The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Dimitris Sioulas - One of the best experts on this subject based on the ideXlab platform.
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Characterization Technique for Evaluation of Razor Blade Steel
internal, 2017Co-Authors: Dimitris SioulasAbstract:analysis Objective of the Method For metals carbide grain size is very important metallographic measurement because it can be directly related
Guoxiu Wang - One of the best experts on this subject based on the ideXlab platform.
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3d Metal Carbide mesoporous carbon hybrid architecture as a new polysulfide reservoir for lithium sulfur batteries
Advanced Functional Materials, 2016Co-Authors: Weizhai Bao, W X Zhang, Xin Guo, Guoxiu WangAbstract:3D Metal Carbide@mesoporous carbon hybrid architecture (Ti3C2Tx@Meso-C, TX ≈ FxOy) is synthesised and applied as cathode material hosts for lithium-sulfur batteries. Exfoliated-Metal Carbide (Ti3C2Tx) nanosheets have high electronic conductivity and contain rich functional groups for effective trapping of polysulfides. Mesoporous carbon with a robust porous structure provides sufficient spaces for loading sulfur and effectively cushion the volumetric expansion of sulfur cathodes. Theoretical calculations have confirmed that Metal Carbide can absorb sulfur and polysulfides, therefore extending the cycling performance. The Ti3C2Tx@Meso-C/S cathodes have achieved a high capacity of 1225.8 mAh g−1 and more than 300 cycles at the C/2 current rate. The Ti3C2Tx@Meso-C hybrid architecture is a promising cathode host material for lithium-sulfur batteries.
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3D Metal Carbide@Mesoporous Carbon Hybrid Architecture as a New Polysulfide Reservoir for Lithium-Sulfur Batteries
Advanced Functional Materials, 2016Co-Authors: Weizhai Bao, Xin Guo, Wenxue Zhang, Guoxiu WangAbstract:3D Metal Carbide@mesoporous carbon hybrid architecture (Ti3C2Tx@Meso-C, TX ≈ FxOy) is synthesised and applied as cathode material hosts for lithium-sulfur batteries. Exfoliated-Metal Carbide (Ti3C2Tx) nanosheets have high electronic conductivity and contain rich functional groups for effective trapping of polysulfides. Mesoporous carbon with a robust porous structure provides sufficient spaces for loading sulfur and effectively cushion the volumetric expansion of sulfur cathodes. Theoretical calculations have confirmed that Metal Carbide can absorb sulfur and polysulfides, therefore extending the cycling performance. The Ti3C2Tx@Meso-C/S cathodes have achieved a high capacity of 1225.8 mAh g−1 and more than 300 cycles at the C/2 current rate. The Ti3C2Tx@Meso-C hybrid architecture is a promising cathode host material for lithium-sulfur batteries.
Francesc Illas - One of the best experts on this subject based on the ideXlab platform.
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room temperature methane capture and activation by ni clusters supported on tic 001 effects of Metal Carbide interactions on the cleavage of the c h bond
Journal of the American Chemical Society, 2019Co-Authors: Hector Prats, Francesc Viñes, Ramon A Gutierrez, Juan Jose Pinero, Stefan T Bromley, Pedro J Ramirez, Jose A Rodriguez, Francesc IllasAbstract:Methane is an extremely stable molecule, a major component of natural gas, and also one of the most potent greenhouse gases contributing to global warming. Consequently, the capture and activation of methane is a challenging and intensively studied topic. A major research goal is to find systems that can activate methane, even at low temperatures. Here, combining ultrahigh vacuum catalytic experiments, X-ray photoemission spectra, and accurate density functional theory (DFT) based calculations, we show that small Ni clusters dispersed on the (001) surface of TiC are able to capture and dissociate methane at room temperature. Our DFT calculations reveal that two-dimensional Ni clusters are responsible for this chemical transformation, confirming that the lability of the supported clusters appears to be a critical aspect in the strong adsorption of methane. A small energy barrier of 0.18 eV is predicted for CH4 dissociation into adsorbed methyl and atomic hydrogen species. In addition, the calculated reaction free energy profile at 300 K and 1 atm of CH4 shows no effective energy barriers in the system. Comparison with other reported systems which activate methane at room temperature, including oxide and zeolite-based materials, indicates that a different chemistry takes place on our Metal/Carbide system. The discovery of a Carbide-based surface able to activate methane at low temperatures paves the road for the design of new types of catalysts which can efficiently convert this hydrocarbon into other added-value chemicals, with implications in climate change mitigation.
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Brønsted–Evans–Polanyi Relationship for Transition Metal Carbide and Transition Metal Oxide Surfaces
Journal of Physical Chemistry C, 2013Co-Authors: Francesc Viñes, Aleksandra Vojvodic, Frank Abild-pedersen, Francesc IllasAbstract:The splitting of O2 on transition Metal, transition Metal Carbide, and transition Metal oxide surfaces is analyzed in the framework of Bronsted–Evans–Polanyi (BEP) relationships. It is shown that these hold for all three types of substrates, thus giving support to the idea of universality behind these useful relationships. Moreover, comparison of the BEP relationships for the three substrates suggests a significantly higher catalytic activity on Metal Carbides and rutile Metal oxides.
Markus Antonietti - One of the best experts on this subject based on the ideXlab platform.
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low cost Metal Carbide nanocrystals as binding and electrocatalytic sites for high performance li s batteries
Nano Letters, 2018Co-Authors: Fei Zhou, Xuan Luo, Bin Jiang, Hongbin Yao, Markus AntoniettiAbstract:Lithium sulfur (Li–S) batteries are considered as promising energy storage systems for the next generation of batteries due to their high theoretical energy densities and low cost. Much effort has been made to improve the practical energy densities and cycling stability of Li–S batteries via diverse designs of materials nanostructure. However, achieving simultaneously good rate capabilities and stable cycling of Li–S batteries is still challenging. Herein, we propose a strategy to utilize a dual effect of Metal Carbide nanoparticles decorated on carbon nanofibers (MC NPs-CNFs) to realize high rate performance, low hysteresis, and long cycling stability of Li–S batteries in one system. The adsorption experiments of lithium polysulfides (LiPS) to MC NPs and corresponding theoretical calculations demonstrate that LiPS are likely to be adsorbed and diffused on the surface of MC NPs because of their moderate chemical bonding. MC NPs turn out to have also an electrocatalytic role and accelerate electrochemical ...
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a general salt templating method to fabricate vertically aligned graphitic carbon nanosheets and their Metal Carbide hybrids for superior lithium ion batteries and water splitting
Journal of the American Chemical Society, 2015Co-Authors: Jixin Zhu, Markus Antonietti, Ken Sakaushi, Guylhaine Clavel, Menny Shalom, Timpatrick FellingerAbstract:The synthesis of vertically aligned functional graphitic carbon nanosheets (CNS) is challenging. Herein, we demonstrate a general approach for the fabrication of vertically aligned CNS and Metal Carbide@CNS composites via a facile salt templating induced self-assembly. The resulting vertically aligned CNS and Metal Carbide@CNS structures possess ultrathin walls, good electrical conductivity, strong adhesion, excellent structural robustness, and small particle size. In electrochemical energy conversion and storage such unique features are favorable for providing efficient mass transport as well as a large and accessible electroactive surface. The materials were tested as electrodes in a lithium ion battery and in electrochemical water splitting. The vertically aligned nanosheets exhibit remarkable lithium ion storage properties and, concurrently, excellent properties as electrocatalysts for hydrogen evolution.
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synthesis of crystalline Metal nitride and Metal Carbide nanostructures by sol gel chemistry
Nano Today, 2011Co-Authors: Cristina Giordano, Markus AntoniettiAbstract:Summary Attention toward nanosized Metal nitrides and Carbides is rapidly increasing thanks to their chemical characteristics that make them as valid and sustainable alternatives to noble Metals in catalysis and to air-sensitive Metals or oxides for applications under harsh conditions. They are mostly used as bulk phase or micron sized powders, due to an intrinsic difficulty to synthesize them as nanoparticles in a systematic and scalable fashion. However, nanosized Metal nitrides and Carbides could exhibit improved performances, e.g. in catalysis due to a higher surface area, and can be shaped more easily than corresponding larger grains for further specific applications. Recently, sol–gel chemistry has closed this gap and now enables the simple, cheap, and sustainable production of Metal nitride and Carbide nanoparticles. In the present review we give an overview on recent sol–gel based pathways for the synthesis of Metal nitride and Carbide nanoparticles, believing that a better knowledge of the potentialities of these still hardly touched materials stimulates research interest and applications.
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Metal Nitride and Metal Carbide Nanoparticles by a Soft Urea Pathway
Chemistry of Materials, 2009Co-Authors: Cristina Giordano, Christian Erpen, Weitang Yao, Bettina Milke, Markus AntoniettiAbstract:An easy way to produce several Metal nitrides and Metal Carbides at relatively low temperature (800 °C) using simple and mainly nontoxic precursor is presented. The procedure has been shown to be rather general and it was possible to synthesize TiN, VN, NbN, GaN, Mo2N, W2N, CrN, NbC(N), TiC(N), WC, Mo2C, and Cr3C2 nanoparticles using urea or close derivatives as both nitrogen or carbon source and the growth controlling system. In every case, a homogeneous gel-like starting product has been formed that is converted by calcination into the corresponding Metal nitride or Metal Carbide (including mixed species), without any preliminary treatments or further purifications. Samples were characterized by XRD, TEM, SEM, EA, and BET, and the products were shown to be well-defined and rather homogeneous.
Weizhai Bao - One of the best experts on this subject based on the ideXlab platform.
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3d Metal Carbide mesoporous carbon hybrid architecture as a new polysulfide reservoir for lithium sulfur batteries
Advanced Functional Materials, 2016Co-Authors: Weizhai Bao, W X Zhang, Xin Guo, Guoxiu WangAbstract:3D Metal Carbide@mesoporous carbon hybrid architecture (Ti3C2Tx@Meso-C, TX ≈ FxOy) is synthesised and applied as cathode material hosts for lithium-sulfur batteries. Exfoliated-Metal Carbide (Ti3C2Tx) nanosheets have high electronic conductivity and contain rich functional groups for effective trapping of polysulfides. Mesoporous carbon with a robust porous structure provides sufficient spaces for loading sulfur and effectively cushion the volumetric expansion of sulfur cathodes. Theoretical calculations have confirmed that Metal Carbide can absorb sulfur and polysulfides, therefore extending the cycling performance. The Ti3C2Tx@Meso-C/S cathodes have achieved a high capacity of 1225.8 mAh g−1 and more than 300 cycles at the C/2 current rate. The Ti3C2Tx@Meso-C hybrid architecture is a promising cathode host material for lithium-sulfur batteries.
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3D Metal Carbide@Mesoporous Carbon Hybrid Architecture as a New Polysulfide Reservoir for Lithium-Sulfur Batteries
Advanced Functional Materials, 2016Co-Authors: Weizhai Bao, Xin Guo, Wenxue Zhang, Guoxiu WangAbstract:3D Metal Carbide@mesoporous carbon hybrid architecture (Ti3C2Tx@Meso-C, TX ≈ FxOy) is synthesised and applied as cathode material hosts for lithium-sulfur batteries. Exfoliated-Metal Carbide (Ti3C2Tx) nanosheets have high electronic conductivity and contain rich functional groups for effective trapping of polysulfides. Mesoporous carbon with a robust porous structure provides sufficient spaces for loading sulfur and effectively cushion the volumetric expansion of sulfur cathodes. Theoretical calculations have confirmed that Metal Carbide can absorb sulfur and polysulfides, therefore extending the cycling performance. The Ti3C2Tx@Meso-C/S cathodes have achieved a high capacity of 1225.8 mAh g−1 and more than 300 cycles at the C/2 current rate. The Ti3C2Tx@Meso-C hybrid architecture is a promising cathode host material for lithium-sulfur batteries.