The Experts below are selected from a list of 12096 Experts worldwide ranked by ideXlab platform
Xiue Jiang - One of the best experts on this subject based on the ideXlab platform.
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facile preparation of porous carbon nanosheets without template and their excellent Electrocatalytic Property
ACS Applied Materials & Interfaces, 2013Co-Authors: Yichen Wang, Xiue JiangAbstract:A novel porous carbon nanosheet was successfully fabricated by a one-step annealing process with folic acid as the carbon source in the absence of any other reagents or templates. The product exhibited a large specific surface area and good porosity. Meanwhile, the carbon nanosheets as a metal-free catalyst showed a high Electrocatalytic activity toward the oxygen reduction reaction (ORR) in alkaline solution, including superior onset and reduction potentials as well as a nearly four-electron pathway.
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facile green synthesis of nitrogen doped carbon supported ultrafine silver catalyst with enhanced Electrocatalytic Property
Electrochimica Acta, 2013Co-Authors: Yichen Wang, Haibin Wu, Xiue JiangAbstract:We have demonstrated a facile and green strategy to synthesize ultrafine silver nanoparticles monodispersed on N-doped three-dimensional carbon nanocloud surfaces without any toxic reagent. Folic acid was employed as the carbon precursor for forming N-doped carbon nanoflakes by a hydrothermal method. The as-prepared products can serve as both reducing agent and substrate, on which a high density of ultrafine Ag nanocrystals is stably grown in a homogeneously dispersive state spontaneously at room temperature. A feasible synthesis mechanism has been proposed by characterization of carbon precursor, nanomaterials composited without and with silver nanoparticles. It was found that the ethylenic and oxygenated groups led to the reduction process. The nanohybrids showed an enhanced Electrocatalytic activity toward oxygen reduction reaction (ORR) in alkaline solution via a four-electron pathway. The catalyst also exhibited strong duration of methanol and good stability compared to commercial Pt/C catalysts. (C) 2013 Elsevier Ltd. All rights reserved.
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facile green synthesis of nitrogen doped carbon supported ultrafine silver catalyst with enhanced Electrocatalytic Property
Electrochimica Acta, 2013Co-Authors: Yichen Wang, Xiue JiangAbstract:Abstract We have demonstrated a facile and green strategy to synthesize ultrafine silver nanoparticles monodispersed on N-doped three-dimensional carbon nanocloud surfaces without any toxic reagent. Folic acid was employed as the carbon precursor for forming N-doped carbon nanoflakes by a hydrothermal method. The as-prepared products can serve as both reducing agent and substrate, on which a high density of ultrafine Ag nanocrystals is stably grown in a homogeneously dispersive state spontaneously at room temperature. A feasible synthesis mechanism has been proposed by characterization of carbon precursor, nanomaterials composited without and with silver nanoparticles. It was found that the ethylenic and oxygenated groups led to the reduction process. The nanohybrids showed an enhanced Electrocatalytic activity toward oxygen reduction reaction (ORR) in alkaline solution via a four-electron pathway. The catalyst also exhibited strong duration of methanol and good stability compared to commercial Pt/C catalysts.
Yichen Wang - One of the best experts on this subject based on the ideXlab platform.
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facile preparation of porous carbon nanosheets without template and their excellent Electrocatalytic Property
ACS Applied Materials & Interfaces, 2013Co-Authors: Yichen Wang, Xiue JiangAbstract:A novel porous carbon nanosheet was successfully fabricated by a one-step annealing process with folic acid as the carbon source in the absence of any other reagents or templates. The product exhibited a large specific surface area and good porosity. Meanwhile, the carbon nanosheets as a metal-free catalyst showed a high Electrocatalytic activity toward the oxygen reduction reaction (ORR) in alkaline solution, including superior onset and reduction potentials as well as a nearly four-electron pathway.
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facile green synthesis of nitrogen doped carbon supported ultrafine silver catalyst with enhanced Electrocatalytic Property
Electrochimica Acta, 2013Co-Authors: Yichen Wang, Haibin Wu, Xiue JiangAbstract:We have demonstrated a facile and green strategy to synthesize ultrafine silver nanoparticles monodispersed on N-doped three-dimensional carbon nanocloud surfaces without any toxic reagent. Folic acid was employed as the carbon precursor for forming N-doped carbon nanoflakes by a hydrothermal method. The as-prepared products can serve as both reducing agent and substrate, on which a high density of ultrafine Ag nanocrystals is stably grown in a homogeneously dispersive state spontaneously at room temperature. A feasible synthesis mechanism has been proposed by characterization of carbon precursor, nanomaterials composited without and with silver nanoparticles. It was found that the ethylenic and oxygenated groups led to the reduction process. The nanohybrids showed an enhanced Electrocatalytic activity toward oxygen reduction reaction (ORR) in alkaline solution via a four-electron pathway. The catalyst also exhibited strong duration of methanol and good stability compared to commercial Pt/C catalysts. (C) 2013 Elsevier Ltd. All rights reserved.
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facile green synthesis of nitrogen doped carbon supported ultrafine silver catalyst with enhanced Electrocatalytic Property
Electrochimica Acta, 2013Co-Authors: Yichen Wang, Xiue JiangAbstract:Abstract We have demonstrated a facile and green strategy to synthesize ultrafine silver nanoparticles monodispersed on N-doped three-dimensional carbon nanocloud surfaces without any toxic reagent. Folic acid was employed as the carbon precursor for forming N-doped carbon nanoflakes by a hydrothermal method. The as-prepared products can serve as both reducing agent and substrate, on which a high density of ultrafine Ag nanocrystals is stably grown in a homogeneously dispersive state spontaneously at room temperature. A feasible synthesis mechanism has been proposed by characterization of carbon precursor, nanomaterials composited without and with silver nanoparticles. It was found that the ethylenic and oxygenated groups led to the reduction process. The nanohybrids showed an enhanced Electrocatalytic activity toward oxygen reduction reaction (ORR) in alkaline solution via a four-electron pathway. The catalyst also exhibited strong duration of methanol and good stability compared to commercial Pt/C catalysts.
Hong Yang - One of the best experts on this subject based on the ideXlab platform.
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synthesis and oxygen reduction Electrocatalytic Property of platinum hollow and platinum on silver nanoparticles
Chemistry of Materials, 2010Co-Authors: Zhenmeng Peng, Jianbo Wu, Hong YangAbstract:Pt-on-Ag bimetallic nanoparticles were prepared based on a heterogeneous nucleation and growth method. Interestingly, platinum hollow nanoparticles could be obtained by selectively removing the silver cores from Pt-on-Ag nanoparticles. High-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray (EDX) analysis with a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM), and X-ray diffraction (XRD) were used to characterize these nanostructures. The observation that Pt hollows can be produced from Pt-on-Ag nanoparticles through the dissolution of Ag metal cores indicates that particle-on-particle nanodendrites were most likely derived from the products formed through the Stranski−Krastanov (SK) growth. The carbon-supported Pt hollow catalysts, which possessed much higher catalytic activity in oxygen reduction reaction (ORR) than the Pt-on-Ag nanoparticles, were also better than a commercial Pt catalyst (E-tek, 20% Pt). The nanometer-sized textures of th...
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Synthesis and Electrocatalytic Property of cubic and spherical nanoparticles of cobalt platinum alloys
Frontiers of Chemical Engineering in China, 2010Co-Authors: Xiaowei Teng, Hong YangAbstract:This paper describes the morphological control and Electrocatalytic Property of CoPt nanoparticles. Both cubic and spherical CoPt nanoparticles were made using cobalt carbonyl and platinum 2,4-pentanedionate under different reaction temperatures in the presence of capping reagents, which included adamantanecarboxylic acid and hexadecylamine. Effects of heterogeneous species on shape of the CoPt nanoparticles were examined by replacing cobalt carbonyl with silver acetylacetonate. Our results suggest that the formation of different shapes of CoPt particles could be attributed to the affinity between cobalt and platinum, and the effects of capping agents. The size and shape dependent Electrocatalytic properties of these nanoparticles were examined based on the direct methanol oxidation reaction.
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synthesis and oxygen reduction Electrocatalytic Property of pt on pd bimetallic heteronanostructures
Journal of the American Chemical Society, 2009Co-Authors: Zhenmeng Peng, Hong YangAbstract:Platinum-on-palladium bimetallic heterogeneous nanostructures were prepared using a sequential synthetic method, in which 3-nm Pt particles grew on the surfaces of 5-nm Pd nanoparticles. Electrochemical study of carbon-supported Pt-on-Pd heteronanostructures shows not only enhancement in Electrocatalytic activity for oxygen reduction reaction (ORR) but also much improved stability in comparison to a commercial platinum catalyst (E-TEK, 20 wt % Pt, diameter: 2.5 nm). The greatly suppressed hydroxyl adsorption on active sites by introducing Pd was attributed to the enhanced activity, while the retention of active surface area, morphology, and composition because of the large overall bimetallic particle size and unique architectures could be the key factors for the much improved stability over 30 000 cycles. Our work shows heterogeneous platinum-on-metal bimetallic nanostructures offer new opportunities to the design of hierarchically ordered multifunctional fuel cell catalysts.
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designer platinum nanoparticles control of shape composition in alloy nanostructure and Electrocatalytic Property
Nano Today, 2009Co-Authors: Zhenmeng Peng, Hong YangAbstract:Summary Recent advances in the design and preparation of platinum-based nanostructures and their applications as electrocatalysts for low-temperature fuel cells are reviewed. Discussions are focused on the fundamental understanding and new experimental designs in the control of shape, composition and nanoscale structure of platinum and its alloy particles in colloidal systems. We explain the formation of various heteronanostructures using the Frank–van der Merwe (FM), Volmer–Weber (VW) and Stranski–Krastanov (SK) growth modes. Phenomena that exist in nanometer-sized regime, such as the disappearance of miscibility gaps for certain platinum alloys are given special attentions. The relationship between electronic structure or surface atomic arrangement and catalytic properties of platinum-based nanostructures is discussed.
Lin Zhang - One of the best experts on this subject based on the ideXlab platform.
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decoration of ultrafine platinum ruthenium particles on functionalized graphene sheets in supercritical fluid and their Electrocatalytic Property
Journal of Nanoparticle Research, 2012Co-Authors: Jian Zhao, Hao Xue, Lin ZhangAbstract:We report a simple and effective supercritical fluid route to uniformly load ultrafine metal nanoparticles on the hydrophobic surfaces of graphene sheets. In the presence of supercritical carbon dioxide, PtRu alloy nanoparticles are decorated evenly on functionalized graphene sheets (FGSs) upon the reduction of organic platinum (II) and ruthenium (III) precursors, and its application as an electrocatalyst for methanol oxidation is studied. Transmission electron microscopy observation shows that highly dispersed PtRu metallic nanoparticles with an average size of about 3.11 nm are uniformly and densely distributed on the hydrophobic surface of FGSs. X-ray diffraction patterns demonstrate that the particles had a face-centered cubic crystal structure, and X-ray photoelectron spectroscopy analysis indicates the existence of zero-valence metals. Compared with the widely used Vulcan XC-72 carbon black, the PtRu/FGS composites exhibit superior catalytic activity and stability for methanol oxidation. The huge surface area of graphene and uniform distribution of nanosized metal particles are two critical factors for the significantly enhanced Electrocatalytic efficiency. The findings suggest that the supercritical fluid method is highly efficient in preparing graphene-supported metallic catalysts, and FGSs serve as a favorable Electrocatalytic carrier for direct methanol fuel cells.
Zhenmeng Peng - One of the best experts on this subject based on the ideXlab platform.
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shape enhanced ammonia electro oxidation Property of a cubic platinum nanocrystal catalyst prepared by surfactant free synthesis
Journal of Materials Chemistry, 2013Co-Authors: Changlin Zhang, Sang Youp Hwang, Zhenmeng PengAbstract:Carbon-supported cubic platinum nanocrystals (PtNC/C) with clean surfaces have been prepared using a facile, scalable, and surfactant-free method, in which impregnated Pt precursors on a C support are reduced in a mixture of hydrogen and carbon monoxide. The influence of synthesis parameters on the morphology of final products is investigated. The cubic Pt/C is studied for the catalytic Property in electro-oxidation of ammonia. It exhibits a significant shape effect, with much improved activity and better durability compared to commercial Pt/C and Pt particles with other morphologies. The observed shape dependency of Electrocatalytic Property is attributed to changes in electronic/geometric structures and varying coverage of Nad, a poisoning species, on different Pt surfaces.
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synthesis and oxygen reduction Electrocatalytic Property of platinum hollow and platinum on silver nanoparticles
Chemistry of Materials, 2010Co-Authors: Zhenmeng Peng, Jianbo Wu, Hong YangAbstract:Pt-on-Ag bimetallic nanoparticles were prepared based on a heterogeneous nucleation and growth method. Interestingly, platinum hollow nanoparticles could be obtained by selectively removing the silver cores from Pt-on-Ag nanoparticles. High-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray (EDX) analysis with a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM), and X-ray diffraction (XRD) were used to characterize these nanostructures. The observation that Pt hollows can be produced from Pt-on-Ag nanoparticles through the dissolution of Ag metal cores indicates that particle-on-particle nanodendrites were most likely derived from the products formed through the Stranski−Krastanov (SK) growth. The carbon-supported Pt hollow catalysts, which possessed much higher catalytic activity in oxygen reduction reaction (ORR) than the Pt-on-Ag nanoparticles, were also better than a commercial Pt catalyst (E-tek, 20% Pt). The nanometer-sized textures of th...
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synthesis and oxygen reduction Electrocatalytic Property of pt on pd bimetallic heteronanostructures
Journal of the American Chemical Society, 2009Co-Authors: Zhenmeng Peng, Hong YangAbstract:Platinum-on-palladium bimetallic heterogeneous nanostructures were prepared using a sequential synthetic method, in which 3-nm Pt particles grew on the surfaces of 5-nm Pd nanoparticles. Electrochemical study of carbon-supported Pt-on-Pd heteronanostructures shows not only enhancement in Electrocatalytic activity for oxygen reduction reaction (ORR) but also much improved stability in comparison to a commercial platinum catalyst (E-TEK, 20 wt % Pt, diameter: 2.5 nm). The greatly suppressed hydroxyl adsorption on active sites by introducing Pd was attributed to the enhanced activity, while the retention of active surface area, morphology, and composition because of the large overall bimetallic particle size and unique architectures could be the key factors for the much improved stability over 30 000 cycles. Our work shows heterogeneous platinum-on-metal bimetallic nanostructures offer new opportunities to the design of hierarchically ordered multifunctional fuel cell catalysts.
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designer platinum nanoparticles control of shape composition in alloy nanostructure and Electrocatalytic Property
Nano Today, 2009Co-Authors: Zhenmeng Peng, Hong YangAbstract:Summary Recent advances in the design and preparation of platinum-based nanostructures and their applications as electrocatalysts for low-temperature fuel cells are reviewed. Discussions are focused on the fundamental understanding and new experimental designs in the control of shape, composition and nanoscale structure of platinum and its alloy particles in colloidal systems. We explain the formation of various heteronanostructures using the Frank–van der Merwe (FM), Volmer–Weber (VW) and Stranski–Krastanov (SK) growth modes. Phenomena that exist in nanometer-sized regime, such as the disappearance of miscibility gaps for certain platinum alloys are given special attentions. The relationship between electronic structure or surface atomic arrangement and catalytic properties of platinum-based nanostructures is discussed.