Alloying degree, particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent（s） used in the preparation process can affect the particle size and alloying de...Alloying degree, particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent（s） used in the preparation process can affect the particle size and alloying degree of the object substance, which lead to a great positive impact on its properties. In this work, three types of solvents and their mixtures were used in preparation of the Pt-Ru/C catalysts by chemical reduction of metal precursors with sodium borohydride at room temperature. The structure of the catalysts was characterized by X-ray diffraction （XRD） and Transmission electron microscopy （TEM）. The catalytic activity and stability for methanol electro-oxidation were studied by Cyclic Voltammetry （CV） and Chronoamperometry （CA）. Pt-Ru/C catalyst prepared in H2O or binary solvents of H2O and isopropanol had large particle size and low alloying degree leading to low catalytic activity and less stability in methanol electro-oxidation. When tetrahydrofuran was added to the above solvent systems, Pt-Ru/C catalyst prepared had smaller particle size and higher alloying degree which resulted in better catalytic activity, lower onset and peak potentials, compared with the above catalysts. Moreover, the catalyst prepared in ternary solvents of isopropanol, water and tetrahydrofuran had the smallest particle size, and the high alloying degree and the dispersion kept unchanged. Therefore, this kind of catalyst showed the highest catalytic activity and good stability for methanol electro-oxidation.展开更多
This research aims at increasing the utilization of platinum-ruthenium alloy(Pt-Ru)catalysts and thus lowering the catalyst loading in anodes for methanol electrooxidation.The direct methanol fuel cell’s(DMFC)anodic ...This research aims at increasing the utilization of platinum-ruthenium alloy(Pt-Ru)catalysts and thus lowering the catalyst loading in anodes for methanol electrooxidation.The direct methanol fuel cell’s(DMFC)anodic catalysts,Pt-Ru/C,were prepared by chemical reduction with a reduc-ing agent added in two kinds of solutions under different circumstances.The reducing agent was added in hot solution with the protection of inert gases or just air,and in cold solu-tion with inert gases.The catalysts were treated at different temperatures.Their performance was tested by cyclic voltam-metry and potentiostatic polarization by utilizing their inher-ent powder microelectrode in 0.5 mol/L CH3OH and 0.5 mol/L H2SO4 solution.The structures and micro-surface images of the catalysts were determined and observed by X-ray diffrac-tion and transmission electron microscopy,respectively.The catalyst prepared in inert gases showed a better catalytic performance for methanol electrooxidation than that prepared in air.It resulted in a more homogeneous distribution of the Pt-Ru alloy in carbon.Its size is small,only about 4.5 nm.The catalytic performance is affected by the order of the reducing agent added.The performance of the catalyst pre-pared by adding the reductant at constant temperature of the solution is better than that prepared by adding it in the solu-tion at 0℃ and then heating it up to the reducing temperature.The structure of the catalyst was modified,and there was an increase in the conversion of ruthenium into the alloyed state and an increase in particle size with the ascension of heat treatment temperature.In addition,the stability of the catalyst was improved after heat treatment.展开更多
It is reported for the first time that the Pt - Ru/C catalyst was prepared with the solid phase reaction method.Cyclic voltammetric measurements indicated that the anodic peak potential of ethanol at the electrode wit...It is reported for the first time that the Pt - Ru/C catalyst was prepared with the solid phase reaction method.Cyclic voltammetric measurements indicated that the anodic peak potential of ethanol at the electrode with the Pt - Ru/C catalyst prepared with the solid phase reaction method was0.54V and the peak current was100mA · cm -2 .While the anodic peak potential and peak current were0.64V and43mA · cm -2 respectively at the Pt - Ru/C catalyst prepared with the traditional liquid phase reaction method.It illustrated that the electrocatalytic activity of the Pt - Ru/C catalyst prepared with the solid phase reaction method was much better than that of the Pt - Ru/C catalyst prepared with the traditional liquid phase reaction method.It is because the Pt - Ru/C catalyst prepared with the solid phase reaction method is of low crystallinity and high dispersivity.展开更多
基金supported by 863 Project(No.2006AA05Z102)the Cultivation Fund of the Key Scientific and Technical Innovation Project,Ministry of Education of China (No.707050)+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education (No.20060610023)Chengdu Natural Science Foundation (Nos.06GGYB449GX-030,and 07GGZD139GX)
文摘Alloying degree, particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent（s） used in the preparation process can affect the particle size and alloying degree of the object substance, which lead to a great positive impact on its properties. In this work, three types of solvents and their mixtures were used in preparation of the Pt-Ru/C catalysts by chemical reduction of metal precursors with sodium borohydride at room temperature. The structure of the catalysts was characterized by X-ray diffraction （XRD） and Transmission electron microscopy （TEM）. The catalytic activity and stability for methanol electro-oxidation were studied by Cyclic Voltammetry （CV） and Chronoamperometry （CA）. Pt-Ru/C catalyst prepared in H2O or binary solvents of H2O and isopropanol had large particle size and low alloying degree leading to low catalytic activity and less stability in methanol electro-oxidation. When tetrahydrofuran was added to the above solvent systems, Pt-Ru/C catalyst prepared had smaller particle size and higher alloying degree which resulted in better catalytic activity, lower onset and peak potentials, compared with the above catalysts. Moreover, the catalyst prepared in ternary solvents of isopropanol, water and tetrahydrofuran had the smallest particle size, and the high alloying degree and the dispersion kept unchanged. Therefore, this kind of catalyst showed the highest catalytic activity and good stability for methanol electro-oxidation.
基金supported financially by Heilongjiang Natural Science Foundation(B0201)Harbin Institute of Technology(HIT 2002.39).
文摘This research aims at increasing the utilization of platinum-ruthenium alloy(Pt-Ru)catalysts and thus lowering the catalyst loading in anodes for methanol electrooxidation.The direct methanol fuel cell’s(DMFC)anodic catalysts,Pt-Ru/C,were prepared by chemical reduction with a reduc-ing agent added in two kinds of solutions under different circumstances.The reducing agent was added in hot solution with the protection of inert gases or just air,and in cold solu-tion with inert gases.The catalysts were treated at different temperatures.Their performance was tested by cyclic voltam-metry and potentiostatic polarization by utilizing their inher-ent powder microelectrode in 0.5 mol/L CH3OH and 0.5 mol/L H2SO4 solution.The structures and micro-surface images of the catalysts were determined and observed by X-ray diffrac-tion and transmission electron microscopy,respectively.The catalyst prepared in inert gases showed a better catalytic performance for methanol electrooxidation than that prepared in air.It resulted in a more homogeneous distribution of the Pt-Ru alloy in carbon.Its size is small,only about 4.5 nm.The catalytic performance is affected by the order of the reducing agent added.The performance of the catalyst pre-pared by adding the reductant at constant temperature of the solution is better than that prepared by adding it in the solu-tion at 0℃ and then heating it up to the reducing temperature.The structure of the catalyst was modified,and there was an increase in the conversion of ruthenium into the alloyed state and an increase in particle size with the ascension of heat treatment temperature.In addition,the stability of the catalyst was improved after heat treatment.
文摘It is reported for the first time that the Pt - Ru/C catalyst was prepared with the solid phase reaction method.Cyclic voltammetric measurements indicated that the anodic peak potential of ethanol at the electrode with the Pt - Ru/C catalyst prepared with the solid phase reaction method was0.54V and the peak current was100mA · cm -2 .While the anodic peak potential and peak current were0.64V and43mA · cm -2 respectively at the Pt - Ru/C catalyst prepared with the traditional liquid phase reaction method.It illustrated that the electrocatalytic activity of the Pt - Ru/C catalyst prepared with the solid phase reaction method was much better than that of the Pt - Ru/C catalyst prepared with the traditional liquid phase reaction method.It is because the Pt - Ru/C catalyst prepared with the solid phase reaction method is of low crystallinity and high dispersivity.
