atomic ratio, e.g., Pd 2 Ag 1 /C, the dilated lattice constant of Pd is independent of the reducing temperature, indicating the alloy degree for the Pd 2 Ag 1 /C-t catalysts is comparable. The average metal particle size for the Pd 2 Ag 1 /C-t catalysts increases from 3.4 to 5.2 nm with H 2 reduction temperature increasing from 180 to 500 deg. C. The potentiodynamic measurements on ethanol electrooxidation reaction (EOR) show that the catalytic activities for the Pd x Ag y /C-t catalysts toward the EOR are improved by alloying Pd with Ag. At typical potential of a working fuel cell, e.g., -0.4 V vs. Hg/HgO, the EOR current density presents a volcano shape as a function of the

  8. Ethanol electro-oxidation in an alkaline medium using Pd/C, Au/C and PdAu/C electrocatalysts prepared by electron beam irradiation

    International Nuclear Information System (INIS)

    Geraldes, Adriana Napoleão; Furtunato da Silva, Dionisio; Pino, Eddy Segura; Martins da Silva, Júlio César; Brambilla de Souza, Rodrigo Fernando; Hammer, Peter; Spinacé, Estevam Vitório; Neto, Almir Oliveira; Linardi, Marcelo; Coelho dos Santos, Mauro

    2013-01-01

    Carbon-supported Pd, Au and bimetallic PdAu (Pd:Au 90:10, 50:50 and 30:70 atomic ratios) electrocatalysts were prepared using electron beam irradiation. The obtained materials were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their catalytic activities toward ethanol electro-oxidation were evaluated in an alkaline medium using electrochemical techniques, in situ attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) analysis and a single alkaline direct ethanol fuel cell (ADEFC). EDX analyses showed that the actual Pd:Au atomic ratios were very similar to the nominal ones. X-ray diffractograms of PdAu/C electrocatalysts evidenced the presence of Pd-rich (fcc) and Au-rich (fcc) phases. TEM analysis showed a homogeneous dispersion of nanoparticles on the carbon support, with an average size in the range of 3–5 nm and broad size distributions. Cyclic voltammetry (CV) and chronoamperometry (CA) experiments revealed the superior ambient activity toward ethanol electro-oxidation of PdAu/C electrocatalysts with Pd:Au ratios of 90:10 and 50:50. In situ ATR-FTIR spectroscopy measurements have shown that the mechanism for ethanol electro-oxidation is dependent on catalyst composition, leading to different reaction products, such as acetaldehyde and acetate, depending on the number of electrons transferred. Experiments on a single ADEFC were conducted between 50 and 90 °C, and the best performance of 44 mW cm −2 in 2.0 mol L −1 ethanol was obtained at 85 °C for the Pd:Au 90:10 catalysts. This superior performance is most likely associated with enhancement of ethanol adsorption on Pd, oxidation of the intermediates, the presence of gold oxide-hydroxyl species, low mean particle diameters and better distribution of particles on the support

  9. PtRu nanoparticles embedded in nitrogen doped carbon with highly stable CO tolerance and durability

    Science.gov (United States)

    Ling, Ying; Yang, Zehui; Yang, Jun; Zhang, Yunfeng; Zhang, Quan; Yu, Xinxin; Cai, Weiwei

    2018-02-01

    As is well known, the lower durability and sluggish methanol oxidation reaction (MOR) of PtRu alloy electrocatalyst blocks the commercialization of direct methanol fuel cells (DMFCs). Here, we design a new PtRu electrocatalyst, with highly stable CO tolerance and durability, in which the PtRu nanoparticles are embedded in nitrogen doped carbon layers derived from carbonization of poly(vinyl pyrrolidone). The newly fabricated electrocatalyst exhibits no loss in electrochemical surface area (ECSA) and MOR activity after potential cycling from 0.6-1.0 V versus reversible hydrogen electrode, while commercial CB/PtRu retains only 50% of its initial ECSA. Meanwhile, due to the same protective layers, the Ru dissolution is decelerated, resulting in stable CO tolerance. Methanol oxidation reaction (MOR) testing indicates that the activity of newly fabricated electrocatalyst is two times higher than that of commercial CB/PtRu, and the fuel cell performance of the embedded PtRu electrocatalyst was comparable to that of commercial CB/PtRu. The embedded PtRu electrocatalyst is applicable in real DMFC operation. This study offers important and useful information for the design and fabrication of durable and CO tolerant electrocatalysts.

  10. Preparation and characterization of RuO2/polyaniline/polymer binder composite electrodes for supercapacitor applications

    Directory of Open Access Journals (Sweden)

    SUZANA SOPČIĆ

    2012-03-01

    Full Text Available The composite electrodes consisting of amorphous and hydrous RuO2, polyaniline and polymeric binder, Nafion® or poly(vinilydene fluoride were prepared. The electro¬chem-ical and pseudocapacitive properties of the prepared electrodes were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the responses of composite electrodes are very sensitive to the presence of individual components and their respective ratio in the mixture. The difference in the electro-chemical behavior was explained by the different physico-chemical properties of the polymeric binders.

  11. 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.

  12. A facile approach to prepare crumpled CoTMPyP/electrochemically reduced graphene oxide nanohybrid as an efficient electrocatalyst for hydrogen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Juanjuan, E-mail: majj0518@hotmail.com [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore (Singapore); Liu, Lin; Chen, Qian; Yang, Min [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Wang, Danping [School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore (Singapore); Tong, Zhiwei [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Chen, Zhong, E-mail: aszchen@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore (Singapore)

    2017-03-31

    Highlights: • Crumpled CoTMPyP/ERGO hybrid was successfully prepared by a facile two-step process. • CoTMPyP nanoaggregates are homogeneously distributed over the graphene surface. • CoTMPyP/ERGO hybrid film shows good electrocatalytic activity and stability for HER. - Abstract: Elaborate design and synthesis of efficient and stable non-Pt electrocatalysts for some renewable energy related conversion/storage processes are one of the major goals of sustainable chemistry. Herein, we report a facile method to fabricate Co porphyrin functionalized electrochemically reduced graphene oxide (CoTMPyP/ERGO) thin film by direct assembly of oppositely charged tetrakis(N-methylpyridyl) porphyrinato cobalt (CoTMPyP) and GO nanosheets under mild conditions followed by an electrochemical reduction procedure. STEM analysis confirms that CoTMPyP nanoaggregates are homogeneously distributed over the graphene surface. The electrochemical properties of CoTMPyP/ERGO were investigated by cyclic voltammetry, linear sweep voltammetry and electrochemical impedance spectroscopy. The results demonstrate that CoTMPyP/ERGO nanohybrid film can serve as excellent electrocatalyst for hydrogen evolution in alkaline solution with high activity and stability. The intimate contact and efficient electron transfer between CoTMPyP and ERGO, as well as the crumpled structure, contribute to the improvement of the electrocatalytic performance.

  13. Preparation of RuO2-TiO2/Nano-graphite composite anode for electrochemical degradation of ceftriaxone sodium.

    Science.gov (United States)

    Li, Dong; Guo, Xiaolei; Song, Haoran; Sun, Tianyi; Wan, Jiafeng

    2018-06-05

    Graphite-like material is widely used for preparing various electrodes for wastewater treatment. To enhance the electrochemical degradation efficiency of Nano-graphite (Nano-G) anode, RuO 2 -TiO 2 /Nano-G composite anode was prepared through the sol-gel method and hot-press technology. RuO 2 -TiO 2 /Nano-G composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and N 2 adsorption-desorption. Results showed that RuO 2 , TiO 2 and Nano-G were composited successfully, and RuO 2 and TiO 2 nanoparticles were distributed uniformly on the surface of Nano-G sheet. Specific surface area of RuO 2 -TiO 2 /Nano-G composite was higher than that of TiO 2 /Nano-G composite and Nano-G. Electrochemical performances of RuO 2 -TiO 2 /Nano-G anode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy. RuO 2 -TiO 2 /Nano-G anode was applied to electrochemical degradation of ceftriaxone. The generation of hydroxyl radical (OH) was measured. Results demonstrated that RuO 2 -TiO 2 /Nano-G anode displayed enhanced electrochemical degradation efficiency towards ceftriaxone and yield of OH, which is derived from the synergetic effect between RuO 2 , TiO 2 and Nano-G, which enhance the specific surface area, improve the electrochemical oxidation activity and lower the charge transfer resistance. Besides, the possible degradation intermediates and pathways of ceftriaxone sodium were identified. This study may provide a viable and promising prospect for RuO 2 -TiO 2 /Nano-G anode towards effective electrochemical degradation of antibiotics from wastewater. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. Engineering Ru@Pt Core-Shell Catalysts for Enhanced Electrochemical Oxygen Reduction Mass Activity and Stability

    Directory of Open Access Journals (Sweden)

    Ariel Jackson

    2018-01-01

    Full Text Available Improving the performance of oxygen reduction reaction (ORR electrocatalysts is essential for the commercial efficacy of many renewable energy technologies, including low temperature polymer electrolyte fuel cells (PEFCs. Herein, we report highly active and stable carbon-supported Ru@Pt core-shell nanoparticles (Ru@Pt/C prepared by a wet chemical synthesis technique. Through rotating disc electrode testing, the Ru@Pt/C achieves an ORR Pt mass-based activity of 0.50 A mgPt−1 at 0.9 V versus the reversible hydrogen electrode (RHE, which exceeds the activity of the state-of-the-art commercial Pt/C catalyst as well as the Department of Energy 2020 PEFC electrocatalyst activity targets for transportation applications. The impact of various synthetic parameters, including Pt to Ru ratios and catalyst pretreatments (i.e., annealing are thoroughly explored. Pt-based mass activity of all prepared Ru@Pt/C catalysts was found to exceed 0.4 mgPt−1 across the range of compositions investigated, with the maximum activity catalyst having a Ru:Pt ratio of 1:1. This optimized composition of Ru@Pt/C catalyst demonstrated remarkable stability after 30,000 accelerated durability cycles (0.6 to 1.0 V vs. RHE at 125 mV s−1, maintaining 85% of its initial mass activity. Scanning transmission electron microscopy energy dispersive spectroscopy (STEM-EDS analysis at various stages of electrochemical testing demonstrated that the Pt shell can provide sufficient protection against the dissolution of the otherwise unstable Ru core.

  15. Engineering Ru@Pt Core-Shell Catalysts for Enhanced Electrochemical Oxygen Reduction Mass Activity and Stability.

    Science.gov (United States)

    Jackson, Ariel; Strickler, Alaina; Higgins, Drew; Jaramillo, Thomas Francisco

    2018-01-12

    Improving the performance of oxygen reduction reaction (ORR) electrocatalysts is essential for the commercial efficacy of many renewable energy technologies, including low temperature polymer electrolyte fuel cells (PEFCs). Herein, we report highly active and stable carbon-supported Ru@Pt core-shell nanoparticles (Ru@Pt/C) prepared by a wet chemical synthesis technique. Through rotating disc electrode testing, the Ru@Pt/C achieves an ORR Pt mass-based activity of 0.50 A mg Pt -1 at 0.9 V versus the reversible hydrogen electrode (RHE), which exceeds the activity of the state-of-the-art commercial Pt/C catalyst as well as the Department of Energy 2020 PEFC electrocatalyst activity targets for transportation applications. The impact of various synthetic parameters, including Pt to Ru ratios and catalyst pretreatments (i.e., annealing) are thoroughly explored. Pt-based mass activity of all prepared Ru@Pt/C catalysts was found to exceed 0.4 mg Pt -1 across the range of compositions investigated, with the maximum activity catalyst having a Ru:Pt ratio of 1:1. This optimized composition of Ru@Pt/C catalyst demonstrated remarkable stability after 30,000 accelerated durability cycles (0.6 to 1.0 V vs. RHE at 125 mV s -1 ), maintaining 85% of its initial mass activity. Scanning transmission electron microscopy energy dispersive spectroscopy (STEM-EDS) analysis at various stages of electrochemical testing demonstrated that the Pt shell can provide sufficient protection against the dissolution of the otherwise unstable Ru core.

  16. Effects of composition on structure and activity of PtRu/C catalysts.

    Science.gov (United States)

    Wiltshire, Richard J K; King, Colin R; Rose, Abigail; Wells, Peter P; Davies, Hazel; Hogarth, Martin P; Thompsett, David; Theobald, Brian; Mosselmans, Fredrick W; Roberts, Mark; Russell, Andrea E

    2009-04-07

    A series of carbon supported PtRu bimetallic catalysts with varying Pt:Ru ratio were prepared and characterised using ex situ and in situ XRD, in situ EXAFS at 0 V vs. RHE, ex situ XPS and monolayer CO stripping voltammetry. Although the catalysts were found to be well mixed/alloyed, with no evidence of unalloyed Ru (oxides) present, the surfaces of the electrocatalyst nanoparticles were found to be enriched with Pt compared to the nominal bulk composition. The methanol oxidation activities of the catalysts were determined in 1.0 mol dm(-3) H2SO4. In agreement with published studies of polycrystalline bulk PtRu alloys the catalyst with a 0.6 surface fraction of Pt was found to give the best methanol oxidation activity at 30 degrees C. However, at 80 degrees C a greater surface fraction of Ru could be tolerated, with some activity at low current densities found for a Pt surface fraction as low as 0.2. The results support the conclusion that a limited amount of methanol dehydrogenation occurs at Ru sites or Ru dominated surface ensembles at 80 degrees C.

  17. Preparation and electrochemistry of graphene nanosheets–multiwalled carbon nanotubes hybrid nanomaterials as Pd electrocatalyst support for formic acid oxidation

    International Nuclear Information System (INIS)

    Yang Sudong; Shen Chengmin; Lu Xiangjun; Tong Hao; Zhu Jiajia; Zhang Xiaogang; Gao Hongjun

    2012-01-01

    Highlights: ► Graphene nanosheets–MWCNTs (GNS–CNTs) composites as Pd electrocatalysts support were synthesized by in situ reduction method. ► The direct electrooxidation of HCOOH is improved on the GNS–CNTs based catalyst. ► Both activity and durability of GNS–CNTs based catalyst are improved greatly. ► Pd/GNS–CNTs catalysts exhibit excellent performance when the mass ratio of GO to CNTs is 5:1. - Abstract: Graphene nanosheets–MWCNTs (GNS–CNTs) composites were synthesized by in situ reduction method, and then palladium nanoparticles (NPs) were supported on the GNS–CNTs by a microwave-assisted polyol process. Microstructure measurements showed that the graphene nanosheets and the CNTs formed a uniform nanocomposite with CNTs absorbed on the graphene nanosheets surface and/or filled between the graphene nanosheets. Compared to Pd/Vulcan XC-72R carbon, Pd/GNS, or Pd/CNTs catalysts, the Pd/GNS–CNTs catalysts exhibit excellent electrocatalytic activity and stability for formic acid electro-oxidation when the mass ratio of GO to CNTs is 5:1. The superior performance of Pd/GNS–CNTs catalysts may arise from large surface area utilization for NPs and enhanced electronic conductivity of the supports. Therefore, the GNS–CNTs composite should be a promising carbon material for application as electrocatalyst support in fuel cells.

  18. Performance PtSnRh electrocatalysts supported on carbon-Sb2O5.SbO2 for the electro-oxidation of ethanol, prepared by an alcohol-reduction process

    International Nuclear Information System (INIS)

    Castro, Jose Carlos

    2013-01-01

    PtSnRh electrocatalysts supported on carbon-Sb 2 O 5 .SnO 2 , with metal loading of 20 wt%, were prepared by an alcohol-reduction process, using H 2 PtCl 6 .6H 2 O (Aldrich), RhCl 3 .xH 2 O (Aldrich) and SnCl 2 .2H 2 O (Aldrich), as source of metals; Sb 2 O 5 .SnO 2 (ATO) and carbon Vulcan XC72, as support; and ethylene glycol as reducing agent. The electrocatalysts obtained were characterized physically by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The diffractograms showed which PtSnRh/C-ATO electrocatalysts had FCC structure of Pt and Pt alloys, besides several peaks associated with SnO 2 and ATO. The average sizes of crystallites were between 2 and 4 nm. TEM micrographs showed a good distribution of the nanoparticles on the support. The average sizes of particles were between 2 and 3 nm, with good agreement for the average size of the crystallites. The performances of the electrocatalysts were analyzed by electrochemical techniques and in real conditions of operation using single direct ethanol fuel cell. In the chronoamperometry at 50 deg C, the electrocatalysts with carbon (85 wt%) and ATO (15 wt%) support, showed the best activity, and the atomic proportions which achieved the best results were PtSnRh(70:25:05) e (90:05:05). PtSnRh(70:25:05)/85C+15ATO electrocatalysts showed the best performance in a direct ethanol fuel cell. (author)

  19. Prepare now to counsel patients on RU486. Women speak about the abortion pill.

    Science.gov (United States)

    1995-04-01

    The advantages of RU-486 to most women who are educated about it are obvious, but the experience can be both empowering and traumatic because they are essentially performing the abortion on themselves. A research organization in Los Angeles initiated eight focus groups with 73 sexually active women ages 18-34 in Los Angeles, Portland, and New York City to find out about the acceptability of this new abortifacient. 63% of the participants had heard about it but were not quite sure about what it was. After the counseling sessions they were given the option of choosing a method of abortion. 38% chose RU-486 (mainly to avoid surgery and anesthesia), 34% chose vacuum aspiration, and 26% remained undecided. Some providers of family planning predict that RU-486 would be preferred because of the avoidance of surgical abortion and the comfort of doing the procedure in their own homes. At an abortion clinic in Paris, France, only a few women would not choose RU-486 because of the emotional impact of seeing the expelled conceptus. Others were relieved to realize that the expelled embryo was only a mass of cells not a baby. Seeing the expelled embryo could, in fact, prevent pregnancies in the future, because surgical abortions, in which tissues taken are not seen, are often easier to forget. More information will be forthcoming about this procedure from a US study initiated by the Population Council at 12 sites involving 2100 women. The trials will be finished by mid-1995 and approval of the Food and Drug Administration will be expected in time for marketing in 1996.

  20. Electrocatalyst advances for hydrogen oxidation in phosphoric acid fuel cells

    Science.gov (United States)

    Stonehart, P.

    1984-01-01

    The important considerations that presently exist for achieving commercial acceptance of fuel cells are centered on cost (which translates to efficiency) and lifetime. This paper addresses the questions of electrocatalyst utilization within porous electrode structures and the preparation of low-cost noble metal electrocatalyst combinations with extreme dispersions of the metal. Now that electrocatalyst particles can be prepared with dimensions of 10 A, either singly or in alloy combinations, a very large percentage of the noble metal atoms in a crystallite are available for reaction. The cost savings for such electrocatalysts in the present commercially driven environment are considerable.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-05-15

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

  2. Preparation and characterization of electrocatalysts based on palladium for electro-oxidation of alcohols in alkaline medium; Preparacao e caracterizacao de eletrocatalisadores a base de paladio para oxidacao eletroquimica de alcoois em meio alcalino

    Energy Technology Data Exchange (ETDEWEB)

    Brandalise, Michele

    2012-07-01

    In this study Pd/C, Au/C, PdAu/C, PdAuPt/C, PdAuBi/C and PdAuIr/C electrocatalysts were prepared by the sodium borohydride reduction method for the electrochemical oxidation of methanol, ethanol and ethylene glycol. This methodology consists in mix an alkaline solution of sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. The electrocatalysts were characterized by energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry. The electrochemical oxidation of the alcohols was studied by chronoamperometry using a thin porous coating technique. The mechanism of ethanol electro-oxidation was studied by Fourier Transformed Infrared (FTIR) in situ. The most effective electrocatalysts were tested in alkaline single cells directly fed with methanol, ethanol or ethylene glycol. Preliminary studies showed that the most suitable atomic composition for preparing the ternary catalysts is 50:45:05. Electrochemical data in alkaline medium show that the electrocatalysts PdAuPt/C (50:45:05) showed the better activity for methanol electro oxidation, while PdAuIr/C was the most active for ethanol oxidation and PdAuBi/C (50:45:05) was the most effective for ethylene glycol oxidation in alkaline medium. These results show that the addition of gold in the composition of electrocatalysts increases their catalytic activities. The spectroelectrochemical FTIR in situ data permitted to conclude that C-C bond is not broken and the acetate is formed. (author)

  3. Investigation of methanol oxidation on a highly active and stable Pt–Sn electrocatalyst supported on carbon–polyaniline composite for application in a passive direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Amani, Mitra [Department of Chemical Engineering, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Kazemeini, Mohammad [Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Hamedanian, Mahboobeh [Department of Chemistry, Faculty of Science, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Pahlavanzadeh, Hassan [Department of Chemical Engineering, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Gharibi, Hussein, E-mail: h.gharibi@utah.edu [Department of Chemistry, Faculty of Science, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Department of Material Science & Engineering, 122 S Campus Drive, University of Utah, Salt Lake City, UT 84112 (United States)

    2015-08-15

    Highlights: • PtSn/C-PANI performed superior in the MOR compared with a commercial PtRu/C. • Catalytic activity of PtRu/C was highly reduced during the accelerated durability test. • Anode of the PtSn/C-PANI in a passive DMFC lowered methanol crossover by 30%. - Abstract: Polyaniline fiber (PANI) was synthesized and utilized to fabricate a vulcan–polyaniline (C-PANI) composite. Pt/C-PANI and PtSn/C-PANI electro-catalysts with different Pt:Sn atomic ratios were prepared by the impregnation method. These electro-catalysts, along with commercial PtRu/C (Electrochem), were characterized with respect to their structural and electrochemical properties in methanol oxidation reaction (MOR). PtSn(70:30)/C-PANI showed excellent performance in MOR, the obtained maximum current density being about 40% and 50% higher than that for PtRu/C and Pt/C-PANI, respectively. It was also found that the CO tolerance and stability of PtSn(70:30)/C-PANI was considerably higher than that of PtRu/C. Finally, the performance of these two materials was compared in a passive direct methanol fuel cell (DMFC). The DMFC test results demonstrated that the membrane electrode assembly (MEA) prepared using PtSn(70:30)/C-PANI anode catalyst performed more satisfactorily in terms of maximum power density and lower methanol crossover.

  4. Ancient Chemistry "Pharaoh's Snakes" for Efficient Fe-/N-Doped Carbon Electrocatalysts.

    Science.gov (United States)

    Ren, Guangyuan; Gao, Liangliang; Teng, Chao; Li, Yunan; Yang, Hequn; Shui, Jianglan; Lu, Xianyong; Zhu, Ying; Dai, Liming

    2018-04-04

    The method of fabricating nonprecious metal electrocatalysts with high activity and durability through a facile and eco-friendly procedure is of great significance to the development of low-cost fuel cells and metal-air batteries. Herein, we present that an ancient chemical reaction of "Pharaoh's snakes" can be a fast and convenient technique to prepare Fe-/N-doped carbon (Fe/N-C) nanosheet/nanotube electrocatalysts with sugar, soda, melamine, and iron nitrate as precursors. The resultant Fe/N-C catalyst has a hierarchically porous structure, a large surface area, and uniformly distributed active sites. The catalyst shows high electrocatalytic activities toward both the oxygen reduction reaction with a half-wave potential of 0.90 V (vs reversible hydrogen electrode) better than that of Pt/C and the oxygen evolution reaction with an overpotential of 0.46 V at the current density of 10 mA cm -2 comparable to that of RuO 2 . The activity and stability of the catalyst are also evaluated in primary and rechargeable Zn-air batteries. In both conditions, three-dimensional Fe/N-C exhibited performances superior to Pt/C. Our work demonstrates a success of utilizing an ancient science to make a state-of-the-art electrocatalyst.

  5. Mesoporous MCM-41 embeded with Ru(II)-based chemosensor: Preparation, characterization, and emission variation towards pH

    International Nuclear Information System (INIS)

    Jingxia, Wang

    2014-01-01

    In this article, a pH sensing mesoporous MCM-41 material containing covalently bonded Ru(II) complex in the silicate network was prepared and named as Ru–MCM-41. The emission signal shows a tendency to decrease upon increasing pH values. The luminescent pH sensor can be explained by the protonation and deprotonation of the PIP ligand (PIP=2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline) and the fact that the mesoporousity of the MCM-41 matrix favors the –OH that diffused to the complex, resulting in quick emission quenching. It also shows a slight sensitivity towards dissolved molecular oxygen and varying temperatures, which, however, may not be too troublesome for actual applications. The sensing mechanism is also investigated. - Highlights: • An Ru complex was covalently grafted in mesoporous silicate network. • The emission signal decreased with increasing pH values. • The protonation and deprotonation of the ligand caused emission variation. • The emission was insensitive towards oxygen and temperature

  6. An electrochemical method to prepare of Pd/Cu2O/MWCNT nanostructure as an anode electrocatalyst for alkaline direct ethanol fuel cells

    International Nuclear Information System (INIS)

    Rostami, Hussein; Rostami, Abbas Ali; Omrani, Abdollah

    2016-01-01

    This study reports an electrochemical method to fabrication of palladium nanoparticles (Pd NPs) promoted with cuprous oxide (Cu 2 O) supported on multi-walled carbon nanotube (Pd/Cu 2 O/MWCNT). First, Cu 2 O is electrodeposited on treated MWCNTs in the optimum deposition conditions. Then, the Pd nanostructure is electrochemically fabricated on Cu 2 O/MWCNT electrode by cycling the potential between +0.5 to −1.0 V in negative direction. The prepared electrodes are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The electrocatalytic performance of Pd/Cu 2 O/MWCNT electrocatalyst for ethanol oxidation reaction (EOR) is investigated by cyclic voltammetric (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) measurements. The formation of the Pd/Cu 2 O/MWCNT is confirmed by EDX and XRD techniques. The onset potential of Pd/Cu 2 O/MWCNT shifts to negative values by 120 mV compared to the onset potential of Pd/MWCNT. Much higher I f /I b value is obtained for Pd/Cu 2 O/MWCNT compared to other Pd-based catalysts indicating Cu 2 O could significantly enhance the stability and CO poisoning tolerance of the Pd towards ethanol electrooxidation. The results revealed that the prepared Pd/Cu 2 O/MWCNT catalyst can be a promising anode catalyst for alkaline direct ethanol fuel cells.

  7. Performance and selectivity of PtxSn/C electro-catalysts for ethanol oxidation prepared by reduction with different formic acid concentrations

    International Nuclear Information System (INIS)

    Zignani, Sabrina C.; Baglio, Vincenzo; Linares, José J.; Monforte, Giuseppe; Gonzalez, Ernesto R.; Aricò, Antonino S.

    2012-01-01

    Carbon supported Pt–Sn catalysts were prepared by reduction of Pt and Sn precursors with formic acid and characterized in terms of structure, morphology and surface properties. The electrocatalytic activity for ethanol oxidation was studied in a direct ethanol fuel cell (DEFC) at 70 °C and 90 °C. Electrochemical and physico-chemical data indicated that a proper balance of Pt and Sn species in the near surface region was necessary to maximize the reaction rate. The best atomic surface composition, in terms of electrochemical performance, was Pt:Sn 65:35 corresponding to a bulk composition 75:25 namely Pt 3 Sn 1 /C. The reaction products of ethanol electro-oxidation in single cell and their distribution as a function of the nature of catalyst were determined. Essentially, acetaldehyde and acetic acid were detected as the main reaction products; whereas, a lower content of CO 2 was formed. The selectivity toward acetic acid vs. acetaldehyde increased with the increase of the Sn content and decreased by decreasing the concentration of the reducing agent used in the catalyst preparation. According to the recent literature, these results have been interpreted on the basis of ethanol adsorption characteristics and ligand effects occurring for Sn-rich electrocatalysts.

  8. Electrochemical characterization of Pt-Ru-Pd catalysts for methanol oxidation reaction in direct methanol fuel cells.

    Science.gov (United States)

    Choi, M; Han, C; Kim, I T; An, J C; Lee, J J; Lee, H K; Shim, J

    2011-01-01

    PtRuPd nanoparticles on carbon black were prepared and characterized as electrocatalysts for methanol oxidation reaction in direct methanol fuel cells. Nano-sized Pd (2-4 nm) particles were deposited on Pt/C and PtRu/C (commercial products) by a simple chemical reduction process. The structural and physical information of the PtRuPd/C were confirmed by TEM and XRD, and their electrocatalytic activities were measured by cyclic voltammetry and linear sweep voltammetry. The catalysts containing Pd showed higher electrocatalytic activity for methanol oxidation reaction than the other catalysts. This might be attributed to an increase in the electrochemical surface area of Pt, which is caused by the addition of Pd; this results in increased catalyst utilization.

  9. A simple preparation of very high methanol tolerant cathode electrocatalyst for direct methanol fuel cell based on polymer-coated carbon nanotube/platinum.

    Science.gov (United States)

    Yang, Zehui; Nakashima, Naotoshi

    2015-07-20

    The development of a durable and methanol tolerant electrocatalyst with a high oxygen reduction reaction activity is highly important for the cathode side of direct methanol fuel cells. Here, we describe a simple and novel methodology to fabricate a practically applicable electrocatalyst with a high methanol tolerance based on poly[2,2'-(2,6-pyridine)-5,5'-bibenzimidazole]-wrapped multi-walled carbon nanotubes, on which Pt nanoparticles have been deposited, then coated with poly(vinylphosphonic acid) (PVPA). The polymer coated electrocatalyst showed an ~3.3 times higher oxygen reduction reaction activity compared to that of the commercial CB/Pt and methanol tolerance in the presence of methanol to the electrolyte due to a 50% decreased methanol adsorption on the Pt after coating with the PVPA. Meanwhile, the peroxide generation of the PVPA coated electrocatalyst was as low as 0.8% with 2 M methanol added to the electrolyte, which was much lower than those of the non-PVPA-coated electrocatalyst (7.5%) and conventional CB/Pt (20.5%). Such a high methanol tolerance is very important for the design of a direct methanol fuel cell cathode electrocatalyst with a high performance.

  10. RuO2-TiO2 mixed oxides prepared from the hydrolysis of the metal alkoxides

    International Nuclear Information System (INIS)

    Osman, Julian R.; Crayston, Joe A.; Pratt, Allin; Richens, David T.

    2008-01-01

    The hydrolysis of ruthenium alkoxide/titanium tetraethoxide mixtures to gels and powders containing 30-40 mol% Ru was investigated. Basic or neutral conditions led to powders consisting of 2-10 nm diameter crystalline RuO 2 nanoparticles embedded in a matrix of crystalline (anatase) and amorphous TiO 2 . Acid hydrolysis conditions gave gels containing smaller, amorphous RuO 2 nanoparticles (1-3 nm). In all samples the RuO 2 nanoparticles tended to clump into aggregates up to 0.5 μm across. Acid or neutral hydrolysis of ruthenium ethoxide gave samples which displayed lower surface Ru:Ti ratios as measured by XPS compared to the bulk (XRF), and also contained more low-valent Ru (as measured by XRF), probably due to incomplete hydrolysis of the precursors. These samples also contained more Ru metal after calcination (XRD). Calcination (450 deg. C) was accompanied by Ru-promoted combustion of organic material and led to crystalline (anatase) TiO 2 and Ti x Ru 1-x O 2 solid solution (rutile phase)

  11. Tuning crystal phase of NiS_x through electro-oxidized nickel foam: A novel route for preparing efficient electrocatalysts for oxygen evolution reaction

    International Nuclear Information System (INIS)

    Li, Xiao; Shang, Xiao; Rao, Yi; Dong, Bin; Han, Guan-Qun; Hu, Wen-Hui; Liu, Yan-Ru; Yan, Kai-Li; Chi, Jing-Qi; Chai, Yong-Ming; Liu, Chen-Guang

    2017-01-01

    Highlights: • Electro-oxidized nickel foam as a support has been used to prepare NiS_x phases. • Ni(OH)_2 layer on electro-oxidized NF is responsible for the growth of β-NiS. • NiS_x/NF(Ox) composed of β-NiS and Ni_3S_2 has enhanced electrocatalytic activity. • The growth mechanisms of mixed NiS_x phases of NiS_x/NF(Ox) have been discussed. - Abstract: A facile solvothermal sulfurization using electro-oxidized nickel foam (NF(Ox)) as support has been applied to prepare NiS_x/NF(Ox) electrocatalyst with highly efficient activity for oxygen evolution reaction (OER). XRD patterns confirm the composition of NiS_x/NF(Ox): two kinds of crystal phase including β-NiS and Ni_3S_2. While using bare NF as support under identical conditions, only Ni_3S_2 phase can be detected. SEM images reveal two kinds of morphologies of NiS_x/NF(Ox) including pyramids structure of β-NiS and nanorod-like structure of Ni_3S_2, which implies the tuning effect of electro-pretreatment of NF on the selective preparation of NiS_x crystal phase. It can be speculated that Ni(OH)_2 layer derived from electro-oxidized NF is responsible for the growth of β-NiS while metallic Ni is transformed into Ni_2S_3 during sulfurization. Electrochemical measurements for OER indicate the enhanced electrocatalytic activity of NiS_x/NF(Ox) with a small overpotential of 72 mV to reach 10 mA cm"−"2 compared with Ni_3S_2/NF, which may be ascribed to the improved electron-transfer kinetics relating to the unique atomic configurations and crystalline structures of β-NiS. The electro-oxidation pretreatment of nickel foam provides a simple and convenient method by tuning different NiS_x crystal phases for preparing excellent OER eletrocatalysts.

  12. Tuning crystal phase of NiS{sub x} through electro-oxidized nickel foam: A novel route for preparing efficient electrocatalysts for oxygen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiao; Shang, Xiao [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); Rao, Yi [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); College of Science, China University of Petroleum (East China), Qingdao 266580, PR China (China); Dong, Bin, E-mail: dongbin@upc.edu.cn [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); College of Science, China University of Petroleum (East China), Qingdao 266580, PR China (China); Han, Guan-Qun [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); College of Science, China University of Petroleum (East China), Qingdao 266580, PR China (China); Hu, Wen-Hui; Liu, Yan-Ru; Yan, Kai-Li; Chi, Jing-Qi; Chai, Yong-Ming [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); Liu, Chen-Guang, E-mail: cgliu@upc.edu.cn [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China)

    2017-02-28

    Highlights: • Electro-oxidized nickel foam as a support has been used to prepare NiS{sub x} phases. • Ni(OH){sub 2} layer on electro-oxidized NF is responsible for the growth of β-NiS. • NiS{sub x}/NF(Ox) composed of β-NiS and Ni{sub 3}S{sub 2} has enhanced electrocatalytic activity. • The growth mechanisms of mixed NiS{sub x} phases of NiS{sub x}/NF(Ox) have been discussed. - Abstract: A facile solvothermal sulfurization using electro-oxidized nickel foam (NF(Ox)) as support has been applied to prepare NiS{sub x}/NF(Ox) electrocatalyst with highly efficient activity for oxygen evolution reaction (OER). XRD patterns confirm the composition of NiS{sub x}/NF(Ox): two kinds of crystal phase including β-NiS and Ni{sub 3}S{sub 2}. While using bare NF as support under identical conditions, only Ni{sub 3}S{sub 2} phase can be detected. SEM images reveal two kinds of morphologies of NiS{sub x}/NF(Ox) including pyramids structure of β-NiS and nanorod-like structure of Ni{sub 3}S{sub 2}, which implies the tuning effect of electro-pretreatment of NF on the selective preparation of NiS{sub x} crystal phase. It can be speculated that Ni(OH){sub 2} layer derived from electro-oxidized NF is responsible for the growth of β-NiS while metallic Ni is transformed into Ni{sub 2}S{sub 3} during sulfurization. Electrochemical measurements for OER indicate the enhanced electrocatalytic activity of NiS{sub x}/NF(Ox) with a small overpotential of 72 mV to reach 10 mA cm{sup −2} compared with Ni{sub 3}S{sub 2}/NF, which may be ascribed to the improved electron-transfer kinetics relating to the unique atomic configurations and crystalline structures of β-NiS. The electro-oxidation pretreatment of nickel foam provides a simple and convenient method by tuning different NiS{sub x} crystal phases for preparing excellent OER eletrocatalysts.

  13. One-Pot and Facile Fabrication of Hierarchical Branched Pt-Cu Nanoparticles as Excellent Electrocatalysts for Direct Methanol Fuel Cells.

    Science.gov (United States)

    Cao, Yanqin; Yang, Yong; Shan, Yufeng; Huang, Zhengren

    2016-03-09

    Hierarchical branched nanoparticles are one promising nanostructure with three-dimensional open porous structure composed of integrated branches for superior catalysis. We have successfully synthesized Pt-Cu hierarchical branched nanoparticles (HBNDs) with small size of about 30 nm and composed of integrated ultrathin branches by using a modified polyol process with introduction of poly(vinylpyrrolidone) and HCl. This strategy is expected to be a general strategy to prepare various metallic nanostructures for catalysis. Because of the special open porous structure, the as-prepared Pt-Cu HBNDs exhibit greatly enhanced specific activity toward the methanol oxidation reaction as much as 2.5 and 1.7 times compared with that of the commercial Pt-Ru and Pt-Ru/C catalysts, respectively. Therefore, they are potentially applicable as electrocatalysts for direct methanol fuel cells.

  14. Methanol oxidation reaction on Ti/RuO{sub 2(x)}Pt{sub (1-x)} electrodes prepared by the polymeric precursor method

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, R.G.; Marchesi, L.F.; Mattos-Costa, F.I.; Pereira, E.C. [Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Centro Multidisciplinar para o Desenvolvimento de Materiais Ceramicos, Departamento de Quimica, Universidade Federal de Sao Carlos, Caixa Postal 676, 13560-905 Sao Carlos, SP (Brazil); Oliveira, R.T.S. [Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Centro Multidisciplinar para o Desenvolvimento de Materiais Ceramicos, Departamento de Quimica, Universidade Federal de Sao Carlos, Caixa Postal 676, 13560-905 Sao Carlos, SP (Brazil); Grupo de Materiais Eletroquimicos e Metodos Eletroanaliticos, Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 780, 13566-590 Sao Carlos, SP (Brazil); LEMN, Laboratorio de Eletroquimica e Materiais Nanoestruturados, CCNH-Centro de Ciencias Naturais e Humanas, UFABC-Universidade Federal do ABC, CEP 09.210-170, Rua Santa Adelia 166, Bairro Bangu, Santo Andre, SP (Brazil); Bulhoes, L.O.S. [Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Centro Multidisciplinar para o Desenvolvimento de Materiais Ceramicos, Departamento de Quimica, Universidade Federal de Sao Carlos, Caixa Postal 676, 13560-905 Sao Carlos, SP (Brazil); CENIP, Centro Universitario Central Paulista, UNICEP, Rua Miguel Petroni, 5111, CEP 13563-470, Sao Carlos, SP (Brazil); Santos, M.C. [Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Centro Multidisciplinar para o Desenvolvimento de Materiais Ceramicos, Departamento de Quimica, Universidade Federal de Sao Carlos, Caixa Postal 676, 13560-905 Sao Carlos, SP (Brazil); LEMN, Laboratorio de Eletroquimica e Materiais Nanoestruturados, CCNH-Centro de Ciencias Naturais e Humanas, UFABC-Universidade Federal do ABC, CEP 09.210-170, Rua Santa Adelia 166, Bairro Bangu, Santo Andre, SP (Brazil)

    2007-09-27

    In this work, ruthenium oxide films containing platinum nanoparticles were prepared using the polymeric precursor method on Ti substrates with several molar ratios. This paper aims at presenting the characterization of the Pt content effect in the methanol electrochemical oxidation reaction. The films were physically characterized using X-ray diffraction and both Pt and RuO{sub 2} (rutile) phases were observed. The mean crystallite sizes were 6 nm for Pt and 25 nm for RuO{sub 2}. The X-ray photoelectronic results indicated that on the electrodes surfaces, depending on the substrate, there was RuO{sub 2}, Ru metal and Pt metal. Besides, it was not observed the formation of PtRu alloys. The atomic force microscopy images of the films showed highly rough surfaces. A decrease in the roughness mean square values is observed as the Pt content increases. These last results are similar to electroactive surface area values calculated by redox-couple (K{sub 4}FeCN{sub 6}/K{sub 3}FeCN{sub 6}). There was an increase in the globular size observed on the electrode surface and lower particle dispersion as the Pt content is increased from 12.5 to 75 mol%. Regarding the eletrode electrocatalytical behavior for methanol oxidation, it was observed that the onset oxidation overpotential is displaced towards more negative values as Pt content is decreased. Besides, an increase has been shown in the current density for methanol oxidation of 600% using a Ti/RuO{sub 2}-Pt (87.5:12.5) electrode compared to polycrystalline Pt. (author)

  15. Highly ordered Pd nanowire arrays as effective electrocatalysts for ethanol oxidation in direct alcohol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Xu, C.W. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Wang, H. [Departement of Applied Chemistry, Dongguan University of Technology, Dongguan 523106 (China); Shen, P.K. [School of Physics and Engineering, Sun Yet-Sen University, Guangzhou 510275 (China); Jiang, S.P.

    2007-12-03

    Pd nanowire arrays (NWAs) with high electrochemically active surface area are successfully fabricated using anodized aluminum oxide electrodeposition. The electrocatalytic activity and stability of the Pd NWAs for ethanol electrooxidation are not only significantly higher that of conventional Pd film electrodes, but also higher than that of well-established commercial PtRu/C electrocatalysts. The Pd NWAs show great potential as electrocatalysts for ethanol electrooxidation in alkaline media in direct ethanol fuel cells. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  16. Effects of microstructure and composition of anode Pt based electrocatalysts on performance of direct alcohol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, L.; Li, H.; Yan, S.; Sun, G. [Dalian Inst. of Chemical Physics, Dalian (China). Direct Alcohol Fuel Cell Lab; Xin, Q. [Dalian Inst. of Chemical Physics, Dalian (China). Direct Alcohol Fuel Cell Lab; Dalian Inst. of Chemical Physics, Dalian (China). State Key Laboratory of Catalysis

    2008-07-01

    This paper reported on a study in which platinum (Pt)-based electrocatalysts were synthesized and characterized by XRD, TEM and EDS. The focus of the study was on the relationship between the microstructure and components of PtRu and PtSn catalysts and the performance of direct alcohol fuel cells (DAFCs). All of the Pt-based electrocatalysts were prepared by a modified polyol method. XRD patterns of the 2 catalysts showed that both catalysts have an fcc pattern of Pt. This was also confirmed by the shift of diffraction peaks of Pt in both catalysts. Electrochemical measurements were carried out using an EG and G model 273A potentiostat/galvanostat and a three-electrode test cell at room temperature. Membrane electrode assemblies (MEAs) were fabricated with a pair of stainless steel plates with parallel flow-fields. The MEAs were activated by 1 M methanol/ethanol at 75 degrees C for 3 hours before all the data were collected. The study showed that PtRu is active to methanol electrooxidation while PtSn is active to ethanol electrooxidation. Based on the above experimental analysis, it was determined that the dilatation of Pt lattice parameter is favourable for ethanol adsorption, while the suitable contract of Pt lattice parameter is favorable for methanol electrooxidation. Since Pt is more electronegative than Sn, the partial electrons of Sn atom could be transferred to Pt atom leading to filling of Pt d band. Although Ru is as electronegative as Pt, the electric effect of Pt and Ru may not be as pronounced. 4 refs., 4 figs.

  17. One-step preparation of N-doped graphene/Co nanocomposite as an advanced oxygen reduction electrocatalyst

    International Nuclear Information System (INIS)

    Bai, Fo; Huang, Hao; Tan, Yanlei; Hou, Changmin; Zhang, Ping

    2015-01-01

    Graphical abstract: N-doped graphene/Co nanocomposites were synthesized through one-step pyrolysis process and the product exhibits high performance for ORR and excellent stability in alkaline medium. - Highlights: • N-doped graphene/Co nano-composite is directly synthesized by a one-step method from Co(NO3)2∙6H2O, glucose and dicyandiamide (DCDA). • The electrocatalytic performance of as-prepared NG/Co-0.5 shows the peak potential positively shifts about 10 mV than commercial Pt/C electrode. • The material shows an excellent stability and tolerance to methanol poisoning effects in alkaline medium. - Abstract: N-doped graphene/Co nanocomposites (NG/Co NPs) have been prepared by a simple one-step pyrolysis of Co(NO 3 ) 2 ∙6H 2 O, glucose and dicyandiamide (DCDA). The products with nitrogen doped and suitable graphitic degree perform high electrocatalytic activity (with the reduction peak at −0.099 V vs Ag/AgCl) and near four-electron selectivity for the oxygen reduction reaction (ORR), with excellent stability and durability in alkaline medium comparable to a commercial Pt/C catalyst. Owing to the superb ORR performance, low cost and facile preparation, the catalysts of NG/Co NPs have great potential applications in fuel cells, metal-air batteries and ORR-related electrochemical industries

  18. Effect of the solvent in the catalyst ink preparation on the properties and performance of unsupported PtRu catalyst layers in direct methanol fuel cells

    International Nuclear Information System (INIS)

    Alcaide, Francisco; Álvarez, Garbiñe; Cabot, Pere L.; Genova-Koleva, Radostina; Grande, Hans-Jürgen; Miguel, Oscar

    2017-01-01

    The effect of the organic solvent polarity on the properties of unsupported PtRu catalyst inks and on the performance of the catalyst layers prepared with them for the methanol electrooxidation, has been studied. The light scattering results indicate that the PtRu-Nafion ® aggregates in the inks prepared with n-butyl acetate (NBA) are larger than those prepared with 2-propanol (IPA). The lower polarity of the former favours the aggregation of Nafion ® and nanoparticles. The electron microscopy images and porosimetry measurements of the catalyst layers show that the secondary pore volume between the agglomerates is larger for NBA. The linear sweep voltammetry and eis results for the methanol electrooxidation in the three-electrode cell denote the higher active surface area for NBA and comparable specific oxidation rates of the intermediates in both catalysts layers. The current densities for PtRu anode catalyst layers in single DMFC are higher when the solvent is NBA, the mass transport limitations being much more apparent with IPA. The adapted transmission line equivalent circuit to interpret the impedance results in single DMFC indicates that the proton resistance for NBA is significantly lower than for IPA, thus suggesting that the greater number of accessible active sites for methanol oxidation in the former are well connected to the Nafion ® ionomers and easier transported to the membrane.

  19. Mesoporous N-doped carbons prepared with thermally removable nanoparticle templates: an efficient electrocatalyst for oxygen reduction reaction.

    Science.gov (United States)

    Niu, Wenhan; Li, Ligui; Liu, Xiaojun; Wang, Nan; Liu, Ji; Zhou, Weijia; Tang, Zhenghua; Chen, Shaowei

    2015-04-29

    Thermally removable nanoparticle templates were used for the fabrication of self-supported N-doped mesoporous carbons with a trace amount of Fe (Fe-N/C). Experimentally Fe-N/C was prepared by pyrolysis of poly(2-fluoroaniline) (P2FANI) containing a number of FeO(OH) nanorods that were prepared by a one-pot hydrothermal synthesis and homogeneously distributed within the polymer matrix. The FeO(OH) nanocrystals acted as rigid templates to prevent the collapse of P2FANI during the carbonization process, where a mesoporous skeleton was formed with a medium surface area of about 400 m(2)/g. Subsequent thermal treatments at elevated temperatures led to the decomposition and evaporation of the FeO(OH) nanocrystals and the formation of mesoporous carbons with the surface area markedly enhanced to 934.8 m(2)/g. Electrochemical measurements revealed that the resulting mesoporous carbons exhibited apparent electrocatalytic activity for oxygen reduction reactions (ORR), and the one prepared at 800 °C (Fe-N/C-800) was the best among the series, with a more positive onset potential (+0.98 V vs RHE), higher diffusion-limited current, higher selectivity (number of electron transfer n > 3.95 at +0.75 V vs RHE), much higher stability, and stronger tolerance against methanol crossover than commercial Pt/C catalysts in a 0.1 M KOH solution. The remarkable ORR performance was attributed to the high surface area and sufficient exposure of electrocatalytically active sites that arose primarily from N-doped carbons with minor contributions from Fe-containing species.

  20. Photoelectrocatalytic degradation of indanthrene blue dye using Ti/Ru-based electrodes prepared by a modified Pechini method

    Energy Technology Data Exchange (ETDEWEB)

    Pupo, Marilia M.S.; Costa, Lucas S. da; Figueiredo, Aile C.; Eguiluz, Katlin I. B.; Salazar-Banda, Giancarlo R., E-mail: gianrsb@gmail.com [Universidade Tiradentes, Aracaju, SE (Brazil). Instituto de Tecnologia e Pesquisa. Programa de Pos-Graduacao em Engenharia de Processos; Silva, Ronaldo S. da [Universidade Federal de Sergipe, Sao Cristovao, SE (Brazil). Departamento de Fisica. Laboratorio de Materiais Ceramicos Avancados; Cunha, Frederico G.C. [Universidade Federal de Sergipe, Sao Cristovao, SE (Brazil). Departamento de Fisica

    2013-03-15

    Photoelectrodes were used to treat synthetic textile wastewater contaminated with indanthrene blue dye. Two media of treatment were used (NaCl and Na{sub 2}SO{sub 4}), with variations on temperature, pH, current density, dye and chloride concentration. A modified Pechini method was applied to obtain Ti/Ru-based electrodes (Ti, Ru, Ti{sub 0.5}Ru{sub 0.5}, Ti{sub 0.75}Ru{sub 0.25} and Ti{sub 0.25}Ru{sub 0.75}) containing anatase TiO{sub 2} nanoparticles and a color degradation analysis was done. Physical (atomic force microscopy and X-ray diffractometry) and electrochemical characterizations (cyclic voltammetry) were considered. The condition that yielded highest color removal for the system presented 0.05 mol L-1 NaCl, 100 mA cm-2, 35 Degree-Sign C and pH 7, independent of the dye concentration for the Ti{sub 0.25}Ru{sub 0.75} electrode. (author)

  1. Electrocatalysts for fuel cells

    International Nuclear Information System (INIS)

    Garcia C, M. A.; Fernandez V, S. M.; Vargas G, J. R.

    2008-01-01

    It was investigated the oxygen reduction reaction (fundamental reaction in fuel cells) on electrocatalysts of Pt, Co, Ni and their alloys CoNi, PtCo, PtNi, PtCoNi in H 2 SO 4 0.5 M and KOH 0.5 M as electrolyte. The electrocatalysts were synthesized using mechanical alloying processes and chemical vapor deposition. The electrocatalysts were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray spectroscopy. The evaluation was performed using electrocatalytic technique of rotating disk electrode and kinetic parameters were determined for each electro catalyst. We report the performance of all synthesized electrocatalysts in acid and alkaline means. (Author)

  2. Electrochemical and structural characterization of carbon-supported Pt-Pd bimetallic electrocatalysts prepared by electroless deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, Masato; Beard, Kevin D.; Ma Shuguo; Blom, Douglas A.; St-Pierre, Jean; Van Zee, John W. [Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Monnier, John R., E-mail: monnier@cec.sc.ed [Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2010-10-01

    Electrochemical and structural characteristics of various Pt-Pd/C bimetallic catalysts prepared by electroless deposition (ED) methods have been investigated. Structural analysis was conducted by X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, scanning transmission electron microscopy, and energy dispersive X-ray spectroscopy (EDS). Monometallic Pt or Pd particles were not detected by EDS, indicating the ED methodology formed only bimetallic particles. The size of the Pt-Pd bimetallic particles was smaller than those of a commercially available Pt/C catalyst. The morphology of the Pt on Pd/C catalysts was identified and corresponded to Pd particles partially encapsulated by Pt. The electrochemical characteristics of the lowest Pd loading catalyst (7.0% Pt on 0.5% Pd/C) for the oxygen reduction reaction (ORR) have been investigated by the rotating ring disk electrode technique. The electrochemical activity was equal or lower than the commercially available Pt/C catalyst; however, the amount of hydrogen peroxide observed at the ring was reduced by the Pd, suggesting that such a catalyst has the potential to decrease ionomer degradation in applications. The Pt on Pd/C catalysts also show a higher tolerance to ripening induced by potential cycling. Therefore, catalyst suitability cannot be judged solely by its initial performance; information related to specific degradation mechanisms is also needed for a more complete assessment.

  3. Preparation of Bimetallic Pd-Co Nanoparticles on Graphene Support for Use as Methanol Tolerant Oxygen Reduction Electrocatalysts

    Directory of Open Access Journals (Sweden)

    R. N. Singh

    2012-12-01

    Full Text Available Graphene-supported (40-x wt% Pd x wt% Co (0≤x≤13.33 alloys/composites have been prepared by a microwave-assisted polyol reduction method and been investigated for their structural and electrocatalytic properties for the oxygen reduction reaction (ORR in 0.5 M H2SO4 at 298 K. The study demonstrated that the bimetallic Pd-Co composite nanoparticles are, in fact, alloy nanoparticles with fcc crystalline structure. Partial substitution of Pd by Co (from 3.64 to 13.33 wt% in 40 wt% Pd/graphene decreases the lattice parameter as well as the crystallite size and increases the apparent catalytic activity, the latter, however, being the greatest with 8 wt% Co. The ORR activity of the active 32 wt% Pd 8wt% Co is found to be considerably low when it was deposited on the support multiwall carbon nanotubes under similar conditions. The rotating disk electrode study indicated that the ORR on 32 wt% Pd 8 wt% Co/GNS in 0.5 M H2SO4 follows approximately the four-electron pathway.

  4. Atomically Monodisperse Nickel Nanoclusters as Highly Active Electrocatalysts for Water Oxidation

    KAUST Repository

    Joya, Khurram

    2016-04-08

    Achieving water splitting at low overpotential with high oxygen evolution efficiency and stability is important for realizing solar to chemical energy conversion devices. Herein we report the synthesis, characterization and electrochemical evaluation of highly active nickel nanoclusters (Ni NCs) for water oxidation at low overpotential. These atomically precise and monodisperse Ni NCs are characterized by using UV-visible absorption spectroscopy, single crystal X-ray diffraction and mass spectrometry. The molecular formulae of these Ni NCs are found to be Ni4(PET)8 and Ni6(PET)12 and are highly active electrocatalysts for oxygen evolution without any pre-conditioning. Ni4(PET)8 are slightly better catalysts than Ni6(PET)12 and initiate the oxygen evolution at an amazingly low overpotential of ~1.51 V (vs RHE; η ≈ 280 mV). The peak oxygen evolution current density (J) of ~150 mA cm–2 at 2.0 V (vs. RHE) with a Tafel slope of 38 mV dec–1 is observed using Ni4(PET)8. These results are comparable to the state-of-the art RuO2 electrocatalyst, which is highly expensive and rare compared to Ni-based materials. Sustained oxygen generation for several hours with an applied current density of 20 mA cm–2 demonstrates the long-term stability and activity of these Ni NCs towards electrocatalytic water oxidation. This unique approach provides a facile method to prepare cost-effective, nanoscale and highly efficient electrocatalysts for water oxidation.

  5. High-Performance Pyrochlore-Type Yttrium Ruthenate Electrocatalyst for Oxygen Evolution Reaction in Acidic Media

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jaemin [Department; Shih, Pei-Chieh [Department; Tsao, Kai-Chieh [Department; Pan, Yung-Tin [Department; Yin, Xi [Department; Sun, Cheng-Jun [X-ray; Yang, Hong [Department

    2017-08-17

    Development of acid-stable electrocatalysts with low overpotential for oxygen evolution reaction (OER) is a major challenge for the production of hydrogen directly from water. We report in this paper a pyrochlore yttrium ruthenate (Y2Ru2O7-δ) electrocatalyst that has significantly enhanced performance towards OER in acid media over the best-known catalysts, with an onset overpotential of 190 mV and high stability in 0.1-M perchloric acid solution. X-ray absorption near-edge structure (XANES) indicates Y2Ru2O7-δ electrocatalyst had a low valence state that favors the high OER activity. Density functional theory (DFT) calculation shows this pyrochlore has lower band center energy for the overlap between Ru 4d and O 2p orbitals and therefore more stable Ru-O bond than RuO2, highlighting the effect of yttrium on the enhancement in stability. The Y2Ru2O7-δ pyrochlore is also free of expensive iridium metal, thus a cost-effective candidate for practical applications.

  6. Rapid synthesis of platinum-ruthenium bimetallic nanoparticles dispersed on carbon support as improved electrocatalysts for ethanol oxidation.

    Science.gov (United States)

    Gu, Zhulan; Li, Shumin; Xiong, Zhiping; Xu, Hui; Gao, Fei; Du, Yukou

    2018-07-01

    Bimetallic nanocatalysts with small particle size benefit from markedly enhanced electrocatalytic activity and stability during small molecule oxidation. Herein, we report a facile method to synthesize binary Pt-Ru nanoparticles dispersed on a carbon support at an optimum temperature. Because of its monodispersed nanostructure, synergistic effects were observed between Pt and Ru and the PtRu/C electrocatalysts showed remarkably enhanced electrocatalytic activity towards ethanol oxidation. The peak current density of the Pt 1 Ru 1 /C electrocatalyst is 3731 mA mg -1 , which is 9.3 times higher than that of commercial Pt/C (401 mA mg -1 ). Furthermore, the synthesized Pt 1 Ru 1 /C catalyst exhibited higher stability during ethanol oxidation in an alkaline medium and maintained a significantly higher current density after successive cyclic voltammograms (CVs) of 500 cycles than commercial Pt/C. Our work highlights the significance of the reaction temperature during electrocatalyst synthesis, leading to enhanced catalytic performance towards ethanol oxidation. The Pt 1 Ru 1 /C electrocatalyst has great potential for application in direct ethanol fuel cells. Copyright © 2018 Elsevier Inc. All rights reserved.

  7. Atomically Monodisperse Nickel Nanoclusters as Highly Active Electrocatalysts for Water Oxidation

    KAUST Repository

    Joya, Khurram; Sinatra, Lutfan; AbdulHalim, Lina G.; Joshi, Chakra Prasad; Hedhili, Mohamed N.; Bakr, Osman; Hussain, Irshad

    2016-01-01

    are comparable to the state-of-the art RuO2 electrocatalyst, which is highly expensive and rare compared to Ni-based materials. Sustained oxygen generation for several hours with an applied current density of 20 mA cm–2 demonstrates the long-term stability

  8. Pt{sub X}Ru{sub Y}Ir{sub Z} as a bifunctional electrocatalyst for oxygen reduction reaction in a PEM fuel cell; Pt{sub X}Ru{sub Y}Ir{sub Z} como electrocatalizador bifuncional para la reaccion redox del oxigeno en una celda tipo PEM

    Energy Technology Data Exchange (ETDEWEB)

    Morales, L.; Fernandez, A.M. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico)]. E-mail: limos@cie.unam.mx; Cano, U. [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2009-09-15

    This work presents the synthesis and characterization of the ternary material Pt{sub X}Ru{sub Y}Ir{sub Z}, obtained by chemical reduction with NaBH{sub 4}. Two different atomic compositions were developed (sample A and B) in order to observe the kinetic effect, as suggested by the combinatorial libraries. The main objective of this synthesis is to study the oxygen reduction reaction (ORR and OER) and its potential use in the construction of a bifunctional catalyst. In addition, each of the metals are synthesized separately using the same technique in order to make the corresponding comparison. The compounds obtained were characterized by sweep electron microscopy, x-ray diffraction and composition using fluorescence and energy-dispersive x-ray spectroscopy. The results showed a displacement of the x-ray diffraction peaks for Ir and Pt in sample A, and displacement in sample B for Ru and Ir peaks. These changes suggest the possible formation of a solid solution substitution. Separate cyclic and linear voltamperometry studies were performed for the oxygen reduction and release reactions. The electrochemical analysis showed improved kinetic behavior when combining the three metals according to the composition of sample B. [Spanish] En este trabajo se presenta la sintesis y caracterizacion del material ternario Pt{sub X}Ru{sub Y}Ir{sub Z}, elaborado por la tecnica de Reduccion Quimica utilizando al NaBH{sub 4}. Se elaboraron dos composiciones atomicas diferentes (Muestra A y B) con el fin de observar el efecto cinetico, como lo sugieren las librerias combinatorias. El objetivo principal de esta sintesis es para el estudio de la Reaccion Redox del Oxigeno (RRO y REO) y su potencial uso para la construccion de un catalizador bifuncional. Asi mismo, se realiza la sintesis de cada uno de los metales por separado empleando la misma tecnica, con el proposito de realizar la comparacion correspondiente. Los compuestos obtenidos se caracterizaron por Microscopia Electronica de

  9. Electrocatalysts of platinum, cobalt and nickel prepared by mechanical alloying for the oxygen reduction reaction in H2SO4 0.5M

    International Nuclear Information System (INIS)

    Garcia C, M.A.; Fernandez V, S.M.; Vargas G, J.R.

    2007-01-01

    Metallic powders of Pt, Co and Nickel were processed by mechanical alloyed and electrocatalysts were synthesized for the oxygen reduction reaction, applicable in fuel cells. The structural and morphological characterization was carried out using X-ray Diffraction, scanning electron microscopy and transmission electron microscopy. It was found that the alloyed powders formed agglomerates that consist of crystalline particles of nano metric size. Its were obtained polarization curves by the Electrode of Rotational Disk technique in a solution of H 2 SO 4 0.5 M, used as electrolyte, to evaluate the electrocatalytic activity of mechanically alloyed powders. Tafel graphics were built to determine the kinetic parameters of each electro catalyst. The PtCoNi alloy exhibited the biggest electrocatalytic activity, with the smallest over potential for the oxygen reduction reaction. (Author)

  10. Preparation of supported heterogeneous catalysts by pulse impregnation: Application to Ru[sub 3](CO)[sub 12]/2,2[prime]-bipyridine/SiO[sub 2] catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Haukka, M.; Pakkanen, T.A. (Univ. of Joensuu (Finland))

    1994-07-01

    In this paper, the authors introduce pulse impregnation, a method for preparing supported heterogeneous catalysts by successive impregnation cycles. Pulse impregnation is a method for preparing supported heterogeneous catalysts from the liquid phase. In the pulse-impregnation technique the catalyst surface is grown gradually in consecutive cycles, with each cycle consisting of separate deposition and activation steps. During the deposition step, the catalyst precursor or precursors are deposited onto the support from a suitable solvent. The actual chemically bonded catalyst phase is formed during the activation step (e.g., thermal activation). Pulse impregnation was tested in the separate deposition of 2,2[prime]-bipyridine and Ru[sub 3](CO)[sub 12] onto a silica support, and in the preparation of Ru[sub 3](CO)[sub 12]/2,2[prime]-bipyridine/SiO[sub 2] catalyst, in a column-type reactor system. Macroscopically uniform deposition was achieved with both 2,2[prime]-bipyridine and Ru[sub 3](CO)[sub 12]. Various solvent systems were used to control the amount of solute adsorbed during deposition. In the preparation of the Ru[sub 3](CO)[sub 12]/2,2[prime]-bipyridine/SiO[sub 2] catalyst, the ruthenium content increased nearly linearly with the number of preparation cycles. The effects of the preparation method on the catalyst activity was also tested in 1-hexane hydroformylation. 31 refs., 7 figs., 1 tab.

  11. Characterization of RuO sub 2 electrodes for ferroelectric thin films prepared by metal-organic chemical-vapor deposition using Ru(C sub 1 sub 1 H sub 1 sub 9 O sub 2) sub 3

    CERN Document Server

    Lee, J M; Shin, J C; Hwang, C S; Kim, H J; Suk, C G

    1999-01-01

    Pure and conducting RuO sub 2 thin films were deposited on Si substrates at 250 approx 450 .deg. C using Ru(C sub 1 sub 1 H sub 1 sub 9 O sub 2) sub 3 as a precursor by low-pressure metal-organic chemical-vapor deposition (LP-MOCVD). At a lower deposition temperature,smoother and denser RuO sub 2 thin films were deposited. The RuO sub 2 thin films, which were crack free, adhered well onto the substrates and showed very low resistivities around 45 approx 60 mu OMEGA cm. RuO sub 2 thin films on (Ba, Sr)/TiO sub 3 /Pt/SiO sub 2 /Si showed good properties, indicating that MOCVD RuO sub 2 thin films from Ru(C sub 1 sub 1 H sub 1 sub 9 O sub 2) sub 3 can be applied as electrodes of high-dielectric thin films for capacitors in ultra-large-scale DRAMs.

  12. Electrodeposition of nano-sized bismuth on copper foil as electrocatalyst for reduction of CO{sub 2} to formate

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Weixin; Zhou, Jing; Bei, Jingjing [School of Chemistry and Chemical Engineering, Yancheng Institute of Technology, Yancheng, 224051 (China); Zhang, Rui, E-mail: zhangrui@ycit.cn [School of Chemistry and Chemical Engineering, Yancheng Institute of Technology, Yancheng, 224051 (China); Wang, Lei [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People’s Republic of China, Heilongjiang University, Harbin, 150080 (China); Xu, Qi [School of Chemistry and Chemical Engineering, Yancheng Institute of Technology, Yancheng, 224051 (China); Wang, Wei, E-mail: wangw@ycit.edu.cn [School of Chemistry and Chemical Engineering, Yancheng Institute of Technology, Yancheng, 224051 (China)

    2017-01-30

    Highlights: • Bi/Cu electrode was prepared by depositing nano-sized Bi catalyst on Cu foil. • The Bi/Cu electrode can reduce CO{sub 2} to formate with a low overpotential. • The energy efficiency for reduction of CO{sub 2} to formate can reach to 50%. • A Tafel slope of 128 mV decade{sup −1} was observed for producing formate. - Abstract: Electrochemical reduction of carbon dioxide (CO{sub 2}) to formate is energetically inefficient because high overpotential is required for reduction of CO{sub 2} to formate on most traditional catalysts. In this paper, a novel nano-sized Bi-based electrocatalyst deposited on a Cu foil has been synthesized, which can be used as a cathode for electrochemical reduction of CO{sub 2} to formate with a low overpotential (0.69 V) and a high selectivity (91.3%). The electrocatalyst can show excellent catalytic performance toward reduction of CO{sub 2} which can probably be attributed to the nano-sized structure and the surface oxide layer. The energy efficiency for reduction of CO{sub 2} to formate can reach to 50% when an Ir{sub x}Sn{sub y}Ru{sub z}O{sub 2}/Ti electrode is used as anode, it is one of the highest values found in the literatures and very practicable for sustainable fuel synthesis.

  13. Highly acid-durable carbon coated Co3O4 nanoarrays as efficient oxygen evolution electrocatalysts

    KAUST Repository

    Yang, Xiulin; Li, Henan; Lu, Ang-Yu; Min, Shixiong; Idriss, Zacharie; Hedhili, Mohamed N.; Huang, Kuo-Wei; Idriss, Hicham; Li, Lain-Jong

    2016-01-01

    Most oxygen evolution reaction (OER) electrocatalysts are not stable in corrosive acids. Even the expensive RuO2 or IrO2, the most acid-resistant oxides, can be dissolved at an oxidative potential. Herein, we realize that the failures of OER catalysts are mostly caused by the weak interface between catalysts and the substrates. Hence, the study of the interface structure between catalysts and substrates is critical. In this work, we observe that the cheap OER catalysts Co3O4 can be more durable than the state-of-the-art RuO2 if the interface quality is good enough. The Co3O4 nanosheets deposited on carbon paper (Co3O4/CP) is prepared by electroplating of Co-species and followed by a two-step calcination process. The 1st step occurs in vacuum in order to maintain the surface integrity of the carbon paper and converts Co-species to Co(II)O. The 2nd step is a calcination in ambient conditions which enables the complete transformation of Co(II)O to Co3O4 without degrading the mechanical strength of the Co3O4-CP interface. Equally important, an in situ formation of a layer of amorphous carbon on top of Co3O4 further enhances the OER catalyst stability. Therefore, these key advances make the Co3O4 catalyst highly active toward the OER in 0.5 M H2SO4 with a small overpotential (370 mV), to reach 10 mA/cm2. The observed long lifetime for 86.8 h at a constant current density of 100 mA/cm2, is among the best of the reported in literature so far, even longer than the state-of-art RuO2 on CP. Overall, our study provides a new insight and methodology for the construction of a high-performance and high stability OER electrocatalysts in corrosive acidic environments.

  14. Highly acid-durable carbon coated Co3O4 nanoarrays as efficient oxygen evolution electrocatalysts

    KAUST Repository

    Yang, Xiulin

    2016-04-21

    Most oxygen evolution reaction (OER) electrocatalysts are not stable in corrosive acids. Even the expensive RuO2 or IrO2, the most acid-resistant oxides, can be dissolved at an oxidative potential. Herein, we realize that the failures of OER catalysts are mostly caused by the weak interface between catalysts and the substrates. Hence, the study of the interface structure between catalysts and substrates is critical. In this work, we observe that the cheap OER catalysts Co3O4 can be more durable than the state-of-the-art RuO2 if the interface quality is good enough. The Co3O4 nanosheets deposited on carbon paper (Co3O4/CP) is prepared by electroplating of Co-species and followed by a two-step calcination process. The 1st step occurs in vacuum in order to maintain the surface integrity of the carbon paper and converts Co-species to Co(II)O. The 2nd step is a calcination in ambient conditions which enables the complete transformation of Co(II)O to Co3O4 without degrading the mechanical strength of the Co3O4-CP interface. Equally important, an in situ formation of a layer of amorphous carbon on top of Co3O4 further enhances the OER catalyst stability. Therefore, these key advances make the Co3O4 catalyst highly active toward the OER in 0.5 M H2SO4 with a small overpotential (370 mV), to reach 10 mA/cm2. The observed long lifetime for 86.8 h at a constant current density of 100 mA/cm2, is among the best of the reported in literature so far, even longer than the state-of-art RuO2 on CP. Overall, our study provides a new insight and methodology for the construction of a high-performance and high stability OER electrocatalysts in corrosive acidic environments.

  15. Preparation, characterization and evaluation of electrocatalysts supported on functionalized carbon black for polymer exchange membrane fuel cell applications; Preparacao, caracterizacao e avaliacao de eletrocatalisadores suportados em carbono funcionalizado para aplicacao em celulas a combustivel tipo PEM

    Energy Technology Data Exchange (ETDEWEB)

    Carmo, Marcelo do

    2008-12-18

    The fuel cell technology associated with the growing exigency of low environmental impact energy became prosperous in the world energy scenery. The fuel cell is basically a device that converts directly the chemical energy of a fuel into electrical and thermal energy with a continuous operation by the constant feed of a fuel. Especially, the carbon black Vulcan XC72 is usually employed as an electro catalyst support, and some factors as an accessible and high surface area in order to get maximum particles dispersion, pore size, adequate pore distribution and the presence of functional groups in the carbon black surface are considered fundamental characteristics for an innovative materials development. However, the Vulcan XC72 still reveals insufficient conditions for these purposes. This study consists in the preparation and in the physical chemical characterization of functionalized carbon black by hydrogen peroxide and by polymeric chains with proton conduction properties, and its posterior utilization as electro catalyst support for PEMFC and DMFC application. After the carbon functionalization, an improvement in the carbon black dispersion in water media was observed, a beneficial effect for electro catalyst preparation. It was also observed, that the functional groups and the polymeric chains worked as stabilizers in the particle growing, producing much more homogeneous electrocatalysts, exhibiting smaller average particle size. Especially, in the case of polymeric chains functionalization, a decrease in the ohmic drop was observed for this system, attributed to an improvement in the proton transference. (author)

  16. Nonalloyed carbon-supported PtRu catalysts for PEMFC applications

    NARCIS (Netherlands)

    Papageorgopoulos, D.C.; De Heer, M.P.; Keijzer, M.; Pieterse, J.A.Z.; de Bruijn, F. A.

    2004-01-01

    PtRu(1:1)/C catalysts were prepared by a process that was claimed previously to lead to non-alloyed Pt and Ru particles, using two different precursors, Ru nitrosyl nitrate and Ru chloride hydrate. Both X-ray diffraction and characterization by cyclic voltammetry point toward Pt and Ru being present

  17. Nonalloyed carbon-supported PtRu catalysts for PEMFC applications

    NARCIS (Netherlands)

    Papageorgopoulos, D.C.; Heer, de M.P.; Keijzer, M.; Pieterse, J.A.Z.; Bruijn, de F.A.

    2004-01-01

    PtRu(1:1)/C catalysts were prepared by a process that was claimed previously to lead to nonalloyed Pt and Ru particles, using twodifferent precursors, Ru nitrosyl nitrate and Ru chloride hydrate. Both X-ray diffraction and characterization by cyclic voltammetrypoint toward Pt and Ru being present as

  18. Preparation of PtSnCu/C and PtSn/C electrocatalysts and activation by dealloying processes for ethanol electrooxidation; Preparacao de eletrocatalisadores PtSnCu/C e PtSn/C e ativacao por processos de dealloying para aplicacao na oxidacao eletroquuimica do etanol

    Energy Technology Data Exchange (ETDEWEB)

    Crisafulli, Rudy

    2013-06-01

    PtSnCu/C (with different Pt:Sn:Cu atomic ratios) and PtSn/C (50:50) electrocatalysts were prepared by borohydride (BR) and alcohol-reduction (AR) processes using H{sub 2}PtCl{sub 6}.6H{sub 2}O, SnCl{sub 2}.2H{sub 2}O and CuCl{sub 2}.2H{sub 2}O as metal sources, NaBH{sub 4} and ethylene glycol as reducing agents, 2-propanol and ethylene glycol/water as solvents and carbon black as support. In a further step, these electrocatalysts were activated by chemical (CD) and electrochemical (ED) dealloying processes through acid treatment and thin porous coating technique, respectively. These materials were characterized by energy dispersive X-ray, Xray diffraction, transmission electron microscopy, line scan energy dispersive Xray and cyclic voltammetry. Electrochemical studies for ethanol electro-oxidation were performed by cyclic voltammetry, chronoamperometry and in single Direct Ethanol Fuel Cell using Membrane Electrode Assembly (MEA). The anodic effluents were analysed by gas chromatography. The X-ray diffractograms of the as-synthesized electrocatalysts showed the typical face-centered cubic structure (FCC) of platinum and its alloys. After dealloying, the X-ray diffractograms showed that the Pt FCC structure was preserved. The crystallite sizes of the assynthesized electrocatalysts were in the range of <=2 nm to 3 nm and after dealloying there were no significant variations in sizes. The energy dispersive Xray analysis of the as-synthesized electrocatalysts showed a Pt:Sn and Pt:Sn:Cu atomic ratios similar to the nominal values. After chemical and electrochemical dealloying of the electrocatalysts the ranged Pt:Sn and Pt:Sn:Cu atomic ratios showed that Cu and Sn atoms were removed. However, chemical dealloying process proved to be more efficient for removing Cu and electrochemical dealloying for removing Sn. The line scan energy dispersive X-ray analysis showed that acid and electrochemical treatments were efficient to dealloying Cu and/or Sn superficial atoms of

  19. Electrocatalysts for hydrogen energy

    CERN Document Server

    Losiewicz, Bozena

    2015-01-01

    This special topic volume deals with the development of novel solid state electrocatalysts of a high performance to enhance the rates of the hydrogen or oxygen evolution. It contains a description of various types of metals, alloys and composites which have been obtained using electrodeposition in aqueous solutions that has been identified to be a technologically feasible and economically superior technique for the production of the porous electrodes. The goal was to produce papers that would be useful to both the novice and the expert in hydrogen technologies. This volume is intended to be us

  20. Electrooxidations of ethanol, acetaldehyde and acetic acid using PtRuSn/C catalysts prepared by modified alcohol-reduction process

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Gang [Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Swaidan, Raja [Department of Chemical Engineering, Cooper Union, New York, NY 10003 (United States); Cui, Guofeng [School of Chemistry and Chemical Engineering, Sun-Yat Sen University, Guangzhou 510275 (China)

    2007-10-11

    Well-dispersed ternary PtRuSn catalysts of various atomic ratios (60:30:10, 60:20:20 and 60:10:30) were deposited onto carbon using modified alcohol-reduction process for electrochemical oxidation of ethanol. The alloy phase structure and surface morphology for each variation of the PtRuSn/C catalysts were determined by XRD and HRTEM. In order to evaluate the contributions of Ru and Sn in the different stages of ethanol oxidation, electrochemical oxidations of adsorbed CO, ethanol, acetaldehyde and acetic acid were performed on each PtRuSn/C catalyst. The results indicated that the Ru-rich PtRuSn/C catalyst (60:30:10) exhibited the lowest onset potential for the electrooxidations of adsorbed CO, ethanol and acetaldehyde, revealing that the removal through oxidation of the intermediate C{sub 1} and C{sub 2} species from Pt sites is primarily attributed to the Ru and Pt{sub 3}Sn alloy structures. However, for the overall oxidation of ethanol, the Sn-rich PtRuSn/C catalyst (60:10:30) containing PtSn phase and SnO{sub 2} structure is favorable for the activation of C-C bond breaking, thereby generating higher current density (mass activity) at higher potentials. Moreover, in the electrooxidation of acetic acid, a remarkable improvement for oxidizing acetic acid to C{sub 1} species was observed in the Sn-rich PtRuSn/C catalyst (60:10:30), while the Ru-rich PtRuSn/C catalyst (60:30:10) was almost incapable of breaking the C-C bond to further oxidize acetic acid. The possible reasons for the different reactivities on the studied PtRuSn/C catalysts were discussed based on the removal of intermediates and activation of the C-C bonds on the different surfaces. (author)

  1. Magnetic properties of Heusler alloy Mn2RuGe and Mn2RuGa ribbons

    International Nuclear Information System (INIS)

    Yang, Ling; Liu, Bohua; Meng, Fanbin; Liu, Heyan; Luo, Hongzhi; Liu, Enke; Wang, Wenhong; Wu, Guangheng

    2015-01-01

    Heusler alloys Mn 2 RuGe and Mn 2 RuGa have been prepared by melt-spinning method successfully. Theoretical and experimental studies reveal a ferrimagnetic ground state in the two alloys. The Curie temperatures are 303 K for Mn 2 RuGe and 272 K for Mn 2 RuGa. The calculated total spin moments of Mn 2 RuGe and Mn 2 RuGa are integral values of 2.00 μ B and 1.03 μ B , respectively. And the theoretical spin polarization ratio is also quite high. However, due to the atomic disorder in the ribbons, the saturation moments of them measured at 5 K are smaller than the calculated values, especially that of Mn 2 RuGa. This coincides with the disappearance of the superlattice reflection (111) and (200) peaks in the XRD pattern of Mn 2 RuGa. Annealing Mn 2 RuGa ribbon at 773 K can enhance the atomic ordering. Both saturation magnetic moment and Curie temperature increase obviously after the heat treatment. - Highlights: • Mn 2 RuGe and Mn 2 RuGa have been prepared by melt-spinning successfully. • Ferrimagnetic ground state has been confirmed in Mn 2 RuGe and Mn 2 RuGa. • High spin polarization has been predicted in Mn 2 RuGe. • Melt-spinning can be a possible way to adjust the atomic order of Heusler alloys

  2. Pt, PtCo and PtNi electrocatalysts prepared with mechanical alloying for oxygen reduction reaction in alkaline medium; Electrocatalizadores de Pt, PtCo y PtNi preparados por aleado mecanico para la reaccion de reduccion de oxigeno en medio alcalino

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Contreras, M.A.; Fernandez-Valverde, S.M. [Instituto Nacional de Investigaciones Nucleares, Ocoyoacac, Estado de Mexico (Mexico)]. E-mail: miguel.garcia@inin.gob.mx; Vargas-Garcia, J.R. [ESIQIE-IPN, Mexico D.F. (Mexico

    2009-09-15

    Pt, PtCo and PtNi electrocatalysts were prepared using mechanical alloying and their electrocatalytic activity was investigated for oxygen reduction reaction (ORR) in KOH 0.5 M using cyclic voltametry and rotary disc electrode (RDE) techniques. The electrocatalysts were characterized using x-ray diffraction, sweep electron microscopy, dispersive x-ray transmission and chemical analysis. The physical characterization indicated that all the electrocatalysts are alloys formed by agglomerated particles composed of nanocrystals. The chemical analysis showed the presence of iron in the alloys. For the electrocatalytic evaluation, polarization curves and Koutecky-Levich and Tafel graphs were obtained to determine the kinetic parameters of the electrocatalysts in the study. With the same experimental conditions, the PtCo presented better electrocatalytic performance with a higher exchange current density. [Spanish] Se prepararon electrocatalizadores de Pt, PtCo y PtNi por aleado mecanico y se investigo su actividad electrocatalitica para la reaccion de reduccion de oxigeno (RRO) en KOH 0.5 M utilizando las tecnicas de Voltametria ciclica y Electrodo de Disco Rotatorio. Los electrocatalizadores se caracterizaron por difraccion de rayos X, Microscopia electronica de Barrido, de Transmision y analisis quimico por dispersion de rayos X. La caracterizacion fisica indico que todos los electrocatalizadores son aleaciones formadas de particulas aglomeradas, compuestas de nanocristales. El analisis quimico mostro la presencia de hierro en las aleaciones. Para la evaluacion electrocatalitica se obtuvieron curvas de polarizacion, graficas de Koutecky-Levich y de Tafel para determinar los parametros cineticos de los electrocatalizadores en estudio. En las mismas condiciones experimentales, el PtCo presento el mejor desempeno electrocatalitico con la densidad de corriente de intercambio mas alta.

  3. Performance PtSnRh electrocatalysts supported on carbon-Sb{sub 2}O{sub 5}.SbO{sub 2} for the electro-oxidation of ethanol, prepared by an alcohol-reduction process; Desempenho de eletrocatalisadores PtSnRh suportados em carbono-Sb{sub 2}O{sub 5}.SnO{sub 2} para a oxidacao eletroquimica do etanol, preparados pelo metodo de reducao por alcool

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Jose Carlos

    2013-07-01

    PtSnRh electrocatalysts supported on carbon-Sb{sub 2}O{sub 5}.SnO{sub 2}, with metal loading of 20 wt%, were prepared by an alcohol-reduction process, using H{sub 2}PtCl{sub 6}.6H{sub 2}O (Aldrich), RhCl{sub 3}.xH{sub 2}O (Aldrich) and SnCl{sub 2}.2H{sub 2}O (Aldrich), as source of metals; Sb{sub 2}O{sub 5}.SnO{sub 2} (ATO) and carbon Vulcan XC72, as support; and ethylene glycol as reducing agent. The electrocatalysts obtained were characterized physically by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The diffractograms showed which PtSnRh/C-ATO electrocatalysts had FCC structure of Pt and Pt alloys, besides several peaks associated with SnO{sub 2} and ATO. The average sizes of crystallites were between 2 and 4 nm. TEM micrographs showed a good distribution of the nanoparticles on the support. The average sizes of particles were between 2 and 3 nm, with good agreement for the average size of the crystallites. The performances of the electrocatalysts were analyzed by electrochemical techniques and in real conditions of operation using single direct ethanol fuel cell. In the chronoamperometry at 50 deg C, the electrocatalysts with carbon (85 wt%) and ATO (15 wt%) support, showed the best activity, and the atomic proportions which achieved the best results were PtSnRh(70:25:05) e (90:05:05). PtSnRh(70:25:05)/85C+15ATO electrocatalysts showed the best performance in a direct ethanol fuel cell. (author)

  4. Efficient hydrogen production on MoNi4 electrocatalysts with fast water dissociation kinetics

    Science.gov (United States)

    Zhang, Jian; Wang, Tao; Liu, Pan; Liao, Zhongquan; Liu, Shaohua; Zhuang, Xiaodong; Chen, Mingwei; Zschech, Ehrenfried; Feng, Xinliang

    2017-05-01

    Various platinum-free electrocatalysts have been explored for hydrogen evolution reaction in acidic solutions. However, in economical water-alkali electrolysers, sluggish water dissociation kinetics (Volmer step) on platinum-free electrocatalysts results in poor hydrogen-production activities. Here we report a MoNi4 electrocatalyst supported by MoO2 cuboids on nickel foam (MoNi4/MoO2@Ni), which is constructed by controlling the outward diffusion of nickel atoms on annealing precursor NiMoO4 cuboids on nickel foam. Experimental and theoretical results confirm that a rapid Tafel-step-decided hydrogen evolution proceeds on MoNi4 electrocatalyst. As a result, the MoNi4 electrocatalyst exhibits zero onset overpotential, an overpotential of 15 mV at 10 mA cm-2 and a low Tafel slope of 30 mV per decade in 1 M potassium hydroxide electrolyte, which are comparable to the results for platinum and superior to those for state-of-the-art platinum-free electrocatalysts. Benefiting from its scalable preparation and stability, the MoNi4 electrocatalyst is promising for practical water-alkali electrolysers.

  5. Perovskites As Electrocatalysts for Alkaline Water Electrolysis

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey Valerievich; De La Osa Puebla, Ana Raquel; Jensen, Jens Oluf

    2014-01-01

    such as X-ray diffraction, electrical conductivity, scanning electron microscopy (SEM), energy dispersive microscopy (EDX) and rotating disk electrode. The perovskites tested in this work were both produced by a ball-milling technique and by an auto-combustion synthesis, which appeared to be a fast...... and robust method for synthesis of perovskites with various chemical compositions1. The electrochemical performance of the materials was tested through pellet pressing of the perovskite powders. This involved in some case a time consuming preparation process. Furthermore the technique should show...... the adequate reproducibility.2 In this work we show the development of the method, which was further used to compare the activity of various electrocatalysts (Figures 1,2). The electrocatalytic activity of all prepared perovskites was tested in 1M KOH at 80 °C, using an ink consisting of potassium exchanged...

  6. Preparation of Pb(Zr0.52Ti0.48)O3 thin films on Pt/RuO2 double electrode by a new sol-gel route

    International Nuclear Information System (INIS)

    Kim, S.; Choi, Y.; Kim, C.; Oh, Y.

    1997-01-01

    Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin film on Pt/RuO 2 double electrode was successfully prepared by using new alkoxide endash alkanolamine, sol-gel method. It was observed that the use of Pt/RuO 2 double electrode reduced leakage current, resulting in a marked improvement in the leakage characteristics and more reliable capacitors. Typical P-E hysteresis behavior was observed even at low applied voltage of 5 V, manifesting greatly improved remanance and coercivity. Fatigue and breakdown characteristic, measured at 5 V, showed stable behavior and no degradation in polarization was observed up to 10 11 cycles.copyright 1997 Materials Research Society

  7. Low-Temperature Preparation of (111)-oriented Pb(Zr,Ti)O3 Films Using Lattice-Matched (111)SrRuO3/Pt Bottom Electrode by Metal-Organic Chemical Vapor Deposition

    Science.gov (United States)

    Kuwabara, Hiroki; Sumi, Akihiro; Okamoto, Shoji; Hoko, Hiromasa; Cross, Jeffrey S.; Funakubo, Hiroshi

    2009-04-01

    Pb(Zr0.35Ti0.65)O3 (PZT) films 170 nm thick were prepared at 415 °C by pulsed metal-organic chemical vapor deposition. The (111)-oriented PZT films with local epitaxial growth were obtained on (111)SrRuO3/(111)Pt/TiO2/SiO2/Si substrates and their ferroelectricities were ascertained. Ferroelectricity was improved by postannealing under O2 gas flow up to 550 °C. Larger remanent polarization and better fatigue endurance were obtained using a SrRuO3 top electrode compared to a Pt top electrode for PZT films after annealing at 500 °C.

  8. Preparation and electrochemical characterization of size controlled SnO2-RuO2 composite powder for monolithic hybrid battery

    International Nuclear Information System (INIS)

    Jeon, Young-Ah; No, Kwang-Soo; Choi, Sun Hee; Ahn, Jae pyong; Yoon, Young Soo

    2004-01-01

    Tin oxide (SnO 2 ) powders with a particle size of ∼20 nm were synthesized by a gas condensation method. Ruthenium oxide was loaded by an incipient-wetness method, in which an aqueous solution of RuCl 3 was added to the manufactured SnO 2 powder in an amount that was just sufficient to wet completely the powder. And then, the resulting solution was obtained after freeze-drying to synthesis the smallest particle. The as-synthesized SnO 2 powder with 1.5 wt.% ruthenium oxide (RuO 2 ) exhibited well-developed facets and had a very uniform particle size. The first discharge capacity was lower than comparing to commercial powder because of forming the second phase, but showed good cyclability. A maximum specific electrode capacitance of ∼20 F/g and a maximum specific power of ∼80 W/kg were achieved by manufactured SnO 2 with 1.5 wt.% RuO 2 . This result indicated that the synthesized SnO 2 -RuO 2 composite powder of nano-size scale is candidate for use in fabricating monolithic hybrid batteries using suitable electrolyte as well

  9. High-temperature electrochemical characterization of Ru core Pt shell fuel cell catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Bokach, D.; Fuente, J.L.G. de la; Tsypkin, M.; Ochal, P.; Tunold, R.; Sunde, S.; Seland, F. [Department of Materials Science and Engineering, Norwegian University of Science and Technology (NTNU), Sem Saelands veg 12, N-7491 Trondheim (Norway); Endsjoe, I.C. [Washington Mills AS, NO-7300 Orkanger (Norway)

    2011-12-15

    The electrooxidation of methanol was studied at elevated temperature and pressure by cyclic voltammetry and constant potential experiments at real fuel cell electrocatalysts. Ruthenium core and platinum shell nanoparticles were synthesized by a sequential polyol route, and characterized electrochemically by CO stripping at room temperature to quickly confirm the structure of the synthesized core-shell structure as compared to pure commercial Pt/C and Pt-Ru/C alloy catalysts. A significant promotional effect of Pt decorated Ru cores in the methanol oxidation was found at elevated temperatures and rather high-electrode potentials. A negative potential shift of the methanol oxidation peak is observed for the Ru rate at Pt/C core-shell catalyst at moderate temperatures, while a significant shift to positive potentials of the methanol oxidation peak occurs for Pt/C catalysts. The onset potential for methanol oxidation is lowered some 200 mV from room temperature and up to 120 C for all electrocatalysts, indicating that it is the thermal activity of water adsorption that dictates the onset potential. Direct methanol fuel cell experiments showed only small performance differences between Ru rate at Pt/C and Pt/C anode electrocatalysts, suggesting the necessity of render possible the formation of surface oxygen species at lower electrode potentials. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. The role of CO* as a spectator in CO2 electro-reduction on RuO2

    DEFF Research Database (Denmark)

    Bhowmik, Arghya; Hansen, Heine Anton; Vegge, Tejs

    2017-01-01

    evolution reaction (HER). We show that a moderate CO* coverage (∼50%) is necessary for obtaining methanol as a product and that higher CO* coverages leads to very low overpotential for formic acid evolution. Our analysis also clarifies the importance of the reaction condition for CO2 reduction to liquid......RuO2-based electrocatalysts are found to be active at low overpotential toward direct electrochemical reduction of CO2 to formic acid and methanol. RuO2 can circumvent the thermodynamic bottleneck resulting from the scaling relations observed on metallic electrocatalyst, by utilizing an alternate...

  11. Preparation and characterization of Pd{sub x}Ag{sub y}/C electrocatalysts for ethanol electrooxidation reaction in alkaline media

    Energy Technology Data Exchange (ETDEWEB)

    Li Guanglan [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Jiang Luhua [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Jiang Qian [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Wang Suli [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Sun Gongquan, E-mail: gqsun@dicp.ac.cn [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2011-09-01

    Highlights: {center_dot} The effects of Pd or PdAg particle size and PdAg alloy degrees on the EOR activity are investigated. {center_dot} The Pd lattice constant of the PdAg increases with increasing the Ag content. {center_dot} The EOR activity of the PdAg/C presents a 'volcano' plot with increasing the Pd lattice constant. {center_dot} The optimal Pd/Ag atomic ratio locates between 2/1 and 3/1. {center_dot} The EOR activity of the PdAg/C increases with increasing the PdAg particle size from 3.4 to 5.2 nm. - Abstract: Carbon-supported bimetallic PdAg catalysts with Pd/Ag atomic ratios varying from 4/1 to 1/2 were prepared by an impregnation-reduction method. The impregnated black mixture was treated in H{sub 2}/N{sub 2} atmosphere at a temperature varying from 180 to 500 deg. C. The obtained Pd{sub x}Ag{sub y}/C catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV) and chronoamperometry (CA). XRD results show that the lattice constant of Pd is dilated, suggesting the formation of PdAg alloy. The lattice constant of Pd for the Pd{sub x}Ag{sub y}/C-500 (reduced at 500 deg. C by H{sub 2}) increases linearly and the average metal particle size decreases slightly from 6.8 to 5.1 nm with increasing Ag fractions from 20% to 67% in the PdAg composition. For Pd{sub x}Ag{sub y}/C catalysts with a certain specific Pd/Ag atomic ratio, e.g., Pd{sub 2}Ag{sub 1}/C, the dilated lattice constant of Pd is independent of the reducing temperature, indicating the alloy degree for the Pd{sub 2}Ag{sub 1}/C-t catalysts is comparable. The average metal particle size for the Pd{sub 2}Ag{sub 1}/C-t catalysts increases from 3.4 to 5.2 nm with H{sub 2} reduction temperature increasing from 180 to 500 deg. C. The potentiodynamic measurements on ethanol electrooxidation reaction (EOR) show that the catalytic activities for the Pd{sub x}Ag{sub y}/C-t catalysts toward the EOR are improved by alloying Pd with Ag. At

  12. Ternary Pt/Rh/SnO2 electrocatalysts for oxidizing ethanol to CO2.

    Science.gov (United States)

    Kowal, A; Li, M; Shao, M; Sasaki, K; Vukmirovic, M B; Zhang, J; Marinkovic, N S; Liu, P; Frenkel, A I; Adzic, R R

    2009-04-01

    Ethanol, with its high energy density, likely production from renewable sources and ease of storage and transportation, is almost the ideal combustible for fuel cells wherein its chemical energy can be converted directly into electrical energy. However, commercialization of direct ethanol fuel cells has been impeded by ethanol's slow, inefficient oxidation even at the best electrocatalysts. We synthesized a ternary PtRhSnO(2)/C electrocatalyst by depositing platinum and rhodium atoms on carbon-supported tin dioxide nanoparticles that is capable of oxidizing ethanol with high efficiency and holds great promise for resolving the impediments to developing practical direct ethanol fuel cells. This electrocatalyst effectively splits the C-C bond in ethanol at room temperature in acid solutions, facilitating its oxidation at low potentials to CO(2), which has not been achieved with existing catalysts. Our experiments and density functional theory calculations indicate that the electrocatalyst's activity is due to the specific property of each of its constituents, induced by their interactions. These findings help explain the high activity of Pt-Ru for methanol oxidation and the lack of it for ethanol oxidation, and point to the way to accomplishing the C-C bond splitting in other catalytic processes.

  13. Preparation and evaluation of a multi-component catalyst by using a co-sputtering system for anodic oxidation of ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, S.; Usui, Y.; Kimura, O. [Environmental Technology R and D Center, Ricoh Company, Ltd., 16-1 Shinei-cho, Tsuzuki-ku, Yokohama 224-0035 (Japan); Umeda, M. [Department of Chemistry, Faculty of Engineering, Nagaoka University of Technology, Kamitomioka 1603-1, Nagaoka, Niigata 940-2188 (Japan); Ojima, H.; Uchida, I. [Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, Aramaki-Aoba 07, Aoba-ku, Sendai 980-8579 (Japan)

    2005-12-01

    In this study, a remarkable promotion of ethanol electrooxidation by a Pt--Ru-W alloy is reported for an improvement of the anodic reaction of a direct ethanol fuel cell (DEFC). Pt-based binary and ternary electrocatalysts including Pt-Ru-W deposited onto a Au substrate were prepared by co-sputtering process. By using this process, several metals can be arranged simultaneously and uniformly. The catalysts deposited onto Au were evaluated for anodic electrode in 1moldm{sup -3} ethanol+0.5 moldm{sup -3} sulfuric acid by electrochemical measurements. The performance of Pt-Ru-W was desirable in comparison to that of binary alloys, such as Pt-W, Pt-Sn and Pt-Ru, which exhibit higher catalytic activity than single Pt metal layer electrode. Ethanol electrooxidation on Pt-Ru-W alloy showed a cathodic shift in the onset potential and a higher current density than the binary alloy electrodes. It was found that Pt-Ru-W ternary catalyst effects to not only methanol oxidation reaction but also ethanol oxidation reaction and that the current density of ethanol oxidation with Pt-Ru-W is about 2/3 to that of methanol at 0.5V versus Ag/AgCl. The onset potentials for the ethanol oxidation reaction matched well the anodic peak potentials of the background volutammograms, i.e., 0.15V versus Ag/AgCl for Pt-Ru-W and 0.35V versus Ag/AgCl for Pt-W and Pt-Ru electrodes. That is, it was postulated that the background peak current indicates the generation of oxide species like metal-OH necessary to complete the ethanol oxidation to CO{sub 2}. (author)

  14. Pd-RuSe/C as ORR specific catalyst in alkaline solution containing methanol

    Energy Technology Data Exchange (ETDEWEB)

    Maheswari, S.; Sridhar, P.; Pitchumani, S. [CSIR-Central Electrochemical Research Institute-Madras Unit, CSIR Complex, Chennai 600 113 (India)

    2012-12-15

    Carbon supported RuSe (RuSe/C) catalyst in varying atomic ratios of Ru to Se, namely, 1:1, 2:1, and 3:1 were prepared and their performances were compared with carbon supported Ru (Ru/C). Based on the performance, Palladium was incorporated into as prepared RuSe(2:1)/C and heat treated HTRuSe(2:1)/C. Ru/C, RuSe/C, and Pd-RuSe/C were characterized by X-ray diffraction (XRD) and transmission electron microscopy techniques. The XRD analyses of Ru/C, RuSe/C and Pd-HTRuSe/C show the formation of the hcp structure of Ru particles and the mean particle size was obtained from Ru(101) peak. The electrochemical characterizations of Ru/C, RuSe/C, Pd-HTRuSe(2:1)/C and Pd-RuSe(2:1)/C were conducted by cyclic voltammetry. Linear Sweep Voltammetric studies showed that incorporation of Pd in HTRu-Se(2:1)/C resulted in better catalytic activity toward oxygen reduction with resistance to methanol oxidation. The quantity of hydrogen peroxide produced was obtained from rotating ring disk electrode studies. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. A high-performance mesoporous carbon supported nitrogen-doped carbon electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Xu, Jingjing; Lu, Shiyao; Chen, Xu; Wang, Jianan; Zhang, Bo; Zhang, Xinyu; Xiao, Chunhui; Ding, Shujiang

    2017-12-01

    Investigating low-cost and highly active electrocatalysts for oxygen reduction reactions (ORR) is of crucial importance for energy conversion and storage devices. Herein, we design and prepare mesoporous carbon supported nitrogen-doped carbon by pyrolysis of polyaniline coated on CMK-3. This electrocatalyst exhibits excellent performance towards ORR in alkaline media. The optimized nitrogen-doped mesoporous electrocatalyst show an onset potential (E onset) of 0.95 V (versus reversible hydrogen electrode (RHE)) and half-wave potential (E 1/2) of 0.83 V (versus RHE) in 0.1 M KOH. Furthermore, the as-prepared catalyst presents superior durability and methanol tolerance compared to commercial Pt/C indicating its potential applications in fuel cells and metal-air batteries.

  16. Graphene Composites with Cobalt Sulfide: Efficient Trifunctional Electrocatalysts for Oxygen Reversible Catalysis and Hydrogen Production in the Same Electrolyte.

    Science.gov (United States)

    Wang, Nan; Li, Ligui; Zhao, Dengke; Kang, Xiongwu; Tang, Zhenghua; Chen, Shaowei

    2017-09-01

    Nitrogen and sulfur-codoped graphene composites with Co 9 S 8 (NS/rGO-Co) are synthesized by facile thermal annealing of graphene oxides with cobalt nitrate and thiourea in an ammonium atmosphere. Significantly, in 0.1 m KOH aqueous solution the best sample exhibits an oxygen evolution reaction (OER) activity that is superior to that of benchmark RuO 2 catalysts, an oxygen reduction reaction (ORR) activity that is comparable to that of commercial Pt/C, and an overpotential of only -0.193 V to reach 10 mA cm -2 for hydrogen evolution reaction (HER). With this single catalyst for oxygen reversible electrocatalysis, a potential difference of only 0.700 V is observed in 0.1 m KOH solution between the half-wave potential in ORR and the potential to reach 10 mA cm -2 in OER; in addition, an overpotential of only 450 mV is needed to reach 10 mA cm -2 for full water splitting in the same electrolyte. The present trifunctional catalytic activities are markedly better than leading results reported in recent literature, where the remarkable trifunctional activity is attributed to the synergetic effects between N,S-codoped rGO, and Co 9 S 8 nanoparticles. These results highlight the significance of deliberate structural engineering in the preparation of multifunctional electrocatalysts for versatile electrochemical reactions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Chalcogenide oxygen reduction reaction catalysis: X-ray photoelectron spectroscopy with Ru, Ru/Se and Ru/S samples emersed from aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Lewera, A. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Department of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw (Poland); Inukai, J. [Clean Energy Research Center, University of Yamanashi, 7-32 Miyamae-cho, Kofu 400-0006 (Japan); Zhou, W.P. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Cao, D. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Duong, H.T. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Alonso-Vante, N. [Laboratory of Electrocatalysis, UMR-CNRS 6503, University of Poitiers, F-86022 Poitiers (France)]. E-mail: Nicolas.Alonso.Vante@univ-poitiers.fr; Wieckowski, A. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)]. E-mail: andrzej@scs.uiuc.edu

    2007-05-10

    Oxygen reduction Ru/Se and Ru/S fuel cell surface chalcogenide catalysts were prepared via chemical reaction of reduced Ru nanoparticles with selenium and sulfur in xylenes [D. Cao, A. Wieckowski, J. Inukai, N. Alonso-Vante, J. Electrochem. Soc. 153 (2006) A869]. The chalcogenide samples - as well as the starting chalcogens-free Ru nanoparticle material - were immobilized on a gold disk for X-ray Photoelectron Spectroscopy (XPS) characterization. While we found oxygen in most of the samples, predominantly from Ru oxides, we conclude that the oxygen on Ru/S may be located in subsurface sites: the subsurface oxygen. We also found that the transformation of the oxidized Ru black to metallic Ru required intensive electrochemical treatment, including hydrogen evolution. In contrast, five cyclic voltammetric scans in the potential range from 0.00 and 0.75 V versus RHE were sufficient to remove the oxygen forms from Ru/Se and, to a large extent, from Ru/S. We therefore conclude that Ru metal is protected against oxidation to Ru oxides by the chalcogens additives. The voltammetric treatment in the 0.00 and 0.75 V range also removed the SeO{sub 2} or SO {sub x} forms leaving anionic/elemental Se or S on the surface. Upon larger amplitude voltammetric cycling, from 0.00 to 1.20 V versus RHE, both Se and S were dissolved and the dissolution process was coincidental with the oxygen growth in/on the Ru samples.

  18. Chalcogenide oxygen reduction reaction catalysis: X-ray photoelectron spectroscopy with Ru, Ru/Se and Ru/S samples emersed from aqueous media

    International Nuclear Information System (INIS)

    Lewera, A.; Inukai, J.; Zhou, W.P.; Cao, D.; Duong, H.T.; Alonso-Vante, N.; Wieckowski, A.

    2007-01-01

    Oxygen reduction Ru/Se and Ru/S fuel cell surface chalcogenide catalysts were prepared via chemical reaction of reduced Ru nanoparticles with selenium and sulfur in xylenes [D. Cao, A. Wieckowski, J. Inukai, N. Alonso-Vante, J. Electrochem. Soc. 153 (2006) A869]. The chalcogenide samples - as well as the starting chalcogens-free Ru nanoparticle material - were immobilized on a gold disk for X-ray Photoelectron Spectroscopy (XPS) characterization. While we found oxygen in most of the samples, predominantly from Ru oxides, we conclude that the oxygen on Ru/S may be located in subsurface sites: the subsurface oxygen. We also found that the transformation of the oxidized Ru black to metallic Ru required intensive electrochemical treatment, including hydrogen evolution. In contrast, five cyclic voltammetric scans in the potential range from 0.00 and 0.75 V versus RHE were sufficient to remove the oxygen forms from Ru/Se and, to a large extent, from Ru/S. We therefore conclude that Ru metal is protected against oxidation to Ru oxides by the chalcogens additives. The voltammetric treatment in the 0.00 and 0.75 V range also removed the SeO 2 or SO x forms leaving anionic/elemental Se or S on the surface. Upon larger amplitude voltammetric cycling, from 0.00 to 1.20 V versus RHE, both Se and S were dissolved and the dissolution process was coincidental with the oxygen growth in/on the Ru samples

  19. Synthesis and characterization of PtRu/C catalysts obtained by colloidal and deposition methods for fuel cell applications

    Directory of Open Access Journals (Sweden)

    Egberto Gomes Franco

    2005-06-01

    Full Text Available The purpose of this investigation was to compare catalysts produced by the Bönnemann - colloidal method (PtRu (B1 and PtRu (B2, and those produced by the spontaneous deposition method (PtRu (SD. The catalysts produced by both methods had good electrochemical behavior for methanol oxidation for proton exchange membrane fuel cell applications. The structure of the catalyst was examined by transmission electron microscopy (TEM. Energy dispersive spectroscopic analysis (EDS was used to determine the semi-quantitative composition of the catalysts, and the electrochemical behavior was determined by cyclic voltammetry (CV. The diffractograms of the binary catalysts revealed platinum and ruthenium as the only crystalline phases, as per ICDD data base. The PtRu (B1 catalyst, treated in a reducing atmosphere, has the same structure as PtRu (B2, treated in an oxidising/reducing atmosphere, except that the crystallite size was around 1.7 nm for PtRu (B1 instead of 9.9 nm for PtRu (B2. The catalysts PtRu (B2 and PtRu (SD showed similar cyclic voltammetric behavior, which was better than that of PtRu (B1. Both methods are suitable for the production of electrocatalysts for fuel cell applications. The colloidal method is more expensive than the deposition method, but the former permits the production of ternary and quaternary catalyst systems with enhanced CO tolerance.

  20. NOVEL RU-NI-S ELECTRODE CATALYST FOR PEMFC

    Science.gov (United States)

    The expected results from this project include: a new formula and preparation procedures for Ru-Ni-S catalyst; demonstration of CO and S tolerance of the new catalyst; a small size PEMFC with Ru-Ni-S catalyst and good performance; an...

  1. Electrochemical kinetics and X-ray absorption spectroscopy investigations of select chalcogenide electrocatalysts for oxygen reduction reaction applications

    International Nuclear Information System (INIS)

    Ziegelbauer, Joseph M.; Murthi, Vivek S.; O'Laoire, Cormac; Gulla, Andrea F.; Mukerjee, Sanjeev

    2008-01-01

    Transition metal-based chalcogenide electrocatalysts exhibit a promising level of performance for oxygen reduction reaction applications while offering significant economic benefits over the state of the art Pt/C systems. The most active materials are based on Ru x Se y clusters, but the toxicity of selenium will most likely limit their embrace by the marketplace. Sulfur-based analogues do not suffer from toxicity issues, but suffer from substantially less activity and stability than their selenium brethren. The structure/property relationships that result in these properties are not understood due to ambiguities regarding the specific morphologies of Ru x S y -based chalcogenides. To clarify these properties, an electrochemical kinetics study was interpreted in light of extensive X-ray diffraction, scanning electron microscopy, and in situ X-ray absorption spectroscopy evaluations. The performance characteristics of ternary M x Ru y S z /C (M = Mo, Rh, or Re) chalcogenide electrocatalysts synthesized by the now-standard low-temperature nonaqueous (NA) route are compared to commercially available (De Nora) Rh- and Ru-based systems. Interpretation of performance differences is made in regards to bulk and surface properties of these systems. In particular, the overall trends of the measured activation energies in respect to increasing overpotential and the gross energy values can be explained in regards to these differences

  2. WC as a non-platinum hydrogen evolution electrocatalyst for high temperature PEM water electrolysers

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey; Petrushina, Irina; Christensen, Erik

    2012-01-01

    Tungsten carbide (WC) nanopowder was tested as a non-platinum cathode electrocatalyst for polymer electrolyte membrane (PEM) water electrolysers, operating at elevated temperatures. It was prepared in thermal plasma reactor with confined plasma jet from WO3 precursor in combination with CH4...

  3. MnO2/MCMB electrocatalyst for all solid-state alkaline zinc-air cells

    International Nuclear Information System (INIS)

    Zhang, G.Q.; Zhang, X.G.

    2004-01-01

    Nanostructured MnO 2 /mesocarbon microbeads (MCMB) composite has been prepared successfully for use in zinc-air cell as electrocatalyst for oxygen reaction. The scanning electron microscope (SEM) images showed that the MnO 2 nanorods were formed and covered on the surface of MCMB in bird's nest morphology. X-ray diffraction (XRD) pattern indicated that the MnO 2 has the hollandite structure with a composition approximating KMn 8 O 16 . By the cathodic polarization curve tests, the nanostructured material demonstrated excellent electrocatalytic activity as a kind of oxygen electrode electrocatalyst compared with electrolytic MnO 2 . An all solid-state zinc-air cell has been fabricated with this material as electrocatalyst for oxygen electrode and potassium salt of cross-linked poly(acrylic acid) as an alkaline polymer gel electrolyte. The cell has good discharge characteristics at room temperature

  4. Ru-assisted synthesis of Pd/Ru nanodendrites with high activity for ethanol electrooxidation

    Science.gov (United States)

    Zhang, Ke; Bin, Duan; Yang, Beibei; Wang, Caiqin; Ren, Fangfang; Du, Yukou

    2015-07-01

    Due to the specific physical and chemical properties of a highly branched noble metal, the controllable synthesis has attracted much attention. This article reports the synthesis of Pd/Ru nanodendrites by a facile method using an oil bath in the presence of polyvinyl pyrrolidone, potassium bromide and ascorbic acid. The morphology, structure, and composition of the as-prepared catalysts were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. In the electrochemical measurement, the as-prepared Pd7/Ru1 bimetallic nanodendrites provide a large electrochemically active surface area and exhibit high peak current density in the forward scan toward ethanol electrooxidation, which is nearly four times higher than those of a pure Pd catalyst. The as-prepared Pd7/Ru1 catalysts also exhibit significantly enhanced cycling stability toward ethanol oxidation in alkaline medium, which are mainly ascribed to the synergetic effect between Pd and Ru. This indicates that the Pd7/Ru1 catalysts should have great potential applications in direct ethanol fuel cells.Due to the specific physical and chemical properties of a highly branched noble metal, the controllable synthesis has attracted much attention. This article reports the synthesis of Pd/Ru nanodendrites by a facile method using an oil bath in the presence of polyvinyl pyrrolidone, potassium bromide and ascorbic acid. The morphology, structure, and composition of the as-prepared catalysts were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. In the electrochemical measurement, the as-prepared Pd7/Ru1 bimetallic nanodendrites provide a large electrochemically active surface area and exhibit high peak current density in the forward scan toward ethanol electrooxidation, which is nearly four times higher than those of a pure Pd catalyst. The as-prepared Pd7/Ru1 catalysts also exhibit significantly

  5. Ultrathin nitrogen-doped graphitized carbon shell encapsulating CoRu bimetallic nanoparticles for enhanced electrocatalytic hydrogen evolution

    Science.gov (United States)

    Xu, You; Li, Yinghao; Yin, Shuli; Yu, Hongjie; Xue, Hairong; Li, Xiaonian; Wang, Hongjing; Wang, Liang

    2018-06-01

    Design of highly active and cost-effective electrocatalysts is very important for the generation of hydrogen by electrochemical water-splitting. Herein, we report the fabrication of ultrathin nitrogen-doped graphitized carbon shell encapsulating CoRu bimetallic nanoparticles (CoRu@NCs) and demonstrate their promising feasibility for efficiently catalyzing the hydrogen evolution reaction (HER) over a wide pH range. The resultant CoRu@NC nanohybrids possess an alloy–carbon core–shell structure with encapsulated low-ruthenium-content CoRu bimetallic alloy nanoparticles (10–30 nm) as the core and ultrathin nitrogen-doped graphitized carbon layers (2–6 layers) as the shell. Remarkably, the optimized catalyst (CoRu@NC-2 sample) with a Ru content as low as 2.04 wt% shows superior catalytic activity and excellent durability for HER in acidic, neutral, and alkaline conditions. This work offers a new method for the design and synthesis of non-platium-based electrocatalysts for HER in all-pH.

  6. Design of oxide electrocatalysts for efficient conversion of CO2 into liquid fuels

    DEFF Research Database (Denmark)

    Bhowmik, Arghya

    catalyst development have obtained limited success due to adsorbate scaling relations on metallic surfaces. Preliminary experimental results indicate rutile oxide catalysts are active at very low overpotential, although the scientific understanding is missing. This thesis aims at delivering knowledge....... It is concluded that under experimental condition, CO* coverage is necessary for methanol evolution from RuO2 electrocatalyst, but very high coverage lead to evolution of formic acid and hydrogen together. Building on the understanding of descriptors for CO2RR activity and CO* spectator effects, a new method...... metal atom composition as well as different CO* coverages is done. It is identified that monolayer or lesser amount of iridium oxide on RuO2 catalyst can have a methanol onset potential of -0.2 V below RHE. This is attributed to a combination of ligand effect and adsorbate interaction. Through...

  7. Synthesis of highly active and dual-functional electrocatalysts for methanol oxidation and oxygen reduction reactions

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Qi; Zhang, Geng; Xu, Guangran; Li, Yingjun [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Liu, Baocang [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Gong, Xia [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Zheng, Dafang [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Zhang, Jun [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Wang, Qin, E-mail: qinwang@imu.edu.cn [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China)

    2016-12-15

    Graphical abstract: Ternary RuMPt (M = Fe, Co, Ni, and Cu) nanodendrities (NDs) catalysts, are successfully synthesized by using a facile method. The as-obtained ternary catalysts manifest superior catalytic activity and stability both in terms of surface and mass specific activities toward the methanol oxidation and oxygen reduction reactions, as compared to the binary catalysts and the commercial Pt/C catalysts. - Highlights: • Ternary RuMPt catalysts are synthesized by using a facile method. • The catalysts manifest superior catalytic activity towards the MOR and ORR. • High activities are attributed to enhanced electron density and synergistic effects. - Abstract: The promising Pt-based ternary catalyst is crucial for polymer electrolyte membrane fuel cells (PEMFCs) due to improving catalytic activity and durability for both methanol oxidation reaction and oxygen reduction reaction. In this work, a facile strategy is used for the synthesis ternary RuMPt (M = Fe, Co, Ni, and Cu) nanodendrities catalysts. The ternary RuMPt alloys exhibit enhanced specific and mass activity, positive half-wave potential, and long-term stability, compared with binary Pt-based alloy and the commercial Pt/C catalyst, which is attributed to the high electron density and upshifting of the d-band center for Pt atoms, and synergistic catalytic effects among Pt, M, and Ru atoms by introducing a transition metal. Impressively, the ternary RuCoPt catalyst exhibits superior mass activity (801.59 mA mg{sup −1}) and positive half-wave potential (0.857 V vs. RHE) towards MOR and ORR, respectively. Thus, the RuMPt nanocomposite is a very promising material to be used as dual electrocatalyst in the application of PEMFCs.

  8. Photovoltaic Performance and Characteristics of Dye-Sensitized Solar Cells Prepared with the N719 Thermal Degradation Products Ru(LH)(2)(NCS)(4-tert-butylpyridine) N(Bu)(4) and Ru(LH)(2)(NCS)(1-methylbenzimidazole) N(Bu)(4)

    DEFF Research Database (Denmark)

    Nguyen, P. T.; Binh, X. T. L.; Andersen, A. R.

    2011-01-01

    The dye-sensitized solar cell N719 thermal degradation products [Ru(LH)(2)(NCS)(4-tert-butylpyridine)][N(Bu)(4)] (1) and [Ru(LH)(2)(NCS)(1-methylbenzimidazole)][N(Bu)(4)] (2) were synthesized from [Ru(LH)(2)(NCS)(2)][N(Bu)(4)](2) (N719), (L = 2,2'-bipyridyl-4,4'-dicarboxylic acid) and characterized...

  9. The pH Sensing Properties of RF Sputtered RuO2 Thin-Film Prepared Using Different Ar/O2 Flow Ratio

    Directory of Open Access Journals (Sweden)

    Ali Sardarinejad

    2015-06-01

    Full Text Available The influence of the Ar/O2 gas ratio during radio frequency (RF sputtering of the RuO2 sensing electrode on the pH sensing performance is investigated. The developed pH sensor consists in an RF sputtered ruthenium oxide thin-film sensing electrode, in conjunction with an electroplated Ag/AgCl reference electrode. The performance and characterization of the developed pH sensors in terms of sensitivity, response time, stability, reversibility, and hysteresis are investigated. Experimental results show that the pH sensor exhibits super-Nernstian slopes in the range of 64.33–73.83 mV/pH for Ar/O2 gas ratio between 10/0–7/3. In particular, the best pH sensing performance, in terms of sensitivity, response time, reversibility and hysteresis, is achieved when the Ar/O2 gas ratio is 8/2, at which a high sensitivity, a low hysteresis and a short response time are attained simultaneously.

  10. A model system for carbohydrates interactions on single-crystalline Ru surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thanh Nam

    2015-07-01

    In this thesis, I present a model system for carbohydrate interactions with single-crystalline Ru surfaces. Geometric and electronic properties of copper phthalocyanine (CuPc) on top of graphene on hexagonal Ru(0001), rectangular Ru(10 anti 10) and vicinal Ru(1,1, anti 2,10) surfaces have been studied. First, the Fermi surfaces and band structures of the three Ru surfaces were investigated by high-resolution angle-resolved photoemission spectroscopy. The experimental data and theoretical calculations allow to derive detailed information about the momentum-resolved electronic structure. The results can be used as a reference to understand the chemical and catalytic properties of Ru surfaces. Second, graphene layers were prepared on the three different Ru surfaces. Using low-energy electron diffraction and scanning tunneling microscopy, it was found that graphene can be grown in well-ordered structures on all three surfaces, hexagonal Ru(0001), rectangular Ru(10 anti 10) and vicinal Ru(1,1, anti 2,10), although they have different surface symmetries. Evidence for a strong interaction between graphene and Ru surfaces is a 1.3-1.7 eV increase in the graphene π-bands binding energy with respect to free-standing graphene sheets. This energy variation is due to the hybridization between the graphene pi bands and the Ru 4d electrons, while the lattice mismatch does not play an important role in the bonding between graphene and Ru surfaces. Finally, the geometric and electronic structures of CuPc on Ru(10 anti 10), graphene/Ru(10 anti 10), and graphene/Ru(0001) have been studied in detail. CuPc molecules can be grown well-ordered on Ru(10 anti 10) but not on Ru(0001). The growth of CuPc on graphene/Ru(10 anti 10) and Ru(0001) is dominated by the Moire pattern of graphene. CuPc molecules form well-ordered structures with rectangular unit cells on graphene/Ru(10 anti 10) and Ru(0001). The distance of adjacent CuPc molecules is 15±0.5 Aa and 13±0.5 Aa on graphene/Ru(0001

  11. Biodistribution of Ru-97-labeled DTPA, DMSA and transferrin

    International Nuclear Information System (INIS)

    Som, P.; Oster, Z.H.; Fairchild, R.G.; Atkins, H.L.; Brill, A.B.; Gil, M.C.; Srivastava, S.C.; Meinken, G.E.; Goldman, A.G.; Richards, P.

    1980-01-01

    Ruthenium-97 is being produced at the Brookhaven Linac Isotope Producer (BLIP). The favorable physical properties of Ru-97 and chemical reactivity of ruthenium offer a potential for using this isotope to label compounds useful for delayed scanning. Diethylenetriamine pentaacetic acid (DTPA), 2,3-Dimercaptosuccinic acid (DMSA), and Transferrin (TF) were labeled with Ru-97-chloride. Ru-97-DTPA and In-111-DTPA, injected intravenously, showed similar organ distribution, kinetics, and more than 80% excretion by 0.5 h. Ru-97-DTPA and In-111-DTPA injected into the cisterna magna of dogs showed similar kinetics in brain, blood, and urinary bladder. The energy deposited by 1 mCi In-111-DTPA is twice that from 1 mCi Ru-97-DTPA. High quality camera images of the CSF space in the dog were obtained with both isotopes. Ru-97-DMSA was prepared with and without the addition of SnCl 2 .2H 2 O. Tin-free DMSA was rapidly excreted via the kidneys, whereas for maximum cortical deposition, the tin-containing preparation was superior. This compound is suitable for delayed imaging of both normal and impaired kidneys. Tissue distribution studies were performed in abscess-bearing rats with Ru-97-transferrin. Although blood levels were higher than with Ga-67-citrate, the abscess had twice as much Ru-97-TF as Ga-67-citrate and the Ru-97 muscle activity was one-third that of Ga-67. Imaging of abscess-bearing rabbits with Ru-97-TF visualized the abscesses as early as 1/2 hr after injection. Since the initial images visualize the abscess so clearly and since the TF portion of the compound binds to the abscess, Tc-99m-TF is being studied for the same purpose. Ru-97-labeled compounds are a promising replacement for In-111 and possibly also for Ga-67 compounds with the advantages of lower radiation dose and high quality image

  12. A highly durable fuel cell electrocatalyst based on double-polymer-coated carbon nanotubes.

    Science.gov (United States)

    Berber, Mohamed R; Hafez, Inas H; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2015-11-23

    Driven by the demand for the commercialization of fuel cell (FC) technology, we describe the design and fabrication of a highly durable FC electrocatalyst based on double-polymer-coated carbon nanotubes for use in polymer electrolyte membrane fuel cells. The fabricated electrocatalyst is composed of Pt-deposited polybenzimidazole-coated carbon nanotubes, which are further coated with Nafion. By using this electrocatalyst, a high FC performance with a power density of 375 mW/cm(2) (at 70 ˚C, 50% relative humidity using air (cathode)/H2(anode)) was obtained, and a remarkable durability of 500,000 accelerated potential cycles was recorded with only a 5% loss of the initial FC potential and 20% loss of the maximum power density, which were far superior properties compared to those of the membrane electrode assembly prepared using carbon black in place of the carbon nanotubes. The present study indicates that the prepared highly durable fuel cell electrocatalyst is a promising material for the next generation of PEMFCs.

  13. Newly designed PdRuBi/N-Graphene catalysts with synergistic effects for enhanced ethylene glycol electro-oxidation

    International Nuclear Information System (INIS)

    Li, Tengfei; Huang, Yiyin; Ding, Kui; Wu, Peng; Abbas, Syed Comail; Ghausi, Muhammad Arsalan; Zhang, Teng; Wang, Yaobing

    2016-01-01

    Graphical abstract: We rationally design and synthesize a ternary PdRuBi/NG catalyst with significantly enhanced catalytic activity with synergetic effect of Ru and Bi towards ethylene glycol electro-oxidation. - Abstract: Palladium (Pd)-based catalysts are appealing electro-catalysts for alcohol oxidation reaction in fuel cell, but still not efficient as the complicated oxidation process and sluggish kinetic. Here we rationally design and synthesize a PdRuBi/NG tri-metallic catalyst with space synergetic effect for enhanced ethylene glycol electro-oxidation, in which both Ru and Bi in the catalyst are synergistic effective in promoting catalytic activity of Pd catalytic interlayer by electronic effect and surface modification mechanism respectively. It shows 4.2 times higher peak current density towards ethylene glycol electro-oxidation than commercial Pd/C catalyst, and the catalytic durability is also greatly improved.

  14. A new preparation of a bifunctional crystalline heterogeneous copper electrocatalyst by electrodeposition using a Robson-type macrocyclic dinuclear copper complex for efficient hydrogen and oxygen evolution from water.

    Science.gov (United States)

    Majumder, Samit; Abdel Haleem, Ashraf; Nagaraju, Perumandla; Naruta, Yoshinori

    2017-07-18

    The development of low-cost, stable bifunctional electrocatalysts, which operate in the same electrolyte with a low overpotential for water splitting, including the oxygen evolution reaction and the hydrogen evolution reaction, remains an attractive prospect and a great challenge. In this study, a water soluble Robson-type macrocyclic dicopper(ii) complex has been used for the first time as a catalyst precursor for the generation of a copper-based bifunctional heterogeneous catalyst film, which can be used for both HER and OER at a near neutral pH. In sodium borate buffer at pH 9.20, this complex decomposed to give a Cu(OH) 2 /Cu 2 O-based thin film on FTO that catalyzes both hydrogen production and water oxidation. The morphology, nature and composition of the thin film were fully characterized by scanning electron microscopy, powder X-ray diffraction, X-ray photoelectron, and energy dispersive X-ray spectroscopies. The catalyst film showed high stability during the course of electrolysis in either the cathodic or the anodic direction for more than 4 h. Faradaic efficiencies of ∼92% for HER and ∼96% for OER were achieved. The switch between the two half-reactions of catalytic water splitting was fully reversible in nature.

  15. Two crystalline modifications of RuO4

    International Nuclear Information System (INIS)

    Pley, Martin; Wickleder, Mathias S.

    2005-01-01

    RuO 4 was prepared by oxidation of elemental ruthenium. Two different modifications were obtained and investigated by X-ray single crystal diffraction. RuO 4 -I has cubic symmetry (P4; - 3n,Z=8,a=8.509(1)A), and two independent tetrahedral molecules are present in the unit cell. Within the standard uncertainties in both molecules the distances Ru-O are 1.695A. The second modification, RuO 4 -II, is monoclinic (C2/c,Z=4,a=9.302(4)A,b=4.3967(10)A,c=8.454(4)A,β=116.82(3) o ) and isotypic with OsO 4 . There is one independent molecule in the unit cell, which shows distances Ru-O of 1.697 and 1.701A, respectively

  16. Inelastic scattering on 100Ru

    International Nuclear Information System (INIS)

    Sirota, S.

    1987-01-01

    Aspects of the nuclear structure of 100 Ru whe investigated by means of the scattering of 100 Ru (p,p') 100 Ru* with 16 MeV protons, where 21 states were investigated. The emergent protons were analysed by a magnetic spectrograph, of the enge type with a typical resolution of ≅ 9 KeV. (A.C.A.S.) [pt

  17. Nanostructured carbon-supported Pd electrocatalysts for ethanol oxidation: synthesis and characterization

    International Nuclear Information System (INIS)

    Gacutan, E M; Tongol, B J; Climaco, M I; Telan, G J; Malijan, F; Hsu, H Y; Garcia, J; Fulo, H

    2012-01-01

    The need to lower the construction cost of fuel cells calls for the development of non-Pt based electrocatalysts. Among others, Pd has emerged as a promising alternative to Pt for fuel cell catalysis. This research aims to investigate the synthesis and characterization of nanostructured Pd-based catalysts dispersed on carbon support as anode materials in direct ethanol fuel cells. For the preparation of the first Pd-based electrocatalyst, palladium nanoparticles (NPs) were synthesized via oleylamine (OAm)-mediated synthesis and precursor method with a mean particle size of 3.63 ± 0.59 nm as revealed by transmission electron microscopy (TEM). Carbon black was used as a supporting matrix for the OAm-capped Pd NPs. Thermal annealing and acetic acid washing were used to remove the OAm capping agent. To evaluate the electrocatalytic activity of the prepared electrocatalyst towards ethanol oxidation, cyclic voltammetry (CV) studies were performed using 1.0 M ethanol in basic medium. The CV data revealed the highest peak current density of 11.05 mA cm −2 for the acetic acid-washed Pd/C electrocatalyst. Meanwhile, the fabrication of the second Pd-based electrocatalyst was done by functionalization of the carbon black support using 3:1 (v/v) H 2 SO 4 :HNO 3 . The metal oxide, NiO, was deposited using precipitation method while polyol method was used for the deposition of Pd NPs. X-ray diffraction (XRD) analysis revealed that the estimated particle size of the synthesized catalysts was at around 9.0–15.0 nm. CV results demonstrated a 36.7% increase in the catalytic activity of Pd–NiO/C (functionalized) catalyst towards ethanol oxidation compared to the non-functionalized catalyst. (paper)

  18. Nanostructured carbon-supported Pd electrocatalysts for ethanol oxidation: synthesis and characterization

    Science.gov (United States)

    Gacutan, E. M.; Climaco, M. I.; Telan, G. J.; Malijan, F.; Hsu, H. Y.; Garcia, J.; Fulo, H.; Tongol, B. J.

    2012-12-01

    The need to lower the construction cost of fuel cells calls for the development of non-Pt based electrocatalysts. Among others, Pd has emerged as a promising alternative to Pt for fuel cell catalysis. This research aims to investigate the synthesis and characterization of nanostructured Pd-based catalysts dispersed on carbon support as anode materials in direct ethanol fuel cells. For the preparation of the first Pd-based electrocatalyst, palladium nanoparticles (NPs) were synthesized via oleylamine (OAm)-mediated synthesis and precursor method with a mean particle size of 3.63 ± 0.59 nm as revealed by transmission electron microscopy (TEM). Carbon black was used as a supporting matrix for the OAm-capped Pd NPs. Thermal annealing and acetic acid washing were used to remove the OAm capping agent. To evaluate the electrocatalytic activity of the prepared electrocatalyst towards ethanol oxidation, cyclic voltammetry (CV) studies were performed using 1.0 M ethanol in basic medium. The CV data revealed the highest peak current density of 11.05 mA cm-2 for the acetic acid-washed Pd/C electrocatalyst. Meanwhile, the fabrication of the second Pd-based electrocatalyst was done by functionalization of the carbon black support using 3:1 (v/v) H2SO4:HNO3. The metal oxide, NiO, was deposited using precipitation method while polyol method was used for the deposition of Pd NPs. X-ray diffraction (XRD) analysis revealed that the estimated particle size of the synthesized catalysts was at around 9.0-15.0 nm. CV results demonstrated a 36.7% increase in the catalytic activity of Pd-NiO/C (functionalized) catalyst towards ethanol oxidation compared to the non-functionalized catalyst.

  19. Advancing semiconductor-electrocatalyst systems: application of surface transformation films and nanosphere lithography.

    Science.gov (United States)

    Brinkert, Katharina; Richter, Matthias H; Akay, Ömer; Giersig, Michael; Fountaine, Katherine T; Lewerenz, Hans-Joachim

    2018-05-24

    Photoelectrochemical (PEC) cells offer the possibility of carbon-neutral solar fuel production through artificial photosynthesis. The pursued design involves technologically advanced III-V semiconductor absorbers coupled via an interfacial film to an electrocatalyst layer. These systems have been prepared by in situ surface transformations in electrochemical environments. High activity nanostructured electrocatalysts are required for an efficiently operating cell, optimized in their optical and electrical properties. We demonstrate that shadow nanosphere lithography (SNL) is an auspicious tool to systematically create three-dimensional electrocatalyst nanostructures on the semiconductor photoelectrode through controlling their morphology and optical properties. First results are demonstrated by means of the photoelectrochemical production of hydrogen on p-type InP photocathodes where hitherto applied photoelectrodeposition and SNL-deposited Rh electrocatalysts are compared based on their J-V and spectroscopic behavior. We show that smaller polystyrene particle masks achieve higher defect nanostructures of rhodium on the photoelectrode which leads to a higher catalytic activity and larger short circuit currents. Structural analyses including HRSEM and the analysis of the photoelectrode surface composition by using photoelectron spectroscopy support and complement the photoelectrochemical observations. The optical performance is further compared to theoretical models of the nanostructured photoelectrodes on light scattering and propagation.

  20. Elaboration of a Highly Porous RuII,II Analogue of HKUST-1.

    Science.gov (United States)

    Zhang, Wenhua; Freitag, Kerstin; Wannapaiboon, Suttipong; Schneider, Christian; Epp, Konstantin; Kieslich, Gregor; Fischer, Roland A

    2016-12-19

    When the dinuclear Ru II,II precursor [Ru 2 (OOCCH 3 ) 4 ] is employed under redox-inert conditions, a Ru II,II analogue of HKUST-1 was successfully prepared and characterized as a phase-pure microcrystalline powder. X-ray absorption near-edge spectroscopy confirms the oxidation state of the Ru centers of the paddle-wheel nodes in the framework. The porosity of 1371 m 2 /mmol of Ru II,II -HKUST-1 exceeds that of the parent compound HKUST1 (1049 m 2 / mmol).

  1. Combinatorial discovery of new methanol-tolerant non-noble metal cathode electrocatalysts for direct methanol fuel cells.

    Science.gov (United States)

    Yu, Jong-Sung; Kim, Min-Sik; Kim, Jung Ho

    2010-12-14

    Combinatorial synthesis and screening were used to identify methanol-tolerant non-platinum cathode electrocatalysts for use in direct methanol fuel cells (DMFCs). Oxygen reduction consumes protons at the surface of DMFC cathode catalysts. In combinatorial screening, this pH change allows one to differentiate active catalysts using fluorescent acid-base indicators. Combinatorial libraries of carbon-supported catalyst compositions containing Ru, Mo, W, Sn, and Se were screened. Ternary and quaternary compositions containing Ru, Sn, Mo, Se were more active than the "standard" Alonso-Vante catalyst, Ru(3)Mo(0.08)Se(2), when tested in liquid-feed DMFCs. Physical characterization of the most active catalysts by powder X-ray diffraction, gas adsorption, and X-ray photoelectron spectroscopy revealed that the predominant crystalline phase was hexagonal close-packed (hcp) ruthenium, and showed a surface mostly covered with oxide. The best new catalyst, Ru(7.0)Sn(1.0)Se(1.0), was significantly more active than Ru(3)Se(2)Mo(0.08), even though the latter contained smaller particles.

  2. Nanostructured electrocatalyst for fuel cells : silica templated synthesis of Pt/C composites.

    Energy Technology Data Exchange (ETDEWEB)

    Stechel, Ellen Beth; Switzer, Elise E.; Fujimoto, Cy H.; Atanassov, Plamen Borissov; Cornelius, Christopher James; Hibbs, Michael R.

    2007-09-01

    Platinum-based electrocatalysts are currently required for state-of-the-art fuel cells and represent a significant portion of the overall fuel cell cost. If fuel cell technology is to become competitive with other energy conversion technologies, improve the utilization of precious metal catalysts is essential. A primary focus of this work is on creating enhanced nanostructured materials which improve precious-metal utilization. The goal is to engineer superior electrocatalytic materials through the synthesis, development and investigation of novel templated open frame structures synthesized in an aerosol-based approach. Bulk templating methods for both Pt/C and Pt-Ru composites are evaluated in this study and are found to be limited due to the fact that the nanostructure is not maintained throughout the entire sample. Therefore, an accurate examination of structural effects was previously impossible. An aerosol-based templating method of synthesizing nanostructured Pt-Ru electrocatalysts has been developed wherein the effects of structure can be related to electrocatalytic performance. The aerosol-based templating method developed in this work is extremely versatile as it can be conveniently modified to synthesize alternative materials for other systems. The synthesis method was able to be extended to nanostructured Pt-Sn for ethanol oxidation in alkaline media. Nanostructured Pt-Sn electrocatalysts were evaluated in a unique approach tailored to electrocatalytic studies in alkaline media. At low temperatures, nanostructured Pt-Sn electrocatalysts were found to have significantly higher ethanol oxidation activity than a comparable nanostructured Pt catalyst. At higher temperatures, the oxygen-containing species contribution likely provided by Sn is insignificant due to a more oxidized Pt surface. The importance of the surface coverage of oxygen-containing species in the reaction mechanism is established in these studies. The investigations in this work present

  3. Ru nanostructure fabrication using an anodic aluminum oxide nanotemplate and highly conformal Ru atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Woo-Hee; Park, Sang-Joon; Son, Jong-Yeog; Kim, Hyungjun [Department of Material Science and Engineering, POSTECH Pohang University of Science and Technology, San 31, Hyoja-Dong, Nam-Gu, Pohang 790-784 (Korea, Republic of)

    2008-01-30

    We fabricated metallic nanostructures directly on Si substrates through a hybrid nanoprocess combining atomic layer deposition (ALD) and a self-assembled anodic aluminum oxide (AAO) nanotemplate. ALD Ru films with Ru(DMPD)(EtCp) as a precursor and O{sub 2} as a reactant exhibited high purity and low resistivity with negligible nucleation delay and low roughness. These good growth characteristics resulted in the excellent conformality for nanometer-scale vias and trenches. Additionally, AAO nanotemplates were fabricated directly on Si and Ti/Si substrates through a multiple anodization process. AAO nanotemplates with various hole sizes (30-100 nm) and aspect ratios (2:1-20:1) were fabricated by controlling the anodizing process parameters. The barrier layers between AAO nanotemplates and Si substrates were completely removed by reactive ion etching (RIE) using BCl{sub 3} plasma. By combining the ALD Ru and the AAO nanotemplate, Ru nanostructures with controllable sizes and shapes were prepared on Si and Ti/Si substrates. The Ru nanowire array devices as a platform for sensor devices exhibited befitting properties of good ohmic contact and high surface/volume ratio.

  4. Hollow Au@Pd and Au@Pt core-shell nanoparticles as electrocatalysts for ethanol oxidation reactions

    KAUST Repository

    Song, Hyon Min; Anjum, Dalaver H.; Sougrat, Rachid; Hedhili, Mohamed N.; Khashab, Niveen M.

    2012-01-01

    that individual metals may not catalyze. Here, preparation of hollow Au@Pd and Au@Pt core-shell nanoparticles (NPs) and their use as electrocatalysts are reported. Galvanic displacement with Ag NPs is used to obtain hollow NPs, and higher reduction potential of Au

  5. Tin-oxide-coated single-walled carbon nanotube bundles supporting platinum electrocatalysts for direct ethanol fuel cells

    International Nuclear Information System (INIS)

    Hsu, Ryan S; Higgins, Drew; Chen Zhongwei

    2010-01-01

    Novel tin-oxide (SnO 2 )-coated single-walled carbon nanotube (SWNT) bundles supporting platinum (Pt) electrocatalysts for ethanol oxidation were developed for direct ethanol fuel cells. SnO 2 -coated SWNT (SnO 2 -SWNT) bundles were synthesized by a simple chemical-solution route. SnO 2 -SWNT bundles supporting Pt (Pt/SnO 2 -SWNTs) electrocatalysts and SWNT-supported Pt (Pt/SWNT) electrocatalysts were prepared by an ethylene glycol reduction method. The catalysts were physically characterized using TGA, XRD and TEM and electrochemically evaluated through cyclic voltammetry experiments. The Pt/SnO 2 -SWNTs showed greatly enhanced electrocatalytic activity for ethanol oxidation in acid medium, compared to the Pt/SWNT. The optimal SnO 2 loading of Pt/SnO 2 -SWNT catalysts with respect to specific catalytic activity for ethanol oxidation was also investigated.

  6. Tin-oxide-coated single-walled carbon nanotube bundles supporting platinum electrocatalysts for direct ethanol fuel cells.

    Science.gov (United States)

    Hsu, Ryan S; Higgins, Drew; Chen, Zhongwei

    2010-04-23

    Novel tin-oxide (SnO(2))-coated single-walled carbon nanotube (SWNT) bundles supporting platinum (Pt) electrocatalysts for ethanol oxidation were developed for direct ethanol fuel cells. SnO(2)-coated SWNT (SnO(2)-SWNT) bundles were synthesized by a simple chemical-solution route. SnO(2)-SWNT bundles supporting Pt (Pt/SnO(2)-SWNTs) electrocatalysts and SWNT-supported Pt (Pt/SWNT) electrocatalysts were prepared by an ethylene glycol reduction method. The catalysts were physically characterized using TGA, XRD and TEM and electrochemically evaluated through cyclic voltammetry experiments. The Pt/SnO(2)-SWNTs showed greatly enhanced electrocatalytic activity for ethanol oxidation in acid medium, compared to the Pt/SWNT. The optimal SnO(2) loading of Pt/SnO(2)-SWNT catalysts with respect to specific catalytic activity for ethanol oxidation was also investigated.

  7. Recent progress in electrocatalysts with mesoporous structures for application in polymer electrolyte membrane fuel cells

    OpenAIRE

    Xing, Wei; Wu, Zucheng; Tao, Shanwen

    2016-01-01

    Recently mesoporous materials have drawn great attention in fuel cell related applications, such as preparation of polymer electrolyte membranes and catalysts, hydrogen storage and purification. In this mini-review, we focus on recent developments in mesoporous electrocatalysts for polymer electrolyte membrane fuel cells, including metallic and metal-free catalysts for use as either anode or cathode catalysts. Mesoporous Pt-based metals have been synthesized as anode catalysts with improved a...

  8. Synthesis and characterization of bimetallic metal-organic framework Cu-Ru-BTC with HKUST-1 structure.

    Science.gov (United States)

    Gotthardt, Meike A; Schoch, Roland; Wolf, Silke; Bauer, Matthias; Kleist, Wolfgang

    2015-02-07

    The bimetallic metal-organic framework Cu-Ru-BTC with the stoichiometric formula Cu2.75Ru0.25(BTC)2·xH2O, which is isoreticular to HKUST-1, was successfully prepared in a direct synthesis using mild reaction conditions. The partial substitution of Cu(2+) by Ru(3+) centers in the paddlewheel structure and the absence of other Ru-containing phases was proven using X-ray absorption spectroscopy.

  9. Particle size dependence of CO tolerance of anode PtRu catalysts for polymer electrolyte fuel cells

    Science.gov (United States)

    Yamanaka, Toshiro; Takeguchi, Tatsuya; Wang, Guoxiong; Muhamad, Ernee Noryana; Ueda, Wataru

    An anode catalyst for a polymer electrolyte fuel cell must be CO-tolerant, that is, it must have the function of hydrogen oxidation in the presence of CO, because hydrogen fuel gas generated by the steam reforming process of natural gas contains a small amount of CO. In the present study, PtRu/C catalysts were prepared with control of the degree of Pt-Ru alloying and the size of PtRu particles. This control has become possible by a new method of heat treatment at the final step in the preparation of catalysts. The CO tolerances of PtRu/C catalysts with the same degree of Pt-Ru alloying and with different average sizes of PtRu particles were thus compared. Polarization curves were obtained with pure H 2 and CO/H 2 (CO concentrations of 500-2040 ppm). It was found that the CO tolerance of highly dispersed PtRu/C (high dispersion (HD)) with small PtRu particles was much higher than that of poorly dispersed PtRu/C (low dispersion (LD)) with large metal particles. The CO tolerance of PtRu/C (HD) was higher than that of any commercial PtRu/C. The high CO tolerance of PtRu/C (HD) is thought to be due to efficient concerted functions of Pt, Ru, and their alloy.

  10. When NiO@Ni Meets WS2 Nanosheet Array: A Highly Efficient and Ultrastable Electrocatalyst for Overall Water Splitting.

    Science.gov (United States)

    Wang, Dewen; Li, Qun; Han, Ce; Xing, Zhicai; Yang, Xiurong

    2018-01-24

    The development of low-cost, high-efficiency, and stable bifunctional electrocatalysts toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of paramount importance for large-scale water splitting. Here, we develop a new strategy for the first design and synthesis of a NiO@Ni decorated WS 2 nanosheet array on carbon cloth (NiO@Ni/WS 2 /CC) composite. This composite serves as a unique three-dimensional (3D) synergistic electrocatalyst that not only combines the intrinsic properties of individual NiO@Ni and WS 2 , but also exhibits significantly improved HER and OER activities when compared to that of pure NiO@Ni and WS 2 . This electrocatalyst possesses Pt-like activity for HER and exhibits better OER performance than that for commercial RuO 2 , as well as demonstrating superior long-term durability in alkaline media. Furthermore, it enables an alkaline electrolyzer with a current density of 10 mA cm -2 at a cell voltage as 1.42 V, which is the lowest one among all reported values to date. The excellent performance is mainly attributed to the unique 3D configuration and multicomponent synergies among NiO, Ni, and WS 2 . Our findings provide a new idea to design advanced bifunctional catalysts for water splitting.

  11. When NiO@Ni Meets WS2 Nanosheet Array: A Highly Efficient and Ultrastable Electrocatalyst for Overall Water Splitting

    Directory of Open Access Journals (Sweden)

    Dewen Wang

    2017-12-01

    Full Text Available The development of low-cost, high-efficiency, and stable bifunctional electrocatalysts toward the hydrogen evolution reaction (HER and oxygen evolution reaction (OER is of paramount importance for large-scale water splitting. Here, we develop a new strategy for the first design and synthesis of a NiO@Ni decorated WS2 nanosheet array on carbon cloth (NiO@Ni/WS2/CC composite. This composite serves as a unique three-dimensional (3D synergistic electrocatalyst that not only combines the intrinsic properties of individual NiO@Ni and WS2, but also exhibits significantly improved HER and OER activities when compared to that of pure NiO@Ni and WS2. This electrocatalyst possesses Pt-like activity for HER and exhibits better OER performance than that for commercial RuO2, as well as demonstrating superior long-term durability in alkaline media. Furthermore, it enables an alkaline electrolyzer with a current density of 10 mA cm–2 at a cell voltage as 1.42 V, which is the lowest one among all reported values to date. The excellent performance is mainly attributed to the unique 3D configuration and multicomponent synergies among NiO, Ni, and WS2. Our findings provide a new idea to design advanced bifunctional catalysts for water splitting.

  12. Oxidation study of Cr-Ru hard coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yung-I, E-mail: yichen@mail.ntou.edu.tw; Kuo, Yu-Chu; Chen, Sin-Min

    2012-01-01

    Cr-Ru alloy coatings with Cr content ranging from 47 to 83 at.% were deposited at 400 Degree-Sign C by direct current magnetron co-sputtering with a Ti interlayer on silicon substrates. With a total input power of 300 W, the Cr content in the Cr-Ru coatings increased linearly with the increasing input power of Cr. The intermetallic compound phase Cr{sub 2}Ru with columnar structure was identified for the as-deposited Cr{sub 56}Ru{sub 44} and Cr{sub 65}Ru{sub 35} coatings, resulting in an increase of hardness up to 15-16 GPa. To evaluate the performance of Cr-Ru coatings as a protective coating on glass molding dies, the annealing treatment was conducted at 600 Degree-Sign C in a 50 ppm O{sub 2}-N{sub 2} atmosphere. The outward diffusion and preferential oxidization of Cr in the Cr-Ru coatings resulted in the variations of the crystalline structure, chemical composition distribution, and surface hardness after annealing. X-ray diffraction and transmission electron microscopy (TEM) proved that an oxide scale consisting of Cr{sub 2}O{sub 3} formed on the free surface. Scanning electron microscopy and TEM observed the surface morphology and structural variation. The chemical composition depth profiles were analyzed by Auger electron microscopy, verifying the presence of a Cr-depleted zone beneath the oxide scale. The hardness of Cr{sub 56}Ru{sub 44} and Cr{sub 65}Ru{sub 35} coatings decreased to 11-12 GPa after annealing, accompanied by the replacement of the Cr{sub 2}Ru phase by the Ru phase. - Highlights: Black-Right-Pointing-Pointer We prepared crystalline Cr-Ru alloy coatings by direct current magnetron sputtering. Black-Right-Pointing-Pointer Cr-Ru coatings were annealed at 600 Degree-Sign C for 2 h in a 50 ppm O{sub 2}-N{sub 2} atmosphere. Black-Right-Pointing-Pointer Cr diffused outwardly and oxidized to form a stable and protective oxide scale. Black-Right-Pointing-Pointer The original columnar grains recrystallized to polycrystalline grains.

  13. Preparation of Sr{sub 2}(MgMo){sub 1-x}Ru{sub x}O{sub 6} ceramics for use in a solid oxide fuel cell anode

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, Matheus Eiji Ohno; Florio, Daniel Zanetti de [Universidade Federal do ABC (UFABC), SP (Brazil); Fonseca, Fabio Coral, E-mail: matheus.eiji@aluno.ufabc.edu.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2016-07-01

    Full text: Solid Oxide Fuel Cells are the most efficient devices known for the direct conversion of fuels into electric energy. Such devices have advanced steadily and are already available for specific applications such as portable power and residential stationary generation. The main objective of this work is the development of anodes for SOFC operating directly with renewable fuels, without the addition of water and using strategic fuels such as ethanol and natural gas. Specifically, a family of mixed ionic-electronic compounds has been investigated: the double perovskites with compositions Sr{sub 2}(MgMo){sub 1-x}Ru{sub x}O{sub 6} with x = 0; 1; 2; 5; 10 e 20 at.%. This material has been synthesized by polymeric precursor method. The resins were prepared by combining stoichiometric amounts of the starting solutions. The resulting solution was heated treated under magnetic stirring. The thermal decomposition of the polymeric resin was studied by means of simultaneous thermogravimetric and differential scanning calorimetry up to 1500 °C with heating and cooling rates of 10 °/min in Ar. The thermal decomposition result shows mass loss up to, approximately, 900 °C. However X-ray diffraction analyses of the powder heat treated at 900 °C and 1200 °C presents a considerable content of an undesiderate phase (SrMoO{sub 4}). According to the literature for similar compounds a thermal treatment under reduction conditions could be necessary to obtain the double perovskites single phase. After this treatment the material will be characterized regarding its electrical properties. The expected results will contribute to advance both the understanding of the mixed ionic electronic ceramics and the SOFC technology using renewable fuels. (author)

  14. Electrodeposited nano-scale islands of ruthenium oxide as a bifunctional electrocatalyst for simultaneous catalytic oxidation of hydrazine and hydroxylamine

    Energy Technology Data Exchange (ETDEWEB)

    Zare, Hamid R., E-mail: hrzare@yazduni.ac.ir [Department of Chemistry, Yazd University, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of); Nanotechnology Research Center, Yazd University, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of); Hashemi, S. Hossein; Benvidi, Ali [Department of Chemistry, Yazd University, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of)

    2010-06-04

    For the first time, an electrodeposited nano-scale islands of ruthenium oxide (ruthenium oxide nanoparticles), as an excellent bifunctional electrocatalyst, was successfully used for hydrazine and hydroxylamine electrocatalytic oxidation. The results show that, at the present bifunctional modified electrode, two different redox couples of ruthenium oxides serve as electrocatalysts for simultaneous electrocatalytic oxidation of hydrazine and hydroxylamine. At the modified electrode surface, the peaks of differential pulse voltammetry (DPV) for hydrazine and hydroxylamine oxidation were clearly separated from each other when they co-exited in solution. Thus, it was possible to simultaneously determine hydrazine and hydroxylamine in the samples at a ruthenium oxide nanoparticles modified glassy carbon electrode (RuON-GCE). Linear calibration curves were obtained for 2.0-268.3 {mu}M and 268.3-417.3 {mu}M of hydrazine and for 4.0-33.8 {mu}M and 33.8-78.3 {mu}M of hydroxylamine at the modified electrode surface using an amperometric method. The amperometric method also exhibited the detection limits of 0.15 {mu}M and 0.45 {mu}M for hydrazine and hydroxylamine respectively. RuON-GCE was satisfactorily used for determination of spiked hydrazine in two water samples. Moreover, the studied bifunctional modified electrode exhibited high sensitivity, good repeatability, wide linear range and long-term stability.

  15. Reactions of ethanol on Ru

    NARCIS (Netherlands)

    Sturm, Jacobus Marinus; Liu, Feng; Lee, Christopher James; Bijkerk, Frederik

    2012-01-01

    The adsorption and reactions of ethanol on Ru(0001) were studied with temperatureprogrammed desorption (TPD) and reflection-absorption infrared spectroscopy (RAIRS). Ethanol was found to adsorb intact onto Ru(0001) below 100 K. Heating to 250 K resulted in formation of ethoxy groups, which undergo

  16. Low Pt content of carbon supported Pt-Ni-TiO2 nanotube electrocatalysts for direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Q.Z; Wu, X.; Ma, Z.F. [Shanghai Jiao Tong Univ., Shanghai, (China). Dept. of Chemical Engineering

    2008-07-01

    Interest in titanium oxide (TiO2) nanomaterial is growing due to their special characteristics for optics, catalysis, and photoelectricity conversion. In this study, the anatase/rutile crystalline of TiO2 nanoparticles was synthesized by co-deposition. TiO2 nanotubes were then obtained by microwave irradiations. This paper described the mechanism to fabricate TiO2 nanotubes. The conditions for preparing TiO2 nanotubes by microwave irradiation were optimized. Electrocatalysts were then prepared on the basis of the synthesized TiO2 nanotube. Their performances were investigated by the electro-oxidation of methanol. When Pt electrocatalysts were doped with a certain content of TiO2 nanotubes, they had more electrocatalytic activity for methanol electro-oxidation, particularly if the second transition metal, such as Ni, was added into the electrocatalyst. The electrocatalysts contained 5 and 10 wt per cent of Pt and Ni respectively. The 10 wt per cent TiO2 nanotubes showed better activities than any other catalysts for methanol electro-oxidation. According to XRD and TEM results, the size of nanoparticles of Pt became smaller after adding TiO2 nanotubes into the catalysts. It was concluded that here might be some interactions between Pt, Ni, and TiO2 nanotubes.

  17. Sonochemical synthesis and characterization of Pt/CNT, Pt/TiO2, and Pt/CNT/TiO2 electrocatalysts for methanol electro-oxidation

    International Nuclear Information System (INIS)

    Bedolla-Valdez, Z.I.; Verde-Gómez, Y.; Valenzuela-Muñiz, A.M.; Gochi-Ponce, Y.; Oropeza-Guzmán, M.T.; Berhault, Gilles; Alonso-Núñez, G.

    2015-01-01

    Highlights: • Pt/CNT/TiO 2 electrocatalyst was successfully prepared by the sonochemical method. • The electrocatalyst Pt/CNT/TiO 2 was synthesized without heat treatments, additives or surfactants. • The TiO 2 -Pt interaction improves the CO-tolerance of Pt/CNT/TiO 2 , as well as the electrocatalyst stability. • Low amount of multi-walled carbon nanotubes increases the current density of Pt/CNT/TiO 2 significantly compared to Pt/TiO 2 . - Abstract: Pt electrocatalyst supported on composite formed of multi-walled carbon nanotubes and titanium oxide (CNT/TiO 2 ) was successfully synthesized by a sonochemical method without heat treatments, surfactants or additives. This electrocatalyst could be used for direct methanol fuel cells (DMFC) applications. For comparison, Pt/CNT and Pt/TiO 2 electrocatalysts were prepared as reference samples. Structural properties and morphology of the synthesized materials were examined by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and their specific surface areas were determined by the Brunauer-Emmett-Teller method. The Pt and acid-treated CNT contents were analyzed by inductively coupled plasma atomic emission spectroscopy and thermogravimetric analysis, respectively. The electrochemical properties of the synthesized electrocatalysts were evaluated by cyclic voltammetry (CV) and chronoamperometry in a three-electrode cell at room temperature. The evaluation performed using electrochemical techniques suggests that TiO 2 promotes the CO-tolerance due to TiO 2 -Pt interaction. The CV tests demonstrated that 6 wt.% of acid-treated CNT increases significantly the current density when Pt selectively interacts with TiO 2 .

  18. A Renewable and Ultrasensitive Electrochemiluminescence Immunosenor Based on Magnetic RuL@SiO2-Au~RuL-Ab2 Sandwich-Type Nano-Immunocomplexes

    Directory of Open Access Journals (Sweden)

    Ning Gan

    2011-08-01

    Full Text Available An ultrasensitive and renewable electrochemiluminescence (ECL immunosensor was developed for the detection of tumor markers by combining a newly designed trace tag and streptavidin-coated magnetic particles (SCMPs. The trace tag (RuL@SiO2-Au~RuL-Ab2 was prepared by loading Ru(bpy32+(RuL-conjuged secondary antibodies (RuL-Ab2 on RuL@SiO2 (RuL-doped SiO2 doped Au (RuL@SiO2-Au. To fabricate the immunosensor, SCMPs were mixed with biotinylated AFP primary antibody (Biotin-Ab1, AFP, and RuL@SiO2-Au~RuL-Ab2 complexes, then the resulting SCMP/Biotin-Ab1/AFP/RuL@SiO2-Au~RuL-Ab2 (SBAR sandwich-type immunocomplexes were absorbed on screen printed carbon electrode (SPCE for detection. The immunocomplexes can be easily washed away from the surface of the SPCE when the magnetic field was removed, which made the immunosensor reusable. The present immunosensor showed a wide linear range of 0.05–100 ng mL–1 for detecting AFP, with a low detection limit of 0.02 ng mL–1 (defined as S/N = 3. The method takes advantage of three properties of the immunosensor: firstly, the RuL@SiO2-Au~RuL-Ab2 composite exhibited dual amplification since SiO2 could load large amount of reporter molecules (RuL for signal amplification. Gold particles could provide a large active surface to load more reporter molecules (RuL-Ab2. Accordingly, through the ECL response of RuL and tripropylamine (TPA, a strong ECL signal was obtained and an amplification analysis of protein interaction was achieved. Secondly, the sensor is renewable because the sandwich-type immunocomplexes can be readily absorbed or removed on the SPCE’s surface in a magnetic field. Thirdly, the SCMP modified probes can perform the rapid separation and purification of signal antibodies in a magnetic field. Thus, the present immunosensor can simultaneously realize separation, enrichment and determination. It showed potential application for the detection of AFP in human sera.

  19. A new and general method for the preparation of novel II-heterocyclic derivatives of ruthenium [C5Me5Ru (η6-arene)]X (arene = benzene, thiophene, 3-methylthiophene, benzothiophene, pyridine, 2.6 and 3.5-lutidine, quinoline, acridine). X-ray crystal structure of [(C5Me5)2Ru2Cl2(pyridine)2] PF6

    International Nuclear Information System (INIS)

    Chaudret, B.; Jalon, F.; Perez-Manrique, M.; Lahoz, F.; Plou, F.J.

    1990-01-01

    Zinc reduction of (Cp*RuCl 2 ) n (Cp* = C 5 Me 5 ) in acetone or THF followed by addition of 1 equivalent of an arene or aromatic heterocycle leads to compounds of general formulation [Cp* Ru(arene)]X (X = Cl, BF 4 ). Coordination of benzene is rapid and competes successfully with any other arene. Thiophene and 3-methylthiophene give stable π adducts whereas benzothiophene is coordinated through the benzene not through the heterocyclic ring. 2.6 and 3.5-lutidine coordinate through the ring, thus demonstrating an electronic rather than steric stabilization. Again, quinoline and acridine coordinate through the benzene ring. Pyridine gives an unstable π adduct in THF. A paramagnetic mixed-valence species, byproduct of the reaction in THF, has been characterized by an X-ray crystal structure determination. Crystals are triclinic, space group P-1

  20. Lutidine-derived Ru-CNC hydrogenation pincer catalysts with versatile coordination properties

    NARCIS (Netherlands)

    Filonenko, Georgy A.; Cosimi, Elena; Lefort, Laurent; Conley, Matthew P.; Copéret, Christophe; Lutz, Martin; Hensen, Emiel J M; Pidko, Evgeny A.

    2014-01-01

    Lutidine-derived bis-N-heterocyclic carbene (NHC) ruthenium CNC-pincer complexes (Ru-CNC's) were prepared. Depending on the synthetic procedure, normal (1, 2) or mixed normal/abnormal NHC-complexes (3) are formed. In the presence of phosphazene base, Ru-CNC complexes activate nitriles to give

  1. Methanol Electro-Oxidation on Pt-Ru Alloy Nanoparticles Supported on Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yangchuan Xing

    2009-09-01

    Full Text Available 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, Pt53Ru47/CNT, Pt69Ru31/CNT and Pt77Ru23/CNT, were prepared and investigated in detail. Experiments were conducted at various temperatures, electrode potentials, and methanol concentrations. It was found that the reaction order of methanol electro-oxidation on the PtRu/CNT catalysts was consistent with what has been reported for PtRu alloys with a value of 0.5 in methanol concentrations. However, the electro-oxidation reaction on the PtRu/CNT catalysts displayed much lower activation energies than that on the Pt-Ru alloy catalysts unsupported or supported on carbon black (PtRu/CB. This study provides an overall kinetic evaluation of the PtRu/CNT catalysts and further demonstrates the beneficial role of CNTs.

  2. Interaction of cis-[Ru(DMSO)4Cl2] with acetate-ion in solutions

    International Nuclear Information System (INIS)

    Buslaeva, T.M.; Rudnitskaya, O.V.; Kabanova, A.G.; Fedorova, G.A.

    2000-01-01

    Solutions of cis-[Ru(DMSO) 4 Cl 2 ] in water and alcohols in the presence of CH 3 COONa in dependence on concentration and relation of reagents are studied. It is shown that introduction of acetate-ion in solution of cis-[Ru(DMSO) 4 Cl 2 ] in methanol directs to formation of fac-[Ru(DMSO) 3 Cl 3 ] - which can be separated as sodium salt insoluble in methanol. It is necessary to mention that spectrum of solution of cis-[Ru(DMSO) 4 Cl 2 ] in methanol varies in time but these changes are insignificant in comparison with changes taking place in the presence of CH 3 COONa. Compound Na[Ru(DMSO) 3 (CH 3 COO) 2 Cl] is prepared and characterized spectrally for the first time [ru

  3. 101Ru NQR study in superconducting CeRu2

    International Nuclear Information System (INIS)

    Matsuda, Kazuyuki; Kohori, Yoh; Kohara, Takao

    1995-01-01

    We present measurements of the NQR spectrum and the nuclear spin lattice relaxation rate, 1/T 1 , of 101 Ru in superconducting CeRu 2 from 1.9 K to 10 K. From the NQR spectrum, the electric quadrupole interaction parameters were determined to be ν Q =13.2 MHz and η=0.1/T 1 varies in proportion to temperature in the normal state, and has the Hebel-Slichter coherence peak just below the superconducting transition temperature, T C , of 6.2 K, and decreases exponentially at low temperatures with the energy gap of 2Δ=4.0k B T C . 101 Ru NQR study indicates that CeRu 2 is an s-wave and strong-coupling superconductor. (author)

  4. Activity and Stability of RuOx Based Electrocatalysts for the Oxygen Evolution Reaction

    DEFF Research Database (Denmark)

    Paoli, Elisa Antares

    . By coupling Electrochemical Quartz Crystal Microbalance (EQCM) measurements with Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) analyses of the electrolyte, we emphasize the importance of monitoring the mass loss. Finally, the thesis focuses on improving the stability of ruthenium dioxide under OER...... results show that an improvement of stability can be obtained, slightly decreasing the activity as well. Unfortunately, a drastic enhancement, as hoped, was not detected. Instead the results serve as a starting point from which the strategy and method for stability improvements can be further developed....... activity on oxides and studies on well-defined surfaces are required. Notably, industrial applications demand maximized surface-to-bulk ratio, hence fabrication of catalysts in nanoparticulate form. In this perspective, this project aimed at investigating well-defined mass-selected ruthenium and ruthenium...

  5. A new method to synthesize sulfur-doped graphene as effective metal-free electrocatalyst for oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Chunyang; Sun, Mingjuan [School of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211 (China); Zhu, Mingshan, E-mail: mingshanzhu@yahoo.com [School of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211 (China); Song, Shaoqing [School of Chemistry, Biology and Materials Science, East China Institute of Technology, Nanchang 330013 (China); Jiang, Shujuan, E-mail: sjjiang@ecit.edu.cn [School of Chemistry, Biology and Materials Science, East China Institute of Technology, Nanchang 330013 (China)

    2017-06-15

    Highlights: • S doped graphene was facile synthesized by one-pot solvothermal method. • DMSO acted as S source as well as reaction solvent. • S-RGO worked as an efficient metal-free electrocatalyst for ORR. • S-RGO acted as a promising candidate instead of Pt-based catalyst. - Abstract: The exploration of a metal-free catalyst with highly efficient yet low-cost for the oxygen-reduction reaction (ORR) is under wide spread investigation. In this paper, by using dimethyl sulfoxide (DMSO) as S source as well as solvent, we report a new, low-cost, and facile solvothermal route to synthesize S-doped reduced graphene oxide (S-RGO). The existence of S element in the framework of RGO was solidly confirmed by energy-dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS). The as-synthesized S-RGO can be worked as an efficient metal-free electrocatalyst for ORR. Moreover, compared to commercial Pt/C electrocatalyst, the S-RGO displays superior resistance to crossover effect and stability by evaluating the addition of methanol and CO poisoning experiment. This result not only shows S-RGO as a promising candidate instead of Pt-based catalyst for ORR, but also provides a new approach for the preparation of metal-free electrocatalyst in future.

  6. Characteristics of NixFe1−xOy Electrocatalyst on Hematite as Photoanode for Solar Hydrogen Production

    Directory of Open Access Journals (Sweden)

    Chih-Ping Yen

    2017-11-01

    Full Text Available The use of hematite as the photoanode for photoelectrochemical hydrogen production by solar energy has been actively studied due to its abundance, stability, and adequate optical properties. Deposition of an electrocatalyst overlayer on the hematite may increase kinetics and lower the onset potential for water splitting. NixFe1−xOy is one of the most effective electrocatalysts reported for this purpose. However, the condition and results of the previous reports vary significantly, and a comprehensive model for NixFe1−xOy/hematite is lacking. Here, we report a simple and novel chemical bath deposition method for depositing low-onset-potential NixFe1−xOy electrocatalyst on hematite. With a Ni percentage of 80% and an immersion time of 2 min, the as-prepared NixFe1−xOy overlayer raised the photovoltage from 0.2 V to 0.7 V, leading to a cathodic shift of the onset potential by 400 mV, while maintaining the same level of current density. The dependence of the electrochemical and photoelectrochemical characteristics of the photoanode on the condition of the electrocatalyst was studied systematically and explained based on energy level diagrams and kinetics.

  7. Synthesis and characterisation of dual-phase Y-TZP and RuO2 nanopowders: dense electrode precursors.

    NARCIS (Netherlands)

    van Zyl, W.E.; Winnubst, Aloysius J.A.; Raming, T.P.; Schmuhl, R.; Verweij, H.

    2002-01-01

    The synthesis and characterisation of nanopowders in the dual-phase system tetragonal-Y2O3-doped ZrO2 (Y-TZP) and RuO2 are described. Five powders were prepared from a co-precipitation (CP) method with stoichiometric variation in the RuO2 content (5–46 mol%) and two powders were prepared from

  8. A novel dinuclear Ru(II) complex having a bridging ligand of a rigid and extended structure. Incorporation of an anthraquinone unit and efficient emission quenching

    International Nuclear Information System (INIS)

    Mishra, L.; Choi, Chang-Shik; Araki, Koji

    1997-01-01

    Dinuclear Ru(II) complex having extended conjugation within the bridging ligand was prepared by coupling of the Ru(II) polypyridyl complex having a benzoyl-substituted phenazine unit with diaminoanthraquinone in one step, in which emission from the excited Ru(II) center was efficiently quenched through the anthraquinone unit. (author)

  9. Effect of the leaching of Ru-Se-Fe and Ru-Mo-Fe obtained by mechanical alloying on electrocatalytical behavior for the oxygen reduction reaction

    International Nuclear Information System (INIS)

    Ezeta, A.; Arce, E.M.; Solorza, O.; Gonzalez, R.G.; Dorantes, H.

    2009-01-01

    In the present work, Ru-Se-Fe and Ru-Mo-Fe alloyed nanoparticles were synthesized from high purity powders (Ru, Se and Mo) by means of the high-energy mechanical alloying. Fe was integrated to the alloys because of the erosion of the mill balls. The ORR electrocatalytic performance of the alloys (lixiviated or not) was evaluated in a rotating disc electrode (RDE) at room temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the structure characterization of the materials. Small-particle clusters with granular morphology and nanometric sizes were obtained in all the cases. According to the Tafel parameters from the RDE results, a first order ORR is present in both electrocatalytic systems through a 4e - global multielectron transference to form water: O 2 + 4H + + e - → H 2 O. The electrocatalytic activity showed that the mechanical alloying enabled to obtain nanoparticle electrocatalysts with good ORR performance. Lixiviation of the mechanical alloying powders not improves the catalytical responses.

  10. An electrochemical impedance spectroscopy study of polymer electrolyte membrane fuel cells electrocatalyst single wall carbon nanohorns-supported.

    Science.gov (United States)

    Brandão, Lúcia; Boaventura, Marta; Passeira, Carolina; Gattia, Daniele Mirabile; Marazzi, Renzo; Antisari, Marco Vittori; Mendes, Adélio

    2011-10-01

    Electrochemical impedance spectroscopy (EIS) was used to study the polymer electrolyte membrane fuel cells (PEMFC) performance when using single wall carbon nanohorns (SWNH) to support Pt nanoparticles. Additionally, as-prepared and oxidized SWNH Pt-supports were compared with conventional carbon black. Two different oxidizing treatments were considered: oxygen flow at 500 degrees C and reflux in an acid solution at 85 degrees C. Both oxidizing treatments increased SWNH surface area; oxygen treatment increased surface area 4 times while acid treatment increased 2.6 times. The increase in surface area should be related to the opening access to the inner tube of SWNH. Acid treatment of SWNH increased chemical fragility and decreased electrocatalyst load in comparison with as-prepared SWNH. On the other hand, the oxygen treated SWNH sample allowed to obtain the highest electrocatalyst load. The use of as-prepared and oxygen treated SWNH showed in both cases catalytic activities 60% higher than using conventional carbon black as electrocatalyst support in PEMFC. Moreover, EIS analysis indicated that the major improvement in performance is related to the cathode kinetics in the as-prepared SWNH sample, while concerning the oxidized SWNH sample, the improvements are related to the electrokinetics in both anode and cathode electrodes. These improvements should be related with differences in the hydrophobic character between SWNH and carbon black.

  11. Pd-NiO decorated multiwalled carbon nanotubes supported on reduced graphene oxide as an efficient electrocatalyst for ethanol oxidation in alkaline medium

    Science.gov (United States)

    Rajesh, Dhanushkotti; Indra Neel, Pulidindi; Pandurangan, Arumugam; Mahendiran, Chinnathambi

    2018-06-01

    The synthesis of Pd-NiO nanoparticles decorated multiwalled carbon nanotubes (MWCNTs) on reduced graphene oxide (rGO) for ethanol electrooxidation is reported. NiO nanoparticles (NPs) were deposited on functionalized MWCNTs by wet impregnation method. Pd nanoparticles were formed on NiO-MWCNTs by the addition of PdCl2 and its reduction using NaBH4. The Pd-NiO/MWCNTs nanocomposite then deposited on rGO support using ultrasound irradiation which led to the formation of the Pd-NiO/MWCNTs/rGO electrocatalyst. The prepared electrocatalysts were characterized by XRD, SEM, HR-TEM and XPS analysis. Electrochemical measurements demonstrate that as synthesized Pd-NiO/MWCNTs/rGO electrocatalyst exhibit higher catalytic activity (90.89 mA/cm2) than either Pd/MWCNTs/rGO (43.05 mA/cm2) or Pd/C (28.0 mA/cm2) commercial catalyst. Chronoamperometry study of Pd-NiO/MWCNTs/rGO electrocatalyst showed long-term electrochemical stability. The enhanced catalytic activity of Pd-NiO/MWCNTs/rGO electrocatalyst for electrooxidation of ethanol can be attributed to the synergistic effect between Pd & NiO active sites.

  12. How bimetallic electrocatalysts does work for reactions involved in fuel cells? Example of ethanol oxidation and comparison to methanol

    Energy Technology Data Exchange (ETDEWEB)

    Leger, J.-M.; Rousseau, S.; Coutanceau, C.; Hahn, F.; Lamy, C. [UMR 6503, Electrocatalysis Group, CNRS - University of Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex (France)

    2005-09-05

    Carbon-supported Pt-based nanosized electrocatalysts can be synthesized for methanol and ethanol electrooxidation. The electrocatalytic activity of Pt can be greatly enhanced by using Pt-Ru/C for methanol oxidation or Pt-Sn/C for ethanol oxidation. In situ IR reflectance spectroscopy is a convenient tool to better understand the importance of the different adsorption steps involved in the mechanisms of electrooxidation. With Pt/C, it appears clearly that linearly adsorbed CO is the poisoning species formed during methanol and ethanol oxidation. In the case of methanol, even with Pt-Ru/C (the most active catalyst), adsorbed CO is also a reactive intermediate. The enhancement of activity observed in such a case is due to the possibility to activate water at lower potentials in the presence of Ru. With Pt-Sn/C, the mechanism of the electrooxidation of ethanol is strongly modified. If at low potentials, poisoning with adsorbed CO still exists (as with Pt/C), the oxidation of ethanol at potentials greater than 0.4 V versus RHE occurs through an adsorbed acetyl species which can lead to the formation of acetaldehyde and acetic acid as final products in addition to carbon dioxide. (author)

  13. [Population Council responsible for RU486 clinical trials in USA].

    Science.gov (United States)

    Aguillaume, C J

    1993-04-01

    As a result of the sudden political change that came with the Clinton Administration, RU-486's manufacturer, Roussel-Uclaf, and the Population Council agreed on April 20, 1992, on the manufacture and distribution of RU-486 in the US. In the US, there are less than 1.6 million induced abortions annually. From now on, US women will be able to have a choice between medical and surgical abortion. The Population Council and Roussel-Uclaf have had a contract since 1982. The Council is solely responsible for the phase 2 clinical trial of RU-486 in the US and other countries. It must present to the US Food and Drug Administration (FDA) an amendment allowing it to begin phase 3 clinical trials. The Council will also lead the US medical facilities in this study. It will identify partners for future production of RU-486 and its distribution in the US. It will also submit to FDA a New Drug Application (NDA). FDA will review the scientific literature on RU-486 and evaluate all data submitted by the Population Council. There are still obstacles to be surmounted. The Population Council must demonstrate good judgment when selecting the criteria for choosing a pharmaceutical firm before a Technical Committee which will be part of a group of players promoting women's health, scientific experts, and other interested parties. It must find the necessary funds to conduct the clinical trials and prepare the NDA. Phase 3 clinical trials in the US must have at least 2000 women. They will test RU-486's efficacy, safety, and acceptability among women choosing medical abortion over surgical abortion. Since the Council operates in almost all countries in the world, has innovated contraceptive research and development activities, and has been endorsed by the UN, product approval of RU-486 in the US will affect policy in all countries concerned about abortion.

  14. High activity PtRu/C catalysts synthesized by a modified impregnation method for methanol electro-oxidation

    International Nuclear Information System (INIS)

    Ma Liang; Liu Changpeng; Liao Jianhui; Lu Tianhong; Xing Wei; Zhang Jiujun

    2009-01-01

    A modified impregnation method was used to prepare highly dispersive carbon-supported PtRu catalyst (PtRu/C). Two modifications to the conventional impregnation method were performed: one was to precipitate the precursors ((NH 4 ) 2 PtCl 6 and Ru(OH) 3 ) on the carbon support before metal reduction; the other was to add a buffer into the synthetic solution to stabilize the pH. The prepared catalyst showed a much higher activity for methanol electro-oxidation than a catalyst prepared by the conventional impregnation method, even higher than that of current commercially available, state-of-the-art catalysts. The morphology of the prepared catalyst was characterized using TEM and XRD measurements to determine particle sizes, alloying degree, and lattice parameters. Electrochemical methods were also used to ascertain the electrochemical active surface area and the specific activity of the catalyst. Based on XPS measurements, the high activity of this catalyst was found to originate from both metallic Ru (Ru 0 ) and hydrous ruthenium oxides (RuO x H y ) species on the catalyst surface. However, RuO x H y was found to be more active than metallic Ru. In addition, the anhydrous ruthenium oxide (RuO 2 ) species on the catalyst surface was found to be less active.

  15. Synthesis of Ru/PDMS nano-composites via supercritial deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Minglan [Dept. of Chemical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 (China); Bozbag, Selmi E. [Dept. of Chemical and Biological Engineering, Koç University, 34450 Sariyer, Istanbul (Turkey); Ayala, Christian J.; Aindow, Mark [Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Erkey, Can, E-mail: cerkey@ku.edu.tr [Dept. of Chemical and Biological Engineering, Koç University, 34450 Sariyer, Istanbul (Turkey); Koç University TÜPRAŞ Energy Center (KUTEM), Koç University, 34450 Sariyer, Istanbul (Turkey)

    2016-09-01

    Nanomaterials consisting of Ru nanoparticles dispersed in polydimethylsiloxane films were synthesized by supercritical deposition. The films were impregnated with the organometallic precursor bis(2,2,6,6-tetramethyl-3,5-heptanedionato) (1,5-cyclooctadiene) ruthenium (II) under thermodynamic control in the presence of supercritical carbon dioxide (scCO{sub 2}) at 40 °C and 10.34 MPa. The precursor molecules were then converted to metallic Ru by thermal treatment in flowing N{sub 2} at ambient pressure, resulting in well-dispersed nanoparticles with diameters of ≈2 nm. - Highlights: • PDMS-Ru nanoparticle composites were prepared using supercritical deposition. • PDMS-Ru nanoparticle composites were prepared without using an immobilization agent. • PDMS films were impregnated with Ru(cod)(tmhd){sub 2} in supercritical CO{sub 2}. • The impregnated Ru(cod)(tmhd){sub 2} was then reduced to metallic Ru in flowing N{sub 2}. • The resulting Ru nanoparticles were well-dispersed and had diameters of ≈2 nm.

  16. Laminated structure in internally oxidized Ru-Ta coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yung-I, E-mail: yichen@mail.ntou.edu.tw

    2012-12-01

    During the development of refractory alloy coatings for protective purposes at high temperature under oxygen-containing atmospheres, previous studies noted and examined the internal oxidation phenomenon for Mo-Ru and Ru-Ta coatings. The internally oxidized zone shows a laminated structure, consisting of alternating oxygen-rich and deficient layers stacked with a general orientation. Previous studies proposed a forming mechanism. To investigate in detail, Ru-Ta coatings were prepared with various rotating speeds of a substrate-holder. The coatings were annealed at 600 Degree-Sign C in an atmosphere continuously purged with 1% O{sub 2}-99% Ar mixed gas for 30 min. Transmission electron microscopy was used to examine the laminated-layer periods. Auger electron spectroscopy depth profiles certified the periodical variation of the related constituents. X-ray photoelectron spectroscopy proved the valence variation of Ta in the near surface, accompanied by the introduction of oxygen ions. The inward diffusion of oxygen was dominated by lattice diffusion. - Highlights: Black-Right-Pointing-Pointer Laminated Ru-Ta coatings consisted of a cyclical gradient concentration. Black-Right-Pointing-Pointer The as-deposited coatings showed a laminated structure with a period of 4-34 nm. Black-Right-Pointing-Pointer Internal oxidation of Ru-Ta coatings executed after annealing in 1% O{sub 2}-Ar atmosphere. Black-Right-Pointing-Pointer Oxygen inward diffusion was dominated by lattice diffusion.

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

    International Nuclear Information System (INIS)

    Wang, Yongjiao; Zang, Jianbing; Dong, Liang; Pan, Hong; Yuan, Yungang; Wang, Yanhui

    2013-01-01

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

  18. Catalytic Ammonia Decomposition over High-Performance Ru/Graphene Nanocomposites for Efficient COx-Free Hydrogen Production

    Directory of Open Access Journals (Sweden)

    Gang Li

    2017-01-01

    Full Text Available Highly-dispersed Ru nanoparticles were grown on graphene nanosheets by simultaneously reducing graphene oxide and Ru ions using ethylene glycol (EG, and the resultant Ru/graphene nanocomposites were applied as a catalyst to ammonia decomposition for COx-free hydrogen production. Tuning the microstructures of Ru/graphene nanocomposites was easily accomplished in terms of Ru particle size, morphology, and loading by adjusting the preparation conditions. This was the key to excellent catalytic activity, because ammonia decomposition over Ru catalysts is structure-sensitive. Our results demonstrated that Ru/graphene prepared using water as a co-solvent greatly enhanced the catalytic performance for ammonia decomposition, due to the significantly improved nano architectures of the composites. The long-term stability of Ru/graphene catalysts was evaluated for COx-free hydrogen production from ammonia at high temperatures, and the structural evolution of the catalysts was investigated during the catalytic reactions. Although there were no obvious changes in the catalytic activities at 450 °C over a duration of 80 h, an aggregation of the Ru nanoparticles was still observed in the nanocomposites, which was ascribed mainly to a sintering effect. However, the performance of the Ru/graphene catalyst was decreased gradually at 500 °C within 20 h, which was ascribed mainly to both the effect of the methanation of the graphene nanosheet under a H2 atmosphere and to enhanced sintering under high temperatures.

  19. ETEM Studies of Electrodes and Electro-catalysts

    DEFF Research Database (Denmark)

    Jooss, Christian; Mildner, Stephanie; Beleggia, Marco

    2016-01-01

    Environmental TEM is an excellent tool for gaining insight into the atomic and electronic structure of electro-catalysts under operating conditions. Several electrochemical reactions such as oxidation/reduction processes of electrodes, heterogeneous gas phase catalysis of water splitting...

  20. Electrocatalysts for fuel cells; Electrocatalizadores para celdas de combustible

    Energy Technology Data Exchange (ETDEWEB)

    Garcia C, M. A.; Fernandez V, S. M. [ININ, Depto. de Quimica, Apdo. Postal 18-1027, Col. Escandon, Mexico 11801, D. F. (Mexico); Vargas G, J. R. [IPN, Depto. de Ingenieria Metalurgica, Mexico 07300, D. F. (Mexico)

    2008-07-01

    It was investigated the oxygen reduction reaction (fundamental reaction in fuel cells) on electrocatalysts of Pt, Co, Ni and their alloys CoNi, PtCo, PtNi, PtCoNi in H{sub 2}SO{sub 4} 0.5 M and KOH 0.5 M as electrolyte. The electrocatalysts were synthesized using mechanical alloying processes and chemical vapor deposition. The electrocatalysts were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray spectroscopy. The evaluation was performed using electrocatalytic technique of rotating disk electrode and kinetic parameters were determined for each electro catalyst. We report the performance of all synthesized electrocatalysts in acid and alkaline means. (Author)

  1. O2-enhanced methanol oxidation reaction at novel Pt-Ru-C co-sputtered electrodes

    International Nuclear Information System (INIS)

    Umeda, Minoru; Matsumoto, Yosuke; Inoue, Mitsuhiro; Shironita, Sayoko

    2013-01-01

    Highlights: ► Novel Pt-Ru-C electrodes were prepared by a co-sputtering technique. ► Co-sputtered electrodes with C result in highly efficient O 2 -enhanced methanol oxidation. ► Pt–Ru-alloy-based co-sputtered electrode induces a negative onset potential of methanol oxidation. ► The Pt-Ru-C electrodes allow a negative onset potential of O 2 -enhanced methanol oxidation. ► The optimum atomic ratios of Pt-Ru-C are Pt: 0.24–0.80, Ru: 0.14–0.61, C: 0.06–0.37. -- Abstract: A Pt-Ru-C electrode has been developed using a co-sputtering technique for use as the anode catalyst of a mixed-reactant fuel cell. The physical and electrochemical characteristics of the electrodes demonstrate that co-sputtered Pt and Ru form a Pt–Ru alloy. The crystallite sizes of the catalysts investigated in this study are reduced by the addition of C to the Pt–Ru alloy. Cu stripping voltammograms suggest that the sputtering of C and the formation of the Pt–Ru alloy synergically increase the electrochemical surface area of the electrodes. The methanol oxidation performances of the prepared electrodes were evaluated in N 2 and O 2 atmospheres; the Pt-Ru-C electrodes achieve an O 2 -induced negative shift in the onset potential of the methanol oxidation (E onset ) and enhance the methanol oxidation current density in the O 2 atmosphere. The mechanism of O 2 -enhanced methanol oxidation with a negative E onset at the Pt-Ru-C electrodes is attributed to a change in the electronic structure of Pt due to the formation of Pt–Ru alloy and the generation of O-based adsorption species by the reduction of O 2 . Finally, the composition of the Pt-Ru-C electrode for the O 2 -enhanced methanol oxidation with a negative E onset was found to be optimal at an atomic ratio of Pt: 0.24–0.80, Ru: 0.14–0.61, and C: 0.06–0.37

  2. Development of nanosized electrocatalysts for direct ethanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Mohamedi, M. [Institut National de la Recherche Scientifique, Varennes, PQ (Canada). Centre de l' Energie, Materiaux et Telecommunications

    2008-07-01

    Fuel cells have been touted as a promising power supply for automotive, portable or stationary use. Although methanol is a strong contender as an alternative fuel, the extensive use of this toxic compound is not practical due to environmental hazards. Ethanol is a good substitute because it has a very positive environmental, health, and safety footprint with no major uncertainties or hazards. Ethanol is a hydrogen-rich liquid which has more energy density than methanol. The C-C bond has a determining effect on fuel cell efficiency and the theoretical energy yield. Therefore, a good electrocatalyst towards the complete oxidation of ethanol must activate the C-C bond breaking while avoiding the poisoning of the catalytic surface by carbon monoxide species that occurs with methanol oxidation. The objective of this study was to develop new catalyst nanoparticles of well-controlled shape, size, and composition with excellent stability and better electrocatalytic activity. This paper described the recent achievements regarding the development of a series of PtxSn100-x catalysts prepared by pulsed laser deposition (PLD). It reported on the effect of several deposition parameters on the structure and properties of the deposited catalysts. It also described how these deposition conditions affect the electrocatalytic response of the resulting materials toward ethanol oxidation. Some interesting periodic oscillations were observed at some catalysts during ethanol electrooxidation. 7 refs., 1 fig.

  3. WS{sub 2} nanosheets based on liquid exfoliation as effective electrocatalysts for hydrogen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Han, Guan-Qun [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); College of Science, China University of Petroleum (East China), Qingdao 266580 (China); Liu, Yan-Ru; Hu, Wen-Hui [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); Dong, Bin, E-mail: dongbin@upc.edu.cn [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); College of Science, China University of Petroleum (East China), Qingdao 266580 (China); Li, Xiao; Chai, Yong-Ming; Liu, Yun-Qi [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); Liu, Chen-Guang, E-mail: cgliu@upc.edu.cn [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China)

    2015-11-01

    WS{sub 2} nanosheets (WS{sub 2} NSs) as electrocatalysts for hydrogen evolution reaction (HER) have been prepared based on liquid exfoliation in dimethyl-formamide (DMF) via a direct dispersion and ultrasonication method. X-ray diffraction (XRD) shows the decreasing crystalline of the exfoliated WS{sub 2} (E-WS{sub 2}). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the as prepared E-WS{sub 2} consists of a few two-dimensional nanosheets, with large wrinkles on the surface. Electrochemical measurements show an excellent activity and stability of the E-WS{sub 2}, with a low overpotential of 80 mV and high current density (10 mA cm{sup −2}, at η = 205 mV), which indicates that through the process of exfoliation in DMF, both the dispersion and the amount of active sites have been improved greatly. Therefore, DMF is a promising alternative for exfoliating two-dimensional nanomaterials for highly efficient HER electrocatalysts. - Highlights: • A facile exfoliation process in DMF has been used to prepare E-WS{sub 2} for HER. • E-WS{sub 2} shows the better electrocatalytic activity than bulk WS{sub 2}. • DMF provides a promising alternative for enhancing exfoliation of 2D materials.

  4. WS_2 nanosheets based on liquid exfoliation as effective electrocatalysts for hydrogen evolution reaction

    International Nuclear Information System (INIS)

    Han, Guan-Qun; Liu, Yan-Ru; Hu, Wen-Hui; Dong, Bin; Li, Xiao; Chai, Yong-Ming; Liu, Yun-Qi; Liu, Chen-Guang

    2015-01-01

    WS_2 nanosheets (WS_2 NSs) as electrocatalysts for hydrogen evolution reaction (HER) have been prepared based on liquid exfoliation in dimethyl-formamide (DMF) via a direct dispersion and ultrasonication method. X-ray diffraction (XRD) shows the decreasing crystalline of the exfoliated WS_2 (E-WS_2). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the as prepared E-WS_2 consists of a few two-dimensional nanosheets, with large wrinkles on the surface. Electrochemical measurements show an excellent activity and stability of the E-WS_2, with a low overpotential of 80 mV and high current density (10 mA cm"−"2, at η = 205 mV), which indicates that through the process of exfoliation in DMF, both the dispersion and the amount of active sites have been improved greatly. Therefore, DMF is a promising alternative for exfoliating two-dimensional nanomaterials for highly efficient HER electrocatalysts. - Highlights: • A facile exfoliation process in DMF has been used to prepare E-WS_2 for HER. • E-WS_2 shows the better electrocatalytic activity than bulk WS_2. • DMF provides a promising alternative for enhancing exfoliation of 2D materials.

  5. Round table on RU486.

    Science.gov (United States)

    Shallat, L

    1993-01-01

    As a non-invasive means of early abortion, RU-486 has the potential to increase women's reproductive options; at the same time, the "abortion pill" has stimulated debate about the ethics and safety of new medical technologies. When combined with a prostaglandin (PG), the success rate for RU-486 is 96% for pregnancies of up to 9 weeks' gestation. In France, over 120,000 women have used RU-486/PG to terminate pregnancy, and this regimen is now used in about 25% of abortions. Clinical trials of RU-486 are underway in Cuba, China, India, Singapore, and Zambia. The Program for Appropriate Technology has identified four considerations for introducing RU-486 to developing countries: whether abortion or menstrual regulation is legal; whether women find the method acceptable and can comply with the multiple visit treatment regimen; whether the health infrastructure can support safe method use, including prevention of misuse and provision of appropriate medical backup personnel and facilities; and whether the cost of the regimen is affordable to individuals and/or programs --conditions unlikely to be met in most such countries. Ideal would be development of a medical abortifacient that is single dose and the lowest possible dose of each drug, provokes miscarriage within a more predictable time frame with less acute and prolonged bleeding, is safe and effective beyond two months, has minimal side effects, and maximizes short-term safety and minimizes long-term effects. Technological advances are being undermined, however, by political and religious attacks on the method. Even some feminists have expressed concerns about potential long-term effects of RU-486 use.

  6. Thin RuO2 conducting films grown by MOCVD for microelectronic applications

    International Nuclear Information System (INIS)

    Froehlich, K.; Cambel, V.; Machajdik, D.; Pignard, S.; Baumann, P. K.; Lindner, J.; Schumacher, M.

    2002-01-01

    We have prepared thin RuO 2 films by MOCVD using thermal evaporation of Ru(thd) 2 (cod) solid precursor. The films were prepared at deposition temperatures between 250 and 500 grad C on silicon and sapphire substrates. Different structure was observed for the RuO 2 films on these substrates; the films on Si substrate were polycrystalline, while X-ray diffraction analysis revealed epitaxial growth of RuO 2 on sapphire substrates. Polycrystalline RuO 2 films prepared at temperatures below 300 grad C on Si substrate exhibit smooth surface and excellent step coverage. Highly conformal growth of the RuO 2 films at low temperature and low pressure results in nearly 100% step coverage for sub-mm features with 1:1 aspect ratio. Resistivity of the polycrystalline RuO 2 at room temperature ranged between 100 and 200 μ x Ω x cm. These films are suitable for CMOS and RAM applications. (Authors)

  7. CO tolerance of PdPt/C and PdPtRu/C anodes for PEMFC

    International Nuclear Information System (INIS)

    Garcia, Amanda C.; Paganin, Valdecir A.; Ticianelli, Edson A.

    2008-01-01

    The performance of H 2 /O 2 proton exchange membrane fuel cells (PEMFCs) fed with CO-contaminated hydrogen was investigated for anodes with PdPt/C and PdPtRu/C electrocatalysts. The physicochemical properties of the catalysts were characterized by energy dispersive X-ray (EDX) analyses, X-ray diffraction (XRD) and 'in situ' X-ray absorption near edge structure (XANES). Experiments were conducted in electrochemical half and single cells by cyclic voltammetry (CV) and I-V polarization measurements, while DEMS was employed to verify the formation of CO 2 at the PEMFC anode outlet. A quite high performance was achieved for the PEMFC fed with H 2 + 100 ppm CO with the PdPt/C and PdPtRu/C anodes containing 0.4 mg metal cm -2 , with the cell presenting potential losses below 200 mV at 1 A cm -2 , with respect to the system fed with pure H 2 . For the PdPt/C catalysts no CO 2 formation was seen at the PEMFC anode outlet, indicating that the CO tolerance is improved due to the existence of more free surface sites for H 2 electrooxidation, probably due to a lower Pd-CO interaction compared to pure Pd or Pt. For PdPtRu/C the CO tolerance may also have a contribution from the bifunctional mechanism, as shown by the presence of CO 2 in the PEMFC anode outlet

  8. Nanostructured electrocatalysts with tunable activity and selectivity

    Science.gov (United States)

    Mistry, Hemma; Varela, Ana Sofia; Kühl, Stefanie; Strasser, Peter; Cuenya, Beatriz Roldan

    2016-04-01

    The field of electrocatalysis has undergone tremendous advancement in the past few decades, in part owing to improvements in catalyst design at the nanoscale. These developments have been crucial for the realization of and improvement in alternative energy technologies based on electrochemical reactions such as fuel cells. Through the development of novel synthesis methods, characterization techniques and theoretical methods, rationally designed nanoscale electrocatalysts with tunable activity and selectivity have been achieved. This Review explores how nanostructures can be used to control electrochemical reactivity, focusing on three model reactions: O2 electroreduction, CO2 electroreduction and ethanol electrooxidation. The mechanisms behind nanoscale control of reactivity are discussed, such as the presence of low-coordinated sites or facets, strain, ligand effects and bifunctional effects in multimetallic materials. In particular, studies of how particle size, shape and composition in nanostructures can be used to tune reactivity are highlighted.

  9. Preparation of electrocatalysts by reduction of precursors with sodium citrate

    OpenAIRE

    Briskeby, Stein Trygve; Tsypkin, Mikhail; Tunold, Reidar; Sunde, Svein

    2014-01-01

    In this work synthesis of Pt/C catalysts by reduction of H2PtCl6 with sodium citrate has been investigated. The strong pH-dependence of citrate as a reducing and stabilizing agent has been explored, and an optimum pH range for production of well dispersed catalysts is proposed. To achieve stabilizing and reducing conditions, the presence of both citrate anions and protonated citrates are required. This is achieved in an intermediate pH range between pKa2 and pKa3 (4.76 and 6.4) of citric acid...

  10. 103Ru for tumor scanning, 2

    International Nuclear Information System (INIS)

    Mizukawa, Kiichiro

    1979-01-01

    The mechanism of 103 Ru-uptake in tumors was investigated through the incubation of rat ascites hepatoma cells (AH-130) in vitro with various concentrations of Ru-chloride containing 103 Ru-chloride as a tracer. Quantitative analysis of Ru binding to the cells indicated that ascites hepatoma cells contained high- and low-affinity binding sites for Ru. When ascites hepatoma cells were incubated with Ru after incubation with a low concentration of papain, most of the Ru was not bound to the cells but was found in the medium containing solubilized glycoproteins. However Ru bound mainly to washed cells after the incubation with papain. About 65% of the Ru bound to ascites hepatoma cells was liberated by the papain treatment, and about 45% of the liberated Ru was precipitated by cetyltrimethylammonium bromide, indicating that Ru bound tightly to glycopeptides. These results suggest that the tumor affinity of 103 Ru is related to specific binding to glycopeptides on the tumor cell surface. (author)

  11. Evaluation of Pt−Au/MWCNT (Multiwalled Carbon Nanotubes) electrocatalyst performance as cathode of a proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Beltrán-Gastélum, M.; Salazar-Gastélum, M.I.; Félix-Navarro, R.M.; Pérez-Sicairos, S.; Reynoso-Soto, E.A.; Lin, S.W.; Flores-Hernández, J.R.; Romero-Castañón, T.; Albarrán-Sánchez, I.L.; Paraguay-Delgado, F.

    2016-01-01

    A comparative study between Pt−Au/MWCNT and Pt/C (commercial) as cathodic electrocatalyst of H_2/O_2 fuel cell is performed. Pt−Au/MWCNT is synthesized using the reverse microemulsion method and this procedure is scaled-up in order to prepare membrane-electrode assemblies for fuel cells with an active area of 9 cm"2. Those electrocatalysts are characterized by both physicochemical techniques and electrochemical measurements to evaluate their catalytic activity for ORR (Oxygen Reduction Reaction). In the half-cell study, Pt−Au/MWCNT show higher kinetic current density as cathodic electrocatalyst compared with Pt/C. Likewise, in a fuel cell hardware the maximum power density is significantly higher for Pt−Au/MWCNT cathode (625 mW cm"−"2 at 0.426 V) when compared with Pt/C anode (355 mW cm"−"2 at 0.499 V). - Highlights: • Pt−Au/MWCNT was synthesized by reverse microemulsión method. • Pt−Au/MWCNT and Pt/C were characterized by microscopic and spectroscopic techniques. • Both materials were studied as catalysts for ORR by electrochemical techniques. • Catalysts were used to prepare MEA's, the performance in fuel cell was evaluated. • Maximum power densities were 625 mW cm"−"2 for Pt−Au/MWCNT and 355 mW cm"−"2 for Pt/C.

  12. A highly selective copper-indium bimetallic electrocatalyst for the electrochemical reduction of aqueous CO2to CO

    KAUST Repository

    Rasul, Shahid

    2014-12-23

    The challenge in the electrochemical reduction of aqueous carbon dioxide is in designing a highly selective, energy-efficient, and non-precious-metal electrocatalyst that minimizes the competitive reduction of proton to form hydrogen during aqueous CO2 conversion. A non-noble metal electrocatalyst based on a copper-indium (Cu-In) alloy that selectively converts CO2 to CO with a low overpotential is reported. The electrochemical deposition of In on rough Cu surfaces led to Cu-In alloy surfaces. DFT calculations showed that the In preferentially located on the edge sites rather than on the corner or flat sites and that the d-electron nature of Cu remained almost intact, but adsorption properties of neighboring Cu was perturbed by the presence of In. This preparation of non-noble metal alloy electrodes for the reduction of CO2 provides guidelines for further improving electrocatalysis.

  13. Ru (amp)(bipy)Cl

    Indian Academy of Sciences (India)

    Administrator

    [RuV(amp)(bipy)O]+ intermediate complex which leads to the high affinity for hydrogen atom/hydride abstraction. Acknowledgement. We gratefully acknowledge the financial support from the Department of Science &. Technology, Government of India. We are thankful to Shri Hardyal Singh for his encouragement. Reference.

  14. Hydrothermal Synthesis of Co-Ru Alloy Particle Catalysts for Hydrogen Generation from Sodium Borohydride

    Directory of Open Access Journals (Sweden)

    Marija Kurtinaitienė

    2013-01-01

    Full Text Available We report the synthesis of μm and sub-μm-sized Co, Ru, and Co-Ru alloy species by hydrothermal approach in the aqueous alkaline solutions (pH ≥ 13 containing CoCl2 and/or RuCl3, sodium citrate, and hydrazine hydrate and a study of their catalytic properties for hydrogen generation by hydrolysis of sodium borohydride solution. This way provides a simple platform for fabrication of the ball-shaped Co-Ru alloy catalysts containing up to 12 wt% Ru. Note that bimetallic Co-Ru alloy bowls containing even 7 at.% Ru have demonstrated catalytic properties that are comparable with the ones of pure Ru particles fabricated by the same method. This result is of great importance in view of the preparation of cost-efficient catalysts for hydrogen generation from borohydrides. The morphology and composition of fabricated catalyst particles have been characterized using scanning electron microscopy, energy dispersive X-ray diffraction, and inductively coupled plasma optical emission spectrometry.

  15. One-pot synthesis of graphene supported platinum–cobalt nanoparticles as electrocatalysts for methanol oxidation

    International Nuclear Information System (INIS)

    Kepenienė, V.; Tamašauskaitė-Tamašiūnaitė, L.; Jablonskienė, J.; Semaško, M.; Vaičiūnienė, J.; Vaitkus, R.; Norkus, E.

    2016-01-01

    In the present study the graphene supported platinum–cobalt nanoparticles were prepared via microwave synthesis. The composition of prepared catalysts was examined by Inductively Coupled Plasma Optical Emission Spectroscopy. The shape and size of catalyst particles were determined by Transmission Electron Microscopy. The electrocatalytic activity of the graphene supported platinum–cobalt nanoparticles was investigated towards the electro-oxidation of methanol in an alkaline medium. It has been found that the graphene supported platinum–cobalt nanoparticles having the Pt:Co molar ratio 1:7 show the highest activity towards the electro-oxidation of methanol among the catalysts with the Pt:Co molar ratios equal to 1:1 and 1:44, graphene supported bare Co and Pt/C catalysts. - Highlights: • Preparation of graphene supported Pt-Co nanoparticles by microwave synthesis. • Electrocatalysts for oxidation of methanol. • Higher activity of PtCo/graphene towards methanol oxidation.

  16. One-pot synthesis of graphene supported platinum–cobalt nanoparticles as electrocatalysts for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Kepenienė, V., E-mail: virginalisk@gmail.com [Department of Catalysis, Center for Physical Sciences and Technology, Vilnius LT 01108 (Lithuania); Tamašauskaitė-Tamašiūnaitė, L.; Jablonskienė, J.; Semaško, M.; Vaičiūnienė, J. [Department of Catalysis, Center for Physical Sciences and Technology, Vilnius LT 01108 (Lithuania); Vaitkus, R. [Faculty of Chemistry, Vilnius University, Vilnius LT 03225 (Lithuania); Norkus, E. [Department of Catalysis, Center for Physical Sciences and Technology, Vilnius LT 01108 (Lithuania)

    2016-03-01

    In the present study the graphene supported platinum–cobalt nanoparticles were prepared via microwave synthesis. The composition of prepared catalysts was examined by Inductively Coupled Plasma Optical Emission Spectroscopy. The shape and size of catalyst particles were determined by Transmission Electron Microscopy. The electrocatalytic activity of the graphene supported platinum–cobalt nanoparticles was investigated towards the electro-oxidation of methanol in an alkaline medium. It has been found that the graphene supported platinum–cobalt nanoparticles having the Pt:Co molar ratio 1:7 show the highest activity towards the electro-oxidation of methanol among the catalysts with the Pt:Co molar ratios equal to 1:1 and 1:44, graphene supported bare Co and Pt/C catalysts. - Highlights: • Preparation of graphene supported Pt-Co nanoparticles by microwave synthesis. • Electrocatalysts for oxidation of methanol. • Higher activity of PtCo/graphene towards methanol oxidation.

  17. Synthesis of 3-(4,5-dihydroimidazol-1-YL)propyltriethoxysilane bound Ru(II) complex bearing viologen segment

    International Nuclear Information System (INIS)

    Gurbuz, N.; Seckin, T.; Ozdemir, I.; Cetinkaya, B.

    2005-01-01

    The nanostructured metallopolymers consisting of the partially quaternized 3-(4,5-dihydroimidazol-1-yl)propyl having the viologen group linked covalently through the alkyl spacer its Ru(II) complex have been prepared by sol-gel method. Structural elucidation was done with Fourier transform infrared spectroscopy, ultraviolet spectroscopy, and differential thermal analysis (DTA) [ru

  18. Ni3S2 nanowires grown on nickel foam as an efficient bifunctional electrocatalyst for water splitting with greatly practical prospects

    Science.gov (United States)

    Zhang, Dawei; Li, Jingwei; Luo, Jiaxian; Xu, Peiman; Wei, Licheng; Zhou, Dan; Xu, Weiming; Yuan, Dingsheng

    2018-06-01

    It is essential to synthesize low-cost, earth-abundant bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reactions (OER) for water electrolysis. Herein, we present a one-step sulfurization method to fabricate Ni3S2 nanowires directly grown on Ni foam (Ni3S2 NWs/Ni) as such an electrocatalyst. This synthetic strategy has several advantages including facile preparation, low cost and can even be expanded to large-scale preparation for practical applications. The as-synthesized Ni3S2 NWs/Ni exhibits a low overpotential of 81 and 317 mV to render a current density of 10 mA cm‑2 for the HER and OER, respectively, in 1.0 mol l‑1 KOH solution. The Ni3S2 NWs/Ni was integrated to be the cathode and the anode in the alkaline electrolyzer for overall water splitting with a current density of 10 mA cm‑2 afforded at a cell voltage of 1.63 V. More importantly, this electrolyzer maintained its electrocatalytic activity even after continual water splitting for 30 h. Owing to its simple synthesis process, the earth-abundant electrocatalyst and high performance, this versatile Ni3S2 NWs/Ni electrode will become a promising electrocatalyst for water splitting.

  19. AuRu/meso-Mn2O3: A Highly Active and Stable Catalyst for Methane Combustion

    Science.gov (United States)

    Han, Z.; Fang, J. Y.; Xie, S. H.; Deng, J. G.; Liu, Y. X.; Dai, H. X.

    2018-05-01

    Three-dimensionally ordered mesoporous Mn2O3 (meso-Mn2O3) and its supported Au, Ru, and AuRu alloy (0.49 wt% Au/meso-Mn2O3, 0.48 wt% Ru/meso-Mn2O3, and 0.97 wt% AuRu/meso-Mn2O3 (Au/Ru molar ratio = 0.98)) nanocatalysts were prepared using the KIT-6-templating and polyvinyl alcohol-protected reduction methods, respectively. Physicochemical properties of the samples were characterized by means of numerous techniques, and their catalytic activities were evaluated for the combustion of methane. It is found that among all of the samples, 0.48 wt% Ru/meso-Mn 2O3 and 0.97 wt% AuRu/meso-Mn2O3 performed the best (the reaction temperature (T90% ) at 90% methane conversion was 530-540°C), but the latter showed a better thermal stability than the former. The partial deactivation of 0.97 wt% AuRu/meso-Mn2O3 due to H2O or CO2 introduction was reversible. It is concluded that the good catalytic activity and thermal stability of 0.97 wt% AuRu/meso-Mn2O3 was associated with the high dispersion of AuRu alloy NPs (2-5 nm) on the surface of meso-Mn2O3 and good low-temperature reducibility.

  20. Review of low pressure plasma processing of proton exchange membrane fuel cell electrocatalysts

    OpenAIRE

    Brault , Pascal

    2016-01-01

    Review article; International audience; The present review is describing recent advances in plasma deposition and treatment of low temperature proton exchange membrane fuel cells electrocatalysts. Interest of plasma processing for growth of platinum based, non-precious and metal free electrocatalysts is highlighted. Electrocatalysts properties are tentatively correlated to plasma parameters.

  1. Study of the oxygen reduction reaction using Pt-Rare earths (La, Ce, Er) electrocatalysts for application of PEM fuel cells

    International Nuclear Information System (INIS)

    Gomes, Thiago Bueno

    2013-01-01

    The complexity of the oxygen reduction reaction (ORR) and its potential losses make it responsible for the most part of efficiency losses at the Fuel Cells. For this reaction the electrocatalyst witch is most appropriated and shows better performance is platinum, a noble metal that elevates the cost, raising barriers for Fuel Cells technology to enter the market. First this work focuses on reducing the amount of platinum used in the cathode, by being replaced by rare earths. The most common methods of synthesis involves a large amount of steps and this work proposed to prepare the electrocatalyst through a simpler way that would not take so many steps and time to be done. Using an ultrasound mixer the electrocatalyst was prepared mixing platinum supported on carbon black and the rare earths lanthanum, cerium and erbium oxides to be applied in a half-cell study of the ORR. The Koutecky-Levich plots shows that among the electrocatalysts prepared the Pt80Ce20/C had the catalytic activity close to the commercial BASF platinum on carbon black, suggesting that the reaction was taken by the 4-electron path. As found in some works in literature, among the rare earth used to study the ORR, cerium is the one witch shows the better performance because it is able to store and provide oxygen. This feature is of great interest for the ORR because this reaction is first order to the oxygen concentration. Results show that is possible to reduce the amount of platinum maintaining the same electrocatalyst activity. (author)

  2. Challenges in bimetallic multilayer structure formation: Pt growth on Cu monolayers on Ru(0001)

    DEFF Research Database (Denmark)

    Mancera, Luis A.; Engstfeld, Albert Kilian; Bensch, Andreas

    2017-01-01

    In a joint experimental and theoretical study, we investigated the formation and morphology of PtCu/Ru(0001) bimetallic surfaces grown at room and higher temperatures under UHV conditions. We obtained the PtCu/Ru(0001) surfaces by deposition of Pt atoms on a previously created Cu/Ru(0001) structure...... which includes only one Cu monolayer. Bimetallic surfaces prepared at different Pt coverages are investigated using STM imaging, revealing the existence of reconstruction lines and Cu islands. Although primarily created Cu islands continue growing in size by increasing Pt coverage, a continuous...

  3. The performance and degradation of Pt electrocatalysts on novel carbon carriers for PEMFC applications

    Energy Technology Data Exchange (ETDEWEB)

    Mamat, M.S.; Grant, D.M.; Walker, G.S. [Energy and Sustainability Research Division, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Grigoriev, S.A.; Dzhus, K.A. [Hydrogen Energy and Plasma Technology Institute, Russian Research Center ' ' Kurchatov Institute' ' , Kurchatov sq. 1, 123182 Moscow (Russian Federation)

    2010-07-15

    Electrocatalyst stability is an important factor influencing the performance of polymer electrolyte membrane (PEM) fuel cells and is essential in maintaining the cell output. The aim of this work was to elucidate factors which influence the stability of platinum supported onto graphitic nanofibres (Pt/GNFs) and to compare the performance of these materials with the commonly used Pt/Vulcan electrocatalyst. Platinum nanoparticles (average diameter of 6.9 nm) were supported on GNFs which were prepared by chemical vapour deposition over an unsupported nickel oxide (NiO) catalyst precursor. The performance of Pt/GNFs based electrodes were studied by cyclic voltammetry and a single-cell fuel cell test and were compared with a commercially available carbon nanostructure, Vulcan XC-72, which was also impregnated with Pt nanoparticles. Characterisation of the pre- and post-operation of the Pt/GNFs by XRD and TEM showed that structural changes of the Pt had occurred during testing. It was found that the average diameter of each grain and the degree of agglomeration among particles was increased, creating elongated clusters of Pt along the carbon fibre. Analysis of electrocatalyst post-operation also identified that the sulphate from the Nafion membrane was reacting with the Pt surface forming platinum sulphide (PtS). These phases were confirmed by the presence of low intensity, but sharp XRD peaks, attributed to a few large diameter particles (49 nm). These two factors resulted in current density dropping from 0.2 A/cm{sup 2} to 0.1 A/cm{sup 2} (at 0.70 V) over a 25 h test period. (author)

  4. Pd nanowire arrays as electrocatalysts for ethanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hong; Cheng, Faliang [Dongguan University of Technology, Dongguan 523106 (China); Xu, Changwei; Jiang, Sanping [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2007-05-15

    Highly ordered Pd nanowire arrays were prepared by template-electrodeposition method using anodic aluminum oxide template. The Pd nanowire arrays, in this paper, have high electrochemical active surface and show excellent catalytic properties for ethanol electrooxidation in alkaline media. The activity of Pd nanowire arrays for ethanol oxidation is not only higher that of Pd film, but also higher than that of commercial E-TEK PtRu(2:1 by weight)/C. The micrometer sized pores and channels in nanowire arrays act as structure units. They make liquid fuel diffuse into and products diffuse out of the catalysts layer much easier, therefore, the utilization efficiency of catalysts gets higher. Pd nanowire arrays are stable catalysts for ethanol oxidation. The nanowire arrays may be a great potential in direct ethanol fuel cells and ethanol sensors. (author)

  5. High index surfaces of Au-nanocrystals supported on one-dimensional MoO3-nanorod as a bi-functional electrocatalyst for ethanol oxidation and oxygen reduction

    International Nuclear Information System (INIS)

    Karuppasamy, L.; Chen, C.Y.; Anandan, S.; Wu, J.J.

    2017-01-01

    Highlights: •Synthesis of a new class of Au nanocrystals enclosed with high index surface supported on MoO 3 nanorods by ultrasonic probe method. •The role of supporting materials reduces the loading of Au and acts as a co-catalyst. •The as prepared electrocatalyst exhibits enhanced catalytic activity and stability towards both EOR and ORR. -- Abstract: The design of highly active electrocatalyst for ethanol electrooxidation (EOR) and oxygen reduction reaction (ORR) is of great significance for the improvement of efficient direct ethanol fuel cells (DEFCs). Therefore, creating high index facets nanocrystals with abundant catalytic active sites of stepped atoms is an effective way to enhance the electrocatalytic performance. In this article, we prepared the high index surface structures of Au nanocrystals supported on one-dimensional (1-D) MoO 3 nanorods by using two steps ultrasonic probe irradiation method. The size and physical properties of as electrocatalysts were studied by using field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and x-ray diffraction (XRD) instrumentation. Besides, the catalytic activity of as Au-MoO 3 electrocatalyst was determined by using cyclic voltammetry (CV), chronoamperometric (CA), electrochemical impedance spectroscopy (EIS), CO-stripping, and linear sweep voltammetry-rotating disk electrode (LSV-RDE). As a consequence, the Au-MoO 3 nanocomposites has been considered as an effective electrocatalyst for both ethanol oxidation and oxygen reduction reaction.

  6. Green Synthesis of Three-Dimensional Hybrid N-Doped ORR Electro-Catalysts Derived from Apricot Sap

    Directory of Open Access Journals (Sweden)

    Ramesh Karunagaran

    2018-01-01

    Full Text Available Rapid depletion of fossil fuel and increased energy demand has initiated a need for an alternative energy source to cater for the growing energy demand. Fuel cells are an enabling technology for the conversion of sustainable energy carriers (e.g., renewable hydrogen or bio-gas into electrical power and heat. However, the hazardous raw materials and complicated experimental procedures used to produce electro-catalysts for the oxygen reduction reaction (ORR in fuel cells has been a concern for the effective implementation of these catalysts. Therefore, environmentally friendly and low-cost oxygen reduction electro-catalysts synthesised from natural products are considered as an attractive alternative to currently used synthetic materials involving hazardous chemicals and waste. Herein, we describe a unique integrated oxygen reduction three-dimensional composite catalyst containing both nitrogen-doped carbon fibers (N-CF and carbon microspheres (N-CMS synthesised from apricot sap from an apricot tree. The synthesis was carried out via three-step process, including apricot sap resin preparation, hydrothermal treatment, and pyrolysis with a nitrogen precursor. The nitrogen-doped electro-catalysts synthesised were characterised by SEM, TEM, XRD, Raman, and BET techniques followed by electro-chemical testing for ORR catalysis activity. The obtained catalyst material shows high catalytic activity for ORR in the basic medium by facilitating the reaction via a four-electron transfer mechanism.

  7. Green Synthesis of Three-Dimensional Hybrid N-Doped ORR Electro-Catalysts Derived from Apricot Sap.

    Science.gov (United States)

    Karunagaran, Ramesh; Coghlan, Campbell; Shearer, Cameron; Tran, Diana; Gulati, Karan; Tung, Tran Thanh; Doonan, Christian; Losic, Dusan

    2018-01-28

    Rapid depletion of fossil fuel and increased energy demand has initiated a need for an alternative energy source to cater for the growing energy demand. Fuel cells are an enabling technology for the conversion of sustainable energy carriers (e.g., renewable hydrogen or bio-gas) into electrical power and heat. However, the hazardous raw materials and complicated experimental procedures used to produce electro-catalysts for the oxygen reduction reaction (ORR) in fuel cells has been a concern for the effective implementation of these catalysts. Therefore, environmentally friendly and low-cost oxygen reduction electro-catalysts synthesised from natural products are considered as an attractive alternative to currently used synthetic materials involving hazardous chemicals and waste. Herein, we describe a unique integrated oxygen reduction three-dimensional composite catalyst containing both nitrogen-doped carbon fibers (N-CF) and carbon microspheres (N-CMS) synthesised from apricot sap from an apricot tree. The synthesis was carried out via three-step process, including apricot sap resin preparation, hydrothermal treatment, and pyrolysis with a nitrogen precursor. The nitrogen-doped electro-catalysts synthesised were characterised by SEM, TEM, XRD, Raman, and BET techniques followed by electro-chemical testing for ORR catalysis activity. The obtained catalyst material shows high catalytic activity for ORR in the basic medium by facilitating the reaction via a four-electron transfer mechanism.

  8. Ternary electrocatalysts for oxidizing ethanol to carbon dioxide: making ir capable of splitting C-C bond.

    Science.gov (United States)

    Li, Meng; Cullen, David A; Sasaki, Kotaro; Marinkovic, Nebojsa S; More, Karren; Adzic, Radoslav R

    2013-01-09

    Splitting the C-C bond is the main obstacle to electrooxidation of ethanol (EOR) to CO(2). We recently demonstrated that the ternary PtRhSnO(2) electrocatalyst can accomplish that reaction at room temperature with Rh having a unique capability to split the C-C bond. In this article, we report the finding that Ir can be induced to split the C-C bond as a component of the ternary catalyst. We characterized and compared the properties of several carbon-supported nanoparticle (NP) electrocatalysts comprising a SnO(2) NP core decorated with multimetallic nanoislands (MM' = PtIr, PtRh, IrRh, PtIrRh) prepared using a seeded growth approach. An array of characterization techniques were employed to establish the composition and architecture of the synthesized MM'/SnO(2) NPs, while electrochemical and in situ infrared reflection absorption spectroscopy studies elucidated trends in activity and the nature of the reaction intermediates and products. Both EOR reactivity and selectivity toward CO(2) formation of several of these MM'/SnO(2)/C electrocatalysts are significantly higher compared to conventional Pt/C and Pt/SnO(2)/C catalysts. We demonstrate that the PtIr/SnO(2)/C catalyst with high Ir content shows outstanding catalytic properties with the most negative EOR onset potential and reasonably good selectivity toward ethanol complete oxidation to CO(2).

  9. Palladium-based electrocatalysts for ethanol oxidation reaction in DEFC

    International Nuclear Information System (INIS)

    Moraes, L.P.R. de; Elsheikh, A.; Silva, E. L. da; Radtke, C.; Amico, S.C.; Malfatti, C.F.

    2014-01-01

    Direct ethanol fuel cells require the use of electrocatalysts to promote bond cleavage of the ethanol molecule in an efficient way. Currently, most electrocatalysts contain platinum, which enables improved catalytic activity and stability in acidic media. However platinum presents high cost and low availability. Based on that, novel catalysts have been developed, such as those based on palladium and its alloys, which have attained excellent results in the oxidation of ethanol in alkaline media. In this work, Pd, PdSn and PdNiSn catalysts supported on Vulcan XC72R carbon were synthesized via impregnation/reduction. The electrocatalysts were characterized by RBS, XRD and cyclic voltammetry. The X-ray diffraction results showed the formation of an alloy and not the deposition of isolated elements. The synthesized catalysts displayed good catalytic activity, as observed by cyclic voltammetry, being the best electrochemical performance achieved by the ternary alloy. (author)

  10. Engineering Platinum Alloy Electrocatalysts in Nanoscale for PEMFC Application

    Energy Technology Data Exchange (ETDEWEB)

    He, Ting [Idaho National Laboratory

    2016-03-01

    Fuel cells are expected to be a key next-generation energy source used for vehicles and homes, offering high energy conversion efficiency and minimal pollutant emissions. However, due to large overpotentials on anode and cathode, the efficiency is still much lower than theoretically predicted. During the past decades, considerable efforts have been made to investigate synergy effect of platinum alloyed with base metals. But, engineering the alloy particles in nanoscale has been a challenge. Most important challenges in developing nanostructured materials are the abilities to control size, monodispersity, microcomposition, and even morphology or self-assembly capability, so called Nanomaterials-by-Design, which requires interdisciplinary collaborations among computational modeling, chemical synthesis, nanoscale characterization as well as manufacturing processing. Electrocatalysts, particularly fuel cell catalysts, are dramatically different from heterogeneous catalysts because the surface area in micropores cannot be electrochemically controlled on the same time scale as more transport accessible surfaces. Therefore, electrocatalytic architectures need minimal microporous surface area while maximizing surfaces accessible through mesopores or macropores, and to "pin" the most active, highest performance physicochemical state of the materials even when exposed to thermodynamic forces, which would otherwise drive restructuring, crystallization, or densification of the nanoscale materials. In this presentation, results of engineering nanoscale platinum alloy particles down to 2 ~ 4 nm will be discussed. Based on nature of alloyed base metals, various synthesis technologies have been studied and developed to achieve capabilities of controlling particle size and particle microcomposition, namely, core-shell synthesis, microemulsion technique, thermal decomposition process, surface organometallic chemical method, etc. The results show that by careful engineering the

  11. Highly Active PdNi/RGO/Polyoxometalate Nanocomposite Electrocatalyst for Alcohol Oxidation.

    Science.gov (United States)

    Hu, Jing; Wu, Xiaofeng; Zhang, Qingfan; Gao, Mingyan; Qiu, Haifang; Huang, Keke; Feng, Shouhua; Wang, Tingting; Yang, Ying; Liu, Zhelin; Zhao, Bo

    2018-02-27

    A PdNi/RGO/polyoxometalate nanocomposite has been successfully synthesized by a simple wet-chemical method. Characterizations such as transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy are employed to verify the morphology, structure, and elemental composition of the as-prepared nanocomposite. Inspired by the fast-developing fuel cells, the electrochemical catalytic performance of the nanocomposite toward methanol and ethanol oxidation in alkaline media is further tested. Notably, the nanocomposite exhibits excellent catalytic activity and long-term stability toward alcohol electrooxidation compared with the PdNi/RGO and commercial Pd/C catalyst. Furthermore, the electrochemical results reveal that the prepared nanocomposite is attractive as a promising electrocatalyst for direct alcohol fuel cells, in which the phosphotungstic acid plays a crucial role in enhancing the electrocatalytic activities of the catalyst.

  12. New ruthenium (II) complexes derived from pyridinopyrazoline and pyridinopyrazole: /sup 1/H, /sup 13/C and /sup 99/Ru NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Marzin, C.; Budde, F.; Steel, P.J.; Lerner, D.

    1987-01-01

    A series of RuL/sub 3//sup 2+/(A), Ru(bpy) L/sub 2//sup 2+/(B) and Ru(bpy)/sub 2/L/sup 2+/(C) complexes with pyridinopyrazole and pyridinopyrazoline ligands L have been prepared; their study allows the evaluation of the ligand ..pi..-acceptor ability on the complex properties; especially /sup 99/Ru and Ru/sup 2//Ru/sup 3+/ oxidation potential measurements show a good ..pi..-acceptor behavior of one of the pyridinopyrazoline ligands. All the B and C type complexes and most of the RuL/sub 3//sup 2+/ ones, emit at 77 K which is rather unusual; one of these gives rise to a double emission, possibly from two isomers. NMR studies show the presence of geometric isomers for A and B type complexes and of diastereoisomeric ones for complexes A, B and C when L includes a pyrazoline unit. 37 refs.

  13. Metalloradical Reactivity of RuI and Ru0 Stabilized by an Indole-Based Tripodal Tetraphosphine Ligand

    NARCIS (Netherlands)

    van de Watering, F.F.; van der Vlugt, J.I.; Dzik, W.I.; de Bruin, B.; Reek, J.N.H.

    2017-01-01

    The tripodal, tetradentate tris(1-(diphenylphosphanyl)-3-methyl-1H-indol-2-yl)phosphane PP3-ligand 1 stabilizes Ru in the RuII, RuI, and Ru0 oxidation states. The octahedral [(PP3)RuII(Cl)2] ( 2 ), distorted trigonal bipyramidal [(PP3)RuI(Cl)] ( 3 ), and trigonal bipyramidal [(PP3)Ru0(N2)] ( 4 )

  14. Effect of copper oxide electrocatalyst on CO2 reduction using Co3O4 as anode

    Directory of Open Access Journals (Sweden)

    V.S.K. Yadav

    2016-09-01

    Full Text Available The reduction of carbon dioxide (CO2 to products electrochemically (RCPE in 0.5 M NaHCO3 and Na2CO3 liquid phase electrolyte solutions was investigated. Cobalt oxide (Co3O4 as anode and cuprous oxide (Cu2O as the cathode were considered, respectively. The impacts of applied potential with time of reaction during reduction of CO2 to products were studied. The anode and cathode were prepared by depositing electrocatalysts on the graphite plate. Ultra-fast liquid chromatography (UFLC was used to analyze the products obtained from the reduction of CO2. The feasible way of reduction by applying voltages with current densities was clearly correlated. The results illustrate the capability of electrocatalyst successfully to remove atmospheric CO2 in the form of valuable chemicals. Maximum Faradaic efficiency of ethanol was 98.1% at 2 V and for formic acid (36.6% at 1.5 V was observed in NaHCO3. On the other hand, in Na2CO3 electrolyte solution maximum efficiency for ethanol was 55.21% at 1.5 V and 25.1% for formic acid at 2 V. In both electrolytes other end products like methanol, propanol, formaldehyde and acetic acid were formed at various applied voltage and output current densities.

  15. Optimizing Carbonaceous Nanostructure Composition as a Substrate to Grow Co Electrocatalysts

    Directory of Open Access Journals (Sweden)

    M Pourreza

    2018-02-01

    Full Text Available Global warming and other adverse environmental effects of fossil fuels have forced humans to consider clean and renewable energy resources. In this context, hydrogen production from water splitting reaction is a key approach. In order to reduce required overpotential for water oxidation reaction, it is necessary to use low cost and earth abundant electrocatalysts like Co, Cu, Fe, Mn, Ni and Zn nanostructures. Herein, cobalt nanostructures on steel-mesh substrate were applied. Electrochemical method was used for growth of Co nanoflakes because of its simplicity and scalability for commercial approach. On the other hand, using carbonaceous support layers including nanomaterials such as graphene and carbon nanotubes, can reduce overpotential and increase efficiency of the electrocatalyst.  According to the results, 40 wt% of graphene oxide and 60 wt% of carbon nanotubes in prepared carbon paste led to better growth for cobalt oxide nanoflakes. For the mentioned layer, cobalt was detected in metallic crystalline phase and the overpotential and electrical resistance measured 305 mV and 20 Ω, respectively.

  16. Structure and magnetic properties of Heusler alloy Co{sub 2}RuSi melt-spun ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Yuepeng; Ma, Yuexing; Hao, Hongyue [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Luo, Hongzhi, E-mail: luo_hongzhi@163.com [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Meng, Fanbin; Liu, Heyan [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Liu, Enke; Wu, Guangheng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2017-08-01

    Highlights: • New Heusler alloy Co{sub 2}RuSi has been prepared by melt-spinning successfully. • Magnetic and electronic properties of Co{sub 2}RuSi were investigated. • Ru has a strong site preference for A, C sites in the lattice of Co{sub 2}RuSi. • Site preference of Ru cannot be determined by “number of valence electrons”. - Abstract: Heusler alloy Co{sub 2}RuSi has been synthesized by melt-spinning technology successfully. Co{sub 2}RuSi bulk sample after annealing is composed of an HCP Co-rich phase and a BCC Ru-Si phase, but melt-spinning can suppress the precipitation of the HCP phase and produce a single Co{sub 2}RuSi Heusler phase. In the XRD pattern, it is found that Ru has a strong preference for the (A, C) sites, though it has fewer valence electrons compared with Co. This site preference is different from the case in Heusler alloys containing only 3d elements and is supported further by first-principles calculations. Melt-spun Co{sub 2}RuSi has a M{sub s} of 2.67 μ{sub B}/f.u. at 5 K and a Tc of 491 K. An exothermic peak is observed at 871 K in the DTA curve, corresponding to the decomposition of the Heusler phase. Finally, the site preference and magnetic properties of Co{sub 2}RuSi were discussed based on electronic structure calculation and charge density difference.

  17. Conductivity study of thermally stabilized RuO2/polythiophene nanocomposites

    Science.gov (United States)

    Hebbar, Vidyashree; Bhajantri, R. F.

    2018-04-01

    The polymer nanocomposites of Ruthenium oxide (RuO2) filled polythiophene (PT) were synthesized by polymerization using chemical method. The purity of the synthesized polymer composite is verified using X-Ray diffraction (XRD). The structural discrepancies of the RuO2 filled PT composites are studied by Fourier transform infrared (FT-IR) spectroscopy. The phase transition and thermal stability of the prepared composite is revised by thermal characterization such as differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The DC conductivity of RuO2 filled PT composite in the form of pellets is calculated using current-voltage (I-V) characterization by two-probe method. The enhancement in conductivity with increased RuO2 content in PT matrix is examined, which is the required property for electrical and electronic applications in supercapacitors.

  18. Effect of TiO_2 Loading on Pt-Ru Catalysts During Alcohol Electrooxidation

    International Nuclear Information System (INIS)

    Hasa, Bjorn; Kalamaras, Evangelos; Papaioannou, Evangelos I.; Vakros, John; Sygellou, Labrini; Katsaounis, Alexandros

    2015-01-01

    Highlights: • TiO_2 can be used to modify Pt-Ru based electrodes for alcohol oxidation. • TiO_2 modified electrodes with lower amount of metals had higher active surface area than pure Pt-Ru electrodes. • TiO_2 modified electrodes showed comparable performance with pure Pt-Ru electrode both in a single cell and in a PEM fuel cell under alcohol fuelling. - Abstract: In this study, Pt-Ru based electrodes modified by TiO_2 were prepared by means of thermal decomposition of chloride and isopropoxide precursors on Ti substrates, characterised by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), electrochemical techniques and CO stripping and used as anodes for alcohol oxidation. The minimization of the metal loading without electrocatalytic activity losses was also explored. TiO_2 was chosen due to its chemical stability, low cost and excellent properties as substrate for metal dispersion. It was found that TiO_2 loading up to 50% results in a 3-fold increase of the Electrochemically Active Surface (EAS). This conclusion has been confirmed by CO stripping experiments. All samples have been evaluated during the electrochemical oxidation of methanol, ethanol and glycerol. In all cases, the Pt_2_5-Ru_2_5-(TiO_2)_5_0 electrode had better electrocatalytic activity than the pure Pt_5_0-Ru_5_0 anode. The best modified electrode, (Pt_2_5-Ru_2_5-(TiO_2)_5_0), was also evaluated as anode in a PEM fuel cell under methanol fuelling conditions. The observed higher performance of the TiO_2 modified electrodes was attributed to the enhanced Pt-Ru dispersion as well as the formation of smaller Pt and Ru particles.

  19. Low content of Pt supported on Ni-MoCx/carbon black as a highly durable and active electrocatalyst for methanol oxidation, oxygen reduction and hydrogen evolution reactions in acidic condition

    Science.gov (United States)

    Zhang, Yan; Zang, Jianbing; Jia, Shaopei; Tian, Pengfei; Han, Chan; Wang, Yanhui

    2017-08-01

    Nickel and molybdenum carbide modified carbon black (Ni-MoCx/C) was synthesized by a two-step microwave-assisted deposition/carbonthermal reduction method and characterized by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy and X-ray photoelectron spectroscopy. The as-prepared Ni-MoCx/C supported Pt (10 wt%) electrocatalyst (10Pt/Ni-MoCx/C) was synthesized through a microwave-assisted reduction method and 10Pt/Ni-MoCx/C exhibited high electrocatalytic activity for methanol oxidation, oxygen reduction and hydrogen evolution reactions. Results showed that 10Pt/Ni-MoCx/C electrocatalyst had better electrocatalytic activity and stability performance than 20 wt% Pt/C (20Pt/C) electrocatalyst. Among them, the electrochemical surface area of 10Pt/Ni-MoCx/C reached 68.4 m2 g-1, which was higher than that of 20Pt/C (63.2 m2 g-1). The enhanced stability and activity of 10Pt/Ni-MoCx/C electrocatalyst were attributed to: (1) an anchoring effect of Ni and MoCx formed during carbonthermal reduction process; (2) a synergistic effect among Pt, Ni, MoOx and MoCx. These findings indicated that 10Pt/Ni-MoCx/C was a promising electrocatalyst for direct methanol fuel cells.

  20. Electrocatalysts of platinum, cobalt and nickel prepared by mechanical alloying for the oxygen reduction reaction in H{sub 2}SO{sub 4} 0.5M; Electrocatalizadores de Platino, Cobalto y Niquel preparados por Aleado Mecanico para la reaccion de reduccion de oxigeno en H{sub 2}SO{sub 4} 0.5M

    Energy Technology Data Exchange (ETDEWEB)

    Garcia C, M.A.; Fernandez V, S.M.; Vargas G, J.R. [lNIN, Depto. de Quimica, 52750 La Marquesa, Estado de Mexico (Mexico)

    2007-07-01

    Metallic powders of Pt, Co and Nickel were processed by mechanical alloyed and electrocatalysts were synthesized for the oxygen reduction reaction, applicable in fuel cells. The structural and morphological characterization was carried out using X-ray Diffraction, scanning electron microscopy and transmission electron microscopy. It was found that the alloyed powders formed agglomerates that consist of crystalline particles of nano metric size. Its were obtained polarization curves by the Electrode of Rotational Disk technique in a solution of H{sub 2}SO{sub 4} 0.5 M, used as electrolyte, to evaluate the electrocatalytic activity of mechanically alloyed powders. Tafel graphics were built to determine the kinetic parameters of each electro catalyst. The PtCoNi alloy exhibited the biggest electrocatalytic activity, with the smallest over potential for the oxygen reduction reaction. (Author)

  1. Palladium-cobalt particles as oxygen-reduction electrocatalysts

    Science.gov (United States)

    Adzic, Radoslav [East Setauket, NY; Huang, Tao [Manorville, NY

    2009-12-15

    The present invention relates to palladium-cobalt particles useful as oxygen-reducing electrocatalysts. The invention also relates to oxygen-reducing cathodes and fuel cells containing these palladium-cobalt particles. The invention additionally relates to methods for the production of electrical energy by using the palladium-cobalt particles of the invention.

  2. CuZn Alloy- Based Electrocatalyst for CO2 Reduction

    KAUST Repository

    Alazmi, Amira

    2014-01-01

    , especially when the electronic energy is derived from renewable energies, such as solar, wind, geo-thermal and tidal. To achieve this goal, the development of an efficient electrocatalyst for CO2 reduction is essential. In this thesis, studies on CuZn alloys

  3. Low temperature synthesis of Ru-Cu alloy nanoparticles with the compositions in the miscibility gap

    Science.gov (United States)

    Martynova, S. A.; Filatov, E. Yu.; Korenev, S. V.; Kuratieva, N. V.; Sheludyakova, L. A.; Plusnin, P. E.; Shubin, Yu. V.; Slavinskaya, E. M.; Boronin, A. I.

    2014-04-01

    A complex salt [Ru(NH3)5Cl][Cu(C2O4)2H2O]-the precursor of nanoalloys combining ruthenium and copper was prepared. It crystallizes in the monoclinic space group P21/n. Thermal properties of the prepared salt were examined in different atmospheres (helium, hydrogen, oxygen). Thermal decomposition of the precursor in inert atmosphere was thoroughly examined and the intermediate products were characterized. Experimental conditions for preparation of copper-rich (up to 12 at% of copper) metastable solid solution CuxRu1-x (based on Ru structure) were optimized, what is in sharp contrast to the bimetallic miscibility gap known for the bulk counterparts in a wide composition range. Catalytic properties of copper-ruthenium oxide composite were tested in catalytic oxidation of CO.

  4. Mechanochemical synthesis of Co and Ni decorated with chemically deposited Pt as electrocatalysts for oxygen reduction reaction

    International Nuclear Information System (INIS)

    Flores-Rojas, E.; Cabañas-Moreno, J.G.; Pérez-Robles, J.F.; Solorza-Feria, O.

    2016-01-01

    High energy milling in combination with galvanic displacement were used for the preparation of bimetallic nanocatalysts. Co and Ni monometallic powders milled for 30 and 20 h, respectively were both produced in air atmosphere and used as precursors for the preparation of M-Pt (M = Co,Ni) compounds. Nanosized monometallic powders were physically supported on Vulcan carbon, and covered with 20 wt%Pt through a Galvanic Displacement Reaction (GDR) to produce Co-20Pt/C and Ni-20Pt/C electrocatalysts. XRD was used for phase identification on milled powders and for demonstrating structural transformations of Co powders during milling. Results on unmilled metallic Co powder show a predominant HCP structure modifying to a FCC structure after milling. Ni powders maintain their same FCC structure. Energy Dispersive X-Ray Spectometry (EDX) was used for chemical composition analysis on milled powders at several milling times. Scanning Transmission Electron Microscopy (STEM) show the formation of heterogeneous particle with ∼10 nm in size for both electrocatalysts. The electrocatalytic activity was evaluated by Cyclic Voltammetry (CV) and steady state Rotating Disk Electrode (RDE) for the Oxygen Reduction Reaction (ORR) in 0.1 M HClO_4. The kinetic parameters on Co-20Pt/C conducted to the highest mass activity for the cathodic reaction. - Highlights: • Monometallic powders of Co, and Ni were used as precursors for the preparation of M-Pt (M = Co,Ni) electrocatalysts. • Nanosized monometallic powders were decorated with Pt by a Galvanic Displacement Reaction. • The kinetic parameters on Co-20Pt/C conducted to the highest mass activity for the ORR reaction.

  5. Electroless plating of Ni–B film as a binder-free highly efficient electrocatalyst for hydrazine oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Xiao-Ping; Dai, Hong-Bin, E-mail: mshbdai@scut.edu.cn; Wu, Lin-Song; Wang, Ping, E-mail: mspwang@scut.edu.cn

    2017-07-01

    Graphical abstract: A Ni–B film was grown on Ni foam to form a binder-free highly efficient electrocatalyst for hydrazine oxidation in alkaline medium. The newly-developed Ni–B/Ni foam electrocatalyst may promote the practical application of hydrazine as a viable energy carrier for fuel cells. - Highlights: • A Ni–B film grown on Ni foam electrocatalyst is prepared by the electrless plating. • The Ni–B film shows high activity and stability for N{sub 2}H{sub 4} electrooxidation reaction. • The improved catalytic property is ascribed to B-tuned electronic structure of Ni. • The resultant catalyst may promote application of N{sub 2}H{sub 4} as a viable energy carrier. - Abstract: Hydrazine is a promising energy carrier for fuel cells owing to its combined advantages of high theoretical cell voltage, high-power density, and no greenhouse gas emission. By using an electroless plating process, we have prepared a robust Ni–B film grown on Ni foam that is highly effective for hydrazine electrooxidation in alkaline media. The effects of reaction temperature, concentrations of hydrous hydrazine and sodium hydroxide in the fuel solution on performance of hydrazine electrooxidation reaction are investigated. The mechanistic reason for the property advantage of as-prepared Ni–B/Ni foam catalyst over the relevant catalysts is discussed based on careful kinetics studies and characterization. The facile synthesis of Ni-based catalyst with high activity and good stability is of clear significance for the development of hydrous hydrazine as a viable energy carrier.

  6. Electroless plating of Ni–B film as a binder-free highly efficient electrocatalyst for hydrazine oxidation

    International Nuclear Information System (INIS)

    Wen, Xiao-Ping; Dai, Hong-Bin; Wu, Lin-Song; Wang, Ping

    2017-01-01

    Graphical abstract: A Ni–B film was grown on Ni foam to form a binder-free highly efficient electrocatalyst for hydrazine oxidation in alkaline medium. The newly-developed Ni–B/Ni foam electrocatalyst may promote the practical application of hydrazine as a viable energy carrier for fuel cells. - Highlights: • A Ni–B film grown on Ni foam electrocatalyst is prepared by the electrless plating. • The Ni–B film shows high activity and stability for N_2H_4 electrooxidation reaction. • The improved catalytic property is ascribed to B-tuned electronic structure of Ni. • The resultant catalyst may promote application of N_2H_4 as a viable energy carrier. - Abstract: Hydrazine is a promising energy carrier for fuel cells owing to its combined advantages of high theoretical cell voltage, high-power density, and no greenhouse gas emission. By using an electroless plating process, we have prepared a robust Ni–B film grown on Ni foam that is highly effective for hydrazine electrooxidation in alkaline media. The effects of reaction temperature, concentrations of hydrous hydrazine and sodium hydroxide in the fuel solution on performance of hydrazine electrooxidation reaction are investigated. The mechanistic reason for the property advantage of as-prepared Ni–B/Ni foam catalyst over the relevant catalysts is discussed based on careful kinetics studies and characterization. The facile synthesis of Ni-based catalyst with high activity and good stability is of clear significance for the development of hydrous hydrazine as a viable energy carrier.

  7. Mechanochemical synthesis of Co and Ni decorated with chemically deposited Pt as electrocatalysts for oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Rojas, E.; Cabañas-Moreno, J.G. [Programa de Nanociencias y Nanotecnología, Centro de Investigación y de Estudios Avanzados, CINVESTAV-IPN, Av. Instituto Politécnico Nacional 2508, Col. Zacatenco, 07360 Mexico City (Mexico); Pérez-Robles, J.F. [Programa de Nanociencias y Nanotecnología, Centro de Investigación y de Estudios Avanzados, CINVESTAV-IPN, Av. Instituto Politécnico Nacional 2508, Col. Zacatenco, 07360 Mexico City (Mexico); Dpto. Ciencia de los Materiales, CINVESTAV-IPN Unidad Queretaro, Libramiento Norponiente No. 2000 Fracc. Real de Juriquilla, 76230, Queretaro (Mexico); Solorza-Feria, O., E-mail: osolorza@cinvestav.mx [Programa de Nanociencias y Nanotecnología, Centro de Investigación y de Estudios Avanzados, CINVESTAV-IPN, Av. Instituto Politécnico Nacional 2508, Col. Zacatenco, 07360 Mexico City (Mexico); Depto. Química, CINVESTAV-IPN, 07360, México City (Mexico)

    2016-11-01

    High energy milling in combination with galvanic displacement were used for the preparation of bimetallic nanocatalysts. Co and Ni monometallic powders milled for 30 and 20 h, respectively were both produced in air atmosphere and used as precursors for the preparation of M-Pt (M = Co,Ni) compounds. Nanosized monometallic powders were physically supported on Vulcan carbon, and covered with 20 wt%Pt through a Galvanic Displacement Reaction (GDR) to produce Co-20Pt/C and Ni-20Pt/C electrocatalysts. XRD was used for phase identification on milled powders and for demonstrating structural transformations of Co powders during milling. Results on unmilled metallic Co powder show a predominant HCP structure modifying to a FCC structure after milling. Ni powders maintain their same FCC structure. Energy Dispersive X-Ray Spectometry (EDX) was used for chemical composition analysis on milled powders at several milling times. Scanning Transmission Electron Microscopy (STEM) show the formation of heterogeneous particle with ∼10 nm in size for both electrocatalysts. The electrocatalytic activity was evaluated by Cyclic Voltammetry (CV) and steady state Rotating Disk Electrode (RDE) for the Oxygen Reduction Reaction (ORR) in 0.1 M HClO{sub 4}. The kinetic parameters on Co-20Pt/C conducted to the highest mass activity for the cathodic reaction. - Highlights: • Monometallic powders of Co, and Ni were used as precursors for the preparation of M-Pt (M = Co,Ni) electrocatalysts. • Nanosized monometallic powders were decorated with Pt by a Galvanic Displacement Reaction. • The kinetic parameters on Co-20Pt/C conducted to the highest mass activity for the ORR reaction.

  8. Peierls-distorted Ru-chains and boron dumbbells in Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} from first-principles calculations and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Touzani, Rachid S.; Mbarki, Mohammed; Chen, Ximeng [Institute of Inorganic Chemistry, RWTH Aachen University (Germany); Fokwa, Boniface P.T. [Institute of Inorganic Chemistry, RWTH Aachen University (Germany); Department of Chemistry, University of California Riverside (UCR), Riverside, CA (United States)

    2016-09-15

    Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} phases were recently predicted by GGA-VASP structure optimization to crystallize in the Nb{sub 2}OsB{sub 2}-type structure. Although the Fe-based (Mo{sub 2}FeB{sub 2} type) and Os-based (Nb{sub 2}OsB{sub 2} type, superstructure variant of Mo{sub 2}FeB{sub 2} type) analogues have been synthesized and characterized successfully, the Ru-based phases remained unknown. Crystal structure prediction of Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} phases, using an evolutionary algorithm, led to the AlMn{sub 2}B{sub 2}-type structure in contrast to the aforementioned optimization; however, phonon calculations showed that the Nb{sub 2}OsB{sub 2}-type phases are dynamically more stable than the AlMn{sub 2}B{sub 2}-type phases. A slightly modified synthetic strategy finally led to the successful preparation of the predicted phases. The extremely quick arc-melting procedure, under argon atmosphere, not only led to a quantitative amount of the phases but also to single crystals suitable for structure determination. Powder and single-crystal X-ray diffraction as well as EDX analysis of the metal ratio have confirmed the GGA-VASP structure optimization: Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} compounds indeed crystallize isotypically with Nb{sub 2}OsB{sub 2} structure, a superstructure variant of Mo{sub 2}FeB{sub 2} type, in which B-dumbbells and Peierls-distorted Ru-chains are found. Susceptibility measurements on a Ta{sub 2}RuB{sub 2} single crystal reveal no superconducting transition down to 2 K, even though some features in the band structures of both phases, similar to those reported in superconducting NbRuB, hinted at possible superconductivity. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Microwave Assisted Synthesis of Osmium Electrocatalysts for the Oxygen Reduction Reaction in the Absence and Presence of Aqueous Methanol

    Directory of Open Access Journals (Sweden)

    Edgar Borja-Arco

    2011-01-01

    Full Text Available Osmium electrocatalysts for the oxygen reduction reaction (ORR were prepared by microwave irradiation of Os3(CO12 at different experimental conditions. The materials obtained were structurally characterized by FT-IR, micro-Raman spectroscopy and X-ray diffraction. Their chemical compositions were obtained by EDS. The electrocatalytic properties for the oxygen reduction reaction were evaluated by rotating disk electrode measurements in 0.5 mol L-1 H2SO4, in the absence and presence of aqueous methanol. The kinetic parameters, such as Tafel slope, exchange current density, and charge transfer coefficient are reported.

  10. Evaluation of the Optimum Composition of Low-Temperature Fuel Cell Electrocatalysts for Methanol Oxidation by Combinatorial Screening.

    Science.gov (United States)

    Antolini, Ermete

    2017-02-13

    Combinatorial chemistry and high-throughput screening represent an innovative and rapid tool to prepare and evaluate a large number of new materials, saving time and expense for research and development. Considering that the activity and selectivity of catalysts depend on complex kinetic phenomena, making their development largely empirical in practice, they are prime candidates for combinatorial discovery and optimization. This review presents an overview of recent results of combinatorial screening of low-temperature fuel cell electrocatalysts for methanol oxidation. Optimum catalyst compositions obtained by combinatorial screening were compared with those of bulk catalysts, and the effect of the library geometry on the screening of catalyst composition is highlighted.

  11. Inner-shell photodetachment from Ru-

    International Nuclear Information System (INIS)

    Dumitriu, I.; Gorczyca, T. W.; Berrah, N.; Bilodeau, R. C.; Pesic, Z. D.; Rolles, D.; Walter, C. W.; Gibson, N. D.

    2010-01-01

    Inner-shell photodetachment from Ru - was studied near and above the 4p excitation region, 29-to-91-eV photon energy range, using a merged ion-photon-beam technique. The absolute photodetachment cross sections of Ru - ([Kr]4d 7 5s 2 ) leading to Ru + , Ru 2+ , and Ru 3+ ion production were measured. In the near-threshold region, a Wigner s-wave law, including estimated postcollision interaction effects, locates the 4p 3/2 detachment threshold between 40.10 and 40.27 eV. Additionally, the Ru 2+ product spectrum provides evidence for simultaneous two-electron photodetachment (likely to the Ru + 4p 5 4d 6 5s 2 state) located near 49 eV. Resonance effects are observed due to interference between transitions of the 4p electrons to the quasibound 4p 5 4d 8 5s 2 states and the 4d→εf continuum. Despite the large number of possible terms resulting from the Ru - 4d open shell, the cross section obtained from a 51-state LS-coupled R-matrix calculation agrees qualitatively well with the experimental data.

  12. Study on oxidization of Ru and its application as electrode of PZT capacitor for FeRAM

    International Nuclear Information System (INIS)

    Jia Ze; Ren Tianling; Liu Tianzhi; Hu Hong; Zhang Zhigang; Xie Dan; Liu Litian

    2007-01-01

    Oxidization for Ru through anneal with plenteous oxygen atmosphere and its application as the top electrode of sol-gel PZT capacitor are investigated in this study. PZT capacitor with RuO 2 or oxygen-doped Ru as top electrode can be obtained from Ru/PZT/Pt capacitor through slow-rate anneal at 650 deg. C for 20 min in cannulation furnace. It has larger remanent polarization, better rectangle shape, better fatigue properties and lower leakage current than the other capacitors with PZT film prepared by the same process and different top electrodes in this study. Plenteous oxygen atmosphere and 650 deg. C in cannulation furnace are important conditions for the oxidation of Ru and renewed crystallization of PZT in this capacitor. Plenteous oxygen at interface can compensate the oxygen vacancies at PZT/electrode interface, which results in the above good characteristics

  13. Electrochemical Reduction of CO2 on IrxRu(1–x)O2(110) Surfaces 

    DEFF Research Database (Denmark)

    Bhowmik, Arghya; Hansen, Heine Anton; Vegge, Tejs

    2017-01-01

    with oxygen-coordinated intermediates that can circumvent the limitations imposed by the scaling relations on metal catalysts. Here, we introduce an innovative concept of ligand effects in oxide catalysts. Both IrO2 and RuO2 binds OH* and other intermediates from the electrochemical reduction of CO2 (CO2RR......High overpotentials and low faradic efficiencies plague metal catalysts for direct conversion of CO2 to methanol and other liquid fuels. RuO2-based electrocatalysts have been observed to evolve methanol at low overpotentials, which has been attributed to an alternative reaction mechanism......) strongly, but the stable and miscible system IrxRu(1-x)O2 exhibits anomalous weaker binding energy in the presence of CO* spectators, because of Ru–Ir ligand effects. The weakened adsorbate binding leads to a very low CO2RR onset potential (methanol evolution at −0.2 V RHE). An Ir atom at the bridge site...

  14. Formation of graphene on Ru(0001) surface

    Institute of Scientific and Technical Information of China (English)

    Pan Yi; Shi Dong-Xia; Gao Hong-Jun

    2007-01-01

    We report on the formation of a graphene monolayer on a Ru(0001) surface by annealing the Ru(0001) crystal.The samples are characterized by scanning tunnelling microscopy (STM) and Auger electron spectroscopy (AES). STM images show that the Moiré pattern is caused by the graphene layer mismatched with the underlying Ru(0001) surface and has an N × N superlattice. It is further found that the graphene monolayer on a Ru(0001) surface is very stable at high temperatures. Our results provide a simple and convenient method to produce a graphene monolayer on the Ru(0001) surface, which is used as a template for fabricating functional nanostructures needed in future nano devices and catalysis.

  15. Modified Graphene as Electrocatalyst towards Oxygen Reduction Reaction for Fuel Cells

    International Nuclear Information System (INIS)

    Qazzazie, D; Yurchenko, O; Beckert, M; Mülhaupt, R; Urban, G

    2014-01-01

    This paper reports modified graphene-based materials as metal-free electrocatalysts for oxygen reduction reaction (ORR) with outstanding electrocatalytic activity in alkaline conditions. Nitrogen-doped graphene samples are synthesized by a novel procedure. The defect density in the structure of the prepared materials is investigated by Raman spectroscopy. Further structural characterization by X-ray photoelectron spectroscopy reveals the successful nitrogen doping of graphene. The electrochemical characterization of graphene and nitrogen-doped graphene in 0.1 M KOH solution demonstrates the material's electrocatalytic activity towards ORR. For graphene an onset potential of – 0.175 V vs. Ag/AgCl reference electrode is determined, while for nitrogen-doped graphene the determined onset potential is – 0.160 V. Thus, the electrocatalytic activity of nitrogen-doped graphene towards ORR is enhanced which can be ascribed to the effect of nitrogen doping

  16. Modified Graphene as Electrocatalyst towards Oxygen Reduction Reaction for Fuel Cells

    Science.gov (United States)

    Qazzazie, D.; Beckert, M.; Mülhaupt, R.; Yurchenko, O.; Urban, G.

    2014-11-01

    This paper reports modified graphene-based materials as metal-free electrocatalysts for oxygen reduction reaction (ORR) with outstanding electrocatalytic activity in alkaline conditions. Nitrogen-doped graphene samples are synthesized by a novel procedure. The defect density in the structure of the prepared materials is investigated by Raman spectroscopy. Further structural characterization by X-ray photoelectron spectroscopy reveals the successful nitrogen doping of graphene. The electrochemical characterization of graphene and nitrogen-doped graphene in 0.1 M KOH solution demonstrates the material's electrocatalytic activity towards ORR. For graphene an onset potential of - 0.175 V vs. Ag/AgCl reference electrode is determined, while for nitrogen-doped graphene the determined onset potential is - 0.160 V. Thus, the electrocatalytic activity of nitrogen-doped graphene towards ORR is enhanced which can be ascribed to the effect of nitrogen doping.

  17. Discovery of fuel cell anode electrocatalysts and dehydrogenation catalysts using combinatorial techniques

    Science.gov (United States)

    Chan, Benny Chun Wai

    A gas diffusion optical screening method was developed for the discovery of catalysts for the electro-oxidation of reformate gas (H2 with 100 ppm CO). The screening cell was designed to accommodate a gas diffusion layer, 715 member catalyst array, and an electrolyte container. Since protons are generated during H2 oxidation, a pH sensitive fluorphore was used to identify active compositions. The cell showed no detectable iR drop across the array and ranked activity of two commercial PtRu and one Pt catalysts. Over 95% of a given catalyst fluoresced at the initial onset potential and a 5 mV difference in onset potential of two different catalysts was statistically different. A gas diffusion half cell was designed similar to the optical screening cell to obtain current-potential curves of bulk catalysts. The screening results correlated with half cell and fuel cell data, internally validating the method. The combinatorial method was then applied to search for catalysts in the PtRuMoIrRh composition space. The catalysts on the array were prepared by hydrogen reduction of the metals salts on carbon. The most active catalysts were from the Pt enriched regions of the PtRuMoRh quaternary. Bulk catalysts were prepared from the active regions and tested in the gas diffusion half cell. The most active catalysts in the optical screening were also the most active catalysts in the half cell. When any homemade catalysts were compared to commercial PtRu, however, the performance was worse. A high surface area, high catalyst activity synthetic method is the most important factor to reliably screen catalysts for "real world" fuel cell application. High surface area catalysts were tested for direct methanol oxidation activity. The optical screening method was compared with disk electrode, high throughput fuel cell testing, and fuel cell testing. Six catalysts examined included two commercial PtRu catalysts, a Pt catalyst, and three homemade PtRu catalysts of varying activity

  18. Metal-Organic-Framework-Derived Hybrid Carbon Nanocages as a Bifunctional Electrocatalyst for Oxygen Reduction and Evolution.

    Science.gov (United States)

    Liu, Shaohong; Wang, Zhiyu; Zhou, Si; Yu, Fengjiao; Yu, Mengzhou; Chiang, Chang-Yang; Zhou, Wuzong; Zhao, Jijun; Qiu, Jieshan

    2017-08-01

    The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are cornerstone reactions for many renewable energy technologies. Developing cheap yet durable substitutes of precious-metal catalysts, especially the bifunctional electrocatalysts with high activity for both ORR and OER reactions and their streamlined coupling process, are highly desirable to reduce the processing cost and complexity of renewable energy systems. Here, a facile strategy is reported for synthesizing double-shelled hybrid nanocages with outer shells of Co-N-doped graphitic carbon (Co-NGC) and inner shells of N-doped microporous carbon (NC) by templating against core-shell metal-organic frameworks. The double-shelled NC@Co-NGC nanocages well integrate the high activity of Co-NGC shells into the robust NC hollow framework with enhanced diffusion kinetics, exhibiting superior electrocatalytic properties to Pt and RuO 2 as a bifunctional electrocatalyst for ORR and OER, and hold a promise as efficient air electrode catalysts in Zn-air batteries. First-principles calculations reveal that the high catalytic activities of Co-NGC shells are due to the synergistic electron transfer and redistribution between the Co nanoparticles, the graphitic carbon, and the doped N species. Strong yet favorable adsorption of an OOH* intermediate on the high density of uncoordinated hollow-site C atoms with respect to the Co lattice in the Co-NGC structure is a vital rate-determining step to achieve excellent bifunctional electrocatalytic activity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Effect of W on activity of Pt-Ru/C catalyst for methanol electrooxidation in acidic medium

    International Nuclear Information System (INIS)

    Wang Zhenbo; Zuo Pengjian; Yin Geping

    2009-01-01

    The effect of W on the activity of Pt-Ru/C catalyst was investigated. The Pt-Ru-W/C and Pt-Ru/C-TR catalysts were prepared by thermal reduction method. Comparison was made to a homemade Pt-Ru/C-CR catalyst prepared by chemical reduction. Their performances were tested by using a glassy carbon thin film electrode through cyclic voltammetric and chronoamperometric curves. The particle size, structure, composition, and surface state of homemade catalyst were determined by means of X-ray diffraction (XRD), energy dispersive analysis of X-ray (EDAX), transmission electron microscopy (TEM), and X-ray photoelectron spectrometry (XPS). The result of XRD analysis shows that the homemade ternary catalyst exhibits face-centered cubic structure and has smaller lattice parameter than Pt-alone and homemade Pt-Ru/C catalysts. The particle size of Pt-Ru-W/C catalyst is relatively large of 6.5 nm. Its electrochemically active specific area is 20 m 2 g -1 less than that of Pt-Ru/C-CR, and much twice as big as that of Pt-Ru/C-TR. But, XPS analysis shows that the addition of W changes the surface state of Pt components in the alloy and can clean Pt surface active sites which are adsorbed by hydrogen. The electrocatalytic activity and tolerance performance to CO ads of Pt-Ru-W/C catalyst for methanol electrooxidation is the best due to the promoting function of W in comparison with homemade Pt-Ru/C ones.

  20. Ethanol Electro-oxidation on Novel Electrocatalyst PtVSnO2/C in Acidic Media

    International Nuclear Information System (INIS)

    Jin, Biyao; Sun, Hongyan; Huang, Minghui; Zhao, Lianhua

    2014-01-01

    Graphical abstract: - Highlights: • Novel electrocatalyst PtVSnO 2 /C is synthesized by a modified Bönnemann method. • Adding Sn and V changes the geometric and electronic structure of Pt. • PtVSnO 2 /C improved catalytic activity and the ability of resisting CO poisoning. - Abstract: A novel carbon-supported Pt-V-SnO 2 catalyst is prepared by a modified Bönnemann method. Pt/C, PtV/C, and PtSnO 2 /C are used for comparative analysis to study PtVSnO 2 /C in terms of its structure and electrocatalytic activity for the ethanol oxidation reaction (EOR). Characterization of its structural properties by X-ray diffraction (XRD) and transmission electron microscopy (TEM) is described. It is shown that the Pt lattice parameter decreases with the addition of V but increases with the addition of Sn in the PtVSn/C catalyst. TEM analysis reveals that the prepared catalyst particles are in the nanosize range (2-4 nm). EDS confirms the atomic compositions of the synthesized catalysts to be similar to the nominal values. The electrocatalytic activities are characterized by cyclic voltammetry (CV) and amperometric i-t curve measurement (i-t) techniques. The incorporation of a small amount of V in the PtSnO 2 /C electrocatalyst leads to higher activity for the ethanol oxidation reaction at room temperature. According to the Arrhenius equation, the apparent activation energy of PtVSnO 2 /C (3:1:3) for EOR is the lowest among the studied catalysts, which may be attributed to a synergistic effect between Sn and V

  1. A smart strategy to fabricate Ru nanoparticle inserted porous carbon nanofibers as highly efficient levulinic acid hydrogenation catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying; Sun, Cheng-Jun; Brown, Dennis E.; Zhang, Liqiang; Yang, Feng; Zhao, Hairui; Wang, Yue; Ma, Xiaohui; Zhang, Xin; Ren, Yang

    2016-01-01

    Herein, we first put forward a smart strategy to in situ fabricate Ru nanoparticle (NP) inserted porous carbon nanofibers by one-pot conversion of Ru-functionalized metal organic framework fibers. Such fiber precursors are skillfully constructed by cooperative assembly of different proportional RuCl3 and Zn(Ac)2·2H2O along with trimesic acid (H3BTC) in the presence of N,N-dimethylformamide. The following high-temperature pyrolysis affords uniform and evenly dispersed Ru NPs (ca. 12-16 nm), which are firmly inserted into the hierarchically porous carbon nanofibers formed simultaneously. The resulting Ru-carbon nanofiber (Ru-CNF) catalysts prove to be active towards the liquid-phase hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL), a biomass-derived platform molecule with wide applications in the preparation of renewable chemicals and liquid transportation fuels. The optimal GVL yield of 96.0% is obtained, corresponding to a high activity of 9.23 molLAh–1gRu–1, 17 times of that using the commercial Ru/C catalyst. Moreover, the Ru-CNF catalyst is extremely stable, and can be cycled up to 7 times without significant loss of reactivity. Our strategy demonstrated here reveals new possibilities to make proficient metal catalysts, and provides a general way to fabricate metal-carbon nanofiber composites available for other applications.

  2. Synthesis and magnetic properties of carbon-coated FeRu, CoRu, and NiRu nanoalloys

    Energy Technology Data Exchange (ETDEWEB)

    El-Gendy, A.A.; Khavrus, V.O.; Hampel, S.; Leonhardt, A.; Klingeler, R.; Buechner, B. [Leibniz Institute for Solid State and Materials Research (IFW) Dresden (Germany)

    2010-07-01

    Carbon coated FeRu, CoRu and NiRu nanoalloys have been synthesised by high pressure chemical vapour deposition (HPCVD). The formation of the core-shell nanoalloys with a mean diameter around 8 nm has been confirmed by means of high resolution transmission electron microscopy imaging (HRTEM), energy dispersive X-ray (EDX) analysis, and X-ray diffraction (XRD). We show the effect of the synthesis parameters on the actual composition of the nanoalloys and on their magnetic properties and we discuss their feasibility for applications in medical hyperthermia.

  3. Characterization of a titanium-promoted supported platinum electrocatalyst

    International Nuclear Information System (INIS)

    Beard, B.C.; Ross, P.N. Jr.

    1986-01-01

    X-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), and extended x-ray adsorption fine structure (EXAFS) were used for the characte3rization of a highly dispersed Ti[promoted Pt electrocatalyst. This bimetallic catalyst was prepared by addition of TiCl/sub 4/ to a methanol-water solution containing Pt on carbon black catalyst in suspension. Following filtration and air drying (300 0 C), heat-treatments up to 1200 0 C under flowing helium were performed to promote the formation of Pt-Ti alloy phases. XPS indicated the development of a peak at a binding energy of 454.9 eV (assigned to Ti in Pt/sub 3/Ti), which increased in area with heat-treatment such that after the 1200 0 C heat-treatment ≅ 50% of the Ti was converted to the intermetallic phase, Pt/sub 3/Ti. The Pt (4f, 7/2) photoelectron line shifted (+0.3 eV) to 71.2 eV following the 1200 0 C heat-treatment, identical to the Pt(4f, 7/2) binding energy for bulk Pt/sub 3/Ti. XRD showed only fcc reflections, indicating the excess Ti present as TiO/sub 2/ was x-ray amorphous. Prior to heat-treatment of the Ti impregnated catalyst, the fcc reflections indicated a lattice parameter of 3.927 A, identical to that for pure Pt. As heat-treatment temperature increased the lattice parameter decreased to 3.906A, the value for bulk Pt/sub 3/Ti. Particle size estimates indicated a progressive increase in the crystallite size of Pt alloy phase with temperature to a final size of Β150A at 1200 0 C. Definitive proof of an ordered Pt/sub 3/Ti phase was the presence of superlattice diffraction lines from materials heated above 900 0 C. EXAFS of these catalysts confirmed the conversion of an initial Pt-TiO/sub 2/ mixture to Pt/sub 3/Ti at 900 0 -1200 0 C heat-treatment temperatures

  4. RuP{sub 2}-based catalysts with platinum-like activity and higher durability for the hydrogen evolution reaction at all pH values

    Energy Technology Data Exchange (ETDEWEB)

    Pu, Zonghua; Amiinu, Ibrahim Saana; Kou, Zongkui; Li, Wenqiang; Mu, Shichun [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology (China)

    2017-09-11

    Highly active, stable, and cheap Pt-free catalysts for the hydrogen evolution reaction (HER) are under increasing demand for future energy conversion systems. However, developing HER electrocatalysts with Pt-like activity that can function at all pH values still remains as a great challenge. Herein, based on our theoretical predictions, we design and synthesize a novel N,P dual-doped carbon-encapsulated ruthenium diphosphide (RuP{sub 2} rate at NPC) nanoparticle electrocatalyst for HER. Electrochemical tests reveal that, compared with the Pt/C catalyst, RuP{sub 2} rate at NPC not only has Pt-like HER activity with small overpotentials at 10 mA cm{sup -2} (38 mV in 0.5 m H{sub 2}SO{sub 4}, 57 mV in 1.0 m PBS and 52 mV in 1.0 m KOH), but demonstrates superior stability at all pH values, as well as 100 % Faradaic yields. Therefore, this work adds to the growing family of transition-metal phosphides/heteroatom-doped carbon heterostructures with advanced performance in HER. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Combining Ru, Ni and Ni(OH){sub 2} active sites for improving catalytic performance in benzene hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Lihua, E-mail: lihuazhu@stu.xmu.edu.cn [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiang Xi (China); Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Sun, Hanlei; Zheng, Jinbao [Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Yu, Changlin, E-mail: yuchanglinjx@163.com [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiang Xi (China); Zhang, Nuowei [Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Shu, Qing [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiang Xi (China); Chen, Bing H., E-mail: chenbh@xmu.edu.cn [Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)

    2017-05-01

    In this study, the Ru{sub 0.04}Ni{sub 0.96}/C(T) catalysts were successfully prepared by the simple methods of hydrazine-reduction and galvanic replacement, where 0.04/0.96 and T represented the Ru/Ni atomic ratio and reducing temperature of the catalyst in N{sub 2}+10%H{sub 2}, respectively. The nanostructures of the Ru{sub 0.04}Ni{sub 0.96} nanoparticles in the Ru{sub 0.04}Ni{sub 0.96}/C(T) catalysts were controlled by modulating their annealing temperature in N{sub 2}+10%H{sub 2} and characterized by an array of techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy energy dispersive X-ray spectroscopy (STEM-EDS) mapping and high-sensitivity low-energy ion scattering (HS-LEIS). The Ru{sub 0.04}Ni{sub 0.96}/C(30) catalyst, which was composed of Ru clusters or single atoms supported on Ni/Ni(OH){sub 2} nanoparticles, exhibited much better catalytic performance for benzene hydrogenation than the Ru{sub 0.04}Ni{sub 0.96}/C(T) catalysts reduced at above 30 °C, such as Ru{sub 0.04}Ni{sub 0.96}/C(160) with the nanostructure of partial Ru{sub 0.04}Ni{sub 0.9} alloy and Ru{sub 0.04}Ni{sub 0.96}/C(280) with the nanostructure of complete Ru{sub 0.04}Ni{sub 0.9} alloy. The reason was that the synergistic effect of multiple active sites – Ru, Ni and Ni(OH){sub 2} sites was present in the Ru{sub 0.04}Ni{sub 0.96}/C(30) catalyst, where hydrogen was preferentially activated at Ru sites, benzene was probably activated at Ni(OH){sub 2} surface and Ni acted as a “bridge” for transferring activated H{sup ∗} species to activated benzene by hydrogen spillover effect, hydrogenating and forming product – cyclohexane. This study also provided a typical example to illustrate that the synergy effect of multiple active sites can largely improve the catalytic hydrogenation performance. - Highlights: • The Ru

  6. Novel Electronic Structures of Ru-pnictides RuPn (Pn = P, As, Sb)

    Science.gov (United States)

    Goto, H.; Toriyama, T.; Konishi, T.; Ohta, Y.

    Density-functional-theory-based electronic structure calculations are made to consider the novel electronic states of Ru-pnictides RuP and RuAs where the intriguing phase transitions and superconductivity under doping of Rh have been reported. We find that there appear nearly degenerate flat bands just at the Fermi level in the high-temperature metallic phase of RuP and RuAs; the flat-band states come mainly from the 4dxy orbitals of Ru ions and the Rh doping shifts the Fermi level just above the flat bands. The splitting of the flat bands caused by their electronic instability may then be responsible for the observed phase transition to the nonmagnetic insulating phase at low temperatures. We also find that the band structure calculated for RuSb resembles that of the doped RuP and RuAs, which is consistent with experiment where superconductivity occurs in RuSb without Rh doping.

  7. A facile lyophilization synthesis of MoS{sub 2} QDs@graphene as a highly active electrocatalyst for hydrogen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wenzhu; Li, Feng; Wang, Xiang; Tang, Yu; Yang, Yuanyuan; Gao, Wenbin [State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Gansu Provincial Engineering Laboratory for Chemical Catalysis, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Li, Rong, E-mail: liyirong@lzu.edu.cn [State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Gansu Provincial Engineering Laboratory for Chemical Catalysis, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)

    2017-04-15

    Highlights: • The target catalyst was prepared by a facile and novel lyophilization method. • The HER activity of various morphologies of MoS{sub 2}-based catalysts were studied. • The catalyst owns superior dispersion, large active sites and high conductivity. • The catalyst exhibits superior HER activity and long-term stability. - Abstract: The development of robust, active and nonprecious electrocatalysts for hydrogen evolution reaction is quite urgent but still challenging. Here MoS{sub 2} QDs@Graphene is prepared via a facile lyophilization method, which leads to a better dispersion of MoS{sub 2} QDs on the graphene and optimizes the electronic mobility between the MoS{sub 2} layers. Impressively, the electrocatalyst MoS{sub 2} QDs@Graphene demonstrates the remarkable activity for HER in 0.5 M H{sub 2}SO{sub 4} solution, with a current density of 10 mA cm{sup −2} at a low overpotential of 140 mV and strong stability in acid condition. The achieved excellent performance is attributed to its morphology with large amount of active sites fabricated by the lyophilization method. This new method opens new pathway for the fabrication of non-precious metal electrocatalysts achieving high activity.

  8. The Study on the Performance of Carbon Supported PtSnM (M = W, Pd, and Ni) Ternary Electro-Catalysts for Ethanol Electro-Oxidation Reaction.

    Science.gov (United States)

    Noh, Chang Soo; Heo, Dong Hyun; Lee, Ki Rak; Jeon, Min Ku; Sohn, Jung Min

    2016-05-01

    PtSn/C and Pt5Sn4M/C (M = W, Pd, Ni) electrocatalysts were prepared by impregnation method using NaBH4 as a reducing agent. Chemical composition, crystalline size, and alloy formation were determined by EDX, XRD and TEM. The average particle sizes of the synthesized catalysts were approximately 3.64-4.95 nm. The electro-chemical properties were measured by CO stripping, cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. The maximum specific activity of the electro-catalysts for ethanol electro-oxidation was 406.08 mA m(-2) in Pt5Sn4Pd/C. The poisoning rate of the Pt5Sn4Pd/C (0.0017% s(-1)) was 4.5 times lower than that of the PtSn/C (0.0076% s(-1)).

  9. 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. Copyright © 2010 Elsevier Inc. All rights reserved.

  10. Covalent Organic Framework Electrocatalysts for Clean Energy Conversion.

    Science.gov (United States)

    Lin, Chun-Yu; Zhang, Detao; Zhao, Zhenghang; Xia, Zhenhai

    2018-02-01

    Covalent organic frameworks (COFs) are promising for catalysis, sensing, gas storage, adsorption, optoelectricity, etc. owning to the unprecedented combination of large surface area, high crystallinity, tunable pore size, and unique molecular architecture. Although COFs are in their initial research stage, progress has been made in the design and synthesis of COF-based electrocatalysis for the oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, and CO 2 reduction in energy conversion and fuel generation. Design principles are also established for some of the COF materials toward rational design and rapid screening of the best electrocatalysts for a specific application. Herein, the recent advances in the design and synthesis of COF-based catalysts for clean energy conversion and storage are presented. Future research directions and perspectives are also being discussed for the development of efficient COF-based electrocatalysts. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Thermodynamic assessment of the Al-Ru system

    CSIR Research Space (South Africa)

    Prins, SN

    2003-03-01

    Full Text Available describes the order disorder transformation with one Gibbs energy function. The RuAl6 phase was described as a stoichiometric phase and the remaining intermetallic phases (Ru4Al13, RuAl2 and Ru2Al3) were modelled with the sublattice model. The solubility...

  12. Selenide-Based Electrocatalysts and Scaffolds for Water Oxidation Applications

    KAUST Repository

    Xia, Chuan

    2015-11-05

    Selenide-based electrocatalysts and scaffolds on carbon cloth are successfully fabricated and demonstrated for enhanced water oxidation applications. A max­imum current density of 97.5 mA cm−2 at an overpotential of a mere 300 mV and a small Tafel slope of 77 mV dec−1 are achieved, suggesting the potential of these materials to serve as advanced oxygen evolution reaction catalysts.

  13. Selenide-Based Electrocatalysts and Scaffolds for Water Oxidation Applications

    KAUST Repository

    Xia, Chuan; Jiang, Qiu; Zhao, Chao; Hedhili, Mohamed N.; Alshareef, Husam N.

    2015-01-01

    Selenide-based electrocatalysts and scaffolds on carbon cloth are successfully fabricated and demonstrated for enhanced water oxidation applications. A max­imum current density of 97.5 mA cm−2 at an overpotential of a mere 300 mV and a small Tafel slope of 77 mV dec−1 are achieved, suggesting the potential of these materials to serve as advanced oxygen evolution reaction catalysts.

  14. 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 wa......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.......A spray-flame aerosol catalyzation technique was studied for producing Pt-Ru anode electrodes for the direct methanol fuel cell. Catalysts were produced as aerosol nanoparticles in a spray-flame reactor and deposited directly as a thin layer on the gas diffusion layer. The as-prepared catalyst...... was found to be a mixture of nanocrystalline, mostly unalloyed Pt and an amorphous phase mostly of Ru and to a lesser extent of Pt oxides on top of the crystalline phase. The flame-produced Pt1Ru1 demonstrated similar onset potential but similar to 60% higher activity compared to commercially available Pt1...

  15. Facile one-pot synthesis of CoS{sub 2}-MoS{sub 2}/CNTs as efficient electrocatalyst for hydrogen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yan-Ru; Hu, Wen-Hui; Li, Xiao [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); Dong, Bin, E-mail: dongbin@upc.edu.cn [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); College of Science, China University of Petroleum (East China), Qingdao 266580 (China); Shang, Xiao [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); Han, Guan-Qun [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); College of Science, China University of Petroleum (East China), Qingdao 266580 (China); Chai, Yong-Ming [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); Liu, Yun-Qi, E-mail: liuyq@upc.edu.cn [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); Liu, Chen-Guang [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China)

    2016-10-30

    Highlights: • Ternary hybrid CoS{sub 2}-MoS{sub 2}/CNTs electrocatalysts have been prepared. • CNTs as support may provide good conductivity and low the agglomeration of MoS{sub 2}. • CoS{sub 2} with intrinsic metallic conductivity may enhance the activity for HER. • Ternary CoS{sub 2}-MoS{sub 2}/CNTs have the better activity and stability for HER. - Abstract: Ternary hybrid cobalt disulfide-molybdenum disulfides supported on carbon nanotubes (CoS{sub 2}-MoS{sub 2}/CNTs) electrocatalysts have been prepared via a simple hydrothermal method. CNTs as support may provide good conductivity and low the agglomeration of layered MoS{sub 2} structure. CoS{sub 2} with intrinsic metallic conductivity may enhance the activity of the ternary hybrid electrocatalysts for hydrogen evolution reaction (HER). X-ray diffraction (XRD) data confirm the formation of ternary hybrid nanocomposites composed of CNTs, CoS{sub 2} and amorphous MoS{sub 2}. Scanning electron microscopy (SEM) images show that strong combination between MoS{sub 2}, CNTs and regular orthohexagonal CoS{sub 2} has been obtained. The dispersion of each component is good and no obvious agglomeration can be observed. It is found that compared with CoS{sub 2}/CNTs and MoS{sub 2}/CNTs, the ternary CoS{sub 2}-MoS{sub 2}/CNTs have the better activity for HER with a low onset potential of 70 mV (vs. RHE) and a small Talel slope of 67 mV dec{sup −1}, and are extremely stable after 1000 cycles. In addition, the optimal doping ratio of Co to Mo is 2:1, which have better HER activity. It is proved that the introduction of carbon materials and Co atoms could improve the performances of MoS{sub 2}-based electrocatalysts for HER.

  16. Facile one-pot synthesis of CoS_2-MoS_2/CNTs as efficient electrocatalyst for hydrogen evolution reaction

    International Nuclear Information System (INIS)

    Liu, Yan-Ru; Hu, Wen-Hui; Li, Xiao; Dong, Bin; Shang, Xiao; Han, Guan-Qun; Chai, Yong-Ming; Liu, Yun-Qi; Liu, Chen-Guang

    2016-01-01

    Highlights: • Ternary hybrid CoS_2-MoS_2/CNTs electrocatalysts have been prepared. • CNTs as support may provide good conductivity and low the agglomeration of MoS_2. • CoS_2 with intrinsic metallic conductivity may enhance the activity for HER. • Ternary CoS_2-MoS_2/CNTs have the better activity and stability for HER. - Abstract: Ternary hybrid cobalt disulfide-molybdenum disulfides supported on carbon nanotubes (CoS_2-MoS_2/CNTs) electrocatalysts have been prepared via a simple hydrothermal method. CNTs as support may provide good conductivity and low the agglomeration of layered MoS_2 structure. CoS_2 with intrinsic metallic conductivity may enhance the activity of the ternary hybrid electrocatalysts for hydrogen evolution reaction (HER). X-ray diffraction (XRD) data confirm the formation of ternary hybrid nanocomposites composed of CNTs, CoS_2 and amorphous MoS_2. Scanning electron microscopy (SEM) images show that strong combination between MoS_2, CNTs and regular orthohexagonal CoS_2 has been obtained. The dispersion of each component is good and no obvious agglomeration can be observed. It is found that compared with CoS_2/CNTs and MoS_2/CNTs, the ternary CoS_2-MoS_2/CNTs have the better activity for HER with a low onset potential of 70 mV (vs. RHE) and a small Talel slope of 67 mV dec"−"1, and are extremely stable after 1000 cycles. In addition, the optimal doping ratio of Co to Mo is 2:1, which have better HER activity. It is proved that the introduction of carbon materials and Co atoms could improve the performances of MoS_2-based electrocatalysts for HER.

  17. Hollow hemisphere-shaped macroporous graphene/tungsten carbide/platinum nanocomposite as an efficient electrocatalyst for the oxygen reduction reaction

    International Nuclear Information System (INIS)

    Li, Zesheng; Liu, Zhisen; Li, Bolin; Liu, Zhenghui; Li, Dehao; Wang, Hongqiang; Li, Qingyu

    2016-01-01

    Graphical abstract: Newfashioned hollow hemisphere-shaped macroporous graphene/tungsten carbide/platinum (HMG/WC/Pt) nanocomposite with interesting three-dimensional architecture bas been successfully fabricated as an efficient electrocatalyst for the oxygen reduction reaction. - Highlights: • Hollow hemisphere-shaped macroporous graphene is proposed as ORR catalyst support. • Honeycomb-like macroporous graphene/WC/Pt electrocatalyst is firsy prepared for ORR. • The present electrocatalyst exhibited greatly enhanced ORR catalytic activity and stability. - Abstract: Hollow hemisphere-shaped macroporous graphene/tungsten carbide/platinum (HMG/WC/Pt) nanocomposite has been synthesized as an efficient electrocatalyst for the oxygen reduction reaction (ORR). The HMG/WC/Pt sample has been systematically characterized by the X-ray diffraction (XRD), Scanning electron microscope (SEM) and Transmission electron microscopy (TEM). The analysis results indicate that the sample has an interesting three-dimensional hollow hemisphere-shaped macroporous architecture. The results also demonstrate the successful integration of WC and Pt nanoparticles on the HMG, in which the WC nanoparticles are in size of about 10 nm and the Pt nanoparticles are in size of about 3 nm. The as-prepared HMG/WC/Pt electrode displays excellent electrocatalytic performances for the ORR in 0.1 mol L −1 HClO 4 electrolyte. The mass activity (i m at 0.9 V) of HMG/WC/Pt is 206 mA mg −1 Pt, which is about 85% higher than that of Pt/C (112 mA mg −1 Pt). It also displayed a very high activity retention of 84.5% after 2000 cyclic voltammetry cycles for the HMG/WC/Pt, while that of the Pt/C is only 70.5%. The HMG/WC/Pt nanocomposite would be a promising electrocatalytic material for the ORR in Fuel cell applications.

  18. Non-platinum electrocatalysts for PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.; Zhang, L.; Shi, Z.; Hui, R.; Zhang, J. [National Research Council of Canada, Vancouver, BC (Canada). Inst. For Fuel Cell Innovation

    2008-07-01

    High cost, low reliability and durability are the main barriers preventing widespread commercialization of fuel cells. In particular, the platinum (Pt)-based electrocatalysts used in proton exchange membrane (PEM) fuel cells, including direct methanol fuel cells (DMFCs) are major contributors to the high cost of PEM fuel cells. The Institute for Fuel Cell Innovation at the National Research Council of Canada has developed several new non-Pt electrocatalysts for PEM fuel cell applications. This paper presented the research results on these catalysts, including transition metal macrocycles, chalcogenides, and Ir- or Pd-based alloys. It also described catalyst structure modes via theoretical density functional theory (DFT) calculations. Research activities on these electrocatalysts was summarized in terms of catalytic activity and the oxygen reduction reaction (ORR). Typical catalysts such as cobalt(Co)-polypyrrole (PPy) and the chalcogenides show promising results in terms of catalytic activity and a 4-electron reaction mechanism. Efforts are underway to modify both catalyst structure and synthesis methods in order to further improve catalyst performance. 4 refs., 2 figs.

  19. Toward highly stable electrocatalysts via nanoparticle pore confinement.

    Science.gov (United States)

    Galeano, Carolina; Meier, Josef C; Peinecke, Volker; Bongard, Hans; Katsounaros, Ioannis; Topalov, Angel A; Lu, Anhui; Mayrhofer, Karl J J; Schüth, Ferdi

    2012-12-19

    The durability of electrode materials is a limiting parameter for many electrochemical energy conversion systems. In particular, electrocatalysts for the essential oxygen reduction reaction (ORR) present some of the most challenging instability issues shortening their practical lifetime. Here, we report a mesostructured graphitic carbon support, Hollow Graphitic Spheres (HGS) with a specific surface area exceeding 1000 m(2) g(-1) and precisely controlled pore structure, that was specifically developed to overcome the long-term catalyst degradation, while still sustaining high activity. The synthetic pathway leads to platinum nanoparticles of approximately 3 to 4 nm size encapsulated in the HGS pore structure that are stable at 850 °C and, more importantly, during simulated accelerated electrochemical aging. Moreover, the high stability of the cathode electrocatalyst is also retained in a fully assembled polymer electrolyte membrane fuel cell (PEMFC). Identical location scanning and scanning transmission electron microscopy (IL-SEM and IL-STEM) conclusively proved that during electrochemical cycling the encapsulation significantly suppresses detachment and agglomeration of Pt nanoparticles, two of the major degradation mechanisms in fuel cell catalysts of this particle size. Thus, beyond providing an improved electrocatalyst, this study describes the blueprint for targeted improvement of fuel cell catalysts by design of the carbon support.

  20. High performance platinum single atom electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Liu, Jing; Jiao, Menggai; Lu, Lanlu; Barkholtz, Heather M.; Li, Yuping; Wang, Ying; Jiang, Luhua; Wu, Zhijian; Liu, Di-Jia; Zhuang, Lin; Ma, Chao; Zeng, Jie; Zhang, Bingsen; Su, Dangsheng; Song, Ping; Xing, Wei; Xu, Weilin; Wang, Ying; Jiang, Zheng; Sun, Gongquan

    2017-07-01

    For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm-2 at 80 °C with a low platinum loading of 0.09 mgPt cm-2, corresponding to a platinum utilization of 0.13 gPt kW-1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.

  1. Pseudogap behavior of RuP probed by photoemission spectroscopy

    OpenAIRE

    Sato, K.; Ootsuki, D.; Wakisaka, Y.; Saini, N. L.; Mizokawa, T.; Arita, M.; Anzai, H.; Namatame, H.; Taniguchi, M.; Hirai, D.; Takagi, H.

    2012-01-01

    We have studied the electronic structure of RuP and related Ru pnictides using photoemission spectroscopy. Ru 3d core-level and valence-band spectra of RuP show that the Ru valence is +3 with t_{2g}^5 configuration. The photoemisson spectral weight near the Fermi level is moderately suppressed in the pseudogap phase of RuP, consistent with the pseudogap opening of 2\\Delta/k_BT_c ~ 3 (gap size \\Delta ~ 50 meV and transition temperature T_c ~ 330 K). The Ru 3d peak remains sharp in the pseudoga...

  2. MIL-100-Fe derived N-doped Fe/Fe3C@C electrocatalysts for efficient oxygen reduction reaction

    Science.gov (United States)

    Guo, Dakai; Han, Sancan; Wang, Jiacheng; Zhu, Yufang

    2018-03-01

    N-doped porous Fe/Fe3C@C electrocatalysts were prepared by the pyrolysis of the hexamethylenetetramine (HMT)-incorporated MIL-100-Fe at different temperatures (700-1000 °C) under N2 atmosphere. Rotary evaporation of MIL-100-Fe and HMT solution could make more N-enriched HMT molecules enter into the pores of MIL-100-Fe, thus improving nitrogen contents of the final pyrolyzed samples. All pyrolyzed samples show porous textures with middle specific surface areas. The X-ray photoelectron spectroscopy (XPS) results demonstrate the successful introduction of N atoms into carbon framework. Sample Fe-N2-800 prepared by annealing the precursors with the HMT/MIL-100-Fe weight ratio of 2 at 800 °C exhibits the best electrocatalytic activity towards the oxygen reduction reaction (ORR) in terms of onset potential and current density because of high graphitic N and pyridinic N content. The enwrapped Fe/Fe3C nanoparticles and Fe-Nx active sites in these samples could also boost the ORR activity synergistically. Moreover, sample Fe-N2-800 demonstrates a dominant four electron reduction process, as well as excellent long-term operation stability and methanol crossover resistance. Thus, the N-doped Fe/Fe3C@C composites derived from the HMT-incorporated MIL-100-Fe are promising electrocatalysts to replace Pt/C for ORR in practical applications.

  3. Effect of the nanostructure and the surface composition of bimetallic Ni-Ru nanoparticles on the performance of CO methanation

    Science.gov (United States)

    Wang, Jing; Yuan, Changkun; Yao, Nan; Li, Xiaonian

    2018-05-01

    The Ni/SiO2 catalysts with trace Ru promoter were prepared by either polyethylene glycol (PEG)-assisted or PEG-free impregnation method and were used in CO methanation reaction. The presence of PEG molecules was beneficial to form bimetallic Ni-Ru particles with smaller size, better anti-sintering property and low-temperature reducibility on SiO2 support than the conventional PEG-free derived NiRu/SiO2 catalyst. Moreover, it was found that the low-temperature reduction at 573 K was favorable to form bimetallic Ni-Ru particles with more surface Ru atoms. This nanostructure not only allowed the electron transfer happening from Ru0 to Ni0 which led to its higher electron cloud density, but also could reduce the deposition of less reactive carbon on the catalyst. Therefore, the low-temperature reduction enhanced the reaction stability of NiRu/SiO2 catalyst. The increase of reduction temperature from 573 K to 693 K did not change the size of metallic particles, but decreased the amount of surface Ru atoms. It deactivated the catalyst due to the deposition of more less reactive carbon. Although the higher reduction temperature (e.g. 693 and 793 K) was unfavorable to the reaction stability, it created more surface defects. The amount of defects showed a volcano-shaped correlation with the reduction temperature which was consistent with the variation tendency of turnover frequency of CO conversion. Consequently, it evidenced that the amount of surface Ru atoms and defects on the bimetallic Ni-Ru particle played the critical roles on the stability and the intrinsic activity of methanation, respectively.

  4. Ferromagnetism and antiferromagnetism coexistence in SrRu1-xMnxO3: Density functional calculation

    International Nuclear Information System (INIS)

    Hadipour, H.; Fallahi, S.; Akhavan, M.

    2011-01-01

    We have calculated the electronic structure of SrRu 1-x Mn x O 3 using the full potential linearized augmented plane wave method by LSDA and LSDA+U. The antiparallel alignment between the Mn and Ru ions are consistent with the competition between ferromagnetism and antiferromagnetism in the low Mn-doped polycrystalline samples. This is in contrast to the appearance of quantum critical point and FM and AFM transitions in the single crystal measurement. Our results show that the discrepancy between different experimental phase diagrams is related to the conditions of sample preparation and also the difference between the degree of magnetic interactions between the Mn and Ru moments. The DOS and the calculated Mn magnetic moment is similar to the magnetic moment of a purely ionic compound with d 3 configuration. The AFM state has band gap of 1.2 eV at the Fermi energy predicting an insulating behavior. -- Graphical abstract: The antiparallel alignment between the Mn and Ru ions are consistent with the competition between ferromagnetism and antiferromagnetism with the formation of a spin glass phase. We have calculated the electronic structure of SrRu 1-x Mn x O 3 using the full potential linearized augmented plane wave method by LSDA and LSDA+U in the range of both low and high Mn-doping for parallel and antiparallel alignments of Ru and Mn moments. In the low Mn-doped polycrystalline samples with tetragonal structure, the AFM hybridization between Mn and the Ru host lattice strongly favors alignment of the Ru moments, and provides an explanation for retaining of high Curie temperature of SrRuO 3 with Mn substitution. Display Omitted Research highlights: → For the low Mn-doping the AFM coupling between Mn and Ru becomes stable. → Results are consistent with the QCP between FM and AFM transitions in single crystals. → In high Mn-doping, electron correlation is important in predicting the insulating behavior.

  5. Nanoscale decomposition of Nb-Ru-O

    Science.gov (United States)

    Music, Denis; Geyer, Richard W.; Chen, Yen-Ting

    2016-11-01

    A correlative theoretical and experimental methodology has been employed to explore the decomposition of amorphous Nb-Ru-O at elevated temperatures. Density functional theory based molecular dynamics simulations reveal that amorphous Nb-Ru-O is structurally modified within 10 ps at 800 K giving rise to an increase in the planar metal - oxygen and metal - metal population and hence formation of large clusters, which signifies atomic segregation. The driving force for this atomic segregation process is 0.5 eV/atom. This is validated by diffraction experiments and transmission electron microscopy of sputter-synthesized Nb-Ru-O thin films. Room temperature samples are amorphous, while at 800 K nanoscale rutile RuO2 grains, self-organized in an amorphous Nb-O matrix, are observed, which is consistent with our theoretical predictions. This amorphous/crystalline interplay may be of importance for next generation of thermoelectric devices.

  6. Bridgehead isomer effects in bis(phosphido)-bridged diiron hexacarbonyl proton reduction electrocatalysts.

    Science.gov (United States)

    Rahaman, Ahibur; Gimbert-Suriñach, Carolina; Ficks, Arne; Ball, Graham E; Bhadbhade, Mohan; Haukka, Matti; Higham, Lee; Nordlander, Ebbe; Colbran, Stephen B

    2017-03-07

    The influence of the substitution, orientation and structure of the phosphido bridges in [Fe 2 (CO) 6 (μ-PR 2 ) 2 ] electrocatalysts of proton reduction has been studied. The isomers e,a-[Fe 2 (CO) 6 {μ-P(Ar)H} 2 ] (1a(Ar): Ar = Ph, 2'-methoxy-1,1'-binaphthyl (bn')), e,e-[Fe 2 (CO) 6 {μ-P(Ar)H} 2 ] (1b(Ar): Ar = Ph, bn') were isolated from reactions of iron pentacarbonyl and the corresponding primary phosphine, syntheses that also afforded the phosphinidene-capped tri-iron clusters, [Fe 3 (CO) 9 (μ-CO)(μ 3 -Pbn')] (2) and [Fe 3 (CO) 9 (μ 3 -PAr) 2 ] (3(Ar), Ar = Ph, bn'). A ferrocenyl (Fc)-substituted dimer [Fe 2 (CO) 6 {μ:μ'-1,2-(P(CH 2 Fc)CH 2 ) 2 C 6 H 4 }] (4), in which the two phosphido bridges are linked by an o-xylyl group, was also prepared. The molecular structures of complexes 1a(Ph), 1b(Ph), 1b(bn'), 2 and 4 were established by X-ray crystallography. All complexes have been examined as electrocatalysts for proton reduction using p-toluene sulfonic acid in tetrahydrofuran. Cyclic voltammograms of the dimers with acid exhibit two catalysis waves for proton reduction. The first wave, which appears at the potential of the primary reduction, reaches maximum current (turnover) at moderate acid concentrations and is rapidly overtaken by the second wave, which appears at more negative potential. Both of these reductive waves show an initial first order dependence on acid. The electrochemistry and electrocatalyses of the [Fe 2 (CO) 6 (μ-PR 2 ) 2 ] dimers show subtle variations with the nature of the bridging phosphido group(s), including the orientation of bridgehead hydrogen atoms.

  7. H2 splitting on Pt, Ru and Rh nanoparticles supported on sputtered HOPG

    DEFF Research Database (Denmark)

    Fiordaliso, Elisabetta Maria; Murphy, Shane; Nielsen, R.M.

    2012-01-01

    The equilibrium hydrogen exchange rate between adsorbed and gas phase hydrogen at 1bar is measured for Pt, Ru and Rh nanoparticles supported on a sputtered HOPG substrate. The particles are prepared by Electron Beam Physical Vapor Deposition and the diameter of the particles varies between 2 and ...

  8. Nitrogen: Unraveling the Secret to Stable Carbon-Supported Pt-Alloy Electrocatalysts

    Science.gov (United States)

    2013-10-01

    release; distribution is unlimited. Nitrogen: unraveling the secret to stable carbon-supported Pt- alloy electrocatalysts The views, opinions and/or...Nitrogen: unraveling the secret to stable carbon-supported Pt-alloy electrocatalysts Report Title Nitrogen functionalities significantly improve...design and optimization of next generation high performance catalyst materials. Nitrogen: unraveling the secret to stable carbon-supported Pt-alloy

  9. Rare earth metal oxides as BH4-tolerance cathode electrocatalysts for direct borohydride fuel cells

    Institute of Scientific and Technical Information of China (English)

    NI Xuemin; WANG Yadong; GUO Feng; YAO Pei; PAN Mu

    2012-01-01

    Rare earth metal oxides (REMO) as cathode electrocatalysts in direct borohydride fuel cell (DBFC) were investigated.The REMO electrocatalysts tested showed favorable activity to the oxygen electro-reduction reaction and strong tolerance to the attack of BH4- in alkaline electrolytes.The simple membraneless DBFCs using REMO as cathode electrocatalyst and using hydrogen storage alloy as anodic electrocatalyst exhibited an open circuit of about 1 V and peak power of above 60 mW/cm2.The DBFC using Sm2O3 as cathode electrocatalyst showed a relatively better performance.The maximal power density of 76.2 mW/cm2 was obtained at the cell voltage of 0.52 V.

  10. Fabrication and performance of the Pt-Ru/Ni-P/FTO counter electrode for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Ma, Huanmei; Tian, Jianhua; Bai, Shuming; Liu, Xiaodong; Shan, Zhongqiang

    2014-01-01

    Highlights: • Pt-Ru alloy acts as the catalyst of counter electrodes in dye-sensitized solar cell. • Ni-P/FTO (fluorine-doped SnO 2 ) substrate is prepared by electroless plating method. • Pt-Ru/Ni-P/FTO counter electrode is fabricated by electrodeposition method. • The Ni-P sublayer improves the conductivity and light reflectance of FTO substrate. • The cell with Pt-Ru/Ni-P/FTO counter electrode exhibits an improved efficiency. - Abstract: In this paper, Pt-Ru/Ni-P/FTO has been designed and fabricated as the counter electrode for dye-sensitized solar cells. The Pt-Ru catalytic layer and Ni-P alloy sublayer are prepared by traditional electrodeposition method and a simple electroless plating method, respectively, and the preparation conditions have been optimized. The scanning electron microscopy (SEM) images show that the Pt-Ru particles are evenly distributed on FTO and Ni-P/FTO substrate. By X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), it is confirmed that the Ni-P amorphous alloy has been formed, and no other compounds involved Ni and P have been formed. The electrochemical measurement results reveal that the Pt-Ru electrode has higher catalytic activity and stability towards tri-iodine reduction reaction than Pt electrode in the organic medium. The Ni-P sublayer deposited on FTO glasses increases the conductivity and light-reflection ability of the counter electrode, and this contributes to lowering the inner resistance of the cell and improving the light utilization efficiency. Through the photovoltaic test, it is confirmed that the energy conversion efficiency of a single DSSC with the optimized Pt-Ru/Ni-P/FTO counter electrode is increased by 29% compared with that of the cell based on the Pt/FTO counter electrode under the same conditions

  11. The Behavior of the Ru-bda Water Oxidation Catalysts at Low Oxidation States.

    Science.gov (United States)

    Matheu, Roc; Ghaderian, Abolfazl; Francas, Laia; Chernev, Petko; Ertem, Mehmed; Benet-Buchholz, Jordi; Batista, Victor; Haumann, Michael; Gimbert-Suriñach, Carolina; Sala, Xavier; Llobet, Antoni

    2018-06-13

    The Ru complex [RuII(bda-κ-N2O2)(N-NH2)2], 1, (bda2- = (2,2'-bipyridine)-6,6'-dicarboxylate; N-NH2 = 4-(pyridin-4-yl)aniline) is used as a synthetic intermediate to prepare Ru-bda complexes that contain the NO+, acetonitrile (MeCN) or H2O ligands at oxidation states II and III. Complex 1 reacts with excess NO+ to form a Ru complex where the aryl amine ligands N-NH2 in 1 are transformed into diazonium salts (N-N2+ = 4-(pyridin-4-yl)benzenediazonium)) together with the formation of a new Ru-NO group at the equatorial zone, to generate [RuII(bda-κ-N2O)(NO)(N-N2)2]3+, 23+. Similarly, complex 1 can also react with a coordinating solvent, such as MeCN, at room temperature leading to complex [RuII(bda-κ-N2O)(MeCN)(N-NH2)2], 3. Finally in acidic aqueous solutions solvent water coordinates the Ru center forming {[RuII(bda-κ-(NO)3)(H2O)(N-NH3)2](H2O)n}2+, 42+, that is strongly hydrogen bonded with additional water molecules at the second coordination sphere. We have additionally characterized the one electron oxidized complex {[RuIII(bda-κ-(NO)3.5)(H2O)(N-NH3)2](H2O)n}3+, 53+. The coordination mode of the complexes has been studied both in the solid state and in solution through single-crystal XRD, X-ray absorption spectroscopy, variable-temperature NMR and DFT calculations. While the κ-N2O is the main coordination mode for 23+ and 3, an equilibrium that involves isomers with κ-N2O and κ-NO2 coordination modes and neighboring hydrogen bonded water molecules is observed for 42+ and 53+. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Electrocatalytic properties of carbon-supported Pt-Ru catalysts with the high alloying degree for formic acid electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu.; Zhou, Yiming; Tang, Yawen; Lu, Tianhong [College of Chemistry and Environmental Science, Nanjing Normal University, Nanjing 210097 (China)

    2010-07-01

    A series of carbon-supported bimetallic Pt-Ru catalysts with high alloying degree and different Pt/Ru atomic ratio have been prepared by a chemical reduction method in the H{sub 2}O/ethanol/tetrahydrofuran (THF) mixture solvent. The structural and electronic properties of catalysts are characterized using X-ray reflection (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM). The electrooxidation of formic acid on these Pt-Ru nanoparticles are investigated by using cyclic voltammetry, chronoamperometry and CO-stripping measurements. The results of electrochemical measurements illustrate that the alloying degree and Pt/Ru atomic ratio of Pt-Ru catalyst play an important role in the electrocatalytic activity of the Pt-Ru/C catalyst for formic acid electrooxidation due to the bifunctional mechanism and the electronic effect. Since formic acid is an intermediate in the methanol electrooxidation on Pt electrode in acidic electrolyte, the observation provides an additional fundamental understanding of the structure-activity relationship of Pt-Ru catalyst for methanol electrooxidation. (author)

  13. Development of Fe-Ni/YSZ-GDC electro-catalysts for application as SOFC anodes. XRD and TPR characterization, and evaluation in ethanol steam reforming reaction

    Energy Technology Data Exchange (ETDEWEB)

    Paz Fiuza, Raigenis da; Silva, Marcos Aurelio da; Boaventura, Jaime Soares [UFBA, Salvador, Bahia (Brazil). Energy and Materials Science Group

    2010-07-01

    Electro-catalysts based on Fe-Ni alloys were prepared using physical mixture and modified Pechini methods; they were supported on a composite of Yttria Stabilized Zirconia (YSZ) and Gadolinia Doped Ceria (GDC). The composites had compositions of 35% metal load and 65% support (70% wt. YSZ and 30% wt. GDC mixture) (cermets). The samples were characterized by Temperature-Programmed Reduction (TPR) and X-Ray Diffraction (XRD) and evaluated in ethanol steam reforming at 650 C for six hours and in the temperature range 300 - 900 C. The XRD results showed that the bimetallic sample calcined at 800 C formed a mixed oxide (NiFe{sub 2}O{sub 4}) in spinel structure; after reducing the sample in hydrogen, Ni-Fe alloys were formed. The presence of Ni decreased the final reduction temperature of the NiFe{sub 2}O{sub 4} species. The addition of Fe to Ni anchored to YSZ-GDC increased the hydrogen production and inhibits the carbon deposition. The bimetallic 30Fe5Ni samples reached an ethanol conversion of about 95%, and a hydrogen yield up to 48% at 750 C. In general, the ethanol conversion and hydrogen production were independent of the metal content in the electro-catalyst. However, the substitution of Ni for Fe significantly reduced the carbon deposition on the electro-catalyst: 74, 31 and 9 wt. % in the 35Ni, 20Fe15Ni, and 30Fe5Ni samples, respectively. (orig.)

  14. Self-assembled platinum nanoparticles on sulfonic acid-grafted graphene as effective electrocatalysts for methanol oxidation in direct methanol fuel cells.

    Science.gov (United States)

    Lu, Jinlin; Li, Yanhong; Li, Shengli; Jiang, San Ping

    2016-02-15

    In this article, sulfonic acid-grafted reduced graphene oxide (S-rGO) were synthesized using a one-pot method under mild conditions, and used as Pt catalyst supports to prepare Pt/S-rGO electrocatalysts through a self-assembly route. The structure, morphologies and physicochemical properties of S-rGO were examined in detail by techniques such as atomic force microscope (AFM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The S-rGO nanosheets show excellent solubility and stability in water and the average particle size of Pt nanoparticles supported on S-rGO is ~3.8 nm with symmetrical and uniform distribution. The electrocatalytic properties of Pt/S-rGO were investigated for methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). In comparison to Pt supported on high surface area Vulcan XC-72 carbon (Pt/VC) and Pt/rGO, the Pt/S-rGO electrocatalyst exhibits a much higher electrocatalytic activity, faster reaction kinetics and a better stability. The results indicate that Pt/S-rGO is a promising and effective electrocatalyst for MOR of DMFCs.

  15. Self-assembled platinum nanoparticles on sulfonic acid-grafted graphene as effective electrocatalysts for methanol oxidation in direct methanol fuel cells

    Science.gov (United States)

    Lu, Jinlin; Li, Yanhong; Li, Shengli; Jiang, San Ping

    2016-02-01

    In this article, sulfonic acid-grafted reduced graphene oxide (S-rGO) were synthesized using a one-pot method under mild conditions, and used as Pt catalyst supports to prepare Pt/S-rGO electrocatalysts through a self-assembly route. The structure, morphologies and physicochemical properties of S-rGO were examined in detail by techniques such as atomic force microscope (AFM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The S-rGO nanosheets show excellent solubility and stability in water and the average particle size of Pt nanoparticles supported on S-rGO is ~3.8 nm with symmetrical and uniform distribution. The electrocatalytic properties of Pt/S-rGO were investigated for methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). In comparison to Pt supported on high surface area Vulcan XC-72 carbon (Pt/VC) and Pt/rGO, the Pt/S-rGO electrocatalyst exhibits a much higher electrocatalytic activity, faster reaction kinetics and a better stability. The results indicate that Pt/S-rGO is a promising and effective electrocatalyst for MOR of DMFCs.

  16. pH-induced photocurrent switching based on a highly stable drop-casting film of imidazole moiety-containing dinuclear Ru(II) Complex

    International Nuclear Information System (INIS)

    Xue, Long-Xin; Duan, Zhi-Ming; Jia, Jia; Wang, Ke-Zhi; Haga, Masa-aki

    2014-01-01

    Graphical abstract: > Solvent-casting Ru(II) complex modified electrode. > Positive shifting of half-wave potentials of Ru(III)/Ru(II) by pH decreases. > Greatly enhanced cathodic photocurrents by pH decreases. - Highlights: • Solvent-casting Ru(II) complex modified electrode. • Positive shifting of half-wave potentials of Ru(III)/Ru(II) by pH decreases. • Greatly enhanced cathodic photocurrents by pH decreases. - Abstract: A new dinuclear Ru(II) complex of [(H 2 L 1 )Ru(H 2 L 2 )Ru(H 2 L 1 )](ClO 4 ) 4 {H 2 L 1 = 2,6-bis(2-benzimidazolyl)pyridine; H 2 L 2 = 2,6-bis(4-([2,2′:6′,2″-terpyridin]-4′-yl)phenyl)-1,5- dihydrobenzo[1,2-d:4,5-d’]diimidazole} is synthesized and characterized. The Ru(II) complex modified indium-tin oxide electrode prepared using a drop-casting method, exhibited a couple of stable surface-confined Ru(III)/Ru(II)-based redox waves centered at +0.65 V vs saturated calomel electrode that were almost unchanged after 50 consecutive cyclic voltammetry scanning. The modified electrode showed pH-dependent redox behaviors with the formal potential being decreased by 430 mV due to the occurrance of the proton-coupled redox reactions. The cathodic photocurrent generation of the modified electrode was also found to be highly pH-dependent, switching from an “off” state at pH ∼11.0 to an “on” state at pH = 2.20 with an enhancement factor of 18. The modified electrode was shown to have promising applications as photoelectrochemical pH sensing and switching devices

  17. Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making

    Science.gov (United States)

    Kumta, Prashant N.; Kadakia, Karan Sandeep; Datta, Moni Kanchan; Velikokhatnyi, Oleg

    2017-02-07

    The invention provides electro-catalyst compositions for an anode electrode of a proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VII of the Periodic Table. The compositions can be prepared using a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.

  18. Thermal stability and electrochemical properties of PVP-protected Ru nanoparticles synthesized at room temperature

    Science.gov (United States)

    Kumar, Manish; Devi, Pooja; Shivling, V. D.

    2017-08-01

    Stable ruthenium nanoparticles (RuNPs) have been synthesized by the chemical reduction of ruthenium trichloride trihydrate (RuCl3 · 3H2O) using sodium borohydride (NaBH4) as a reductant and polyvinylpyrrolidone (PVP) as a protecting agent in the aqueous medium at room temperature. The nanoparticles thus prepared were characterized by their morphology and structural analysis from transmission electron microscopy (TEM), X-ray powder diffraction (XRD), UV-vis spectroscopy, Fourier transformation infrared and thermogravimetric analysis (TGA) techniques. The TEM image suggested a homogeneous distribution of PVP-protected RuNPs having a small average diameter of 2-4 nm with a chain-like network structure. The XRD pattern also confirmed that a crystallite size is around 2 nm of PVP-protected RuNPs having a single broad peak. The thermal stability studied using TGA, indicated good stability and the electrochemical properties of these nanoparticles revealed that saturation current increases for PVP-protected RuNPs/GC.

  19. Performance of Nafion-TiO2 hybrid membranes and PtSn/C electrocatalysts in PEM type fuel cells fed with ethanol and H2/CO at high temperature

    International Nuclear Information System (INIS)

    Isidoro, Roberta Alvarenga

    2010-01-01

    In this work, Nafion-TiO 2 hybrid electrolytes and PtSn/C electrocatalysts were synthesized for the application in direct ethanol fuel cell operating at high temperature (130 degree C). For this purpose, TiO 2 particles were incorporated in commercial Nafion membranes by an 'in situ' sol gel route. The resulting materials were characterized by gravimetric analysis, water uptake, DSC, XRD and EDX. Electrocatalysts based on carbon dispersed platinum-tin (PtSn/C), with different composition, were produced by alcohol-reduction method and were employed as anodic electrode. The electrocatalysts were characterized by XRD, EDX, XPS and transmission electronic spectroscopy. The electrochemical characterization was conducted by cyclic voltametry, carbon monoxide linear anodic voltammetry (CO stripping), and chronoamperometry. Membrane-electrodes assembly (MEAs) were formed with PtSn/C anodes, Pt/C cathodes and Nafion-TiO 2 hybrids. The performance of these MEA was evaluated in single-cell fed with H2/CO mixture or ethanol solution at the anode and oxygen at the cathode in the temperature range of 80-130 degree C. The analysis showed that the hybrid membranes improved the DEFC performance due to crossover suppression and that PtSn/C 70:30 electrocatalysts, prepared by an alcohol reduction process, showed better performance in ethanol oxidation. (author)

  20. Surface-oxidized cobalt phosphide used as high efficient electrocatalyst in activated carbon air-cathode microbial fuel cell

    Science.gov (United States)

    Yang, Tingting; Wang, Zhong; Li, Kexun; Liu, Yi; Liu, Di; Wang, Junjie

    2017-09-01

    Herein, we report a simplistic method to fabricate the surface-oxidized cobalt phosphide (CoP) nanocrystals (NCs), which is used as electrocatalyst for oxygen reduction reaction (ORR) in microbial fuel cell (MFC) for the first time. The corallite-like CoP NCs are successfully prepared by a hydrothermal reaction following a phosphating treatment in N2 atmosphere. When used as an ORR catalyst, cobalt phosphide shows comparable onset potential, inferior resistance, as well as a small Tafel slope with long-term stability in neutral media. The maximum power density of MFC embellished with 10% CoP reached 1914.4 ± 59.7 mW m-2, which is 108.5% higher than the control. The four-electron pathway, observed by the RDE, plays a crucial role in electrochemical catalytic activity. In addition, material characterizations indicate that the surface oxide layer (CoOx) around the metallic CoP core is important and beneficial for ORR. Accordingly, it can be expected that the as-synthesized CoP will be a promising candidate of the non-precious metal ORR electrocatalysts for electrochemical energy applications.

  1. 3D structured Mo-doped Ni3S2 nanosheets as efficient dual-electrocatalyst for overall water splitting

    Science.gov (United States)

    Wu, Chengrong; Liu, Bitao; Wang, Jun; Su, Yongyao; Yan, Hengqing; Ng, Chuntan; Li, Cheng; Wei, Jumeng

    2018-05-01

    Searching for a cost-effective, high efficient and stable bifunctional electrocatalyst for overall water-splitting is critical to renewable energy systems. In this study, three-dimensional (3D) curved nanosheets of Mo-doped Ni3S2 grown on nickel foam were successfully synthesized via a one-step hydrothermal process. The hydrogen-evolution reaction (HER) and the oxygen-evolution reaction (OER) in alkaline environment of this 3D catalyst are investigated in detail. The results show that it possesses lower overpotential, high current densities and small Tafel slopes both in OER and HER. For HER, the catalysts show excellent electrochemical performance, demonstrating a low over-potential of 212 mV at 10 mA cm-2 with a large decrease of 127 mV compared to the undoped Ni3S2. And it also shows a lower overpotential of 260 mV at 10 mA cm-2 which decreases 30 mV for OER. In addition, it is only need 1.67 V for the overall water splitting at 10 mA cm-2 which is 70 mV. It found that the Mo element would change the morphology of Ni3S2 and induce much more active sites for HER and OER. The as-prepared Mo-doped Ni3S2 bi-functional electrocatalyst could act as the promising electrode materials for water splitting.

  2. N-doped graphene coupled with Co nanoparticles as an efficient electrocatalyst for oxygen reduction in alkaline media

    Science.gov (United States)

    Zhang, Geng; Lu, Wangting; Cao, Feifei; Xiao, Zhidong; Zheng, Xinsheng

    2016-01-01

    Development of low-cost and highly efficient electrocatalysts for oxygen reduction reaction (ORR) is still a great challenge for the large-scale application of fuel cells and metal-air batteries. Herein, a noble metal-free ORR electrocatalyst in the form of N-doped graphene coupled with part of Co nanoparticles encased in N-doped graphitic shells (named as SUCo-0.03-800) is prepared by facile one-step pyrolysis of the mixture of sucrose, urea and cobalt nitrate. The novel structure is confirmed by High Resolution-TEM, XRD, XPS and Raman spectroscopy. SUCo-0.03-800 presents comparable ORR catalytic activity to commercial Pt/C catalyst with a dominating four-electron pathway under alkaline conditions, and both of its mass activity and volume activity also outperform Co-free N-doped graphene and other Co/N-C hybrids with higher Co content, which may probably be ascribed to the high specific surface area, novel structure and synergistic effect between encased Co nanoparticles and N-doped graphitic shell. Additionally, SUCo-0.03-800 also shows outstanding stability and improved selectivity towards ORR, making it a promising alternative to Pt with potential application in fuel cells and metal-air batteries.

  3. Soft landing of bare PtRu nanoparticles for electrochemical reduction of oxygen.

    Science.gov (United States)

    Johnson, Grant E; Colby, Robert; Engelhard, Mark; Moon, Daewon; Laskin, Julia

    2015-08-07

    Magnetron sputtering of two independent Pt and Ru targets coupled with inert gas aggregation in a modified commercial source has been combined with soft landing of mass-selected ions to prepare bare 4.5 nm diameter PtRu nanoparticles on glassy carbon electrodes with controlled size and morphology for electrochemical reduction of oxygen in solution. Employing atomic force microscopy (AFM) it is shown that the nanoparticles bind randomly to the glassy carbon electrode at a relatively low coverage of 7 × 10(4) ions μm(-2) and that their average height is centered at 4.5 nm. Scanning transmission electron microscopy images obtained in the high-angle annular dark field mode (HAADF-STEM) further confirm that the soft-landed PtRu nanoparticles are uniform in size. Wide-area scans of the electrodes using X-ray photoelectron spectroscopy (XPS) reveal the presence of both Pt and Ru in atomic concentrations of ∼9% and ∼33%, respectively. Deconvolution of the high energy resolution XPS spectra in the Pt 4f and Ru 3d regions indicates the presence of both oxidized Pt and Ru. The substantially higher loading of Ru compared to Pt and enrichment of Pt at the surface of the nanoparticles is confirmed by wide-area analysis of the electrodes using time-of-flight medium energy ion scattering (TOF-MEIS) employing both 80 keV He(+) and O(+) ions. The activity of electrodes containing 7 × 10(4) ions μm(-2) of bare 4.5 nm PtRu nanoparticles toward the electrochemical reduction of oxygen was evaluated employing cyclic voltammetry (CV) in 0.1 M HClO4 and 0.5 M H2SO4 solutions. In both electrolytes a pronounced reduction peak was observed during O2 purging of the solution that was not evident during purging with Ar. Repeated electrochemical cycling of the electrodes revealed little evolution in the shape or position of the voltammograms indicating high stability of the nanoparticles supported on glassy carbon. The reproducibility of the nanoparticle synthesis and deposition was

  4. Synthesis of Pt-Ru PSB-Py catalysis by {gamma}-irradiation and their electrocatalytic efficiency for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jung Ah; Sim, Kwang Sik; Choi, Seong Ho [Hannam University, Daejeon (Korea, Republic of); Jung, Sung Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-09-15

    We report here that deposition of Pt-Ru catalysis on the surface of core-shell conductive balls by radiation-chemical reduction of Pt and Ru ions, in order to use as catalysis in a fuel cell. The poly(styrene-co-4-vinylphenylboronic acid)-pyrrole (PSB-Py) with core-shell structure was obtained by in situ polymerization of pyrrole in the presence of the poly(styrene-co-4-vinylphenylboronic acid) (PSB). Subsequently, Pt-Ru catalysis were deposited onto PSB-Py ball by {gamma}-irradiation, in the presence/absence of poly(vinypyrolidone) (PVP) to prepare electrocatalysis for a fuel cell. The catalytic efficiency of Pt-Ru PSB-Py catalyst was examined for carbon monoxide (CO) stripping and methanol oxidation.

  5. Synthesis of Pt-Ru PSB-Py catalysis by γ-irradiation and their electrocatalytic efficiency for methanol oxidation

    International Nuclear Information System (INIS)

    Yoon, Jung Ah; Sim, Kwang Sik; Choi, Seong Ho; Jung, Sung Hee

    2009-01-01

    We report here that deposition of Pt-Ru catalysis on the surface of core-shell conductive balls by radiation-chemical reduction of Pt and Ru ions, in order to use as catalysis in a fuel cell. The poly(styrene-co-4-vinylphenylboronic acid)-pyrrole (PSB-Py) with core-shell structure was obtained by in situ polymerization of pyrrole in the presence of the poly(styrene-co-4-vinylphenylboronic acid) (PSB). Subsequently, Pt-Ru catalysis were deposited onto PSB-Py ball by γ-irradiation, in the presence/absence of poly(vinypyrolidone) (PVP) to prepare electrocatalysis for a fuel cell. The catalytic efficiency of Pt-Ru PSB-Py catalyst was examined for carbon monoxide (CO) stripping and methanol oxidation

  6. Investigation of ethanol electrooxidation on a Pt-Ru-Ni/C catalyst for a direct ethanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhen-Bo; Yin, Ge-Ping; Zhang, Jian; Sun, Ying-Chao; Shi, Peng-Fei [Department of Applied Chemistry, Harbin Institute of Technology, Harbin (China 150001)

    2006-09-29

    This research is aimed to improve the utilization and activity of anodic alloy catalysts and thus to lower the contents of noble metals and the catalyst loading on anodes for ethanol electrooxidation. The DEFC anodic catalysts, Pt-Ru-Ni/C and Pt-Ru/C, were prepared by a chemical reduction method. Their performances were tested by using a glassy carbon working electrode and cyclic voltammetric curves, chronoamperometric curves and half cell measurement in a solution of 0.5molL{sup -1} CH{sub 3}CH{sub 2}OH and 0.5molL{sup -1} H{sub 2}SO{sub 4}. The composition of the Pt-Ru-Ni and Pt-Ru surface particles were determined by EDAX analysis. The particle size and lattice parameter of the catalysts were determined by means of X-ray diffraction (XRD). XRD analysis showed that both of the catalysts exhibited face centered cubic structures and had smaller lattice parameters than a Pt-alone catalyst. Their particle sizes were small, about 4.5nm. No significant differences in the ethanol electrooxidation on both electrodes were found using cyclic voltammetry, especially regarding the onset potential for ethanol electrooxidation. The electrochemically active specific areas of the Pt-Ru-Ni/C and Pt-Ru/C catalysts were almost the same. But, the catalytic activity of the Pt-Ru-Ni/C catalyst was higher for ethanol electrooxidation than that of the Pt-Ru/C catalyst. Their tolerance to CO formed as one of the intermediates of ethanol electrooxidation, was better than that of the Pt-Ru/C catalyst. (author)

  7. CuZn Alloy- Based Electrocatalyst for CO2 Reduction

    KAUST Repository

    Alazmi, Amira

    2014-06-01

    ABSTRACT CuZn Alloy- Based Electrocatalyst for CO2 Reduction Amira Alazmi Carbon dioxide (CO2) is one of the major greenhouse gases and its emission is a significant threat to global economy and sustainability. Efficient CO2 conversion leads to utilization of CO2 as a carbon feedstock, but activating the most stable carbon-based molecule, CO2, is a challenging task. Electrochemical conversion of CO2 is considered to be the beneficial approach to generate carbon-containing fuels directly from CO2, especially when the electronic energy is derived from renewable energies, such as solar, wind, geo-thermal and tidal. To achieve this goal, the development of an efficient electrocatalyst for CO2 reduction is essential. In this thesis, studies on CuZn alloys with heat treatments at different temperatures have been evaluated as electrocatalysts for CO2 reduction. It was found that the catalytic activity of these electrodes was strongly dependent on the thermal oxidation temperature before their use for electrochemical measurements. The polycrystalline CuZn electrode without thermal treatment shows the Faradaic efficiency for CO formation of only 30% at applied potential ~−1.0 V vs. RHE with current density of ~−2.55 mA cm−2. In contrast, the reduction of oxide-based CuZn alloy electrode exhibits 65% Faradaic efficiency for CO at lower applied potential about −1.0 V vs. RHE with current density of −2.55 mA cm−2. Furthermore, stable activity was achieved over several hours of the reduction reaction at the modified electrodes. Based on electrokinetic studies, this improvement could be attributed to further stabilization of the CO2•− on the oxide-based Cu-Zn alloy surface.

  8. Benchmarking heterogeneous electrocatalysts for the oxygen evolution reaction.

    Science.gov (United States)

    McCrory, Charles C L; Jung, Suho; Peters, Jonas C; Jaramillo, Thomas F

    2013-11-13

    Objective evaluation of the activity of electrocatalysts for water oxidation is of fundamental importance for the development of promising energy conversion technologies including integrated solar water-splitting devices, water electrolyzers, and Li-air batteries. However, current methods employed to evaluate oxygen-evolving catalysts are not standardized, making it difficult to compare the activity and stability of these materials. We report a protocol for evaluating the activity, stability, and Faradaic efficiency of electrodeposited oxygen-evolving electrocatalysts. In particular, we focus on methods for determining electrochemically active surface area and measuring electrocatalytic activity and stability under conditions relevant to an integrated solar water-splitting device. Our primary figure of merit is the overpotential required to achieve a current density of 10 mA cm(-2) per geometric area, approximately the current density expected for a 10% efficient solar-to-fuels conversion device. Utilizing the aforementioned surface area measurements, one can determine electrocatalyst turnover frequencies. The reported protocol was used to examine the oxygen-evolution activity of the following systems in acidic and alkaline solutions: CoO(x), CoPi, CoFeO(x), NiO(x), NiCeO(x), NiCoO(x), NiCuO(x), NiFeO(x), and NiLaO(x). The oxygen-evolving activity of an electrodeposited IrO(x) catalyst was also investigated for comparison. Two general observations are made from comparing the catalytic performance of the OER catalysts investigated: (1) in alkaline solution, every non-noble metal system achieved 10 mA cm(-2) current densities at similar operating overpotentials between 0.35 and 0.43 V, and (2) every system but IrO(x) was unstable under oxidative conditions in acidic solutions.

  9. Enhanced photocurrent in RuL2(NCS)2/di-(3-aminopropyl)-viologen/SnO2/ITO system

    International Nuclear Information System (INIS)

    Lee, Wonjoo; Kwak, Chang Gon; Mane, R.S.; Min, Sun Ki; Cai, Gangri; Ganesh, T.; Koo, Gumae; Chang, Jinho; Cho, Byung Won; Kim, Sei-Ki; Han, Sung-Hwan

    2008-01-01

    A Ru(2,2'-bipyridine-4,4'-dicarboxylic acid) 2 (NCS) 2 [RuL 2 (NCS) 2 ]/di-(3-aminopropyl)-viologen (DAPV)/tin oxide (SnO 2 ) system was prepared and applied to extensive photocurrent generation with its maximum surface area. The SnO 2 thin films on tin-doped indium oxide (ITO) were prepared using the chemical bath deposition method. Then, RuL 2 (NCS) 2 /DAPV on SnO 2 /ITO was easily prepared using self-assembled monolayers (SAMs). The photocurrent measurement of the system showed an excellent photocurrent of 20 nA cm -2 under the air mass 1.5 conditions (100 mW cm -2 ), which was increased by a factor of four compared to ones without SnO 2 layers

  10. Nano-electrochemical deposition of fuel cells electrocatalysts

    CSIR Research Space (South Africa)

    Mathe

    2008-11-01

    Full Text Available stream_source_info Mathe_2008.pdf.txt stream_content_type text/plain stream_size 34594 Content-Encoding UTF-8 stream_name Mathe_2008.pdf.txt Content-Type text/plain; charset=UTF-8 1 Nano-electrochemical deposition... of fuel cells electrocatalysts MK MATHE a,*, TS MKWIZU a,b, I CUKROWSKI b * ,aCSIR Materials Science and Manufacturing, Energy and Processes, PO Box 395, Pretoria, 0001 bDepartment of Chemistry, University of Pretoria, Pretoria, 0002 Email: kmathe...

  11. Significance of β-dehydrogenation in ethanol electro-oxidation on platinum doped with Ru, Rh, Pd, Os and Ir.

    Science.gov (United States)

    Sheng, Tian; Lin, Wen-Feng; Hardacre, Christopher; Hu, P

    2014-07-14

    In the exploration of highly efficient direct ethanol fuel cells (DEFCs), how to promote the CO2 selectivity is a key issue which remains to be solved. Some advances have been made, for example, using bimetallic electrocatalysts, Rh has been found to be an efficient additive to platinum to obtain high CO2 selectivity experimentally. In this work, the mechanism of ethanol electrooxidation is investigated using the first principles method. It is found that CH3CHOH* is the key intermediate during ethanol electrooxidation and the activity of β-dehydrogenation is the rate determining factor that affects the completeness of ethanol oxidation. In addition, a series of transition metals (Ru, Rh, Pd, Os and Ir) are alloyed on the top layer of Pt(111) in order to analyze their effects. The elementary steps, α-, β-C-H bond and C-C bond dissociations, are calculated on these bimetallic M/Pt(111) surfaces and the formation potential of OH* from water dissociation is also calculated. We find that the active metals increase the activity of β-dehydrogenation but lower the OH* formation potential resulting in the active site being blocked. By considering both β-dehydrogenation and OH* formation, Ru, Os and Ir are identified to be unsuitable for the promotion of CO2 selectivity and only Rh is able to increase the selectivity of CO2 in DEFCs.

  12. Nitrogen Doped Graphene Supported Pt Nanoflowers as Electrocatalysts for Oxidation of Formaldehyde.

    Science.gov (United States)

    Xie, Aijuan; Zhou, Wenting; Luo, Shiping; Chen, Yu; Zhou, Xiaoqing; Chao, Yao

    2017-02-01

    A facile Pt nanoflowers/nitrogen-doped graphene (PtNFs/NG) electrocatalyst was prepared via depositing Pt nanoflowers (PtNFs) onto the nitrogen-doped graphene (NG) matrix with urea as the nitrogen source and PtNFs/NG modified glassy carbon electrode (GCE) was prepared by electro-chemical method. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscope, X-ray photoelectron spectroscopy (XPS) and Scanning electron microscope (SEM) were used to characterize the resulting composites. Also oxidation of formaldehyde on the resulting PtNFs/NG modified electrode was investigated. The influence of deposition time, electrodeposition potential and formaldehyde concentration on electrooxidation of formaldehyde was detected, the experimental results indicate the high performance of PtNFs/NG catalyst for formaldehyde oxidation is at electrodeposition time of 300 s with the applied potential of −0.3 V. Electrochemical process, electrocatalytic stability and chronoamperometry were also inspected, it was indicated that formalde-hyde oxidation reaction on the PtNFs/NG electrode is diffusion-controlled and PtNFs/NG exhibits a high catalytic activity, stability as well as excellent poisoning-tolerance towards formaldehyde oxidation, which is attributed to the synergistic effect of PtNFs and NG. It turns out that PtNFs/NG can be used in direct liquid-feed fuel cells as a promising alternative catalyst.

  13. Electro-catalysts for hydrogen production from ethanol for use in SOFC anodes

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcos Aurelio da; Paz Fiuza, Raigenis da; Guedes, Bruna C.; Pontes, Luiz A.; Boaventura, Jaime Soares [UFBA, Salvador, Bahia (Brazil). Energy and Materials Science Group

    2010-07-01

    Nickel and cobalt catalysts, supported on YSZ, were prepared by wet impregnation, with and without citric acid; the metal load was 10 and 35% by weight. The catalyst composition was studied by XRF, XPS and SEM-EDS. At low metal concentration, the results of these techniques presented comparables figures; at high concentration, SEM-EDS suggested a non-uniform distribution. The analysis showed that the solids were mixed oxides and formed an alloy after reduction. The surface passivation was possible under controlled conditions. The catalytic test with the steam reforming of ethanol indicated that the metal load had almost no effect on the catalytic activity, but decreased its selectivity. Afterwards, a unitary SOFC was prepared with deposition of the cathode layer. AFM and EIS were used for the characterization of SOFC components. They showed that the electro-catalyst surface was almost all covered with the metal phase, including the large pore walls of the anode. The YSZ phase dominates the material conductance of the complete SOFC assembly (anode/electrolyte/cathode). The unitary SOFC was tested with hydrogen, gaseous ethanol or natural gas; the SOFC operating with ethanol and hydrogen fuel presented virtually no over-potential. (orig.)

  14. Metabolism and dosimetry of 106Ru inhaled as 106RuO4 by beagle dogs

    International Nuclear Information System (INIS)

    Snipes, M.B.

    1981-01-01

    This report provides metabolism and dosimetry data for inhaled ruthenium developed from studies in Beagle dogs that were exposed by inhalation to 106 RuO 4 . Twenty-six dogs were exposed nose-only to 106 RuO 4 and sacrificed at times from 2 hr to 512 days after inhalation exposure. Ninety-nine percent of the initial body burden was retained with an effective half-time of 1.2 days, 0.7% with a half-time of 14 days and 0.3% with a half-time of 170 days. Initial deposition was primarily in the nasopharyngeal and tracheobronchial regions. Results for deposition and retention of 106 Ru inhaled as 106 RuO 4 in dogs were similar to what has been observed for humans. The data for dogs were used to develop a model to predict potential radiation exposure patterns for humans after inhalation exposure to 106 RuO 4 . The model indicates that for humans the nasopharyngeal region, lower large intestine, and tracheobronchial epithelium would receive approx. 36, 13 and 10 times, respectively, the dose to 500 days after inhalation exposure to 106 RuO 4 that the lung would receive. The nasopharyngeal region should be considered the critical region for inhalation exposures to 106 RuO 4 . (author)

  15. Influence of Support Material of PtSnNiGa/C Electrocatalysts for Ethanol Oxidation

    Directory of Open Access Journals (Sweden)

    Deise M Santos

    2017-07-01

    Full Text Available Ethanol is a promising alternative source for fuel cells due to its low toxicity and high power density. However, the cleavage of the C-C bond, CO poisoning, and low electrocatalyst stability are still considered crucial issues. To overcome this limitation, binary, ternary and quaternary electrocatalysts have been investigated along with new carbon supports. This paper presents a physicochemical and electrochemical investigation of quaternary PtSnNiGa/C electrocatalysts supported on Vulcan XC72 and Printex-L6 carbons and also a carbon produced by natural gas pyrolysis in an Argon plasma torch (Black Plasma. The electrochemical characterization was performed through cyclic voltammetry, chronoamperometry, chronopotentiometry and electrochemical impedance spectroscopy in the presence of ethanol 1.0 mol L-1. Energy dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy and transmission electron microscopy were also carried out for physicochemical characterization. The electrochemical results show that the quaternary electrocatalysts supported on Vulcan XC72 and Printex-L6 carbons display a high current normalized by Pt mass and are more stable than the electrocatalyst supported on Black Plasma. In addition, the quaternary electrocatalysts with reduced Pt loading display better electrocatalytic activity towards the EOR compared to high Pt loading electrocatalysts. DOI: http://dx.doi.org/10.17807/orbital.v9i3.949 

  16. Stable and efficient nitrogen-containing-carbon based electrocatalysts for reactions in energy conversion systems.

    Science.gov (United States)

    Wang, Sicong; Teng, Zhenyuan; Wang, Chengyin; Wang, Guoxiu

    2018-05-17

    High activity and stability are crucial for practical electrocatalysts used for reactions in fuel cells, metal-air batteries and water electrolysis including ORR, HER, OER and oxidation reactions of formic acid and alcohols. N-C based electrocatalysts have shown promising prospects for catalyzing these reactions, however, there is no systematic review for strategies toward engineering active and stable N-C based electrocatalysts reported by far. Herein, a comprehensive comparison of recently reported N-C based electrocatalysts regarding both electrocatalytic activity and long-term stability is presented. In the first part of this review, relationships between electrocatalytic reactions and element selections for modifying N-C based materials are discussed. Afterwards, synthesis methods for N-C based electrocatalysts are summarized, and synthetic strategies for highly stable N-C based electrocatalysts are presented. Multiple tables containing data on crucial parameters for both electrocatalytic activity and stability are displayed in this review. Finally, constructing M-Nx moieties is proposed as the most promising engineering strategy for stable N-C based electrocatalysts. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Preparation of Pt–Ru bimetallic catalyst supported on carbon ...

    Indian Academy of Sciences (India)

    Unknown

    †Laboratoire de Photonique, ‡Institut de Physique et Interfaces, Ecole Polytechnique Federale de Lausanne,. CH-1015 ... In this communication, we report the use of polyphenyl ... The open end structure of the tube has been confirmed by.

  18. Tetrapropylammonium ion influence on the synthesis of Pt Ru/carbon hybrids by hydrothermal carbonization

    International Nuclear Information System (INIS)

    Tusi, M.M.; Polanco, N.S.O.; Brandalise, M.; Correa, O.V.; Silva, A.C.; Oliveira Neto, A.; Linardi, M.; Spinace, E.V.

    2010-01-01

    PtRu/Carbon hybrid materials were prepared by hydrothermal carbonization using starch as carbon source and reducing agent and H 2 PtCl 6 .6H 2 O e RuCl 3 .xH 2 O as metals source and catalyst of the carbonization process. The materials were prepared in the following conditions: without pH adjustment, in the absence and in the presence of tetrapropylammonium chloride (TPACl), and adjusting the pH using potassium hydroxide (KOH) or tetrapropylammonium hydroxide (TPAOH). The obtained materials were treated under argon atmosphere at 900 deg C and characterized by SEM/EDX, BET isotherm, XRD and TEM. The electro-oxidation of methanol was studied by chronoamperometry. The material prepared using TPAOH showed the best performance for methanol electro-oxidation. (author)

  19. Improvement of energy conversion efficiency and power generation in direct borohydride-hydrogen peroxide fuel cell: The effect of Ni-M core-shell nanoparticles (M = Pt, Pd, Ru)/Multiwalled Carbon Nanotubes on the cell performance

    Science.gov (United States)

    Hosseini, M. G.; Mahmoodi, R.

    2017-12-01

    In this study, core@shell nanoparticles with Ni as a core material and Pt, Pd and Ru as shell materials are synthesized on multiwalled carbon nanotube (MWCNT) as catalyst support using the sequence reduction method. The influence of Ni@Pt, Ni@Pd and Ni@Ru core@shell nanoparticles on MWCNT toward borohydride oxidation in alkaline solution is investigated by various three-electrode electrochemical techniques. Also, the impact of these anodic electrocatalysts on the performance of direct borohydride-hydrogen peroxide fuel cell (DBHPFC) is evaluated. The structural and morphological properties of electrocatalysts are studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). The results of three electrode investigations show that Ni@Pd/MWCNT has excellent catalytic activity since borohydride oxidation current density on Ni@Pd/MWCNT (34773.27 A g-1) is 1.37 and 9.19 times higher than those of Ni@Pt/MWCNT (25347.27 A g-1) and Ni@Ru/MWCNT (3782.83 A g-1), respectively. Also, the energy conversion efficiency and power density of DBHPFC with Ni@Pd/MWCNT (246.82 mW cm-2) increase to 34.27% and 51.53% respect to Ni@Pt/MWCNT (162.24 mW cm-2) and Ni@Ru/MWCNT (119.62 mW cm-2), respectively. This study reveals that Ni@Pd/MWCNT has highest activity toward borohydride oxidation and stability in fuel cell.

  20. Assessment for the role of rare earth oxide in the R2O3 - RuO2 - Pt composite electrode

    International Nuclear Information System (INIS)

    Do Ngoc Lien; Nguyen Van Sinh

    2004-01-01

    Our work has showed several results related to assessment for the role of rare earth oxide in the R 2 O 3 - RuO 2 - Pt composite electrode. The precursor method was used for preparing composite electrode in the following forms: a- RuO 2 - Pt electrode b- La 2 O 3 (55%) - RuO 2 (45%) - Pt electrode c- CeO 2 (60%) - RuO 2 (40%) - Pt electrode By measurements of anodic polarization and cyclic potential for the types of a, b, c electrodes we can see that the La 2 O 3 (55%) - 45% RuO 2 - Pt electrode will be the best anodic electrode. It means that the partial replacement of ruthenium oxide by lanthanum oxide in composite oxide electrode will be an effective one. (author)

  1. The effects of rare earths on activity and surface properties of Ru/γ-Al2O3 catalyst for water gas shift reaction

    Directory of Open Access Journals (Sweden)

    Laitao Luo

    2007-04-01

    Full Text Available A series of Ru-RE/γ- Al2O3 (RE = Ce, Pr, La, Sm, Tb or Gd and Ru/γ- Al2O3 catalysts were prepared by impregnation method. The influence of rare earths on the catalytic performance of Ru/γ- Al2O3 catalyst for the water gas shift reaction was studied. The catalysts were characterized by X-ray diffraction (XRD, temperature programmed reduction (TPR, temperature programmed desorption (TPD, and CO chemisorption. The results show that the addition of rare earths increases the catalytic activity of Ru based catalyst. Among these cerium is the most remarkably. The addition of cerium increases the active surface area, improves the dispersion of ruthenium, and weakens the interaction between ruthenium and the support. Cerium also affects the adsorption and reduction properties of Ru/γ-Al2O3 catalyst.

  2. The influence of copper in dealloyed binary platinum–copper electrocatalysts on methanol electroxidation catalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Poochai, Chatwarin [Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Veerasai, Waret, E-mail: waret.vee@mahidol.ac.th [Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Somsook, Ekasith [Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Dangtip, Somsak [Department of Physics, and NANOTEC COE at Mahidol University, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand)

    2015-08-01

    In this study, we prepared and characterized carbon paper-supported dealloyed binary Pt–Cu core–shell electrocatalysts (denoted as Pt{sub x}Cu{sub (100−x)/}CP) by cyclic co-electrodeposition and selective copper dealloying in an acidic medium, and we investigated the effect of the copper content in the samples on the catalytic activities toward methanol electroxidation reaction (MOR). X-ray photo-emission spectroscopy (XPS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) indicated that the structure of dealloyed binary Pt–Cu catalysts possessed a Pt-rich shell and a Cu rich core. X-ray absorption near edge spectroscopy (XANES) displayed that the oxidation states of Pt and Cu were zero and one, respectively, implying the formation of metallic Pt and Cu{sub 2}O, respectively. X-ray diffraction spectroscopy (XRD) confirmed that Cu was inserted into a face-centered cubic Pt structure forming Pt–Cu alloys. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) displayed a cubic shape of Pt/CP and a spherical shape of Pt{sub x}Cu{sub (100−x)/}CP with several hundred nanometer sizes of agglomeration that depended on the Cu content. Cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy were performed to confirm that the sample of Pt{sub 70}Cu{sub 30}/CP exhibited the best catalytic activities in terms of the specific current, current density, catalytic poisoning tolerance, and stability. - Graphical abstract: Display Omitted - Highlights: • Binary electrocatalysts of Pt{sub x}Cu{sub (100−x)}/CP were prepared by cyclic co-electrodeposition and selective copper dealloying. • The structures of Pt{sub x}Cu{sub (100−x)}/CP were a Pt rich shell and a Cu rich core. • The Pt{sub 70}Cu{sub 30}/CP was the excellent catalytic activity towards methanol electrooxidation and CO{sub ads} tolerance.

  3. Radiolytic Synthesis of Pt-Ru Catalysts Based on Functional Polymer-Grafted MWNT and Their Catalytic Efficiency for CO and MeOH

    Directory of Open Access Journals (Sweden)

    Dae-Soo Yang

    2011-01-01

    Full Text Available Pt-Ru catalysts based on functional polymer-grafted MWNT (Pt-Ru@FP-MWNT were prepared by radiolytic deposition of Pt-Ru nanoparticles on functional polymer-grafted multiwalled carbon nanotube (FP-MWNT. Three different types of functional polymers, poly(acrylic acid (PAAc, poly(methacrylic acid (PMAc, and poly(vinylphenyl boronic acid (PVPBAc, were grafted on the MWNT surface by radiation-induced graft polymerization (RIGP. Then, Pt-Ru nanoparticles were deposited onto the FP-MWNT supports by the reduction of metal ions using γ-irradiation to obtain Pt-Ru@FP-MWNT catalysts. The Pt-Ru@FP-MWNT catalysts were then characterized by XRD, XPS, TEM ,and elemental analysis. The catalytic efficiency of Pt-Ru@FP-MWNT catalyst was examined for CO stripping and MeOH oxidation for use in a direct methanol fuel cell (DMFC. The Pt-Ru@PVPBAc-MWNT catalyst shows enhanced activity for electro-oxidation of CO and MeOH oxidation over that of the commercial E-TEK catalyst.

  4. Properties and microstructure of the Ru-coated carbon nano tube counter electrode for dye-sensitized solar cells.

    Science.gov (United States)

    Han, Jeungjo; Yu, Byungkwan; Noh, Yunyoung; Suh, Young Joon; Kim, Moon J; Yoo, Kicheon; Ko, Min Jae; Song, Ohsung

    2014-08-01

    In this study, we investigated the performance of dye-sensitized solar cells (DSSCs) with the ruthenium (Ru) coated multi-walled carbon nanotube (MWCNT) on the counter electrode (CE). High purity MWCNT (0.01~0.06 g) was sprayed on glass/fluorine-doped tin oxide (FTO). Then 30 nm-thick Ru thin films were coated on a MWCNT template at low temperature by atomic layer deposition (ALD) using RuDi and O2 as precursor to prepare Ru-CNT CE and the 0.45 cm2 DSSC device of glass/FTO/TiO2/Dye (N719)/electrolyte (C6DMII, GSCN)/Ru-CNT CE was fabricated. The surface morphology of CEs and the energy conversion efficiency of the DSSC device were characterized by scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), and photocurrent-voltage (I-V) measurement. We confirmed that effective surface of the CE increased linearly as the amount of MWCNT spray increased and the crystallized Ru was deposited very conformally around the MWCNT nano template. Moreover, the efficiency of the DSSC increased up to 3.3% as the amount of MWCNT increased.

  5. スクッテルド鉱型化合物LnRu4P12(Ln=ランタニド)の構造と電子物性

    OpenAIRE

    内海, 貴徳; 関根, ちひろ; 木村, 繁之; 井上, 雅士; 城谷, 一民

    1999-01-01

    Ternary ruthenium phosphides LnRu4P12 (Ln=La,Ce,Pr,Nd,Sm,Eu,Gd and Tb) with the filled skutterudite-type structure have been prepared at high temperatures and high pressures. The crystal structure of a new compound TbRu4P12 is refined by the Rietveld analysis of the powder X-ray diffraction data. The physical properties of LnRu4P12 have been studied by means of electrical resistivity, magnetic susceptibility, magnetization and specific-heat measurements at low temperatures. LaRu4P12 is a supe...

  6. Low-energy optics of Sr{sub 1-x}Ca{sub x}RuO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Geiger, Diana; Scheffler, Marc; Dressel, Martin [1. Physikalisches Institut, Universitaet Stuttgart (Germany); Schneider, Melanie; Gegenwart, Philipp [I. Physikalisches Institut, Georg-August-Universitaet, Goettingen (Germany)

    2012-07-01

    The pseudo-cubic perovskite ruthenates SrRuO{sub 3} and CaRuO{sub 3} have recently attracted interest due to their unconventional electronic properties. For both materials, non-Fermi liquid behavior has been reported in previous optical studies at infrared frequencies. In addition to these two pure compounds, the doping series Sr{sub 1-x}Ca{sub x}RuO{sub 3} offers a rich phase diagram: going from the itinerant ferromagnet SrRuO{sub 3} to the paramagnet CaRuO{sub 3}, indications for a quantum phase transition at x{approx}0.8 have been found. Using THz spectroscopy at frequencies between 5 cm{sup -1} and 45 cm{sup -1}, we have studied thin-film samples of the Sr{sub 1-x}Ca{sub x}RuO{sub 3} system, which were prepared by metalorganic aerosol deposition. From transmission and phase measurements we have determined the frequency-dependent conductivity for a set of temperatures between 5 K and 300 K, and we discuss it in the framework of the extended Drude model with frequency-dependent relaxation rate and effective mass. While for pure SrRuO{sub 3} as well as for doped systems approaching the quantum phase transition we find conventional metallic Drude behavior, CaRuO{sub 3} exhibits highly unusual optical properties which we compare to results of dc measurements on these thin films, which also revealed temperature ranges with non-Fermi liquid behavior.

  7. A bio-inspired N-doped porous carbon electrocatalyst with hierarchical superstructure for efficient oxygen reduction reaction

    Science.gov (United States)

    Miao, Yue-E.; Yan, Jiajie; Ouyang, Yue; Lu, Hengyi; Lai, Feili; Wu, Yue; Liu, Tianxi

    2018-06-01

    The bio-inspired hierarchical "grape cluster" superstructure provides an effective integration of one-dimensional carbon nanofibers (CNF) with isolated carbonaceous nanoparticles into three-dimensional (3D) conductive frameworks for efficient electron and mass transfer. Herein, a 3D N-doped porous carbon electrocatalyst consisting of carbon nanofibers with grape-like N-doped hollow carbon particles (CNF@NC) has been prepared through a simple electrospinning strategy combined with in-situ growth and carbonization processes. Such a bio-inspired hierarchically organized conductive network largely facilitates both the mass diffusion and electron transfer during the oxygen reduction reactions (ORR). Therefore, the metal-free CNF@NC catalyst demonstrates superior catalytic activity with an absolute four-electron transfer mechanism, strong methanol tolerance and good long-term stability towards ORR in alkaline media.

  8. Graphene-cobaltite-Pd hybrid materials for use as efficient bifunctional electrocatalysts in alkaline direct methanol fuel cells.

    Science.gov (United States)

    Sharma, Chandra Shekhar; Awasthi, Rahul; Singh, Ravindra Nath; Sinha, Akhoury Sudhir Kumar

    2013-12-14

    Hybrid materials comprising of Pd, MCo2O4 (where M = Mn, Co or Ni) and graphene have been prepared for use as efficient bifunctional electrocatalysts in alkaline direct methanol fuel cells. Structural and electrochemical characterizations were carried out using X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, chronoamperometry and cyclic, CO stripping, and linear sweep voltammetries. The study revealed that all the three hybrid materials are active for both methanol oxidation (MOR) and oxygen reduction (ORR) reactions in 1 M KOH. However, the Pd-MnCo2O4/GNS hybrid electrode exhibited the greatest MOR and ORR activities. This active hybrid electrode has also outstanding stability under both MOR and ORR conditions, while Pt- and other Pd-based catalysts undergo degradation under similar experimental conditions. The Pd-MnCo2O4/GNS hybrid catalyst exhibited superior ORR activity and stability compared to even Pt in alkaline solutions.

  9. Soft template synthesis of mesoporous Co3O4/RuO2.xH2O composites for electrochemical capacitors

    International Nuclear Information System (INIS)

    Liu Yang; Zhao Weiwei; Zhang Xiaogang

    2008-01-01

    Co 3 O 4 /RuO 2 .xH 2 O composites with various Ru content (molar content of Ru = 5%, 10%, 20%, 50%) were synthesized by one-step co-precipitation method. The precursors were prepared via adjusting pH of the mixed aqueous solutions of Co(NO 3 ) 2 .6H 2 O and RuCl 3 .0.5H 2 O by using Pluronic123 as a soft template. For the composite with molar ratio of Co:Ru = 1:1 annealed at 200 deg. C, Brunauer-Emmet-Teller (BET) results indicated that the composite showed mesoporous structure, and the specific surface area of the composite was as high as 107 m 2 g -1 . The electrochemical performances of these composites were measured in 1 M KOH electrolyte. Compared with the composite prepared without template, the composite with P123 exhibited a higher specific capacitance. When the molar content of Ru was rising, the specific capacitance of the composites increased significantly. It was also observed that the crystalline structures as well as the electrochemical activities were strongly dependent on the annealing temperature. A capacitance of 642 F/g was obtained for the composite (Co:Ru = 1:1) annealed at 150 deg. C. Meanwhile, the composites also exhibited good cycle stability. Besides, the morphologies and textural characteristic of the samples were also investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM)

  10. Ratiometric Fluorescence Sensing and Real-Time Detection of Water in Organic Solvents with One-Pot Synthesis of Ru@MIL-101(Al)-NH2.

    Science.gov (United States)

    Yin, Hua-Qing; Yang, Ji-Chun; Yin, Xue-Bo

    2017-12-19

    Ratiometric fluorescence detection attracts much attention because of its decreased environmental influence and easy-to-differentiate color and intensity change. Herein, a guest-encapsulation metal-organic framework (MOF), Ru@MIL-NH 2 , is prepared with 2-aminoterephthalic acid, AlCl 3 , and Ru(bpy) 3 2+ by a simple one-pot method for ratiometric fluorescence sensing of water in organic solvents. The rational selection of the excitation wavelength provides dual emission at 465 and 615 nm from Ru@MIL-NH 2 under a single excitation of 300 nm. High sensitivity, low detection limit (0.02% v/v), wide response range (0-100%), and fast response (less than 1 min) are obtained for ratiometric fluorescence sensing of water under single excitation with Ru@MIL-NH 2 as the probe. Moreover, the result of water content is independent of the concentration of Ru@MIL-NH 2 as the merit of ratiometric fluorescence detection. The response mechanism reveals that the protonation of the nitrogen atom of the MIL-NH 2 , the π-conjugation system, and the stable fluorescence of Ru(bpy) 3 2+ achieve the ratiometric fluorescence. The analysis of real spirit samples confirms the proposed method. A test strip is prepared with Ru@MIL-NH 2 for convenient use. We believe that such turn-on ratiometric host-guest MOFs and the rational selection of excitation wavelength will offer guidance for ratiometric fluorescence detection with wide applications.

  11. Electroerosion method for preparation of saturated solutions of ruthenium hydroxochloride

    International Nuclear Information System (INIS)

    Mikhalev, V.A.; Andrianov, G.A.; Zhadanov, B.V.; Ryazanov, A.I.

    1987-01-01

    A pilot plant for carrying out electroerosion processes using pulse current of high unit power is developed. The solution process of metallic Ru in concentrated HCl is investigated. The possibility of preparation of ruthenium hydroxochloride solutions of 300 g/l concentration is established; it gives the possibility of Ru solution under conditions similar to the process of salting out

  12. Bio-inspired routes for synthesizing efficient nanoscale platinum electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jennifer N. [Univ. of California, San Diego, CA (United States); Wang, Joseph [Univ. of California, San Diego, CA (United States)

    2014-08-31

    The overall objective of the proposed research is to use fundamental advances in bionanotechnology to design powerful platinum nanocrystal electrocatalysts for fuel cell applications. The new economically-viable, environmentally-friendly, bottom-up biochemical synthetic strategy will produce platinum nanocrystals with tailored size, shape and crystal orientation, hence leading to a maximum electrochemical reactivity. There are five specific aims to the proposed bio-inspired strategy for synthesizing efficient electrocatalytic platinum nanocrystals: (1) isolate peptides that both selectively bind particular crystal faces of platinum and promote the nucleation and growth of particular nanocrystal morphologies, (2) pattern nanoscale 2-dimensional arrays of platinum nucleating peptides from DNA scaffolds, (3) investigate the combined use of substrate patterned peptides and soluble peptides on nanocrystal morphology and growth (4) synthesize platinum crystals on planar and large-area carbon electrode supports, and (5) perform detailed characterization of the electrocatalytic behavior as a function of catalyst size, shape and morphology. Project Description and Impact: This bio-inspired collaborative research effort will address key challenges in designing powerful electrocatalysts for fuel cell applications by employing nucleic acid scaffolds in combination with peptides to perform specific, environmentally-friendly, simultaneous bottom-up biochemical synthesis and patterned assembly of highly uniform and efficient platinum nanocrystal catalysts. Bulk synthesis of nanoparticles usually produces a range of sizes, accessible catalytic sites, crystal morphologies, and orientations, all of which lead to inconsistent catalytic activities. In contrast, biological systems routinely demonstrate exquisite control over inorganic syntheses at neutral pH and ambient temperature and pressures. Because the orientation and arrangement of the templating biomolecules can be precisely

  13. Tungsten carbide encapsulated in nitrogen-doped carbon with iron/cobalt carbides electrocatalyst for oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jie; Chen, Jinwei, E-mail: jwchen@scu.edu.cn; Jiang, Yiwu; Zhou, Feilong; Wang, Gang; Wang, Ruilin, E-mail: rl.wang@scu.edu.cn

    2016-12-15

    Graphical abstract: A hybrid catalyst was prepared via a quite green and simple method to achieve an one-pot synthesis of the N-doping carbon, tungsten carbides, and iron/cobalt carbides. It exhibited comparable electrocatalytic activity, higher durability and ability to methanol tolerance compared with commercial Pt/C to ORR. - Highlights: • A novel type of hybrid Fe/Co/WC@NC catalysts have been successfully synthesized. • The hybrid catalyst also exhibited better durability and methanol tolerance. • Multiple effective active sites of Fe{sub 3}C, Co{sub 3}C, WC, and NC help to improve catalytic performance. - Abstract: This work presents a type of hybrid catalyst prepared through an environmental and simple method, combining a pyrolysis of transition metal precursors, a nitrogen-containing material, and a tungsten source to achieve a one-pot synthesis of N-doping carbon, tungsten carbides, and iron/cobalt carbides (Fe/Co/WC@NC). The obtained Fe/Co/WC@NC consists of uniform Fe{sub 3}C and Co{sub 3}C nanoparticles encapsulated in graphitized carbon with surface nitrogen doping, closely wrapped around a plate-like tungsten carbide (WC) that functions as an efficient oxygen reduction reaction (ORR) catalyst. The introduction of WC is found to promote the ORR activity of Fe/Co-based carbide electrocatalysts, which is attributed to the synergistic catalysts of WC, Fe{sub 3}C, and Co{sub 3}C. Results suggest that the composite exhibits comparable electrocatalytic activity, higher durability, and ability for methanol tolerance compared with commercial Pt/C for ORR in alkaline electrolyte. These advantages make Fe/Co/WC@NC a promising ORR electrocatalyst and a cost-effective alternative to Pt/C for practical application as fuel cell.

  14. Polyelectrolyte-based electrochemiluminescence enhancement for Ru(bpy){sub 3}{sup 2+} loaded by SiO{sub 2} nanoparticle carrier and its high sensitive immunoassay

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Zhi-Li; Song, Tian-Mei; Chen, Zhe [College of Pharmaceutical Science, Soochow University, Suzhou 215123 (China); Guo, Wu-Run [College of Pharmaceutical Science, Soochow University, Suzhou 215123 (China); College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637002 (China); Xie, Hong-Ping, E-mail: hpxie@suda.edu.cn [College of Pharmaceutical Science, Soochow University, Suzhou 215123 (China); Xie, Lian, E-mail: xielian@suda.edu.cn [College of Pharmaceutical Science, Soochow University, Suzhou 215123 (China)

    2015-03-03

    Highlights: • Preparation of strong ECL nanoparticles PAA–Ru@SiO{sub 2}/[PAA⋯Ru&Nafion⋯Ru]. • Ion-pair macromolecule PAA–Ru formed to greatly increase the doping amount. • PAA&Nafion membrane increased the amount of ion-exchanged Ru(bpy){sub 3}{sup 2+}. • PAA&Nafion membrane enhanced the ability of electron transfer. • Realized antibody labeling and established a high-sensitive immunoassay. - Abstract: In this paper the strong electrochemiluminescence (ECL) nanoparticles have been prepared based on the anionic polyelectrolyte sodium polyacrylate (PAA)-ECL enhancement for Ru(bpy){sub 3}{sup 2+}, which were loaded by the carrier of SiO{sub 2} nanoparticle. There were two kinds of Ru(bpy){sub 3}{sup 2+} for the as-prepared nanoparticles, the doped one and the exchanged one. The former was loaded inside the ECL nanoparticles by doping, in a form of ion-pair macromolecules PAA–Ru(bpy){sub 3}{sup 2+}. The corresponding ECL was enhanced about 2 times owing to the doping increase of Ru(bpy){sub 3}{sup 2+}. The latter was loaded on the PAA-doped Nafion membrane by ion exchange. The corresponding ECL was enhanced about 3 times owing to the ion-exchanging increase of Ru(bpy){sub 3}{sup 2+}. At the same time, ECL intensity of the doped-inside Ru(bpy){sub 3}{sup 2+} was further enhanced 13 times because polyelectrolyte PAA in the doped membrane could obviously enhance electron transfer between the doped Ru(bpy){sub 3}{sup 2+} and the working electrode. Furthermore, based on hydrophobic regions of the doped membrane antibody labeling could be easily realized by the as-prepared nanoparticles and then a high sensitive ECL immunoassay for HBsAg was developed. The linear range was between 1.0 and 100 pg mL{sup −1} (R{sup 2} = 0.9912). The detection limit could be as low as 0.11 pg mL{sup −1} (signal-to-noise ratio = 3)

  15. Highly efficient and stable MoP-RGO nanoparticles as electrocatalysts for hydrogen evolution

    International Nuclear Information System (INIS)

    Wu, Zexing; Wang, Jie; Zhu, Jing; Guo, Junpo; Xiao, Weiping; Xuan, Cuijuan; Lei, Wen; Wang, Deli

    2017-01-01

    Graphical abstract: Graphene supported MoP (MoP-RGO) was synthesized through a facile solvothermal reaction followed by high-temperature phosphating treatment method. The material exhibits an outstanding HER performance in both acid and alkaline media. RGO act as a substrate which can not only avoid the nanoparticles aggregation, but also facilitate the electron transfer during the electrocatalytic process. - Abstract: Electrochemical splitting of water to obtain hydrogen plays a vital role in high energy density devices, especially for fuel cells. In this work, reduced graphene oxide supported molybdenum phosphide nanoparticles (MoP-RGO) were prepared via a facile solvothermal reaction followed by high-temperature phosphating treatment. The electrochemical measurement results indicate that the MoP-RGO nanocomposite obtained at 900 °C exhibits excellent electrocatalytic activity for hydrogen evolution reaction (HER) with overpotentials of 117 mV and 150 mV at a current density of 10 mA cm"−"2 in acid and alkaline media, respectively. Furthermore, the instability of the catalyst in basic medium was systemically investigated. This work provides a facile strategy for the synthesis of cost-effective carbon supported metal phosphide as HER electrocatalyst.

  16. 3D Analysis of Fuel Cell Electrocatalyst Degradation on Alternate Carbon Supports.

    Science.gov (United States)

    Sneed, Brian T; Cullen, David A; Reeves, Kimberly S; Dyck, Ondrej E; Langlois, David A; Mukundan, Rangachary; Borup, Rodney L; More, Karren L

    2017-09-06

    Understanding the mechanisms associated with Pt/C electrocatalyst degradation in proton exchange membrane fuel cell (PEMFC) cathodes is critical for the future development of higher-performing materials; however, there is a lack of information regarding Pt coarsening under PEMFC operating conditions within the cathode catalyst layer. We report a direct and quantitative 3D study of Pt dispersions on carbon supports (high surface area carbon (HSAC), Vulcan XC-72, and graphitized carbon) with varied surface areas, graphitic character, and Pt loadings ranging from 5 to 40 wt %. This is accomplished both before and after catalyst-cycling accelerated stress tests (ASTs) through observations of the cathode catalyst layer of membrane electrode assemblies. Electron tomography results show Pt nanoparticle agglomeration occurs predominantly at junctions and edges of aggregated graphitized carbon particles, leading to poor Pt dispersion in the as-prepared catalysts and increased coalescence during ASTs. Tomographic reconstructions of Pt/HSAC show much better initial Pt dispersions, less agglomeration, and less coarsening during ASTs in the cathode. However, a large loss of the electrochemically active surface area (ECSA) is still observed and is attributed to accelerated Pt dissolution and nanoparticle coalescence. Furthermore, a strong correlation between Pt particle/agglomerate size and measured ECSA is established and is proposed as a more useful metric than average crystallite size in predicting degradation behavior across different catalyst systems.

  17. PtPb nanoparticle electrocatalysts: control of activity through synthetic methods

    International Nuclear Information System (INIS)

    Ghosh, Tanushree; Matsumoto, Futoshi; McInnis, Jennifer; Weiss, Marilyn; Abruna, Hector D.; DiSalvo, Francis J.

    2009-01-01

    Solution phase synthesis of intermetallic nanoparticles without using surfactants (for catalytic applications) and subsequent control of size distribution remains a challenge: of growing interest, but not widely explored yet. To understand the questions in the syntheses of Pt containing intermetallic nanoparticles (as electrocatalysts for direct fuel cells) by using sodium naphthalide as the reducing agent, the effects of the Pt precursors' organic ligands were investigated. PtPb syntheses were studied as the model case. In particular, methods that lead to nanoparticles that are independent single crystals are desirable. Platinum acetylacetonate, which is soluble in many organic solvents, has ligands that may interfere less with nanoparticle growth and ordering. Interesting trends, contrary to expectations, were observed when precursors were injected into a reducing agent solution at high temperatures. The presence of acetylacetonate, from the precursor, on the nanoparticles was confirmed by ATR, while SEM imaging showed evidence of morphological changes in the nanoparticles with increasing reaction temperature. A definite relationship between domain size and extent of observed residue (organic material and sodium) present on the particles could be established. By varying post-reaction solvent removal techniques, room temperature crystallization of PtPb nanoparticles was also achieved. Electrochemical activity of the nanoparticles was also much higher than that of nanoparticles synthesized by previous reaction schemes using sodium naphthalide as the reducing agent. Along with the above mentioned techniques, BET, TEM, CBED, SAED, and XRD were used as characterization tools for the prepared nanoparticles.

  18. Co- and defect-rich carbon nanofiber films as a highly efficient electrocatalyst for oxygen reduction

    Science.gov (United States)

    Kim, Il To; Song, Myeong Jun; Shin, Seoyoon; Shin, Moo Whan

    2018-03-01

    Many efforts are continuously devoted to developing high-efficiency, low-cost, and highly scalable oxygen reduction reaction (ORR) electrocatalysts to replace precious metal catalysts. Herein, we successfully synthesize Co- and defect-rich carbon nanofibers (CNFs) using an efficient heat treatment approach involving the pyrolysis of electrospun fibers at 370 °C under air. The heat treatment process produces Co-decorated CNFs with a high Co mass ratio, enriched pyridinic N, Co-pyridinic Nx clusters, and defect-rich carbon structures. The synergistic effects from composition and structural changes in the designed material increase the number of catalytically active sites for the ORR in an alkaline solution. The prepared Co- and defect-rich CNFs exhibit excellent ORR activities with a high ORR onset potential (0.954 V vs. RHE), a large reduction current density (4.426 mA cm-2 at 0.40 V), and a nearly four-electron pathway. The catalyst also exhibits a better long-term durability than commercial Pt/C catalysts. This study provides a novel hybrid material as an efficient ORR catalyst and important insight into the design strategy for CNF-based hybrid materials as electrochemical electrodes.

  19. Ethanol Oxidation Reaction Using PtSn/C+Ce/C Electrocatalysts: Aspects of Ceria Contribution

    International Nuclear Information System (INIS)

    De Souza, R.F.B.; Silva, J.C.M.; Assumpção, M.H.M.T.; Neto, A.O.; Santos, M.C.

    2014-01-01

    The ethanol oxidation reaction (EOR) was investigated using PtSn/C + Ce/C electrocatalysts in different mass ratios (58:42, 53:47, and 42:58) prepared using the polymeric precursor method. Transmission electron microscopy (TEM) experiments showed particles sizes in the range of 3 to 7 nm. Changes in the net parameters observed for Pt suggest the incorporation of Sn into the Pt crystalline network with the formation of an alloy mixture with the SnO 2 phase. Among the PtSn/C + Ce/C catalysts investigated, the 53:47 composition showed the highest activity towards the EOR. In this case, the j versus t curves obtained in the presence of ethanol in acidic media exhibited a current density 90% higher than that observed with the commercial PtSn/C (ETEK). Correspondingly, during the experiments performed on single direct ethanol fuel cells, the maximum power density obtained using PtSn/C + Ce/C (53:47) as the anode was approximately 60% higher than that obtained using the commercial catalyst. FTIR data showed that the observed behavior for ethanol oxidation may be explained in terms of a synergic effect of bifunctional mechanism with electronic effects, in addition to a chemical effect of ceria that provides oxygen-containing species to oxidize acetaldehyde to acetic acid

  20. Monodispersed porous flowerlike PtAu nanocrystals as effective electrocatalysts for ethanol oxidation

    Science.gov (United States)

    Li, Shumin; Xu, Hui; Xiong, Zhiping; Zhang, Ke; Wang, Caiqin; Yan, Bo; Guo, Jun; Du, Yukou

    2017-11-01

    Designing and tuning the bimetallic nanoparticles with desirable morphology and structure can embody them with greatly enhanced electrocatalytic activity and stability towards liquid fuel oxidation. We herein reported a facile one-pot method for the controlled synthesis of monodispersed binary PtAu nanoflowers with abundant exposed surface area. Owing to its fantastic structure, synergistic and electronic effect, such as-prepared PtAu nanoflowers exhibited outstandingly high electrocatalytic activity with the mass activity of 6482 mA mg-1 towards ethanol oxidation, which is 28.3 times higher than that of commercial Pt/C (227 mA mg-1). More interesting, the present PtAu nanoflower catalysts are more stable for the ethanol oxidation reaction in the alkaline with lower current density decay and retained a much higher current density after successive CVs of 500 cycles than that of commercial Pt/C. This work may open a new way for maximizing the catalytic performance of electrocatalysts towards ethanol oxidation by synthesizing shape-controlled alloy nanoparticles with more surface active sites to enhance the performances of direct fuel cells reaction, chemical conversion, and beyond.

  1. Halloysite-derived nitrogen doped carbon electrocatalysts for anion exchange membrane fuel cells

    Science.gov (United States)

    Lu, Yaxiang; Wang, Lianqin; Preuß, Kathrin; Qiao, Mo; Titirici, Maria-Magdalena; Varcoe, John; Cai, Qiong

    2017-12-01

    Developing the low-cost, highly active carbonaceous materials for oxygen reduction reaction (ORR) catalysts has been a high-priority research direction for durable fuel cells. In this paper, two novel N-doped carbonaceous materials with flaky and rod-like morphology using the natural halloysite as template are obtained from urea nitrogen source as well as glucose (denoted as GU) and furfural (denoted as FU) carbon precursors, respectively, which can be directly applied as metal-free electrocatalysts for ORR in alkaline electrolyte. Importantly, compared with a benchmark Pt/C (20wt%) catalyst, the as-prepared carbon catalysts demonstrate higher retention in diffusion limiting current density (after 3000 cycles) and enhanced methanol tolerances with only 50-60mV negative shift in half-wave potentials. In addition, electrocatalytic activity, durability and methanol tolerant capability of the two N-doped carbon catalysts are systematically evaluated, and the underneath reasons of the outperformance of rod-like catalysts over the flaky are revealed. At last, the produced carbonaceous catalysts are also used as cathodes in the single cell H2/O2 anion exchange membrane fuel cell (AEMFC), in which the rod-like FU delivers a peak power density as high as 703 mW cm-2 (vs. 1106 mW cm-2 with a Pt/C benchmark cathode catalyst).

  2. Iron-Induced Activation of Ordered Mesoporous Nickel Cobalt Oxide Electrocatalyst for the Oxygen Evolution Reaction.

    Science.gov (United States)

    Deng, Xiaohui; Öztürk, Secil; Weidenthaler, Claudia; Tüysüz, Harun

    2017-06-28

    Herein, ordered mesoporous nickel cobalt oxides prepared by the nanocasting route are reported as highly active oxygen evolution reaction (OER) catalysts. By using the ordered mesoporous structure as a model system and afterward elevating the optimal catalysts composition, it is shown that, with a simple electrochemical activation step, the performance of nickel cobalt oxide can be significantly enhanced. The electrochemical impedance spectroscopy results indicated that charge transfer resistance increases for Co 3 O 4 spinel after an activation process, while this value drops for NiO and especially for CoNi mixed oxide significantly, which confirms the improvement of oxygen evolution kinetics. The catalyst with the optimal composition (Co/Ni 4/1) reaches a current density of 10 mA/cm 2 with an overpotential of a mere 336 mV and a Tafel slope of 36 mV/dec, outperforming benchmarked and other reported Ni/Co-based OER electrocatalysts. The catalyst also demonstrates outstanding durability for 14 h and maintained the ordered mesoporous structure. The cyclic voltammograms along with the electrochemical measurements in Fe-free KOH electrolyte suggest that the activity boost is attributed to the generation of surface Ni(OH) 2 species that incorporate Fe impurities from the electrolyte. The incorporation of Fe into the structure is also confirmed by inductively coupled plasma optical emission spectrometry.

  3. Carbon monoxide oxidation on bimetallic Ru/Au(111 surfaces

    Directory of Open Access Journals (Sweden)

    ROLF-JÜRGEN BEHM

    2001-02-01

    Full Text Available The electrochemical deposition of Ru on Au(111 was performed in 0.5 M H2SO4+10-4 M RuCl3 . The obtained bimetallic Ru/Au(111 surfaces were character-ised by cyclic voltammetry and in situ STM in 0.5 MH2SO4. The Ru deposit consists of nanoscale islands, which merge with increasing coverage. Two different types of bimetallic Ru/Au(111 surfaces with respect to the distribution of Ru islands over the Au(111 substrate surface were obtained. When the deposition was performed at potentials more positive than the range of Au(111 reconstruction, homogeneous nucleation occured resulting in a random distribution of Ru islands. When the deposition was performed on reconstructed Au(111 at low overpotentials, selective nucleation occured resulting in the replication of the Au(111 reconstruction. Only at higher deposition overpotentials, can multilayer deposits be formed, which exhibit a very rough surface morphology. The electrocatalytic activity of such structurally well defined Ru/Au(111 bimetallic surfaces was studied towards CO oxidation with the Ru coverage ranging from submonolayer to several monolayer. COstripping commences at about 0.2 Vand occurs over a broad potential range. The observed influence of the Ru structure on the CO stripping voltammetry is explained by local variations in the COadsorption energy, caused by differences in the local Ru structure and by effects induced by the Au(111 substrate.

  4. The provenance investigation on ancient chinese Ru porcelains by NAA

    International Nuclear Information System (INIS)

    Gao Zhengyao; Wang Jie; Chen Songhua

    1997-01-01

    The 28 samples of glazes and bodies of ancient Chinese Ru porcelains are analyzed by neutron activation. The 36 element contents in each sample are determined. The neutron activation analysis (NAA) data are analyzed by fuzzy cluster. The trend cluster diagram is obtained. The result shows that the ancient Chinese Ru porcelains were most probably from the same raw material source though they were from different time, fired in different kilns and in different colors. The near provenance relation between ancient Jun porcelain and ancient Ru porcelain is preliminarily analyzed. The two modern Ru porcelains approximate to ancient Ru porcelains, one becomes estranged from ancient Ru porcelains. Jingdezhen porcelain is unconcerned with Ru porcelains

  5. Study of fluorine doped (Nb,Ir)O_2 solid solution electro-catalyst powders for proton exchange membrane based oxygen evolution reaction

    International Nuclear Information System (INIS)

    Kadakia, Karan Sandeep; Jampani, Prashanth H.; Velikokhatnyi, Oleg I.; Datta, Moni Kanchan; Patel, Prasad; Chung, Sung Jae; Park, Sung Kyoo; Poston, James A.; Manivannan, Ayyakkannu; Kumta, Prashant N.

    2016-01-01

    Graphical abstract: High surface area (∼300 m"2/g) nanostructured powders of nominal composition (Nb_1_−_xIr_x)O_2 and (Nb_1_−_xIr_x)O_2:10F have been synthesized and tested as oxygen evolution electro-catalysts for PEM based water electrolysis using a simple two-step chemical synthesis procedure. Superior electrochemical activity was demonstrated by fluorine doped compositions of (Nb_1_−_xIr_x)O_2 with an optimal composition (Nb_0_._7_5Ir_0_._2_5)O_2:10F (x = 0.25) demonstrating on-par performance with commercial hydrated IrO_2 and nanostructured in-house chemically synthesized IrO_2. Using first principles calculations, the electronic structure modification resulting in ∼75 at.% reduction (experimentally observed) in noble metal content without loss in catalytic performance and stability has been established. - Highlights: • (Nb_1_−_xIr_x)O_2:10F nanopowder electrocatalysts have been wet chemically synthesized. • (Nb_0_._7_5Ir_0_._2_5)O_2:10F exhibits superior electrochemical activity than pure IrO_2. • Stability of the (Nb,Ir)O_2:10F nanomaterials is comparable to pure (Nb,Ir)O_2. • High surface area F doped (Nb,Ir)O_2 are promising OER anode electro-catalysts. - Abstract: High surface area (∼300 m"2/g) nanostructured powders of (Nb_1_−_xIr_x)O_2 and (Nb_1_−_xIr_x)O_2:10F (∼100 m"2/g) have been examined as promising oxygen evolution reaction (OER) electro-catalysts for proton exchange membrane (PEM) based water electrolysis. Nb_2O_5 and 10 wt.% F doped Nb_2O_5 powders were prepared by a low temperature sol-gel process which were then converted to solid solution (Nb,Ir)O_2 and 10 wt.% F doped (Nb,Ir)O_2 [(NbIr)O_2:10F] electro-catalysts by soaking in IrCl_4 followed by heat treatment in air. Electro-catalyst powders of optimal composition (Nb_0_._7_5Ir_0_._2_5)O_2:10F with ∼75 at.% reduction in noble metal content exhibited comparable OER activity to commercial hydrated IrO_2 and nanostructured in-house chemically synthesized IrO_2

  6. Study of fluorine doped (Nb,Ir)O{sub 2} solid solution electro-catalyst powders for proton exchange membrane based oxygen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Kadakia, Karan Sandeep [Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Jampani, Prashanth H., E-mail: pjampani@pitt.edu [Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Velikokhatnyi, Oleg I.; Datta, Moni Kanchan [Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Center for Complex Engineered Multifunctional Materials, University of Pittsburgh, PA 15261 (United States); Patel, Prasad [Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Chung, Sung Jae [Mechanical Engineering and Materials Science, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Park, Sung Kyoo [Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Poston, James A.; Manivannan, Ayyakkannu [US Department of Energy, National Energy Technology Laboratory, Morgantown, WV 26507 (United States); Kumta, Prashant N. [Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Center for Complex Engineered Multifunctional Materials, University of Pittsburgh, PA 15261 (United States); Mechanical Engineering and Materials Science, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Department of Oral Biology, School of Dental Medicine, University of Pittsburgh, PA 15217 (United States)

    2016-10-15

    Graphical abstract: High surface area (∼300 m{sup 2}/g) nanostructured powders of nominal composition (Nb{sub 1−x}Ir{sub x})O{sub 2} and (Nb{sub 1−x}Ir{sub x})O{sub 2}:10F have been synthesized and tested as oxygen evolution electro-catalysts for PEM based water electrolysis using a simple two-step chemical synthesis procedure. Superior electrochemical activity was demonstrated by fluorine doped compositions of (Nb{sub 1−x}Ir{sub x})O{sub 2} with an optimal composition (Nb{sub 0.75}Ir{sub 0.25})O{sub 2}:10F (x = 0.25) demonstrating on-par performance with commercial hydrated IrO{sub 2} and nanostructured in-house chemically synthesized IrO{sub 2}. Using first principles calculations, the electronic structure modification resulting in ∼75 at.% reduction (experimentally observed) in noble metal content without loss in catalytic performance and stability has been established. - Highlights: • (Nb{sub 1−x}Ir{sub x})O{sub 2}:10F nanopowder electrocatalysts have been wet chemically synthesized. • (Nb{sub 0.75}Ir{sub 0.25})O{sub 2}:10F exhibits superior electrochemical activity than pure IrO{sub 2}. • Stability of the (Nb,Ir)O{sub 2}:10F nanomaterials is comparable to pure (Nb,Ir)O{sub 2}. • High surface area F doped (Nb,Ir)O{sub 2} are promising OER anode electro-catalysts. - Abstract: High surface area (∼300 m{sup 2}/g) nanostructured powders of (Nb{sub 1−x}Ir{sub x})O{sub 2} and (Nb{sub 1−x}Ir{sub x})O{sub 2}:10F (∼100 m{sup 2}/g) have been examined as promising oxygen evolution reaction (OER) electro-catalysts for proton exchange membrane (PEM) based water electrolysis. Nb{sub 2}O{sub 5} and 10 wt.% F doped Nb{sub 2}O{sub 5} powders were prepared by a low temperature sol-gel process which were then converted to solid solution (Nb,Ir)O{sub 2} and 10 wt.% F doped (Nb,Ir)O{sub 2} [(NbIr)O{sub 2}:10F] electro-catalysts by soaking in IrCl{sub 4} followed by heat treatment in air. Electro-catalyst powders of optimal composition (Nb{sub 0.75}Ir

  7. Nanostructured Electrocatalysts for All-Vanadium Redox Flow Batteries.

    Science.gov (United States)

    Park, Minjoon; Ryu, Jaechan; Cho, Jaephil

    2015-10-01

    Vanadium redox reactions have been considered as a key factor affecting the energy efficiency of the all-vanadium redox flow batteries (VRFBs). This redox reaction determines the reaction kinetics of whole cells. However, poor kinetic reversibility and catalytic activity towards the V(2+)/V(3+) and VO(2+)/VO2(+) redox couples on the commonly used carbon substrate limit broader applications of VRFBs. Consequently, modified carbon substrates have been extensively investigated to improve vanadium redox reactions. In this Focus Review, recent progress on metal- and carbon-based nanomaterials as an electrocatalyst for VRFBs is discussed in detail, without the intention to provide a comprehensive review on the whole components of the system. Instead, the focus is mainly placed on the redox chemistry of vanadium ions at a surface of various metals, different dimensional carbons, nitrogen-doped carbon nanostructures, and metal-carbon composites. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Magnetic interactions in praseodymium ruthenate Pr{sub 3}RuO{sub 7} with fluorite-related structure

    Energy Technology Data Exchange (ETDEWEB)

    Inabayashi, Masaki; Doi, Yoshihiro; Wakeshima, Makoto; Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.jp

    2017-06-15

    . Significant spin polarization is seen on the magnetic Pr and Ru ions, but there is also some on the O(1), (3) ligands of Ru. - Highlights: • New fluorite-related quaternary praseodymium ruthenates were prepared. • Pr{sub 3}RuO{sub 7} shows an antiferromagnetic transition at 55 K. • The Ru-O-Pr superexchange interactions are three-dimensional.

  9. High electrochemical performance of RuO_2–Fe_2O_3 nanoparticles embedded ordered mesoporous carbon as a supercapacitor electrode material

    International Nuclear Information System (INIS)

    Xiang, Dong; Yin, Longwei; Wang, Chenxiang; Zhang, Luyuan

    2016-01-01

    The electrode materials RuO_2 or RuO_2–Fe_2O_3 nanoparticle embedded OMC (ordered mesoporous carbon) are prepared by the method of impregnation and heating in situ. The mesoporous structure optimized the electron and proton conducting pathways, leading to the enhanced capacitive performances of the composite materials. The average nanoparticle size of RuO_2 and RuO_2–Fe_2O_3 is 2.54 and 1.96 nm, respectively. The fine RuO_2–Fe_2O_3 nanoparticles are dispersed evenly in the pore channel wall of the two-dimensional mesoporous carbon without blocking the mesoporous channel, and they have a higher specific surface area, a larger pore volume, a proper pore size and a small charge transfer impedance value. The special electrochemical capacitance of RuO_2–Fe_2O_3/OMC tested in acid electrolyte (H_2SO_4) is measured to be as high as 1668 F g"−"1, which is higher than that of RuO_2/OMC. Meanwhile, the supercapacitor properties of the RuO_2–Fe_2O_3/OMC composites show a good cycling performance of 93% capacitance retention (3000 cycles), a better reversibility, a higher energy density (134 Wh kg"−"1) and power density (4000 W kg"−"1). The composite electrode of RuO_2–Fe_2O_3/OMC, which combines a double layer capacitance with pseudo-capacitance, is proved to be suitable for ideal high performance electrode material of a hybrid supercapacitor application. - Highlights: • The nanocomposites of RuO_2–Fe_2O_3/OMC are prepared by impregnation and heating in situ. • The fine RuO_2–Fe_2O_3 nanoparticles distribute in the pore channel wall of OMC. • We discuss a reversible redox reaction mechanism of RuO_2–Fe_2O_3/OMC in acid solutions. • RuO_2–Fe_2O_3 nanoparticles embedded OMC shows a higher supercapacitive performance.

  10. Influence of the electronic structures on the heterogeneous photoelectrocatalytic performance of Ti/Ru{sub x}Sn{sub 1-x}O{sub 2} electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zhijie, E-mail: 1061739408@qq.com [College of Materials Science and Engineering, Fuzhou University, Fuzhou, Fujian 350108 (China); Zhu, Junqiu, E-mail: zhujunqiu@xmut.edu.com [School of Chemical Engineering and Materials Science, Quanzhou Normal University, Quanzhou, Fujian 362000 (China); Zhang, Shuai, E-mail: 601314274@qq.com [College of Materials Science and Engineering, Fuzhou University, Fuzhou, Fujian 350108 (China); Shao, Yanqun, E-mail: yqshao1989@163.com [College of Materials Science and Engineering, Fuzhou University, Fuzhou, Fujian 350108 (China); Lin, Deyuan, E-mail: lindeyuan_fj@126.com [Electric Power Research Institute of State Grid Fujian Electric Power Co. Ltd., Fuzhou 350007 (China); Zhou, Jianfeng, E-mail: 1277018923@qq.com [College of Materials Science and Engineering, Fuzhou University, Fuzhou, Fujian 350108 (China); Chen, Yunxiang, E-mail: rogerchen@163.com [Electric Power Research Institute of State Grid Fujian Electric Power Co. Ltd., Fuzhou 350007 (China); Tang, Dian, E-mail: diantang@fzu.edu.cn [College of Materials Science and Engineering, Fuzhou University, Fuzhou, Fujian 350108 (China)

    2017-07-05

    Highlights: • Ti/Ru{sub x}Sn{sub 1-x}O{sub 2} electrodes possessed photocatalytic and electrocatalytic activity were prepared by thermal decomposition method. • The effect of electronic structure on electronic conductivity, electrocatalytic and photocatalytic activity were studied. • The photoelectric-synergistic catalytic activity of the Ti/Ru{sub x}Sn{sub 1-x}O{sub 2} electrodes was studied upon UV irradiation. • The Ti/Ru{sub 0.05}Sn{sub 0.95}O{sub 2} electrode has good catalytic activity and excellent stability. - Abstract: DSA-type Ti/Ru{sub x}Sn{sub 1-x}O{sub 2} electrodes were prepared by thermal decomposition method as photoelectrocatalysts (PECs) and extensively characterized by various sophisticated techniques. First-principles calculations was employed to study the effects of Ru content on the electronic structures of the Ru{sub x}Sn{sub 1-x}O{sub 2} coatings. The photoelectric-synergistic catalytic activity of the Ti/Ru{sub x}Sn{sub 1-x}O{sub 2} electrodes was evaluated for the degradation of methyl orange (MO) in aqueous solution. The results show that the RuO{sub 2}−SnO{sub 2} solid solution could be formed. The band gaps of the Ru{sub x}Sn{sub 1-x}O{sub 2} coatings gradually decreased and eventually turned into metallic conductivity with the increase of ruthenium content. As a PEC electrode, reducing band gap is helpful to improve electronic conductivity and the electrocatalytic activity, but not always advantageous to increase the photocatalytic activity. Because too narrow band gap will sacrifice the photogenerated charge carriers and thus reduce photocatalytic activity of the electrode. In our experiments, the rate constant of Ti/Ru{sub 0.05}Sn{sub 0.95}O{sub 2} electrode increased with increasing Ru content and exhibited the maximum rate for 5% Ru loading. The stability test showed the photoelectrocatalytic activity of the Ti/Ru{sub 0.05}Sn{sub 0.95}O{sub 2} electrode almost had no attenuation after 100 h photoelectrolysis, revealing

  11. Improved capacity and rate capability of Ru-doped and carbon-coated Li4Ti5O12 anode material

    International Nuclear Information System (INIS)

    Lin, Chih-Yuan; Jhan, Yi-Ruei; Duh, Jenq-Gong

    2011-01-01

    Highlights: → By using a simple one-step solid-state reactions method synthesizes Li 4 Ru 0.01 Ti 4.99 O 12 /C anode material. → Combining the Ru-doped and carbon-coated techniques to fabricate Li 4 Ru 0.01 Ti 4.99 O 12 /C effectively enhance the diffusion rate of Li + and significantly reduce surface electronic resistance of Li 4 Ti 5 O 12 . → Li 4 Ru 0.01 Ti 4.99 O 12 /C delivers 120 and 110 mAh g -1 at 5 and 10 C charge/discharge rate, respectively, after 100 charge/discharge cycles. - Abstract: Pure Li 4 Ti 5 O 12 , modified Li 4 Ti 5 O 12 /C, Li 4 Ru 0.01 Ti 4.99 O 12 and Li 4 Ru 0.01 Ti 4.99 O 12 /C were successfully prepared by a modified solid-state method and its electrochemical properties were investigated. From the XRD patterns, the added sugar or doped Ru did not affect the spinel structure. The results of electrochemical properties revealed that Li 4 Ru 0.01 Ti 4.99 O 12 /C showed 120 and 110 mAh/g at 5 and 10 C rate after 100 charge/discharge cycles. Li 4 Ru 0.01 Ti 4.99 O 12 /C exhibited the best rate capability and the highest capacity at 5 and 10 C charge/discharge rate owing to the increase of electronic conductivity and the reduction of interface resistance between particles of Li 4 Ti 5 O 12 .It is expected that the Li 4 Ru 0.01 Ti 4.99 O 12 /C will be a promising anode material to be used in high-rate lithium ion battery.

  12. Average resonance capture studies of 102Ru

    International Nuclear Information System (INIS)

    Shi, Z.R.; Casten, R.F.; Stachel, J.; Bruce, A.M.

    1984-01-01

    The 102 Ru nucleus has been investigated via the ARC technique which ensures a complete set of J/sup π/ = 0 + , 1 +- , 2 +- , 3 +- , 4 +- , and 5 + levels up to 2 MeV. The results are discussed in the framework of the IBA-1 with Consistent Q. The calculations show good agreement with the empirical data especially for the O 2 + state, suggesting that it can be described in terms of collective degrees of freedom

  13. Carbon supported Pd-Ni and Pd-Ru-Ni nanocatalysts for the alkaline direct ethanol fuel cell (DEFC)

    CSIR Research Space (South Africa)

    Mathe, MK

    2011-08-01

    Full Text Available Carbon supported Pd-Ni and Pd-Ru-Ni nanocatalysts were prepared by the chemical reduction method, using sodium borohydride and ethylene glycol mixture as the reducing agent. The catalytic activity towards ethanol electro-oxidation in alkaline medium...

  14. Carbon supported Pd-Sn and Pd-Ru-Sn nanocatalysts for ethanol electro-oxidation in alkaline medium

    CSIR Research Space (South Africa)

    Modibedi, RM

    2011-04-01

    Full Text Available Carbon supported Pd-Sn and Pd-Ru-Sn nanocatalysts were prepared by the chemical reduction method, using sodium borohydride and ethylene glycol mixture as the reducing agent. The catalytic activity towards ethanol electro-oxidation in alkaline medium...

  15. Highly Selective Hydrogenation of Levulinic Acid to γ-Valerolactone Over Ru/ZrO2 Catalysts

    NARCIS (Netherlands)

    Filiz, B.C.; Gnanakumar, E.S.; Martinez-Arias, A.; Gengler, R.; Rudolf, P.; Rothenberg, G.; Shiju, N.R.

    We studied the catalytic hydrogenation of levulinic acid over zirconia supported ruthenium catalysts. Four different Ru/ZrO2 catalysts were prepared by different pre-treatments and using different zirconium supports (ZrOx(OH)4−2x and ZrO2). Although the final compositions of the catalysts are the

  16. Highly Selective Hydrogenation of Levulinic Acid to gamma-Valerolactone Over Ru/ZrO2 Catalysts

    NARCIS (Netherlands)

    Filiz, Bilge Coskuner; Gnanakumar, Edwin S.; Martinez-Arias, Arturo; Gengler, Regis; Rudolf, Petra; Rothenberg, Gadi; Shiju, N. Raveendran

    We studied the catalytic hydrogenation of levulinic acid over zirconia supported ruthenium catalysts. Four different Ru/ZrO2 catalysts were prepared by different pre-treatments and using different zirconium supports (ZrOx(OH)(4-2x) and ZrO2). Although the final compositions of the catalysts are the

  17. Pulse electrodeposition of Pt and Pt–Ru methanol-oxidation nanocatalysts onto carbon nanotubes in citric acid aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Huei-Yu [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Hsieh, Chien-Kuo [Department of Materials Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan, ROC (China); Tsai, Ming-Chi; Wei, Yu-Hsuan; Yeh, Tsung-Kuang [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Tsai, Chuen-Horng, E-mail: tsai@aec.gov.tw [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China)

    2015-06-01

    In this study, platinum nanoparticle/carbon nanotube (Pt NP/CNT) and platinum–ruthenium nanoparticle (Pt–Ru NP/CNT) hybrid nanocatalysts were prepared by the pulse-electrodeposition method in different aqueous solutions containing citric acid (CA) or sulfuric acid (SA). The electrocatalytic properties of the Pt NP/CNT and Pt–Ru NP/CNT electrodes prepared using different aqueous solutions were investigated for methanol oxidation. The results show that the electrochemical mass activities of these hybrid nanocatalysts prepared in the CA aqueous solution were increased by factors of 1.46 and 2.77 for Pt NPs and Pt–Ru NPs, respectively, compared with those prepared in SA aqueous solutions using the same procedure. These increased mass activities are attributed to the CA playing dual roles as both a stabilizing agent and a particle size reducing agent in the aqueous solutions. The approach developed in this work enables further reductions in the particle sizes of noble-metal nanocatalysts. - Highlights: • Pulse-electrodeposition of Pt or Pt–Ru nanoparticles on carbon nanotubes • Carbon nanotubes used as a catalyst-supporting material • Citric acid used as reducing agent in the aqueous electrodeposition solutions • Electrochemical activity for methanol oxidation improved by a factor of 1.46 to 2.77.

  18. Laser Spectroscopy of Ruthenium Containing Diatomic Molecules: RuH/D and RuP.

    Science.gov (United States)

    Adam, Allan G.; Konder, Ricarda M.; Nickerson, Nicole M.; Linton, Colan; Tokaryk, D. W.

    2015-06-01

    In the last few years, the Cheung group in Hong Kong and the Steimle group in Arizona have successfully studied several ruthenium containing diatomic molecules, RuX (X =C, O, N, B, using the laser-ablation molecular jet technique. Based on this success, the UNB spectroscopy group decided to try and find the optical signatures of other RuX molecules. Using CH_3OH and PH_3 as reactant gases, the RuH and RuP diatomic molecules have been detected in surveys of the 420 - 675 nm spectral region. RuD has also been made using fully deuterated methanol as a reactant. Dispersed fluorescence experiments have been performed to determine ground state vibrational frequencies and the presence of any low-lying electronic states. Rotationally resolved spectra for these molecules have also been taken and the analysis is proceeding. The most recent results will be presented. F. Wang et al., Journal of Chemical Physics 139, 174318 (2013). N. Wang et al., Journal of Physical Chemistry A 117, 13279 (2013). T. Steimle et al., Journal of Chemical Physics 119, 12965 (2003). N. Wang et al., Chemical Physics Letters 547, 21 (2012).

  19. Spectroscopy of {sup 96}Ru and {sup 98}Ru: structures of varied character at N {>=} 52

    Energy Technology Data Exchange (ETDEWEB)

    Reviol, W; Garg, U; Aprahamian, A; Davis, B F; Herr, M C; Naguleswaran, S; Walpe, J C; Ye, D [Notre Dame Univ., IN (United States); Ahmad, I; Carpenter, M P; Janssens, R V.F.; Khoo, T L; Lauritsen, T; Liang, Y [Argonne National Lab., IL (United States)

    1992-08-01

    The authors have investigated the onset of deformation at N {>=} 52 by performing high-spin gamma spectroscopy of {sup 96-98}Ru using the {sup 65}Cu({sup 36}S,pxn) reaction with the Argonne-Notre Dame {gamma}-ray facility. From the coincidence data associated with high multiplicity (k {>=} 8) events, they have established two main band structures in {sup 96-98}Ru which extend the previously-known level schemes significantly (up to > 20 {Dirac_h}). In {sup 96}Ru, one of the newly observed structures consists of five rotation-like E2 transitions and feeds into the known 9{sup (-)} state; the other structure bypasses the first one, and based on the observed level-spacings, is tentatively described as vibration-like. A rotational-like structure above a spin of 8 {Dirac_h}, along with a parallel vibration-like structure, has been observed in {sup 98}Ru as well. The data also contain some evidence for a weak sequence of dipole (presumably M1) transitions in {sup 96}Ru. This structure might be similar to the high-K oblate bands recently observed in {sup 119-123}I and {sup 198-20P}b. 9 refs., 3 figs.

  20. Enhanced Hydrogen Evolution Reactions on Nanostructured Cu{sub 2}ZnSnS{sub 4} (CZTS) Electrocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Digraskar, Renuka V.; Mulik, Balaji B. [Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, MH (India); Walke, Pravin S. [National Centre for Nanosciences and Nanotechnology, University of Mumbai, Mumbai 400098, MH (India); Ghule, Anil V. [Department of Chemistry, Shivaji University, Kolhapur, 416004, MH (India); Sathe, Bhaskar R., E-mail: bhaskarsathe@gmail.com [Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, MH (India)

    2017-08-01

    stability ( > 500 cycles) and lower charge transfer resistance. This sonochemically fabricated CZTSs nanoparticles are leading to significantly reduce cell cost and simplification of preparation process over existing high efficiency Pt and other nobel metal-free cathode electrocatalyst.

  1. Nitrogen-Doped Hollow Carbon Spheres with Embedded Co Nanoparticles as Active Non-Noble-Metal Electrocatalysts for the Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Ruohao Xing

    2018-02-01

    Full Text Available Transition metal (Fe, Co, Ni complexes on carbon nanomaterials are promising candidates as electrocatalysts towards the oxygen reduction reaction (ORR. In this paper, nitrogen-doped hollow carbon spheres with embedded Co nanoparticles were successfully prepared via a controllable synthesis strategy. The morphology characterization shows that the hollow carbon spheres possess an average diameter of ~150 nm with a narrow size distribution and a shell thickness of ~14.5 nm. The content of N doping ranges from 2.1 to 6.6 at.% depending on the calcination temperature from 900 to 1050 °C. Compared with commercial Pt/C, the Co-containing nitrogen-doped hollow carbon spheres prepared at 900 °C (CoNHCS-900 as an ORR electrocatalyst shows a half-wave potential shift of only ∆E1/2 = 55 mV, but a superior stability of about 90.2% maintenance after 20,000 s in the O2-saturated 0.1 M KOH at a rotating speed of 1600 rpm. This could be ascribed to the synergistic effects of N-containing moieties, Co-Nx species, and Co nanoparticles, which significantly increase the density of active sites and promote the charge transfer during the ORR process.

  2. Porous Co3O4 nanorods anchored on graphene nanosheets as an effective electrocatalysts for aprotic Li-O2 batteries

    Science.gov (United States)

    Yuan, Mengwei; Yang, Yan; Nan, Caiyun; Sun, Genban; Li, Huifeng; Ma, Shulan

    2018-06-01

    The large over-potential during the battery operation is a great obstacle for the application of Li-O2 batteries. The porous structure and electrical conductivity of the electrocatalysts are significant for the electrocatalytic performance of Li-O2 batteries. In this work, a porous Co3O4/GN nanocomposite (Co3O4 nanorods anchored on graphene nanosheets) is prepared via a facile hydrothermal method assisted with heat treatment. The unique structure of Co3O4/GN endows efficient electrocatalystic activity for Li-O2 batteries. In comparison to the Co3O4, the Co3O4/GN demonstrates a better cycle performance showing more than 40 cycles with a 1500 mAh g-1 capacity limit strategy at a current density of 300 mA g-1, and a reduced over-potential of 110 mV at high current density (1200 mA g-1). The Co3O4/GN also displays a high initial specific capacity (7600 mAh g-1) and a good reversibility in full cycle with a coulombic efficiency of 99.8% in the first cycle. The impressed cyclability, specific capacity, rate performance, and low over-potentials indicate that the as-prepared Co3O4/GN nanocomposite is a promising catalyst candidate for reversible Li-O2 batteries.

  3. Au-MnO{sub 2}/MWNT and Au-ZnO/MWNT as oxygen reduction reaction electrocatalyst for polymer electrolyte membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Imran Jafri, Razack; Sujatha, N.; Ramaprabhu, S. [Alternative Energy and Nanotechnology Laboratory (AENL), Nano Functional Materials Technology Centre (NFMTC), Department of Physics, Indian Institute of Technology Madras, Chennai (India); Rajalakshmi, N. [Center for Fuel Cell Technology (ARCI), Madavakkam, Chennai (India)

    2009-08-15

    Bi-functional catalysts based on Au supported on oxide based nanomaterials for use in fuel cells were evaluated by electrochemical methods for oxygen reduction reaction (ORR) in Polymer Electrolyte Membrane Fuel Cell (PEMFC). Metal oxide coated multi walled carbon nanotubes (MWNTs) (MnO{sub 2}/MWNT and ZnO/MWNT) were prepared by reduction of potassium permanganate and oxidation of Zn powder on MWNT surface respectively. Au-MnO{sub 2}/MWNT and Au-ZnO/MWNT were prepared by chemical reduction of chloroauric acid on MnO{sub 2}/MWNT and ZnO/MWNT. The samples were characterized and linear sweep voltammetric studies were performed in N{sub 2} saturated, O{sub 2} saturated and methanol containing 1 M KOH solution and the results have been discussed. A single fuel cell was also constructed using Au-MnO{sub 2}/MWNT and Au-ZnO/MWNT as ORR electrocatalysts. A maximum power density of 45 mW/cm{sup 2} and 56 mW/cm{sup 2} was obtained with Au-MnO{sub 2}/MWNT and Au-ZnO/MWNT respectively. Additionally, the methanol tolerance of these electrocatalysts has been investigated and results have been discussed. (author)

  4. Substituent-directed structural and physicochemical controls of diruthenium catecholate complexes with ligand-unsupported Ru-Ru bonds.

    Science.gov (United States)

    Chang, Ho-Chol; Mochizuki, Katsunori; Kitagawa, Susumu

    2005-05-30

    A family of diruthenium complexes with ligand-unsupported Ru-Ru bonds has been systematically synthesized, and their crystal structures and physical properties have been examined. A simple, useful reaction between Ru2(OAc)4Cl (OAc- = acetate) and catechol derivatives in the presence of bases afforded a variety of diruthenium complexes, generally formulated as [Na(n){Ru2(R4Cat)4}] (n = 2 or 3; R4 = -F4, -Cl4, -Br4, -H4, -3,5-di-t-Bu, and -3,6-di-t-Bu; Cat(2-) = catecholate). The most characteristic feature of the complexes is the formation of short ligand-unsupported Ru-Ru bonds (2.140-2.273 A). These comprehensive studies were carried out to evaluate the effects of the oxidation states and the substituents governing the molecular structures and physicochemical properties. The Ru-Ru bond distances, rotational conformations, and bending structures of the complexes were successfully varied. The results presented in this manuscript clearly demonstrate that the complexes with ligand-unsupported Ru-Ru bonds can sensitively respond to redox reactions and ligand substituents on the basis of the greater degree of freedom in their molecular structures.

  5. A new ion imprinted polymer based on Ru(III)-thiobarbituric acid complex for solid phase extraction of ruthenium(III) prior to its determination by ETAAS

    International Nuclear Information System (INIS)

    Zambrzycka, Elżbieta; Godlewska-Żyłkiewicz, Beata

    2014-01-01

    A new ruthenium ion imprinted polymer was prepared from the Ru(III) 2-thiobarbituric acid complex (the template), methacrylic acid or acrylamide (the functional monomers), and ethylene glycol dimethacrylate (the cross-linking agent) using 2,2′-azobisisobutyronitrile as the radical initiator. The ion imprinted polymer was characterized and used as a selective sorbent for the solid phase extraction of Ru(III) ions. The effects of type of functional monomer, sample volume, solution pH and flow rate on the extraction efficiency were studied in the dynamic mode. Ru(III) ion was quantitatively retained on the sorbents in the pH range from 3.5 to 10, and can be eluted with 4 mol L−1 aqueous ammonia. The affinity of Ru(III) for the ion imprinted polymer based on the acrylamide monomer is weaker than that for the polymer based on the methacrylic acid monomer, which therefore was used in interference studies and in analytical applications. Following extraction of Ru(III) ions with the imprint and their subsequent elution from the polymer with aqueous ammonia, Ru(III) was detected by electrothermal atomic absorption spectrometry with a detection limit of 0.21 ng mL −1 . The method was successfully applied to the determination of trace amounts of Ru(III) in water, waste, road dust and platinum ore (CRM SARM 76) with a reproducibility (expressed as RSD) below 6.4 %. (author)

  6. Effect of Ni and noble metals (Ru, Pd and Pt) on performance of bifunctional MoP/SiO2 for hydroconversion of methyl laurate

    Science.gov (United States)

    Nie, Ziyang; Zhang, Zhena; Chen, Jixiang

    2017-10-01

    SiO2 supported bifunctional MoP catalysts modified with different metal promoters (Ni, Ru, Pd, Pt), where Mo/Ni and Mo/M(M = Ru, Pd and Pt) atomic ratios was respectively 10 and 40, were prepared by TPR method from the phosphate precursors. It was found that the introduction of metal promoters facilitated the reduction of phosphate precursor and enhanced the dispersion of MoP. However, the MoP catalyst acidity was scarcely influenced by the small amount of metal promoters. In the hydroconversion of methyl laurate, the promoters enhanced the MoP catalyst activity for conversion of methyl laurate and hydrogenation of alkenes (intermediate), but reduced isomerization ability. Among the promoters, Ru was an optimum to decrease selectivity to alkenes while maintain high selectivity to iso-alkanes, and Mo40RuP showed better stability than MoP. At 380 °C and 3.0 MPa, the conversion of methyl laurate, the total selectivity to C11 and C12 hydrocarbons and the selectivity to iso-alkanes maintained at 100%, ∼94% and ∼30% on Mo40RuP during 102 h, respectively. The good stability of Mo40RuP is ascribed to that the presence of Ru prevented the sintering of MoP particles and suppressed carbon deposition.

  7. Investigation of amorphous RuMoC alloy films as a seedless diffusion barrier for Cu/p-SiOC:H ultralow-k dielectric integration

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Guohua [Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences, Shenzhen (China); The Chinese University of Hong Kong, Shatin, Hong Kong (China); Liu, Bo [Sichuan University, Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Chengdu (China); Li, Qiran [CNRS-Universite Paris Sud UMR 8622, Institut d' Electronique Fondamentale, Orsay (France)

    2015-08-15

    Ultrathin RuMoC amorphous films prepared by magnetron co-sputtering with Ru and MoC targets in a sandwiched scheme Si/p-SiOC:H/RuMoC/Cu were investigated as barrier in copper metallization. The evolution of final microstructure of RuMoC alloy films show sensitive correlation with the content of doped Mo and C elements and can be easily controlled by adjusting the sputtering power of the MoC target. There was no signal of interdiffusion between the Cu and SiOC:H layer in the sample of Cu/RuMoC/p-SiOC:H/Si, even annealing up to 500 C. Very weak signal of oxygen have been confirmed in the RuMoC barrier layer both as-deposited and after being annealed, and a good performance on preventing oxygen diffusion has been proved. Leakage current and resistivity evaluations also reveal the excellent thermal reliability of this Si/p-SiOC:H/RuMoC/Cu film stack at the temperatures up to 500 C, indicating its potential application in the advanced barrierless Cu metallization. (orig.)

  8. Fabrication of iron-doped cobalt oxide nanocomposite films by electrodeposition and application as electrocatalyst for oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jingxuan; Wang, Xuemei; Qin, Dongdong; Xue, Zhonghua; Lu, Xiaoquan, E-mail: luxq@nwnu.edu.cn

    2014-11-30

    Highlights: • We fabricated the Fe-doped Co{sub 3}O{sub 4} nanofilms for the first time by potentiostatic electrodeposition method. • The Fe was doped homogeneously in the nanofilms by this method. • Among the different concentration ratios of Co{sup 2+}/Fe{sup 2+}, nanofilm with the ratio of 1:5 exhibits the optimal performance in electrochemical properties assessments. • The Fe-doped Co{sub 3}O{sub 4} nanofilms in this work exhibit good electrocatalytic activity toward oxygen reduction and appear to be promising cathodic electrocatalyst in alkaline fuel cells. - Abstract: In this work, Fe-doped Co{sub 3}O{sub 4} nanofilms were fabricated by electrodeposition on FTO glass substrates for the first time. The structures of the as-prepared nanofilms were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Characterization results demonstrate that Fe was doped homogeneously in the nanofilms. As the different concentration ratios of Fe{sup 2+}/Co{sup 2+} were explored, nanofilm with the ratio of 1:5 exhibits the optimal performance in electrochemical properties assessments. It is considered that the difference in the catalytic activities for the ORR of the samples may be due to the fact that the joining of iron changed the catalyst surface's electric state and enhanced the acidity of cobalt centers, on the other hand, the doping process probably modified the absorption property of the nanofilms. The experimental results suggest that the Fe-doped Co{sub 3}O{sub 4} nanofilms in this work exhibit favorable electrocatalytic activity toward ORR and appear to be promising cathodic electrocatalyst in alkaline fuel cells.

  9. Sideward flow of K+ in Ru+Ru and Ni+Ni reactions sat SIS energies

    International Nuclear Information System (INIS)

    Crochet, P.; Herrmann, N.; Wisniewski, K.

    2000-01-01

    Experimental data on K + and proton sideward flow measured with the FOPI detector at SIS/GSI in the reactions Ru+Ru at 1.69 A GeV and Ni+Ni at 1.93 A GeV are presented. The K + sideward flow is found to be anti-correlated (correlated) with the one of protons at low (high) transverse momenta. When compared to the predictions of a transport model, the data favour the existence of an in-medium repulsive K + -nucleon potential. (author)

  10. Electron correlation in CaRuO3 and SrRuO3

    International Nuclear Information System (INIS)

    Singh, Ravi Shankar; Maiti, Kalobaran

    2005-01-01

    We investigate the role of electron correlation in the electronic structure of 4d transition-metal oxides CaRuO 3 and SrRuO 3 . The photoemission spectra collected at different surface sensitivities reveal qualitatively different surface and bulk electronic structures in these systems. Extracted bulk spectra could be simulated using first principle approaches consistently with their thermodynamic parameters within the same model. The estimated electron correlation strength (U/W ∼ 0.2) is significantly weak as expected in 4d systems and resolves the long-standing issue that arose due to the prediction of large U/W similar to 3d systems. (author)

  11. Evaluation of the different supported bifunctional electrocatalysts for unified regenerative cells; Evaluacion de diferentes soportes de electrocatalizadores bifuncionales para celdas regenerativas unificadas

    Energy Technology Data Exchange (ETDEWEB)

    Gurrola, M. P.; Torres-Amaya, D. S.; Duron-Torres, S. M.; Escalante-Garcia, I. L. [Universidad Autonoma de Zacatecas, Unidad Academica de Ciencias Quimicas, Zacatecas (Mexico)]. E-mail: duronsm@prodigy.net.mx; Arriaga-Hurtado, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo, Queretaro (Mexico)

    2009-09-15

    Unified regenerative fuel cells (URFC) represent an alternative to normal regenerative cells, providing decreased costs and space in one single device. The challenges of these systems are even greater than those for conventional fuel cells, with the most pressing technical problem being the optimization of the oxygen electrode. The high operating potentials of these devices in the electrolyzer mode, E >1.6 V vs. ENH, limit the use of supported Pt/Vulcan electrodes. The electroactivity of Pt is not sufficient to catalyze the oxygen evolution reaction (OER) and at these potentials carbon-based supports undergo corrosion. In addition to studies of materials that function as bifunctional catalysts, a significant amount of research is being aimed at the search of new matrixes for use in supporting electrocatalysts for OER and ORR{sup 1,2}. This work presents the preliminary results of the kinetic study of oxygen reactions on different Pt combinations, with IrO{sub 2} and RuO{sub 2} supported by different forms of carbon and substoichiometric titanium oxide. The studies were conducted using cyclical (CV) and linear (LV) voltamperometry for OER and rotary disc electrode (RDE) for the ORR in watery H{sub 2}SO{sub 4} 0.5M solutions. The chronoamperometry (CA) technique provided information about the electrochemical stability of the electrodes. The results indicate that the performance of the electrodes supported by different forms of carbon decreases gradually as a result of corrosion when consecutive cycles of oxygen reduction and formation reactions occur. Titanium oxide provides the greatest stability to electrodes constructed on that material and thus can potentially support oxygen electrodes based on combinations of Pt, IrO{sub 2} and RuO{sub 2} as binfunctional electrocatalysts for the URFC. [Spanish] Las celdas de combustible regenerativas unificadas (URFC) representan una alternativa a las celdas regenerativas normales que implica disminucion de costos y espacio en

  12. Half-Sandwich Ru(II and Os(II Bathophenanthroline Complexes Containing a Releasable Dichloroacetato Ligand

    Directory of Open Access Journals (Sweden)

    Pavel Štarha

    2018-02-01

    Full Text Available We report on the preparation and thorough characterization of cytotoxic half-sandwich complexes [Ru(η6-pcym(bphen(dca]PF6 (Ru-dca and [Os(η6-pcym(bphen(dca]PF6 (Os-dca containing dichloroacetate(1– (dca as the releasable O-donor ligand bearing its own cytotoxicity; pcym = 1-methyl-4-(propan-2-ylbenzene (p-cymene, bphen = 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline. Complexes Ru-dca and Os-dca hydrolyzed in the water-containing media, which led to the dca ligand release (supported by 1H NMR and electrospray ionization mass spectra. Mass spectrometry studies revealed that complexes Ru-dca and Os-dca do not interact covalently with the model proteins cytochrome c and lysozyme. Both complexes exhibited slightly higher in vitro cytotoxicity (IC50 = 3.5 μM for Ru-dca, and 2.6 μM for Os-dca against the A2780 human ovarian carcinoma cells than cisplatin (IC50 = 5.9 μM, while their toxicity on the healthy human hepatocytes was found to be IC50 = 19.1 μM for Ru-dca and IC50 = 19.7 μM for Os-dca. Despite comparable cytotoxicity of complexes Ru-dca and Os-dca, both the complexes modified the cell cycle, mitochondrial membrane potential, and mitochondrial cytochrome c release by a different way, as revealed by flow cytometry experiments. The obtained results point out the different mechanisms of action between the complexes.

  13. Study of the oxygen reduction reaction using Pt-Rare earths (La, Ce, Er) electrocatalysts for application of PEM fuel cells; Estudo da reacao de reducao do oxigenio utilizando eletrocatalisadores a base de Pt-terras raras (La, Ce, Er) para aplicacao em celulas a combustivel tipo PEM

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Thiago Bueno

    2013-07-01

    The complexity of the oxygen reduction reaction (ORR) and its potential losses make it responsible for the most part of efficiency losses at the Fuel Cells. For this reaction the electrocatalyst witch is most appropriated and shows better performance is platinum, a noble metal that elevates the cost, raising barriers for Fuel Cells technology to enter the market. First this work focuses on reducing the amount of platinum used in the cathode, by being replaced by rare earths. The most common methods of synthesis involves a large amount of steps and this work proposed to prepare the electrocatalyst through a simpler way that would not take so many steps and time to be done. Using an ultrasound mixer the electrocatalyst was prepared mixing platinum supported on carbon black and the rare earths lanthanum, cerium and erbium oxides to be applied in a half-cell study of the ORR. The Koutecky-Levich plots shows that among the electrocatalysts prepared the Pt80Ce20/C had the catalytic activity close to the commercial BASF platinum on carbon black, suggesting that the reaction was taken by the 4-electron path. As found in some works in literature, among the rare earth used to study the ORR, cerium is the one witch shows the better performance because it is able to store and provide oxygen. This feature is of great interest for the ORR because this reaction is first order to the oxygen concentration. Results show that is possible to reduce the amount of platinum maintaining the same electrocatalyst activity. (author)

  14. Incorporation of Pt, Ru and Pt-Ru nanoparticles into ordered mesoporous carbons for efficient oxygen reduction reaction in alkaline media

    International Nuclear Information System (INIS)

    Stojmenović, Marija; Momčilović, Milan; Gavrilov, Nemanja; Pašti, Igor A.; Mentus, Slavko; Jokić, Bojan; Babić, Biljana

    2015-01-01

    Ordered mesoporous carbon, volume-doped up to 3 w.% with Pt, Ru and Pt-Ru nanoparticles was synthesized by evaporation-induced self-assembly method, under acidic conditions. The content of incorporated metal was determined by EDX analysis. The X-ray diffractometry confirmed the existence of highly dispersed metallic phases in doped samples. Specific surface area was determined by N 2 -physisorption measurements to range between 452 and 545 m 2 g −1 . Raman spectroscopy of investigated materials indicated highly disordered carbon structure with crystallite sizes around 1.4 nm. In a form of thin-layer electrode on glassy carbon support, in 0.1 M KOH solution, the prepared materials displayed high activity toward oxygen reduction reaction (ORR) in alkaline media, with onset potentials more positive than −0.10 V vs. SCE. The kinetics of O 2 reduction was found to be affected by both the specific surface area and the concentration of metal dopants. The ethanol tolerance of (Pt, Ru)-doped OMCs was found to be higher than that of common Pt/C ORR catalysts. Presented study provides a new route for the synthesis of active and selective ORR catalysts in alkaline media, being competitive with, or superior to, the existing ones in terms of performance and price

  15. Hydrothermal synthesis of Fe_2O_3/polypyrrole/graphene oxide composites as highly efficient electrocatalysts for oxygen reduction reaction in alkaline electrolyte

    International Nuclear Information System (INIS)

    Ren, Suzhen; Ma, Shaobo; Yang, Ying; Mao, Qing; Hao, Ce

    2015-01-01

    Graphical abstract: Fe_2O_3/polypyrrole/graphene oxide electrocatalysts for oxygen reduction reaction (ORR) are successfully prepared through one simple polypyrrole-assisted hydrothermal method and possess very high ORR activity and are able to selectively reduce O_2 to water through the four-electron transfer reaction mechanism in alkaline electrolyte. - Abstract: Advantages in low cost, and excellent catalytic activity of Fe-based nanomaterials dispersed on nitrogen-doped graphene supports render them to be good electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells. Here, Fe_2O_3/polypyrrole/graphene oxide (Fe_2O_3/Ppy/GO) composites with the Fe_2O_3 embedded in the Ppy modified GO are synthesized using hydrothermal method. With an optimal iron atom content ratio of 1.6% in graphene oxide and heat treatment at 800 °C, the Fe_2O_3/Ppy/GO exhibited enhanced catalytic performance for ORR with the onset potential of −0.1 V (vs SCE), cathodic potential of −0.24 V (vs SCE), an approximate 4e"− transfer process in O_2-saturated 0.1 M KOH, and superior stability that only reduced 5% catalytic activity after 5000 cycles. The decisive factors in improving the electrocatalytic and durable performance are the intimate and large contact interfaces between nanocrystallines of Fe_2O_3 and Ppy/GO, in addition to the high electron withdrawing/storing ability and the high conductivity of GO doped with nitrogen from Ppy during the hydrothermal reaction. The Fe_2O_3/Ppy/GO showed significantly improved ORR properties and confirmed that Fe-N-C-based electrocatalysts played a key role in fuel cells.

  16. Development of Fe-Ni/YSZ-GDC electrocatalysts for application as SOFC anodes: XRD and TPR characterization and evaluation in the ethanol steam reforming reaction

    Energy Technology Data Exchange (ETDEWEB)

    da Paz Fiuza, Raigenis; Aurelio da Silva, Marcos; Boaventura, Jaime Soares [Energy and Materials Science Group - GECIM, Institute of Chemistry, Physical Chemistry Department, Universidade Federal da Bahia, 41170290 Salvador, Bahia (Brazil)

    2010-10-15

    Electrocatalysts based on Fe-Ni alloys were prepared by means of modified Pechini and physical mixture methods and using on a composite of Yttria Stabilized Zirconia (YSZ) and Gadolinia-Doped Ceria (GDC) as support. The former method was based on the formation a polymeric precursor that was subsequently calcined; the later method was based on the mixture of NiO and the support. The resulting composites had 35 wt.% metal load and 65 wt.% support (70 wt.% YSZ and 30 wt.% GDC mixture) (cermets). The samples were then characterized by Temperature-Programmed Reduction (TPR) and X-Ray Diffraction (XRD) and evaluated in the ethanol steam reforming at 650 C for 6 h in the temperature range of 300-900 C. The XRD results showed that the bimetallic sample calcined at 800 C formed a mixed oxide (NiFe{sub 2}O{sub 4}) with a spinel structure, which, after reduction in hydrogen, formed Ni-Fe alloys. The presence of Ni was observed to decrease the final reduction temperature of the NiFe{sub 2}O{sub 4} species. The addition of iron to the nickel anchored to YSZ-GDC increased the hydrogen production and inhibited carbon deposition. The resulting bimetallic 30Fe5Ni sample reached an ethanol conversion of about 95% and a hydrogen yield up to 48% at 750 C. In general, ethanol conversion and hydrogen production were independent of the metal content in the electrocatalyst. However, the substitution of nickel for iron significantly reduced carbon deposition on the electrocatalyst: 74, 31, and 9 wt.% in the 35Ni, 20Fe15Ni, and 30Fe5Ni samples, respectively. (author)

  17. Gamma-gamma angular correlation measurement in the 100 Ru

    International Nuclear Information System (INIS)

    Kenchian, G.

    1990-01-01

    An angular correlation automatic spectrometer with two Ge(Li) detectors has been developed. The spectrometer moves automatically, controlled by a microcomputer. The gamma-gamma directional angular correlations of coincidence transitions have been measured in 100 Ru nuclide, following the β + and electron capture of 100 Rh. The 100 Rh source has been produced with 100 Ru(p,n) 100 Rh reaction, using the proton beam of the Cyclotron Accelerator insiding in 100 Ru isotope. (author)

  18. Enhanced anodic Ru(bpy)32+ electrogenerated chemiluminescence by polyphenols

    International Nuclear Information System (INIS)

    Lei Rong; Xu Xiao; Xu Da; Zhu Gang; Li Na; Liu Huwei; Li Kean

    2008-01-01

    Anodic Ru(bpy) 3 2+ electrogenerated chemiluminescence (ECL) can be enhanced by polyphenols in alkaline solution. Spin trapping-electron spin resonance (ESR) experiments verified that reactive oxygen species (ROS) were generated during the electrolysis of Ru(bpy) 3 2+ in alkaline solution, and oxidation of quercetin enhanced Ru(bpy) 3 2+ ECL at anodic potential by producing additional ROS. This ECL enhancement can be used to analyze real sample and evaluate antioxidant activity of polyphenols

  19. Several novel Ru(II) and Ru(III) complexes formed by reduction of (RuO4bipy) and (RuO3phen)2O with hydroquinone and methanol

    International Nuclear Information System (INIS)

    Ishiyama, Toshio

    1975-01-01

    The geometrical isomers, cis-dichloro-trans-(methanol)(hydroquinone)(2,2'-bipyridine)ruthenium(II) and cis-dichloro-cis-(methanol)(hydroquinone)(2,2'-bipyridine)ruthenium(II), [RuCl 2 (MeOH)(QH 2 )bipy] (complex I and II), were synthesized by reduction and substitution reactions of [RuO 4 bipy] and [RuO 2 (OH) 2 bipy] with hydroquinone in hydrochloric acid solution, and methanol. cis-Chloro(hydroquinonato)bis(2,2'-bipyridine)ruthenium(II), cis-[RuCl(QH)(bipy) 2 ], was obtained from the substitution reaction of complex I or II with 2,2'-bipyridine in methanol, and cis-chloro(hydroquinone)bis(2,2'-bipyridine)ruthenium(II) chloride, cis-[RuCl(QH 2 )(bipy) 2 ]Cl, was also obtained from the substitution of cis-trans-[RuCl 2 (MeOH)(QH 2 )bipy] in methanol containing hydrochloric acid. cis-Dihydroxobis(2,2'-bipyridine)ruthenium(II), cis-[Ru(OH) 2 (bipy) 2 ], was obtained by heating an aqueous solution of cis-[RuCl(QH)(bipy) 2 ]. Trihydroxoaquo(1,10-phenanthroline)ruthenium(III), [Ru(OH) 3 (H 2 O)phen] was also synthesized from [RuO 3 phen] 2 O and [Ru(OH) 3 phen] 2 O by reduction reactions similar to those used for [RuCl 2 (MeOH)(QH 2 )bipy]. These complexes were characterized by the infrared, visible and ultraviolet absorption spectra, and also by polarographic and magnetic measurements. The structures are discussed. (auth.)

  20. Dibenzothiophene hydrodesulfurization over Ru promoted alumina based catalysts using in situ generated hydrogen

    International Nuclear Information System (INIS)

    Muhammad, Yaseen; Lu Yingzhou; Shen Chong; Li Chunxi

    2011-01-01

    Catalytic hydrodesulfurization (HDS) of dibenzothiophene (DBT) was carried out in a temperature range of 320-400 o C using in situ generated hydrogen coupled with the effect of selected organic additives for the first time. Four kinds of alumina based catalysts i.e. Co-Mo/Al 2 O 3 , Ni-Mo/Al 2 O 3 , Ru-Co-Mo/Al 2 O 3 and Ru-Ni-Mo/Al 2 O 3 were used for the desulfurization process, which were prepared following incipient impregnation method with fixed metal loadings (wt.%) of Co, Ni, Mo and Ru. The surface area, average pore diameter and pore volume distribution of the fresh and used catalysts were measured by N 2 adsorption using BET method. Catalytic activity was investigated in a batch autoclave reactor in the complete absence of external hydrogen gas. Addition and mutual reaction of specific quantities of water and ethanol provided the necessary in situ hydrogen for the desulfurization reaction. Organic additives like diethylene glycol (DEG), phenol, naphthalene, anthracene, o-xylene, tetralin, decalin and pyridine did impinge the HDS activity of the catalysts in different ways. Liquid samples from reaction products were quantitatively analyzed by HPLC technique while qualitative analyses were made using GC-MS. Both of these techniques showed that Ni-based catalysts were more active than Co-based ones at all conditions. Moreover, incorporation of Ru to both Co and Ni-based catalysts greatly promoted desulfurization activity of these catalysts. DBT conversion of up to 84% was achieved with Ru-Ni-Mo/Al 2 O 3 catalyst at 380 o C temperature for 11 h. Catalyst systems followed the HDS activity order as: Ru-Ni-Mo/Al 2 O 3 > Ni-Mo/Al 2 O 3 > Ru-Co-Mo/Al 2 O 3 > Co-Mo/Al 2 O 3 at all conditions. Cost effectiveness, mild operating conditions and reasonably high catalytic activity using in situ generated hydrogen mechanism proved our process to be useful for HDS of DBT.

  1. Dibenzothiophene hydrodesulfurization over Ru promoted alumina based catalysts using in situ generated hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Muhammad, Yaseen; Shen, Chong; Li, Chunxi [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Lu, Yingzhou [College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2011-02-15

    Catalytic hydrodesulfurization (HDS) of dibenzothiophene (DBT) was carried out in a temperature range of 320-400 C using in situ generated hydrogen coupled with the effect of selected organic additives for the first time. Four kinds of alumina based catalysts i.e. Co-Mo/Al{sub 2}O{sub 3}, Ni-Mo/Al{sub 2}O{sub 3}, Ru-Co-Mo/Al{sub 2}O{sub 3} and Ru-Ni-Mo/Al{sub 2}O{sub 3} were used for the desulfurization process, which were prepared following incipient impregnation method with fixed metal loadings (wt.%) of Co, Ni, Mo and Ru. The surface area, average pore diameter and pore volume distribution of the fresh and used catalysts were measured by N{sub 2} adsorption using BET method. Catalytic activity was investigated in a batch autoclave reactor in the complete absence of external hydrogen gas. Addition and mutual reaction of specific quantities of water and ethanol provided the necessary in situ hydrogen for the desulfurization reaction. Organic additives like diethylene glycol (DEG), phenol, naphthalene, anthracene, o-xylene, tetralin, decalin and pyridine did impinge the HDS activity of the catalysts in different ways. Liquid samples from reaction products were quantitatively analyzed by HPLC technique while qualitative analyses were made using GC-MS. Both of these techniques showed that Ni-based catalysts were more active than Co-based ones at all conditions. Moreover, incorporation of Ru to both Co and Ni-based catalysts greatly promoted desulfurization activity of these catalysts. DBT conversion of up to 84% was achieved with Ru-Ni-Mo/Al{sub 2}O{sub 3} catalyst at 380 C temperature for 11 h. Catalyst systems followed the HDS activity order as: Ru-Ni-Mo/Al{sub 2}O{sub 3}> Ni-Mo/Al{sub 2}O{sub 3}> Ru-Co-Mo/Al{sub 2}O{sub 3}> Co-Mo/Al{sub 2}O{sub 3} at all conditions. Cost effectiveness, mild operating conditions and reasonably high catalytic activity using in situ generated hydrogen mechanism proved our process to be useful for HDS of DBT. (author)

  2. Incorporation of metals (Pt-Ni-Ru) in the zeolite ZSM-5 through ion exchange competitive: synthesis and characterization

    International Nuclear Information System (INIS)

    Barbosa, A.S.; Rodrigues, M.G.F.

    2012-01-01

    Zeolites are very important materials due to their high specific surface area. Moreover, they are suitable for use as catalyst support. Noble metals supported on zeolites have been widely used as catalysts in the petrochemical industry. This paper was prepared and characterized, a powder aiming its use in heterogeneous catalysis. Support was used as ZSM-5 and the method of incorporation of the metals (Ru-PtNi) was competitive ion exchange. The materials (ZSM-5 and Pt-Ni-Ru/ZSM-5) were characterized by spectrophotometry Energy Dispersive X-ray (EDX), X-Ray Diffraction (XRD) and nitrogen physisorption (BET method). Based on the results of X-ray diffraction, it is possible to demonstrate the preservation of the structure of zeolite ZSM-5 after the competitive ion Exchange with metals (Ru-Pt-Ni) and calcination. The dispersion of metals on ZSM-5 did not change the textural characteristics of the zeolite. (author)

  3. Synthesis of Ru nanoparticles confined in magnesium oxide-modified mesoporous alumina and their enhanced catalytic performance during ammonia decomposition

    KAUST Repository

    Tan, Hua

    2012-09-01

    In this work, Ru nanoparticles confined in the channels of ordered mesoporous alumina (MA) and magnesium oxide-modified ordered MA are prepared for the first time via a two-solvent technique, combined with the amorphous citrate route. Structural characterizations reveal that uniform 2-3 nm Ru nanoparticles are highly dispersed in the blockage-free channels of mesoporous supports. The Ru nanoparticles confined in MA modified with 20% molar ratio magnesium oxide exhibited a high catalytic activity and stability during ammonia decomposition due to the optimized particle size, basic support, lack of chlorine, and confined space provided by the channels of the mesoporous supports. © 2012 Elsevier B.V. All rights reserved.

  4. Synthesis of Nanocrystalline RuO2(60%)-SnO2(40%)Powders by Amorphous Citrate Route

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nanometer RuO2-SnO2was synthesized by the citrate-gel method using RuCl3, SnCl4 as cation sources, citric acid as complexing agent and anhydrous ethanol as solvent. The structures of the derived powders were characterized by thermogravimetric and differential thermal analysis, X-ray diffraction, transmission electron microscope, and Brunauer-Emmett-Teller surface area measurement. The pure, fine and amorphous powders was obtained at 160℃. The materials calcined at above 400 ℃ were composed of rutile-type oxide phases having particle sizes of fairly narrow distribution and good thermal resistant properties. By adding SnO2 to RUO2, the Ru metallic phase can be effectively controlled under a traditional temperature of preparation for dimensional stable anode.

  5. Synthesis of Ru nanoparticles confined in magnesium oxide-modified mesoporous alumina and their enhanced catalytic performance during ammonia decomposition

    KAUST Repository

    Tan, Hua; Li, Kun; Sioud, Salim; Cha, Dong Kyu; Amad, Maan H.; Hedhili, Mohamed N.; Al-Talla, Zeyad

    2012-01-01

    In this work, Ru nanoparticles confined in the channels of ordered mesoporous alumina (MA) and magnesium oxide-modified ordered MA are prepared for the first time via a two-solvent technique, combined with the amorphous citrate route. Structural characterizations reveal that uniform 2-3 nm Ru nanoparticles are highly dispersed in the blockage-free channels of mesoporous supports. The Ru nanoparticles confined in MA modified with 20% molar ratio magnesium oxide exhibited a high catalytic activity and stability during ammonia decomposition due to the optimized particle size, basic support, lack of chlorine, and confined space provided by the channels of the mesoporous supports. © 2012 Elsevier B.V. All rights reserved.

  6. Electrochemical investigation of surface area effects on PVD Al-Ni as electrocatalyst for alkaline water electrolysis

    DEFF Research Database (Denmark)

    Kjartansdóttir, Cecilía Kristín; Caspersen, Michael; Egelund, Sune Daaskov

    2014-01-01

    , additional 40mV are gained. For the OER, smaller roughness values were observed with the same activity trend as for the HER. The electrocatalyst are however found not to be stable in the anodic environment during electrolysis. The corrosion mechanism of a skeletal nickel electrocatalyst during the OER...

  7. Manganese dioxide-supported silver bismuthate as an efficient electrocatalyst for oxygen reduction reaction in zinc-oxygen batteries

    International Nuclear Information System (INIS)

    Sun, Yanzhi; Yang, Meng; Pan, Junqing; Wang, Pingyuan; Li, Wei; Wan, Pingyu

    2016-01-01

    In this paper, we present a new efficient composite electrocatalyst, manganese dioxide-supported silver bismuthate (Ag 4 Bi 2 O 5 /MnO 2 ), for oxygen reduction reaction (ORR) in alkaline media. The new electrocatalyst was characterized with scanning electron microscope (SEM), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Electrochemical measurements indicate that the Ag 4 Bi 2 O 5 /MnO 2 composite is a very efficient electrocatalyst for ORR in alkaline media. The physical and electrochemical characterization results suggest that the high activity is ascribed to the support effects from MnO 2 and the synergetic effects among Ag 4 Bi 2 O 5 and MnO 2 . The analysis of rotating disk electrode (RDE) results shows that the ORR occurs via a four-electron pathway on the surface of the Ag 4 Bi 2 O 5 /MnO 2 electrocatalyst. This electrocatalyst was further tested in a designed zinc–oxygen (Zn–O 2 ) battery. This battery can offer a discharge time of 225 h at 120 mA cm −2 , increasing by more than 492% as compared with pure MnO 2 electrocatalyst. It demonstrates that this inexpensive Ag 4 Bi 2 O 5 /MnO 2 electrocatalyst is a viable alternative to platinum electrocatalyst for energy conversion devices.

  8. Bifunctional electrodes with ir and Ru oxide mixtures and pt for unified regenerative cells; Electrodos bifuncionales basados en mezclas de oxidos de Ir y Ru con Pt para celdas regenerativas unificadas

    Energy Technology Data Exchange (ETDEWEB)

    Duron-Torres, S.M.; Escalante-Garcia, I.L. [Universidad Autonoma de Zacatecas, Zacatecas (Mexico); Cruz, J. C.; Arriaga-Hurtado; L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo, Queretaro (Mexico)]. E-mail: duronsm@prodigy.net.mx

    2009-09-15

    Unified regenerative fuel cells (URFC) represent an attractive option to obtain hydrogen and generate energy using a compact device. Nevertheless, the fusion of a fuel cell (PEMFC) and a water electrolyzer continue to be a challenge because of the wide range of conditions to which this type of device is subject. Because of its kinetic characteristics, oxygen reduction reaction (ORR) in PEMFC and oxygen evolution reaction (OER) in PEMWE are the limiting stages of the URFC depending on the mode of operation. The primary focus of research related to URFC is the obtainment of bifunctional electrocatalysts that satisfactorily perform in both oxygen reactions and support the different working conditions found in a fuel cell and an electrolyzer. The present work contributes to the research on bifunctional electrocatalysts and shows some preliminary results from the electrochemical study of different Pt gcc, IrO{sub 2} and RuO{sub 2} mixtures supported in Ebonex® as oxygen electrodes. The electrochemical characterization with cyclic voltamperometry (CV), linear voltamperometry (LV) and electrochemical impedance spectroscopy (EIS) in H{sub 2}SO{sub 4} 0.5 M, in the absence and present of oxygen shows that Ebonex®-supported bifunctional electrodes IrO{sub 2}-Pt and RuO{sub 2}-Pt present reasonable electrocatalytic properties for oxygen evolution and reduction reactions and present the possibility of their use in an URFC. The Ir- based oxide electrodes show greater stability than ruthenium-oxide electrodes. [Spanish] Las celdas de combustible regenerativas unificadas (URFC) representan una atractiva opcion para la obtencion de hidrogeno y generacion de energia en un dispositivo compacto. Sin embargo, la fusion de una celda de combustible (PEMFC) y un electrolizador de agua (PEMWE) sigue siendo un reto por la amplia gama de condiciones a que se sujeta un dispositivo de este tipo. Por sus caracteristicas cineticas, la reaccion de reduccion de oxigeno (ORR) en la PEMFC y la

  9. Selective Hydrogenation of m-Dinitrobenzene to m-Nitroaniline over Ru-SnOx/Al2O3 Catalyst

    Directory of Open Access Journals (Sweden)

    Haiyang Cheng

    2014-07-01

    Full Text Available Series catalysts of Ru-SnOx/Al2O3 with varying SnOx loading of 0–3 wt% were prepared, and their catalytic activity and selectivity have been discussed and compared for the selective hydrogenation of m-dinitrobenzene (m-DNB to m-nitroaniline (m-NAN. The Ru-SnOx/Al2O3 catalysts were characterized by X-ray powder diffraction (XRD, X-ray photoelectron spectroscopy (XPS, transmission electron microscopy (TEM and hydrogen temperature-programmed reduction (H2-TPR and desorption (H2-TPD. Under the modification of SnOx, the reaction activity increased obviously, and the best selectivity to m-NAN reached above 97% at the complete conversion of m-DNB. With the increasing of the SnOx loading, the amount of active hydrogen adsorption on the surface of the catalyst increased according to the H2-TPD analysis, and the electron transferred from Ru to SnOx species, as determined by XPS, inducing an electron-deficient Ru, which is a benefit for the absorption of the nitro group. Therefore, the reaction rate and product selectivity were greatly enhanced. Moreover, the Ru-SnOx/Al2O3 catalyst presented high stability: it could be recycled four times without any loss in activity and selectivity.

  10. Co-catalytic effect of Ni in the methanol electro-oxidation on Pt-Ru/C catalyst for direct methanol fuel cell

    International Nuclear Information System (INIS)

    Wang, Z.B.; Yin, G.P.; Zhang, J.; Sun, Y.C.; Shi, P.F.

    2006-01-01

    This research is aimed to improve the utilization and activity of anodic catalysts, thus to lower the contents of noble metals loading in anodes for methanol electro-oxidation. The direct methanol fuel cell anodic catalysts, Pt-Ru-Ni/C and Pt-Ru/C, were prepared by chemical reduction method. Their performances were tested by using a glassy carbon working electrode through cyclic voltammetric curves, chronoamperometric curves and half-cell measurement in a solution of 0.5 mol/L CH 3 OH and 0.5 mol/L H 2 SO 4 . The composition of the Pt-Ru-Ni and Pt-Ru surface particles were determined by EDAX analysis. The particle size and lattice parameter of the catalysts were determined by means of X-ray diffraction (XRD). XRD analysis showed that both of the catalysts exhibited face-centered cubic structures and had smaller lattice parameters than Pt-alone catalyst. Their sizes are small, about 4.5 nm. No significant differences in the methanol electro-oxidation on both electrodes were found by using cyclic voltammetry, especially regarding the onset potential for methanol electro-oxidation. The electrochemically active-specific areas of the Pt-Ru-Ni/C and Pt-Ru/C catalysts are almost the same. But, the catalytic activity of the Pt-Ru-Ni/C catalyst is higher for methanol electro-oxidation than that of the Pt-Ru/C catalyst. Its tolerance performance to CO formed as one of the intermediates of methanol electro-oxidation is better than that of the Pt-Ru/C catalyst

  11. 103Ru/103mRh generator

    International Nuclear Information System (INIS)

    Bartos, B.; Kowalska, E.; Bilewicz, A.; Skarnemark, G.

    2009-01-01

    103m Rh is a very promising radionuclide for Auger electron therapy due to its very low photon/electron ratio. The goal of the present work was the elaboration a method for production of large quantities of 103m Rh for generator system. It was found that the combination of solvent extraction with evaporation of 103 RuO 4 followed by decomposition of H 5 IO 6 makes it possible to produce 103m Rh of high radionuclidic and chemical purity. (author)

  12. Synergistic effects for the TiO2/RuO2/Pt photodissociation of water

    Energy Technology Data Exchange (ETDEWEB)

    Blondel, G; Harriman, A; Williams, D

    1983-07-01

    Compressed discs of naked TiO2 or TiO2 coated with a thin film of a noble metal (e.g. Pt) do not photodissociate water upon illumination with UV light, but small amounts of H2 are generated if the TiO2 has been reduced in a stream of H2 at 600 C. Discs prepared from mixtures of TiO2/RuO2 facilitate the UV photodissociation of water into H2 and O2 although the yields are very low. When a thin (about 9 nm) film of Pt is applied to the TiO2/RuO2 discs, the yields of H2 and O2 observed upon irradiation with UV light are improved drastically. 25 references.

  13. Promoted Ru on high-surface area graphite for efficient miniaturized production of hydrogen from ammonia

    DEFF Research Database (Denmark)

    Sørensen, Rasmus Zink; Klerke, Asbjørn; Quaade, Ulrich

    2006-01-01

    decomposition. The catalytic activities for production of hydrogen from ammonia are determined for different promoters and promoter levels on graphite supported ruthenium catalysts. The reactivity trends of the Ru/C catalysts promoted with Cs and Ba are in excellent agreement with those known from earlier......Promoted Ru/C catalysts for decomposition of ammonia are incorporated into micro-fabricated reactors for the first time. With the reported preparation technique, the performance is increased more than two orders of magnitude compared to previously known micro-fabricated reactors for ammonia...... studies of both ammonia synthesis and decomposition, and it is shown how proper promotion can facilitate ammonia decomposition at temperatures below 500 K....

  14. In situ Ru K-edge EXAFS of CO adsorption on a Ru modified Pt/C fuel cell catalyst

    International Nuclear Information System (INIS)

    Rose, Abigail; Bilsborrow, Robert; King, Colin R.; Ravikumar, M.K.; Qian Yangdong; Wiltshire, Richard J.K.; Crabb, Eleanor M.; Russell, Andrea E.

    2009-01-01

    The Ru-CO bond of CO adsorbed on a Ru modified Pt/C fuel cell catalyst has been directly probed by in situ EXAFS at the Ru K-edge, providing evidence of a CO:metal surface atom ratio greater than 1:1 and that CO is adsorbed at bridging sites associated with Ru atoms at the surface of the catalyst nanoparticles. This result illustrates the limitations of single crystal models as representations of the bonding of adsorbed species at nanoparticle surfaces.

  15. Electrochemical evaluation of electrocatalysts for fuel cell applications : a practical approach

    Energy Technology Data Exchange (ETDEWEB)

    Atwan, M.H. [General Motors R and D Technical Center, Warren, MI (United States); Gyenge, E.L. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemical and Biological Engineering; Northwood, D.O. [Windsor Univ., ON (Canada). Dept. of Mechanical, Automotive and Materials Engineering

    2010-07-01

    Various electrochemical techniques were used to investigate supported nano-size electrocatalysts during the oxidation of a specific fuel for fuel cell applications. Cyclic voltammetry (CV) on static and dynamic rotating disc electrodes (RDE) and fuel cell station tests demonstrated that the most active catalyst showed the most negative oxidation peak potential. A Tafel equation indicated that a low anodic/cathodic overpotential was a clear indication of higher catalytic activity. The lower overpotential was achieved for a specific current load by ensuring a low Tafel slope and as high an exchange current density as possible. The RDE and fuel cell station tests showed that the best performance was recorded for electrocatalysts with the Tafel slope values and exchange current densities that gave rise to the lowest overpotential. The study demonstrated that RDE and CV can be used to reliably assess electrocatalysts prior to full fuel cell testing. 52 refs., 3 tabs., 6 figs.

  16. Rational design of competitive electrocatalysts for the oxygen reduction reaction in hydrogen fuel cells

    Science.gov (United States)

    Stolbov, Sergey; Alcántara Ortigoza, Marisol

    2012-02-01

    The large-scale application of one of the most promising clean and renewable sources of energy, hydrogen fuel cells, still awaits efficient and cost-effective electrocatalysts for the oxygen reduction reaction (ORR) occurring on the cathode. We demonstrate that truly rational design renders electrocatalysts possessing both qualities. By unifying the knowledge on surface morphology, composition, electronic structure and reactivity, we solve that sandwich-like structures are an excellent choice for optimization. Their constituting species couple synergistically yielding reaction-environment stability, cost-effectiveness and tunable reactivity. This cooperative-action concept enabled us to predict two advantageous ORR electrocatalysts. Density functional theory calculations of the reaction free-energy diagrams confirm that these materials are more active toward ORR than the so far best Pt-based catalysts. Our designing concept advances also a general approach for engineering materials in heterogeneous catalysis.

  17. Phosphine-functionalized graphene oxide, a high-performance electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Ensafi, Ali A.; Golbon Haghighi, Mohsen; Jafari-Asl, Mehdi

    2018-01-01

    Here, a new approach for the synthesis of phosphine-functionalized graphene oxide (GO-PPh2) was developed. Using a simple method, diphenylphosphine group was linked to the hydroxyl group of OH-functionalized graphene that existing at the graphene surface. The electrochemical activity of GO-PPh2 for electrochemical oxygen reduction was checked. The results demonstrated that the new carbon hybrid material has a powerful potential for electrochemical oxygen reduction reaction (ORR). Moreover, GO-PPh2 as an electrocatalyst for ORR exhibited tolerance for methanol or ethanol as a result of crossover effect. In comparison with commercial Pt/C and Pt/rGO electrocatalysts, results showed that GO-PPh2 has a much higher selectivity, better durability, and much better electrochemical stability towards the ORR. The proposed method based on GO-PPh2 introduce an efficient electrocatalyst for further application in fuel cells.

  18. Seawater splitting for high-efficiency hydrogen evolution by alloyed PtNix electrocatalysts

    Science.gov (United States)

    Zheng, Jingjing

    2017-08-01

    Robust electrocatalyst is a prerequisite to realize high-efficiency hydrogen evolution by water splitting. Expensive platinum (Pt) is a preferred electrode catalyst for state-of-the-art hydrogen evolution reaction (HER). We present here a category of alloyed PtNix electrocatalysts by a facile green chemical reduction method, which are used to catalyze HER during seawater splitting. The catalytic performances are optimized by tuning stoichiometric Pt/Ni ratio, yielding a maximized catalytic behavior for PtNi5 electrode. The minimized onset potential is as low as -0.38 V and the corresponding Tafel slope is 119 mV dec-1. Moreover, the launched alloy electrodes have remarkable stability at -1.2 V over 12 h. The high efficiency as well as good durability demonstrates the PtNix electrocatalysts to be promising in practical applications.

  19. Platinum Monolayer Electrocatalysts for Anodic Oxidation of Alcohols.

    Science.gov (United States)

    Li, Meng; Liu, Ping; Adzic, Radoslav R

    2012-12-06

    The slow, incomplete oxidation of methanol and ethanol on platinum-based anodes as well as the high price and limited reserves of Pt has hampered the practical application of direct alcohol fuel cells. We describe the electrocatalysts consisting of one Pt monolayer (one atom thick layer) placed on extended or nanoparticle surfaces having the activity and selectivity for the oxidation of alcohol molecules that can be controlled with platinum-support interaction. The suitably expanded Pt monolayer (i.e., Pt/Au(111)) exhibits a factor of 7 activity increase in catalyzing methanol electrooxidation relative to Pt(111). Sizable enhancement is also observed for ethanol electrooxidation. Furthermore, a correlation between substrate-induced lateral strain in a Pt monolayer and its activity/selectivity is established and rationalized by experimental and theoretical studies. The knowledge we gained with single-crystal model catalysts was successfully applied in designing real nanocatalysts. These findings for alcohols are likely to be applicable for the oxidation of other classes of organic molecules.

  20. Highly efficient and durable TiN nanofiber electrocatalyst supports.

    Science.gov (United States)

    Kim, Hyun; Cho, Min Kyung; Kwon, Jeong An; Jeong, Yeon Hun; Lee, Kyung Jin; Kim, Na Young; Kim, Min Jung; Yoo, Sung Jong; Jang, Jong Hyun; Kim, Hyoung-Juhn; Nam, Suk Woo; Lim, Dong-Hee; Cho, EunAe; Lee, Kwan-Young; Kim, Jin Young

    2015-11-28

    To date, carbon-based materials including various carbon nanostructured materials have been extensively used as an electrocatalyst support for proton exchange membrane fuel cell (PEMFC) applications due to their practical nature. However, carbon dissolution or corrosion caused by high electrode potential in the presence of O2 and/or water has been identified as one of the main failure modes for the device operation. Here, we report the first TiN nanofiber (TNF)-based nonwoven structured materials to be constructed via electrospinning and subsequent two-step thermal treatment processes as a support for the PEMFC catalyst. Pt catalyst nanoparticles (NPs) deposited on the TNFs (Pt/TNFs) were electrochemically characterized with respect to oxygen reduction reaction (ORR) activity and durability in an acidic medium. From the electrochemical tests, the TNF-supported Pt catalyst was better and more stable in terms of its catalytic performance compared to a commercially available carbon-supported Pt catalyst. For example, the initial oxygen reduction performance was comparable for both cases, while the Pt/TNF showed much higher durability from an accelerated degradation test (ADT) configuration. It is understood that the improved catalytic roles of TNFs on the supported Pt NPs for ORR are due to the high electrical conductivity arising from the extended connectivity, high inertness to the electrochemical environment and strong catalyst-support interactions.

  1. Tuning of CO2 Reduction Selectivity on Metal Electrocatalysts.

    Science.gov (United States)

    Wang, Yuhang; Liu, Junlang; Wang, Yifei; Al-Enizi, Abdullah M; Zheng, Gengfeng

    2017-11-01

    Climate change, caused by heavy CO 2 emissions, is driving new demands to alleviate the rising concentration of atmospheric CO 2 levels. Enlightened by the photosynthesis of green plants, photo(electro)chemical catalysis of CO 2 reduction, also known as artificial photosynthesis, is emerged as a promising candidate to address these demands and is widely investigated during the past decade. Among various artificial photosynthetic systems, solar-driven electrochemical CO 2 reduction is widely recognized to possess high efficiencies and potentials for practical application. The efficient and selective electroreduction of CO 2 is the key to the overall solar-to-chemical efficiency of artificial photosynthesis. Recent studies show that various metallic materials possess the capability to play as electrocatalysts for CO 2 reduction. In order to achieve high selectivity for CO 2 reduction products, various efforts are made including studies on electrolytes, crystal facets, oxide-derived catalysts, electronic and geometric structures, nanostructures, and mesoscale phenomena. In this Review, these methods for tuning the selectivity of CO 2 electrochemical reduction of metallic catalysts are summarized. The challenges and perspectives in this field are also discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Carbon-supported iron complexes as electrocatalysts for the cogeneration of hydroxylamine and electricity in a NO-H2 fuel cell: A combined electrochemical and density functional theory study

    Science.gov (United States)

    Sheng, Xia; Alvarez-Gallego, Yolanda; Dominguez-Benetton, Xochitl; Baert, Kitty; Hubin, Annick; Zhao, Hailiang; Mihaylov, Tzvetan T.; Pierloot, Kristine; Vankelecom, Ivo F. J.; Pescarmona, Paolo P.

    2018-06-01

    Carbon-supported iron complexes were investigated as electrocatalysts for the reduction of nitric oxide (NO) in a H2-NO fuel cell conceived for the production of hydroxylamine (NH2OH) with concomitant generation of electricity. Two types of iron complexes with tetradentate ligands, namely bis(salicylidene)ethylenediimine (Salen) and phthalocyanine (Pc), supported on activated carbon or graphite were prepared and evaluated as electrocatalysts, either without further treatment or after pyrolysis at 700 °C. The performance in the reduction of NO of gas diffusion cathodes based on these electrocatalysts was investigated in an electrochemical half cell (3-electrode configuration) using linear sweep voltammetry (LSV). The most promising electrocatalysts were studied further by chronoamperometric experiments in a H2-NO fuel cell, which allowed comparison in terms of power output and hydroxylamine production. Depending on the concentration of the NO feed (6 or 18%), the best electrocatalytic performance was delivered either by FePc or FeSalen. The gas diffusion electrode based on FeSalen supported on activated carbon with 0.3 wt% Fe-loading provided the highest current density (86 A/m2) and the best current efficiency (43%) towards the desired NH2OH when operating at the higher NO concentration (18%). Moreover, FeSalen offers the advantage of being cheaper than FePc. The experimental work was complemented by density functional theory (DFT) calculations, which allowed to shed more light on the reaction mechanism for the reduction of nitric oxide at the atomistic level.

  3. Stability of CoP x Electrocatalysts in Continuous and Interrupted Acidic Electrolysis of Water.

    Science.gov (United States)

    Goryachev, Andrey; Gao, Lu; Zhang, Yue; Rohling, Roderigh Y; Vervuurt, René H J; Bol, Ageeth A; Hofmann, Jan P; Hensen, Emiel J M

    2018-04-11

    Cobalt phosphides are an emerging earth-abundant alternative to platinum-group-metal-based electrocatalysts for the hydrogen evolution reaction (HER). Yet, their stability is inferior to platinum and compromises the large-scale applicability of CoP x in water electrolyzers. In the present study, we employed flat, thin CoP x electrodes prepared through the thermal phosphidation (PH 3 ) of Co 3 O 4 films made by plasma-enhanced atomic layer deposition to evaluate their stability in acidic water electrolysis by using a multi-technique approach. The films were found to be composed of two phases: CoP in the bulk and a P-rich surface CoP x (P/Co>1). Their performance was evaluated in the HER and the exchange current density was determined to be j 0 =-8.9 ⋅ 10 -5  A/cm 2 . The apparent activation energy of HER on CoP x ( E a =81±15 kJ/mol) was determined for the first time. Dissolution of the material in 0.5 M H 2 SO 4 was observed, regardless of the constantly applied cathodic potential, pointing towards a chemical instead of an electrochemical origin of the observed cathodic instability. The current density and HER faradaic efficiency (FE) were found to be stable during chronoamperometric treatment, as the chemical composition of the HER-active phase remained unchanged. On the contrary, a dynamic potential change performed in a repeated way facilitated dissolution of the film, yielding its complete degradation within 5 h. There, the FE was also found to be changing. An oxidative route of CoP x dissolution has also been proposed.

  4. Amorphous nickel/cobalt tungsten sulfide electrocatalysts for high-efficiency hydrogen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lun [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics and Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Wu, Xinglong, E-mail: hkxlwu@nju.edu.cn [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics and Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Department of Physics, NingBo University, NingBo 315001 (China); Zhu, Xiaoshu [Center for Analysis and Testing, Nanjing Normal University, Nanjing 210093 (China); He, Chengyu; Meng, Ming; Gan, Zhixing [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics and Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2015-06-30

    Graphical abstract: - Highlights: • Amorphous nickel/cobalt tungsten sulfides were synthesized by a thermolytic process. • Amorphous NiWS and CoWS could realize hydrogen evolution efficiently. • Ni/Co promotion and annealing alter the porous structure and chemical bonding states. • Active sites on the surface of amorphous WS{sub x} are increased with Ni or Co doping. • Amorphous NiWS and CoWS have immense potentials in water splitting devices. - Abstract: The hydrogen evolution reaction (HER), an appealing solution for future energy supply, requires efficient and inexpensive electrocatalysts with abundant active surface sites. Although crystalline MoS{sub 2} and WS{sub 2} are promising candidates, their activity is dominated by edge sites. Amorphous tungsten sulfide prepared so far lacks the required active sites and its application has thus been hampered. In this work, nickel and cobalt incorporated amorphous tungsten sulfide synthesized by a thermolytic process is demonstrated to enhance the HER efficiency dramatically. The amorphous nickel tungsten sulfide (amorphous NiWS) annealed at 210 °C delivers the best HER performance in this system boasting a Tafel slope of 55 mV per decade and current density of 8.6 mA cm{sup −2} at 250 mV overpotential in a sustained test for 24 h. The introduction of Ni or Co into the catalyst and subsequent thermal treatment alters the porous structure and chemical bonding states thereby increasing the density of active sites on the surface.

  5. Nitrogen-doped micropore-dominant carbon derived from waste pine cone as a promising metal-free electrocatalyst for aqueous zinc/air batteries

    Science.gov (United States)

    Lei, Xiaoke; Wang, Mengran; Lai, Yanqing; Hu, Langtao; Wang, Hao; Fang, Zhao; Li, Jie; Fang, Jing

    2017-10-01

    The exploitation for highly effective and low-cost metal-free catalysts with facile and environmental friendly method for oxygen reduction reaction is still a great challenge. To find an effective method for catalyst synthesis, in this manuscript, waste biomass pine cone is employed as raw material and nitrogen-doped micropore-dominant carbon material with excellent ORR catalytic activity is successfully synthesized. The as-prepared N-doped micropore-dominant carbon possesses a high surface area of 1556 m2 g-1. In addition, this carbon electrocatalyst loaded electrode exhibits a high discharge voltage 1.07 V at the current density of 50 mA cm-2, which can be ascribed to the rich micropores and high content of pyridinic N of the prepared carbon, indicative of great potential in the application of zinc/air batteries.

  6. Recent advances in platinum monolayer electrocatalysts for oxygen reduction reaction: Scale-up synthesis, structure and activity of Pt shells on Pd cores

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, K., E-mail: ksasaki@bnl.go [Brookhaven National Laboratory, Chemistry Department, Upton, NY 11973 (United States); Wang, J.X. [Brookhaven National Laboratory, Chemistry Department, Upton, NY 11973 (United States); Naohara, H. [Toyota Motor Corporation, Susono 410-1193 (Japan); Marinkovic, N. [University of Delaware, Department of Chemical Engineering, Newark, DE 19716 (United States); More, K. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Inada, H. [Hitachi High Technologies America, Pleasanton, CA 94588 (United States); Adzic, R.R., E-mail: adzic@bnl.go [Brookhaven National Laboratory, Chemistry Department, Upton, NY 11973 (United States)

    2010-03-01

    We have established a scale-up synthesis method to produce gram-quantities of Pt monolayer electrocatalysts. The core-shell structure of the Pt/Pd/C electrocatalyst has been verified using the HAADF-STEM Z-contrast images, STEM/EELS, and STEM/EDS line profile analysis. The atomic structure of this electrocatalyst and formation of a Pt monolayer on Pd nanoparticle surfaces were examined using in situ EXAFS. The Pt mass activity of the Pt/Pd/C electrocatalyst for ORR is considerably higher than that of commercial Pt/C electrocatalysts. The results with Pt monolayer electrocatalysts may significantly impact science of electrocatalysis and fuel-cell technology, as they have demonstrated an exceptionally effective way of using Pt that can resolve problems of other approaches, including electrocatalysts' inadequate activity and high Pt content.

  7. Recent advances in platinum monolayer electrocatalysts for oxygen reduction reaction: Scale-up synthesis, structure and activity of Pt shells on Pd cores

    International Nuclear Information System (INIS)

    Sasaki, K.; Wang, J.X.; Naohara, H.; Marinkovic, N.; More, K.; Inada, H.; Adzic, R.R.

    2010-01-01

    We have established a scale-up synthesis method to produce gram-quantities of Pt monolayer electrocatalysts. The core-shell structure of the Pt/Pd/C electrocatalyst has been verified using the HAADF-STEM Z-contrast images, STEM/EELS, and STEM/EDS line profile analysis. The atomic structure of this electrocatalyst and formation of a Pt monolayer on Pd nanoparticle surfaces were examined using in situ EXAFS. The Pt mass activity of the Pt/Pd/C electrocatalyst for ORR is considerably higher than that of commercial Pt/C electrocatalysts. The results with Pt monolayer electrocatalysts may significantly impact science of electrocatalysis and fuel-cell technology, as they have demonstrated an exceptionally effective way of using Pt that can resolve problems of other approaches, including electrocatalysts' inadequate activity and high Pt content.

  8. Supercapacitive performance of hydrous ruthenium oxide (RuO2 ...

    Indian Academy of Sciences (India)

    2016-08-26

    SO4 electrolyte. RuO2.H2O film showed maximum specific capacitance of 192 F.g-1 at a scan rate of 20 mV.s-1. The charge–discharge studies of RuO2.H2O carried out at 300 A.cm-2 current density revealed the specific ...

  9. bond activation and catalysis by Ru -pac complexes

    Indian Academy of Sciences (India)

    and their reactivity towards oxidation of a few organic compounds. Keywords. Kinetics; catalysis; -O–O- bond activation; Ru-pac complex; oxidation. 1. Introduction. Ru-pac complexes exhibit catalytic properties,1 in homogeneous conditions in the presence of oxygen atom donors, that mimic the biological enzymatic oxi-.

  10. Homogeneously Dispersed Co9S8 Anchored on Nitrogen and Sulfur Co-Doped Carbon Derived from Soybean as Bifunctional Oxygen Electrocatalysts and Supercapacitors.

    Science.gov (United States)

    Xiao, Zhen; Xiao, Guozheng; Shi, Minhao; Zhu, Ying

    2018-05-16

    Developing low-cost and highly active multifunctional electrocatalysts to replace noble metal catalysts is crucial for the commercialization of future clean energy technology. Herein, homogeneous Co 9 S 8 nanoparticles anchored on nitrogen and sulfur co-doped porous carbon nanomaterials (CoS@NSCs) are fabricated by pyrolysis of natural soybean treated with cobalt nitrate. The unique porous structures of the soybean are utilized to provide space for the oxidation and complexation reactions for cobalt compounds, thus leading to in situ generation of homogenously dispersed cobalt sulfide nanoparticles that anchored on the N,S co-doped carbon framework. Because of the coupling effect of cobalt sulfide and doping heteroatoms, CoS@NSC-800 not only displays excellent electrocatalytic performances with low overpotential and high current density toward both oxygen reduction reaction and oxygen evolution reaction comparable to the commercial Pt/C catalyst and IrO 2 catalyst, but also might be a promising candidate for high-performance supercapacitors. The method for the preparation of the multifunctional hybrids is simple but effective for the formation of uniformly distributed metal sulfide nanoparticles anchored on carbon materials, therefore providing a new perspective for the design and synthesis of multifunctional electrocatalysts for electrochemical energy conversion and storage at a large scale.

  11. Electroreductions on silver-based electrocatalysts: the use of Ag nanoparticles for CHCl{sub 3} to CH{sub 4} conversion

    Energy Technology Data Exchange (ETDEWEB)

    Aricci, G.; Locatelli, C.; Minguzzi, A.; Vertova, A. [Department of Physical Chemistry and Electrochemistry, University of Milan (Italy); Krpetic, Z.; Porta, F. [Department of Inorganic, Metallorganic and Analytical Chemistry Lamberto Malatesta, University of Milan (Italy); Rondinini, S.

    2009-06-15

    A preliminary investigation on a new class on electrocatalytic materials for the electroreduction of organic halides is presented and discussed. The electrocatalysts are based on silver nanoparticles (Ag-NP), ad hoc synthesised by chemical reduction of an aqueous silver salt in the presence of six different stabilising agents. The colloids are then supported on carbon powder (10% loading) for further characterisation and use. The electrocatalytic properties of the Ag-NP/carbon composites towards the dehalogenation of halocompounds are tested by cyclic voltammetry and by preparative electrolysis. The hydrodehalogenation of trichloromethane, extensively studied by this group, is selected as a model reaction, because of its relevance for the detoxification of wastes. The voltammetric characterisation is performed in an aqueous solution, supporting the composites on cavity microelectrodes. Gas-diffusion electrodes (GDE) based on the most promising Ag-NP composite - and, for reference, on a commercial Ag/C oxygen reduction electrocatalyst - are then tested in an electrolytic process for the progressive conversion of gaseous trichloromethane to less chlorinated compounds, and ultimately to methane. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  12. Hierarchical cobalt poly-phosphide hollow spheres as highly active and stable electrocatalysts for hydrogen evolution over a wide pH range

    Science.gov (United States)

    Wu, Tianli; Pi, Mingyu; Wang, Xiaodeng; Guo, Weimeng; Zhang, Dingke; Chen, Shijian

    2018-01-01

    Exploring highly-efficient and low-cost non-noble metal electrocatalyst toward the hydrogen evolution reaction (HER) is highly desired for renewable energy system but remains challenging. In this work, three dimensional hierarchical porous cobalt poly-phosphide hollow spheres (CoP3 HSs) were prepared by topotactic phosphidation of the cobalt-based precursor via vacuum encapsulation technique. As a porous HER cathode, the CoP3 HSs delivers remarkable electrocatalytic performance over the wide pH range. It needs overpotentials of -69 mV and -118 mV with a small Tafel slope of 51 mV dec-1 to obtain current densities of 10 mA cm-2 and 50 mA cm-2, respectively, and maintains its electrocatalytic performance over 30 h in acidic solution. In addition, CoP3 also exhibit superior electrocatalytic performance and stability under neutral and alkaline conditions for the HER. Both experimental measurements and density functional theory (DFT) calculations are performed to explore the mechanism behind the excellent HER performance. The results of our study make the porous CoP3 HSs as a promising electrocatalyst for practical applications toward energy conversion system and present a new way for designing and fabricating HER electrodes through high degree of phosphorization and nano-porous architecture.

  13. Performance of a PEM water electrolyser using a TaC-supported iridium oxide electrocatalyst

    DEFF Research Database (Denmark)

    Polonský, J.; Mazúr, P.; Paidar, M.

    2014-01-01

    by dispersing the precious metal compound onto a catalyst support. Electrocatalysts with 50, 70 and 90 wt.% of IrO2 on a TaC support were tested in a laboratory PEM water electrolyser and compared with pure IrO2. The temperature was set at 90, 110, 120 and 130 °C respectively and the cell voltage was varied......Polymer electrolyte membrane (PEM) water electrolysis is an attractive way of producing carbon-free hydrogen. One of the drawbacks of this method is the need for precious metal-based electrocatalysts. This calls for a highly efficient utilization of the precious metal, which can be obtained...

  14. Iron Is the Active Site in Nickel/Iron Water Oxidation Electrocatalysts

    Directory of Open Access Journals (Sweden)

    Bryan M. Hunter

    2018-04-01

    Full Text Available Efficient catalysis of the oxygen-evolution half-reaction (OER is a pivotal requirement for the development of practical solar-driven water splitting devices. Heterogeneous OER electrocatalysts containing first-row transition metal oxides and hydroxides have attracted considerable recent interest, owing in part to the high abundance and low cost of starting materials. Among the best performing OER electrocatalysts are mixed Fe/Ni layered double hydroxides (LDH. A review of the available experimental data leads to the conclusion that iron is the active site for [NiFe]-LDH-catalyzed alkaline water oxidation.

  15. Development of new electrocatalysts for proton exchange membrane fuel cells

    International Nuclear Information System (INIS)

    Franco, Egberto Gomes

    2005-01-01

    In this work the colloidal method was chosen to perform the catalysts. This method produces nano catalysts well dispersed in the carbon support. The catalyst systems were performed with platinum, ruthenium, molybdenum, nickel, dysprosium, terbium, samarium and uranium. The method chosen to synthesize catalysts produced binary' and ternary systems with a good distribution of the nano crystals. The quaternary systems performed in this work shows a crystallite size 2 to 3 times greater than the binary and ternary ones. This could indicate that some modifications in the method should be done to improve the electrocatalytic activity of the quaternary systems. The characterization of the catalysts were performed by the following techniques; X-ray fluorescence analysis, X-ray diffraction, X-ray photoelectron spectroscopy, infrared spectroscopy, high resolution transmission electron microscopy, scanning electron microscopy, cyclic voltammetry and polarization curves. The PtRuMo system was identified as the most electro active system by cyclic voltammetry in order to oxidize methanol and ethanol. The PtRuDy system shows a good electrochemical activity to ethanol oxidation, but after the use of ethanol the catalyst lost 42 % of the activity when operating with hydrogen and oxygen. The binary system Pt U presents some promising results, this system start the oxidation of CO in 5 mV vs RHE. Besides this fact, when operating with ethanol the Pt U system shows no degradation of the catalytic activity. (author)

  16. High-Density Stacked Ru Nanocrystals for Nonvolatile Memory Application

    International Nuclear Information System (INIS)

    Ping, Mao; Zhi-Gang, Zhang; Li-Yang, Pan; Jun, Xu; Pei-Yi, Chen

    2009-01-01

    Stacked ruthenium (Ru) nanocrystals (NCs) are formed by rapid thermal annealing for the whole gate stacks and embedded in memory structure, which is compatible with conventional CMOS technology. Ru NCs with high density (3 × 10 12 cm −2 ), small size (2–4 nm) and good uniformity both in aerial distribution and morphology are formed. Attributed to the higher surface trap density, a memory window of 5.2 V is obtained with stacked Ru NCs in comparison to that of 3.5 V with single-layer samples. The stacked Ru NCs device also exhibits much better retention performance because of Coulomb blockade and vertical uniformity between stacked Ru NCs

  17. Co-catalytic effect of Rh and Ru for the ethanol electro-oxidation in amorphous microparticulated alloys

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, Tamara C.; Pierna, Angel R.; Barroso, Javier [Dpto. de Ingenieria Quimica y del Medio Ambiente, Universidad del Pais Vasco, San Sebastian (Spain)

    2011-11-15

    The ethanol electro-oxidation on platinum catalyst in acid media leads to the formation of acetaldehyde and acetic acid as main products. Another problem is the poisoning of the electro-catalyst surface with CO formed during the fuel oxidation reaction. To increase the performance of Direct Ethanol Fuel Cells (DEFCs) it is necessary to develop new electrode materials or modification of the existing Pt catalysts. This work presents the electrochemical response to ethanol and CO oxidation of different compositional amorphous alloys obtained by ball milling technique, used as electrodes. Alloys with Ni{sub 59}Nb{sub 40}Pt{sub 0.6}Rh{sub 0.4} and Ni{sub 59}Nb{sub 40}Pt{sub 0.6}Rh{sub 0.2}Ru{sub 0.2} composi-tions were studied. The current density towards ethanol oxidation decreases with the presence of ruthenium; however, this electrode shows the best tolerance to CO, with lower surface coverage (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Co-catalytic effect of Rh and Ru for the ethanol electro-oxidation in amorphous microparticulated alloys

    International Nuclear Information System (INIS)

    Blanco, Tamara C.; Pierna, Angel R.; Barroso, Javier

    2011-01-01

    The ethanol electro-oxidation on platinum catalyst in acid media leads to the formation of acetaldehyde and acetic acid as main products. Another problem is the poisoning of the electro-catalyst surface with CO formed during the fuel oxidation reaction. To increase the performance of Direct Ethanol Fuel Cells (DEFCs) it is necessary to develop new electrode materials or modification of the existing Pt catalysts. This work presents the electrochemical response to ethanol and CO oxidation of different compositional amorphous alloys obtained by ball milling technique, used as electrodes. Alloys with Ni 59 Nb 40 Pt 0.6 Rh 0.4 and Ni 59 Nb 40 Pt 0.6 Rh 0.2 Ru 0.2 composi-tions were studied. The current density towards ethanol oxidation decreases with the presence of ruthenium; however, this electrode shows the best tolerance to CO, with lower surface coverage (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Electrodeposition of Pt-Ru nanoparticles on fibrous carbon substrates in the presence of nonionic surfactant: Application for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Alex; Gyenge, Elod L.; Oloman, Colin W. [Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC (Canada)

    2006-07-28

    Liquid crystalline and micellar aqueous solutions of the nonionic surfactant Triton X-100 were used to direct the electrodeposition of Pt-Ru nanoparticles onto graphite felts, which were investigated as novel anodes for the direct methanol fuel cell. The effects of surfactant concentration, current density and deposition time in the preparation of these three-dimensional electrodes were studied in a factorial experiment and the electrodes were characterized by SEM and ICP-AES. Cyclic voltammetry, chronoamperometry and chronopotentiometry were carried out to assess the activity of the catalyzed felts for methanol oxidation. The presence of Triton X-100 (40-60wt.%) coupled with an acidic plating solution were essential for the efficient co-electrodeposition of Ru in the presence of Pt to yield approximately a 1:1 Pt:Ru atomic ratio in the deposit. The highest mass specific activity, 24Ag{sup -1} at 298K (determined by chronoamperometry after 180s at 0V versus Hg/Hg{sub 2}SO{sub 4}, K{sub 2}SO{sub 4std}), was obtained for the Pt-Ru electrodeposited in the presence of 40wt.% Triton X-100 at 60Am{sup -2}, 298K for 90min. Surfactant mediated electrodeposition is a promising method for meso-scale (ca. 10-60nm diameter) catalyst particle preparation on three-dimensional electrodes. (author)

  20. Electrodeposition of Pt-Ru nanoparticles on fibrous carbon substrates in the presence of nonionic surfactant: Application for methanol oxidation

    International Nuclear Information System (INIS)

    Bauer, Alex; Gyenge, Elod L.; Oloman, Colin W.

    2006-01-01

    Liquid crystalline and micellar aqueous solutions of the nonionic surfactant Triton X-100 were used to direct the electrodeposition of Pt-Ru nanoparticles onto graphite felts, which were investigated as novel anodes for the direct methanol fuel cell. The effects of surfactant concentration, current density and deposition time in the preparation of these three-dimensional electrodes were studied in a factorial experiment and the electrodes were characterized by SEM and ICP-AES. Cyclic voltammetry, chronoamperometry and chronopotentiometry were carried out to assess the activity of the catalyzed felts for methanol oxidation. The presence of Triton X-100 (40-60 wt.%) coupled with an acidic plating solution were essential for the efficient co-electrodeposition of Ru in the presence of Pt to yield approximately a 1:1 Pt:Ru atomic ratio in the deposit. The highest mass specific activity, 24 A g -1 at 298 K (determined by chronoamperometry after 180 s at 0 V versus Hg/Hg 2 SO 4 , K 2 SO 4std ), was obtained for the Pt-Ru electrodeposited in the presence of 40 wt.% Triton X-100 at 60 A m -2 , 298 K for 90 min. Surfactant mediated electrodeposition is a promising method for meso-scale (ca. 10-60 nm diameter) catalyst particle preparation on three-dimensional electrodes

  1. Electrical enhancement of direct methanol fuel cells by metal-plasma ion implantation Pt-Ru/C multilayer catalysts.

    Science.gov (United States)

    Weng, Ko-Wei; Chen, Yung-Lin; Chen, Ya-Chi; Lin, Tai-Nan

    2009-02-01

    Direct methanol fuel cells (DMFC) have been widely studied owing to their simple cell configuration, high volume energy density, short start-up time, high operational reliability and other favorable characteristics. However, major limitations include high production cost, poisoning of the catalyst and methanol crossover. This study adopts a simple technique for preparing Pt-Ru/C multilayer catalysts, including magnetron sputtering (MS) and metal-plasma ion implantation (MPII). The Pt catalysts were sputtered onto the gas diffusion layer (GDL), followed by the implantation of Ru catalysts using MPII (at an accelerating voltage of 20 kV and an implantation dose of 1 x 10(16) ions/cm2). Pt-Ru is repeatedly processed to prepare Pt-Ru/C multilayer catalysts. The catalyst film structure and microstructure were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electronic microscopy (SEM), respectively. The cell performance was tested using a potential stat/galvano-stat. The results reveal that the membrane electrode assembly (MEA) of four multilayer structures enhances the cell performance of DMFC. The measured power density is 2.2 mW/cm2 at a methanol concentration of 2 M, with an OCV of 0.493 V.

  2. Tunable preparation of ruthenium nanoparticles with superior size-dependent catalytic hydrogenation properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yuan; Luo, Yaodong; Yang, Xuan; Yang, Yaxin; Song, Qijun, E-mail: qsong@jiangnan.edu.cn

    2017-06-15

    Highlights: • A facile and efficient strategy is firstly developed for the synthesis of Ru NPs. • Ru NPs are stable and uniform with the controllable sizes from 2.6 to 51.5 nm. • Ru NPs exhibit size-dependent and superior catalytic hydrogenation activity. - Abstract: Ruthenium (Ru) featured with an unusual catalytic behavior is of great significance in several heterogeneous and electro-catalytic reactions. The preparation of tractable Ru nanocatalysts and the building of highly active catalytic system at ambient temperature remains a grand challenge. Herein, a facile strategy is developed for the controllable preparation of Ru nanoparticles (NPs) with the sizes ranging from 2.6 to 51.5 nm. Ru NPs show superior size-dependent catalytic performance with the best kinetic rate constant as high as −1.52 min{sup −1}, which could far surpass the other traditional noble metals. Ru NPs exert exceedingly efficient low-temperature catalytic activity and good recyclability in the catalytic reduction of nitroaromatic compounds (NACs) and azo dyes. The developed catalytic system provides a distinguishing insight for the artificial preparation of Ru NPs with desired sizes, and allows for the development of rational design rules for exploring catalysts with superior catalytic performances, potentially broadening the applications of metallic NP-enabled catalytic analysis.

  3. Methanol electro-oxidation on Pt-Ru-P/C and Pt-Ru-P/MWCNT in acidic medium

    CSIR Research Space (South Africa)

    Modibedi, M

    2009-06-01

    Full Text Available . The electro-catalytic activity towards methanol oxidation in acidic medium was studied by cyclic voltammetry and linear sweep voltammetry. Pt-Ru-P/MWCNT showed excellent activity compared to that of Pt-Ru-P/C. This may be attributed to the effectiveness...

  4. APPLIED SCIENTOMETRICS: ELIBRARY.RU VS GOOGLE

    Directory of Open Access Journals (Sweden)

    А В Юрков

    2015-12-01

    Full Text Available The practical issues associated with searching reliable information about the publication activity of Russian scientist are discussed in the article. The examples in [1] show that the effective solution of this problem requires the using of different scientometric services: both the domestic eLIBRARY.RU and its Russian Science Citation Index, and the Google Scholar as an alternative. At the time the work is published comparison was not in favor of the domestic resource. However, due to the RSCI project within a short period the eLibrary’s tools for building database of scientific publications have grown significantly and the opportunities to improve the quality of scientometric information become real. The article gives the examples.

  5. Robust Platinum-Based Electrocatalysts for Fuel Cell Applications

    Science.gov (United States)

    Coleman, Eric James

    Polymer electrolyte fuel cells (PEMFCs) are energy conversion devices that exploit the energetics of the reaction between hydrogen fuel and O 2 to generate electricity with water as the only byproduct. PEMFCs have attracted substantial attention due to their high conversion efficiency, high energy density, and low carbon footprint. However, PEMFC performance is hindered by the high activation barrier and slow reaction rates at the cathode where O2 undergoes an overall 4-electron reduction to water. The most efficient oxygen reduction reaction (ORR) catalyst materials to date are Pt group metals due to their high catalytic activity and stability in a wide range of operating conditions. Before fuel cells can become economically viable, efforts must be taken to decrease Pt content while maintaining a high level of ORR activity. This work describes the design and synthesis of a Pt-Cu electrocatalyst with ORR activity exceeding that of polycrystalline Pt. Production of this novel catalyst is quite simple and begins with synthesis of a porous Cu substrate, formed by etching Al from a Cu-Al alloy. The porous Cu substrate is then coated with a Pt layer via a spontaneous electrochemical process known as galvanic replacement. The Pt layer enhances the ORR activity (as measured by a rotating ring-disk electrode (RRDE)) and acts as a barrier towards corrosion of the Cu understructure. Growth of the Pt layer can be manipulated by time, temperature, concentration of Pt precursor, and convection rate during galvanic replacement. Data from analytical and electrochemical techniques confirm multiple Pt loadings have been achieved via the galvanic replacement process. The boost in ORR activity for the PtCu catalyst was determined to be a result of its lower affinity towards (site-blocking) OH adsorption. A unique catalyst degradation study explains the mechanism of initial catalyst ORR deactivation for both monometallic and bimetallic Pt-based catalysts. Finally, a rigorous and

  6. Gold Nanoclusters@Ru(bpy)₃²⁺-Layered Double Hydroxide Ultrathin Film as a Cathodic Electrochemiluminescence Resonance Energy Transfer Probe.

    Science.gov (United States)

    Yu, Yingchang; Lu, Chao; Zhang, Meining

    2015-08-04

    Herein, it is the first report that a cathodic electrochemiluminescence (ECL) resonance energy transfer (ERET) system is fabricated by layer-by-layer (LBL) electrostatic assembly of CoAl layered double hydroxide (LDH) nanosheets with a mixture of blue BSA-gold nanoclusters (AuNCs) and Ru(bpy)3(2+) (denoted as AuNCs@Ru) on an Au electrode. The possible ECL mechanism indicates that the appearance of CoAl-LDH nanosheets generates a long-range stacking order of the AuNCs@Ru on an Au electrode, facilitating the occurrence of the ERET between BSA-AuNC donors and Ru(bpy)3(2+) acceptors on the as-prepared AuNCs@Ru-LDH ultrathin films (UTFs). Furthermore, it is observed that the cathodic ECL intensity can be quenched efficiently in the presence of 6-mercaptopurine (6-MP) in a linear range of 2.5-100 nM with a detection limit of 1.0 nM. On the basis of these interesting phenomena, a facile cathodic ECL sensor has successfully distinguished 6-MP from other thiol-containing compounds (e.g., cysteine and glutathione) in human serum and urine samples. The proposed sensing scheme opens a way for employing the layered UTFs as a platform for the cathodic ECL of Ru(bpy)3(2+).

  7. Single hole spectroscopic strength in 98Ru through the 99Ru(d,t) reaction

    International Nuclear Information System (INIS)

    Rodrigues, M.R.D.; Borello-Lewin, T.; Horodynski-Matsushigue, L.B.; Duarte, J.L.M.; Rodrigues, C.L.; Barbosa, M.D.L.; Silva, G.B. da; Ukita, G.M.

    2002-01-01

    The 99 Ru(d,t) 98 Ru reaction was measured for the first time at 16 MeV incident energy with the Sao Paulo Pelletron-Enge-spectrograph facility employing the nuclear emulsion technique. In all, up to 3.5 MeV, 23 levels were detected, eight of them new; angular distributions are presented for all of them. Least squares fits of distorted wave Born approximation one-neutron pickup predictions to the rather well structured experimental angular distributions enabled the determination of l transfers and of the corresponding spectroscopic factors for 19 of these states, some being tentative attributions. Only transfers of l=0, 2, and 4 were observed. Several states were populated through single l transfers. A pure l=2 transfer is associated with the 2 1 + level and with several other states which are considered collective, as well as with the (4 + ) state at 2.277 MeV, which presents the highest spectroscopic strength. Considering five valence neutrons above the N=50 core, only 41% of the spectroscopic strength expected for 99 Ru was detected

  8. Surface and electrochemical characterization of electrodeposited PtRu alloys

    Science.gov (United States)

    Richarz, Frank; Wohlmann, Bernd; Vogel, Ulrich; Hoffschulz, Henning; Wandelt, Klaus

    1995-07-01

    PtRu alloys of different compositions were electrodeposited on Au. Twelve alloys between 0% and 100% Pt were characterized with surface sensitive spectroscopies (XPS, LEIS) after transfer from an electrochemical cell to an ultra high vaccum chamber without contact to air. The composition of the thus prepared alloys showed a linear dependence on the concentrations of the deposition solution, but was Pt-enriched both in the bulk and (even more so) at the surface. During the electrochemical reduction of the metal cations, sulfur from the supporting electrolyte 1N H 2SO 4 was found to be incorporated into the electrodes. Cyclic voltammetry was used for the determination of the electrocatalytic activity of the electrodes for the oxidation of carbon monoxide. The highest activity for this oxidation as measured by the (peak) potential of the CO oxidation cyclovoltammograms was found for a surface concentration of ˜ 50%Pt. The asymmetry of this "activity curve" (oxidation potential versus Pt surface concentration) is tentatively explained in terms of a surface structural phase separation.

  9. Hierarchically scaffolded CoP/CoP2 nanoparticles: controllable synthesis and their application as a well-matched bifunctional electrocatalyst for overall water splitting.

    Science.gov (United States)

    Li, Wan; Zhang, Shilin; Fan, Qining; Zhang, Fazhi; Xu, Sailong

    2017-05-04

    Transition metal phosphide (TMP) nanostructures have stimulated increasing interest for use in water splitting owing to their abundant natural sources and high activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Typically, the preparation of hierarchical TMPs involves the utilization of expensive or dangerous phosphorus sources, and, in particular, the understanding of topotactic transformations of the precursors to crystalline phases-which could be utilized to enhance electrocatalytic performance-remains very limited. We, herein, report a controllable preparation of CoP/CoP 2 nanoparticles well dispersed in flower-like Al 2 O 3 scaffolds (f-CoP/CoP 2 /Al 2 O 3 ) as a bifunctional electrocatalyst for the HER and OER via the phosphorization of a flower-like CoAl layered double hydroxide precursor. Characterization by in situ X-ray diffraction (XRD) monitored the topotactic transformation underlying the controllable formation of CoP/CoP 2 via tuning the phosphorization time. Electrocatalytic tests showed that an f-CoP/CoP 2 /Al 2 O 3 electrode exhibited a lower onset potential and higher electrocatalytic activity for the HER and OER in the same alkaline electrolyte than electrodes of flower-like and powdered CoP/Al 2 O 3 . The enhanced electrochemical performance was experimentally supported by measuring the electrochemically active surface area. The f-CoP/CoP 2 /Al 2 O 3 composite further generated a current density of 10 mA cm -2 at 1.65 V when used as a bifunctional catalyst for overall water splitting. Our results demonstrate that the preparation route based on the LDH precursor may provide an alternative for investigating diverse TMPs as bifunctional electrocatalysts for water splitting.

  10. Reactive template synthesis of nitrogen-doped graphene-like carbon nanosheets derived from hydroxypropyl methylcellulose and dicyandiamide as efficient oxygen reduction electrocatalysts

    Science.gov (United States)

    Hu, Chun; Zhou, Yao; Ma, Ruguang; Liu, Qian; Wang, Jiacheng

    2017-03-01

    Oxygen reduction reaction (ORR) plays a dominant role in proton exchange membrane fuel cells (PEMFCs). Thus, the design and preparation of efficient ORR electrocatalysts is of high importance. In this work, we successfully prepared a series of nitrogen-doped graphene-like carbon nanosheets (NCNSs) with large pore volumes of up to 1.244 cm3 g-1 and high level of N dopants (5.3-6.8 at%) via a one-step, in-situ reactive template strategy by co-pyrolysis of hydroxypropyl methylcellulose (HPMC) and dicyandiamide (DICY) as the precursors at 1000 °C. The DICY-derived graphitic carbon nitride (g-C3N4) nanosheets could act as the hard template for the confined growth of 2D carbon nanosheets, and the further increase in the pyrolysis temperature could directly remove off the g-C3N4 template by complete decomposition and simultaneously dope N atoms within the carbon nanosheets. The pyridinic and graphitic nitrogen groups are dominant among various N functional groups in the NCNSs. The NCNS_1:10 prepared with the HPMC/DICY mass ratio of 1/10 can be used as the metal-free ORR electrocatalysts with optimal activity (onset potential: -0.1 V vs. SCE; limiting current density: 4.8 mA cm-2) in O2-saturated 0.1 M KOH electrolyte among the NCNSs. Moreover, the NCNS_1:10 demonstrates a dominant four-electron reduction process, as well as excellent long-term operation stability and outstanding methanol crossover resistance. The excellent ORR activity of the NCNS_1:10 should be mainly owing to high contents of pyridinic and graphitic N dopants, large pore volume, hierarchical structures, and microstructural defects.

  11. Tantalum carbide as a novel support material for anode electrocatalysts in polymer electrolyte membrane water electrolysers

    DEFF Research Database (Denmark)

    Polonský, Jakub; Petrushina, Irina; Christensen, Erik

    2012-01-01

    Iridium oxide (IrO2) currently represents a state of the art electrocatalyst for anodic oxygen evolution. Since iridium is both expensive and scarce, the future practical application of this process makes it essential to reduce IrO2 loading on the anodes of PEM water electrolysers. In the present...

  12. Immobilization of molecular cobalt electrocatalyst by hydrophobic interaction with hematite photoanode for highly stable oxygen evolution

    KAUST Repository

    Joya, Khurram

    2015-07-15

    A unique modification of a hematite photoanode with perfluorinated Co-phthalocyanine (CoFPc) by strong binding associated with hydrophobic interaction is demonstrated. The resultant molecular electrocatalyst – hematite photoanode hybrid material showed significant onset shift and high stability for photoelectrochemical oxidation evolution reaction (OER).

  13. Benchmarking Pt-based electrocatalysts for low temperature fuel cell reactions with the rotating disk electrode

    DEFF Research Database (Denmark)

    Pedersen, Christoffer Mølleskov; Escribano, Maria Escudero; Velazquez-Palenzuela, Amado Andres

    2015-01-01

    We present up-to-date benchmarking methods for testing electrocatalysts for polymer exchange membrane fuel cells (PEMFC), using the rotating disk electrode (RDE) method. We focus on the oxygen reduction reaction (ORR) and the hydrogen oxidation reaction (HOR) in the presence of CO. We have chosen...

  14. Immobilization of molecular cobalt electrocatalyst by hydrophobic interaction with hematite photoanode for highly stable oxygen evolution

    KAUST Repository

    Joya, Khurram; Morlanes, Natalia; Maloney, Edward; Rodionov, Valentin; Takanabe, Kazuhiro

    2015-01-01

    A unique modification of a hematite photoanode with perfluorinated Co-phthalocyanine (CoFPc) by strong binding associated with hydrophobic interaction is demonstrated. The resultant molecular electrocatalyst – hematite photoanode hybrid material showed significant onset shift and high stability for photoelectrochemical oxidation evolution reaction (OER).

  15. Application of Ti/RuO{sub 2}-Ta{sub 2}O{sub 5} electrodes in the electrooxidation of ethanol and derivants: Reactivity versus electrocatalytic efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, J.; De Andrade, A.R. [Departamento de Quimica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, 14040-9010 Ribeirao Preto, SP (Brazil); Purgato, F.L.S. [Departamento de Quimica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, 14040-9010 Ribeirao Preto, SP (Brazil); Equipe Electrocatalyse, UMR 6503 CNRS, Universite de Poitiers, 40 Avenue du Recteur Pineau 86022 Poitiers Cedex (France); Kokoh, K.B.; Leger, J.-M. [Equipe Electrocatalyse, UMR 6503 CNRS, Universite de Poitiers, 40 Avenue du Recteur Pineau 86022 Poitiers Cedex (France)

    2008-11-15

    The influence of the