The Experts below are selected from a list of 1725 Experts worldwide ranked by ideXlab platform
Mingwei Chen - One of the best experts on this subject based on the ideXlab platform.
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three dimensional nanoporous co9s4p4 pentlandite as a bifunctional electrocatalyst for overall neutral water splitting
ACS Applied Materials & Interfaces, 2019Co-Authors: Yongwen Tan, Mingwei Chen, Pan Liu, Jiuhui Han, Chun Cheng, Min Luo, Kentaro WatanabeAbstract:Significant progress has recently been achieved in developing noble-metal-free catalysts for electrochemical water splitting in acidic and alkaline electrolytes. However, high-performance bifunctional catalysts toward both hydrogen evolution and oxygen oxidation reactions of neutral water have not been realized in spite of the technical importance for electrochemical hydrogen production in natural environments powered by renewable energy sources of wind, solar, and so on. Here, we report a nanoporous Co9S4P4 pentlandite with three-dimensional bicontinuous Nanoporosity for electrochemical water splitting in neutral solutions. The three-dimensional binder-free catalyst shows a negligible onset overpotential, low Tafel slope, and excellent poisoning tolerance for hydrogen evolution reaction, comparable to or even better than commercial Pt catalysts. Remarkably, the new catalyst also has excellent catalytic activities toward oxygen evolution and, hence, can be used as both anode and cathode for overall neutra...
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enhanced mechanical properties of nanocrystalline boron carbide by Nanoporosity and interface phases
Nature Communications, 2012Co-Authors: Madhav K Reddy, Mingwei Chen, Akihiko Hirata, Takeshi Fujita, Junjie Guo, Yutaka Shinoda, J P Singh, James W MccauleyAbstract:The mechanical properties of structural ceramics are characterized by a high degree of fragility and brittleness. This study demonstrates that, contrary to expectation, their brittleness can be reduced substantially by introducing nanopores together with weak grain boundary phases.
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nanoporous pdni bimetallic catalyst with enhanced electrocatalytic performances for electro oxidation and oxygen reduction reactions
Advanced Functional Materials, 2011Co-Authors: Luyang Chen, Akihiko Hirata, Akihisa Inoue, Takeshi Fujita, Wei Zhang, Mingwei ChenAbstract:A nanoporous PdNi (np-PdNi) bimetallic catalyst fabricated by electrochemically dealloying a Pd20Ni80 alloy in an acid solution is reported. Residual Ni in the nanoporous alloy can be controlled by tuning dealloying potentials and the electrocatalysis of the np-PdNi shows evident dependence on Ni concentrations. With ∼9 at.% Ni, the np-PdNi bimetallic catalyst presents superior electrocatalytic performances in methanol and formic acid electro-oxidation as well as oxygen reduction in comparison with commercial Pd/C and nanoporous Pd (np-Pd). The excellent electrocatalytic properties of the dealloyed np-PdNi bimetallic catalyst appear to arise from the combined effect of unique bicontinuous Nanoporosity and bimetallic synergistic action.
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unusually small electrical resistance of three dimensional nanoporous gold in external magnetic fields
Physical Review Letters, 2008Co-Authors: Takeshi Fujita, S. Maekawa, H Okada, K. Koyama, K. Watanabe, Mingwei ChenAbstract:We report the electric conductivity of three-dimensional (3D) nanoporous gold at low temperatures and in strong magnetic fields. It was found that topologically disordered 3D Nanoporosity leads to extremely low magnetoresistance and anomalous temperature dependence as the characteristic length of nanoporous gold is tuned to be $\ensuremath{\sim}14\text{ }\text{ }\mathrm{nm}$. This study underscores the importance of 3D topology of a nanostructure on electronic transport properties and has implications in manipulating electron transport by tailoring 3D nanostructures.
Akihiko Hirata - One of the best experts on this subject based on the ideXlab platform.
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Three-dimensional bicontinuous nanoporous materials by vapor phase dealloying.
Nature communications, 2018Co-Authors: Jiuhui Han, Zhili Wang, Hao Wang, Pan Liu, Fan Zhang, Chun Cheng, Linghan Chen, Akihiko HirataAbstract:Three-dimensional bicontinuous open (3DBO) Nanoporosity has been recognized as an important nanoarchitecture for catalysis, sensing, and energy storage. Dealloying, i.e., selectively removing a component from an alloy, is an efficient way to fabricate nanoporous materials. However, current electrochemical and liquid-metal dealloying methods can only be applied to a limited number of alloys and usually require an etching process with chemical waste. Here, we report a green and universal approach, vapor-phase dealloying, to fabricate nanoporous materials by utilizing the vapor pressure difference between constituent elements in an alloy to selectively remove a component with a high partial vapor pressure for 3DBO Nanoporosity. We demonstrate that extensive elements, regardless of chemical activity, can be fabricated as nanoporous materials with tunable pore sizes. Importantly, the evaporated components can be fully recovered. This environmentally friendly dealloying method paves a way to fabricate 3DBO nanoporous materials for a wide range of structural and functional applications.
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Three-dimensional bicontinuous nanoporous materials by vapor phase dealloying
Nature Publishing Group, 2018Co-Authors: Jiuhui Han, Zhili Wang, Hao Wang, Pan Liu, Fan Zhang, Chun Cheng, Linghan Chen, Akihiko HirataAbstract:Conventional dealloying methods to produce bicontinuous open nanoporous structures for catalysis are limited to very few alloys and produce chemical waste. Here, the authors develop a green process, vapor-phase dealloying, to selectively remove high partial vapor pressure components and create Nanoporosity in a wide range of alloys
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versatile nanoporous bimetallic phosphides towards electrochemical water splitting
Energy and Environmental Science, 2016Co-Authors: Akihiko Hirata, Hao Wang, Pan Liu, Chun Cheng, Yongwen Tan, Yuhao Shen, Takeshi FujitaAbstract:Alloying is an important approach to improving catalytic activities and realizing new functions of heterogeneous catalysts, which has extensively been employed in fabricating noble metal based bimetallic catalysts. However, it is technically unviable in the synthesis of alloyed transition metal compounds, which are emerging as important catalysts for water splitting, in a controllable manner using conventional wet chemical methods. Here we report nanoporous bimetallic (Co1−xFex)2P phosphides with controllable compositions and tuneable porosity, which are fabricated by the combination of metallurgical alloy design and electrochemical etching. By tailoring the Co/Fe ratios and Nanoporosity, the bimetallic phosphides exhibit versatile catalytic activities towards HER and OER in acidic and basic electrolytes. As both the cathode and the anode of an electrolyser, nanoporous (Co0.52Fe0.48)2P shows an outstanding performance in water electrolysis, comparable to the commercial electrolyser with paired Pt/C and IrO2 catalysts.
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enhanced mechanical properties of nanocrystalline boron carbide by Nanoporosity and interface phases
Nature Communications, 2012Co-Authors: Madhav K Reddy, Mingwei Chen, Akihiko Hirata, Takeshi Fujita, Junjie Guo, Yutaka Shinoda, J P Singh, James W MccauleyAbstract:The mechanical properties of structural ceramics are characterized by a high degree of fragility and brittleness. This study demonstrates that, contrary to expectation, their brittleness can be reduced substantially by introducing nanopores together with weak grain boundary phases.
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nanoporous pdni bimetallic catalyst with enhanced electrocatalytic performances for electro oxidation and oxygen reduction reactions
Advanced Functional Materials, 2011Co-Authors: Luyang Chen, Akihiko Hirata, Akihisa Inoue, Takeshi Fujita, Wei Zhang, Mingwei ChenAbstract:A nanoporous PdNi (np-PdNi) bimetallic catalyst fabricated by electrochemically dealloying a Pd20Ni80 alloy in an acid solution is reported. Residual Ni in the nanoporous alloy can be controlled by tuning dealloying potentials and the electrocatalysis of the np-PdNi shows evident dependence on Ni concentrations. With ∼9 at.% Ni, the np-PdNi bimetallic catalyst presents superior electrocatalytic performances in methanol and formic acid electro-oxidation as well as oxygen reduction in comparison with commercial Pd/C and nanoporous Pd (np-Pd). The excellent electrocatalytic properties of the dealloyed np-PdNi bimetallic catalyst appear to arise from the combined effect of unique bicontinuous Nanoporosity and bimetallic synergistic action.
Takeshi Fujita - One of the best experts on this subject based on the ideXlab platform.
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versatile nanoporous bimetallic phosphides towards electrochemical water splitting
Energy and Environmental Science, 2016Co-Authors: Akihiko Hirata, Hao Wang, Pan Liu, Chun Cheng, Yongwen Tan, Yuhao Shen, Takeshi FujitaAbstract:Alloying is an important approach to improving catalytic activities and realizing new functions of heterogeneous catalysts, which has extensively been employed in fabricating noble metal based bimetallic catalysts. However, it is technically unviable in the synthesis of alloyed transition metal compounds, which are emerging as important catalysts for water splitting, in a controllable manner using conventional wet chemical methods. Here we report nanoporous bimetallic (Co1−xFex)2P phosphides with controllable compositions and tuneable porosity, which are fabricated by the combination of metallurgical alloy design and electrochemical etching. By tailoring the Co/Fe ratios and Nanoporosity, the bimetallic phosphides exhibit versatile catalytic activities towards HER and OER in acidic and basic electrolytes. As both the cathode and the anode of an electrolyser, nanoporous (Co0.52Fe0.48)2P shows an outstanding performance in water electrolysis, comparable to the commercial electrolyser with paired Pt/C and IrO2 catalysts.
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monolayer mos2 films supported by 3d nanoporous metals for high efficiency electrocatalytic hydrogen production
Advanced Materials, 2014Co-Authors: Yongwen Tan, Luyang Chen, Pan Liu, Jiuhui Han, Weitao Cong, Yoshikazu Ito, Xianwei Guo, Z Tang, Takeshi FujitaAbstract:The "edge-free" monolayer MoS2 films supported by 3D nanoporous gold show high catalytic activities towards hydrogen evolution reaction (HER), originating from large out-of-plane strains that are geometrically required to manage the 3D curvature of bicontinuous Nanoporosity. The large lattice bending leads to local semiconductor-to-metal transition of 2H MoS2 and the formation of catalytically active sites for HER.
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enhanced mechanical properties of nanocrystalline boron carbide by Nanoporosity and interface phases
Nature Communications, 2012Co-Authors: Madhav K Reddy, Mingwei Chen, Akihiko Hirata, Takeshi Fujita, Junjie Guo, Yutaka Shinoda, J P Singh, James W MccauleyAbstract:The mechanical properties of structural ceramics are characterized by a high degree of fragility and brittleness. This study demonstrates that, contrary to expectation, their brittleness can be reduced substantially by introducing nanopores together with weak grain boundary phases.
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nanoporous pdni bimetallic catalyst with enhanced electrocatalytic performances for electro oxidation and oxygen reduction reactions
Advanced Functional Materials, 2011Co-Authors: Luyang Chen, Akihiko Hirata, Akihisa Inoue, Takeshi Fujita, Wei Zhang, Mingwei ChenAbstract:A nanoporous PdNi (np-PdNi) bimetallic catalyst fabricated by electrochemically dealloying a Pd20Ni80 alloy in an acid solution is reported. Residual Ni in the nanoporous alloy can be controlled by tuning dealloying potentials and the electrocatalysis of the np-PdNi shows evident dependence on Ni concentrations. With ∼9 at.% Ni, the np-PdNi bimetallic catalyst presents superior electrocatalytic performances in methanol and formic acid electro-oxidation as well as oxygen reduction in comparison with commercial Pd/C and nanoporous Pd (np-Pd). The excellent electrocatalytic properties of the dealloyed np-PdNi bimetallic catalyst appear to arise from the combined effect of unique bicontinuous Nanoporosity and bimetallic synergistic action.
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unusually small electrical resistance of three dimensional nanoporous gold in external magnetic fields
Physical Review Letters, 2008Co-Authors: Takeshi Fujita, S. Maekawa, H Okada, K. Koyama, K. Watanabe, Mingwei ChenAbstract:We report the electric conductivity of three-dimensional (3D) nanoporous gold at low temperatures and in strong magnetic fields. It was found that topologically disordered 3D Nanoporosity leads to extremely low magnetoresistance and anomalous temperature dependence as the characteristic length of nanoporous gold is tuned to be $\ensuremath{\sim}14\text{ }\text{ }\mathrm{nm}$. This study underscores the importance of 3D topology of a nanostructure on electronic transport properties and has implications in manipulating electron transport by tailoring 3D nanostructures.
Ling Zang - One of the best experts on this subject based on the ideXlab platform.
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diffusion controlled detection of trinitrotoluene interior nanoporous structure and low highest occupied molecular orbital level of building blocks enhance selectivity and sensitivity
Journal of the American Chemical Society, 2012Co-Authors: Yanke Che, Dustin E Gross, Helin Huang, Dongjiang Yang, Xiaomei Yang, Emre H Discekici, Zheng Xue, Huijun Zhao, Jeffrey S Moore, Ling ZangAbstract:Development of simple, cost-effective, and sensitive fluorescence-based sensors for explosives implies broad applications in homeland security, military operations, and environmental and industrial safety control. However, the reported fluorescence sensory materials (e.g., polymers) usually respond to a class of analytes (e.g., nitroaromatics), rather than a single specific target. Hence, the selective detection of trace amounts of trinitrotoluene (TNT) still remains a big challenge for fluorescence-based sensors. Here we report the selective detection of TNT vapor using the nanoporous fibers fabricated by self-assembly of carbazole-based macrocyclic molecules. The Nanoporosity allows for time-dependent diffusion of TNT molecules inside the material, resulting in further fluorescence quenching of the material after removal from the TNT vapor source. Under the same testing conditions, other common nitroaromatic explosives and oxidizing reagents did not demonstrate this postexposure fluorescence quenching; rather, a recovery of fluorescence was observed. The postexposure fluorescence quenching as well as the sensitivity is further enhanced by lowering the highest occupied molecular orbital (HOMO) level of the nanofiber building blocks. This in turn reduces the affinity for oxygen, thus allocating more interaction sites for TNT. Our results present a simple and novel way to achieve detection selectivity for TNT by creating Nanoporosity and tuning molecular electronic structure, which when combined may be applied to other fluorescence sensor materials for selective detection of vapor analytes.
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diffusion controlled detection of trinitrotoluene interior nanoporous structure and low highest occupied molecular orbital level of building blocks enhance selectivity and sensitivity
Journal of the American Chemical Society, 2012Co-Authors: Yanke Che, Dustin E Gross, Helin Huang, Dongjiang Yang, Xiaomei Yang, Emre H Discekici, Zheng Xue, Huijun Zhao, Jeffrey S Moore, Ling ZangAbstract:Development of simple, cost-effective, and sensitive fluorescence-based sensors for explosives implies broad applications in homeland security, military operations, and environmental and industrial safety control. However, the reported fluorescence sensory materials (e.g., polymers) usually respond to a class of analytes (e.g., nitroaromatics), rather than a single specific target. Hence, the selective detection of trace amounts of trinitrotoluene (TNT) still remains a big challenge for fluorescence-based sensors. Here we report the selective detection of TNT vapor using the nanoporous fibers fabricated by self-assembly of carbazole-based macrocyclic molecules. The Nanoporosity allows for time-dependent diffusion of TNT molecules inside the material, resulting in further fluorescence quenching of the material after removal from the TNT vapor source. Under the same testing conditions, other common nitroaromatic explosives and oxidizing reagents did not demonstrate this postexposure fluorescence quenching; ...
Katsumi Kaneko - One of the best experts on this subject based on the ideXlab platform.
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conductive and mesoporous single wall carbon nanohorn organic aerogel composites
Langmuir, 2007Co-Authors: Daisuke Noguchi, Cheolmin Yang, Hirofumi Kanoh, Masako Yudasaka, Sumio Iijima, Hideki Tanaka, Katsumi KanekoAbstract:Conductive and mesoporous single-wall carbon nanohorn/resorcinol−formaldehyde aerogel composites were fabricated by embedding organic resorcinol−formaldehyde aerogels with single-wall carbon nanohorns. Samples were characterized with transmission electron microscopy, field emission scanning electron microscopy, nitrogen adsorption at 77 K, and direct-current volume electrical conductivity measurement. It was demonstrated that these composites have important properties, such as controllable Nanoporosity and high electrical conductivity in the range of 10-4 S m-1, which enables many potential applications.
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preparing a magnetically responsive single wall carbon nanohorn colloid by anchoring magnetite nanoparticles
Journal of Physical Chemistry B, 2006Co-Authors: Shigenori Utsumi, Koki Urita, Hirofumi Kanoh, Kazutomo Suenaga, Masako Yudasaka, Sumio Iijima, Katsumi KanekoAbstract:A single-wall carbon nanohorn (SWNH) colloid was made to be magnetically responsive by anchoring magnetite nanoparticles prepared by the homogeneous mixing of FeCl2−FeCl3 and NaOH solutions. Transmission electron microscopy observation showed the high dispersion of magnetite particles of 2−9 nm on the surface of the SWNH colloid, coinciding with the broad X-ray diffraction peaks of the magnetites. The magnetization measurements showed that the magnetite nanoparticles-anchored SWNH (mag-SWNH) colloid has the hybrid property of ferrimagnetism and superparamagnetism. It was demonstrated that mag-SWNH colloid dispersed in water by sonication responded to an external magnetic field, gathering toward a magnet. N2 adsorption experiments showed the high Nanoporosity of mag-SWNHs and that magnetite nanoparticles were preferably anchored at “nanowindow” sites and the entrance sites of interstitial pores. This magnetically responsive SWNH colloid should contribute to the field of drug delivery.
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opening mechanism of internal Nanoporosity of single wall carbon nanohorn
Journal of Physical Chemistry B, 2005Co-Authors: Shigenori Utsumi, Jin Miyawaki, Takaomi Itoi, Nobuyuki Ichikuni, Hirofumi Kanoh, Yoshiyuki Hattori, Masako Yudasaka, Sumio Iijima, Hideki Tanaka, Katsumi KanekoAbstract:Single-wall carbon nanohorn (SWNH), which is a tubular particle with a cone cap, was oxidized in an oxygen flow at various temperatures. N2 adsorption at 77 K, thermogravimetry (TG), differential thermal analysis (DTA), transmission electron microscopy, and Raman spectroscopy measurements were carried out on the oxidized SWNHs. The specific surface area of the oxidized SWNHs can be controlled by oxidation temperature, giving the maximum value of 1420 m2/g. The pore size distribution by the BJH method and the comparison plot of the N2 adsorption isotherms of SWNH oxidized at different temperatures against that of as-grown SWNH revealed the minimum oxidation temperature for opening internal nanopores. TG-DTA analyses determined the components of as-grown SWNH: amorphous carbon 2.5 wt %, defective carbon at the cone part 15 wt %, tubular carbon 70 wt %, and graphitic carbon 12 wt %. These systematic analyses provided the exact internal nanopore volume of 0.49 mL/g for pure SWNH particles.
