Carbide-Derived Nanoporous Carbon and Novel Core−Shell Nanowires
TL;DR: Carbide-derived carbon (CDC) nanowires have been synthesized by the high-temperature treatment of small-diameter β-SiC whiskers with Cl2/H2.
Abstract: Carbide-derived carbon (CDC) nanowires (NWs) have been synthesized by the high-temperature treatment of small-diameter β-SiC whiskers with Cl2/H2 A variety of physical measurements indicate that Si was extracted by exposure to Cl2 and that the C in the carbon nanowires is primarily sp2-bonded From BET measurements, the specific surface area of these carbon nanowires is 13 × 103 m2/g and they contain a network of nanopores Nanoindentation measurements indicate that the SiC-derived C is not a stiff material, the elastic modulus being 50 ± 12 GPa High-temperature treatment of the CDC nanowires under an inert gas significantly increases the degree of graphitization In addition, partial extraction was used to obtain core−shell structures having a thin and also very high surface area CDC shell; further treatment at high temperature was used to produce graphitized carbon shell−crystalline SiC core NWs
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TL;DR: In this paper, a simple yet versatile method to simultaneously achieve the exfoliation and reduction of graphite oxide was proposed, which was shown to achieve specific capacitance values as high as 191 F/g with KOH electrolyte.
790 citations
TL;DR: This review separates the methods into vapor-phase synthesis, solution- phase synthesis, template-based synthesis, and other approaches, such as lithography, electrospinning, and assembly, used to form a variety of heterojunctions from different combinations of semiconductor, metal, carbon, and polymeric materials.
Abstract: There are a variety of methods for synthesizing or fabricating one-dimensional (1D) nanostructures containing heterojunctions between different materials. Here we review recent developments in the synthesis and fabrication of heterojunctions formed between different materials within the same 1D nanostructure or between different 1D nanostructures composed of different materials. Structures containing 1D nanoscale heterojunctions exhibit interesting chemistry as well as size, shape, and material-dependent properties that are unique when compared to single-component materials. This leads to new or enhanced properties or multifunctionality useful for a variety of applications in electronics, photonics, catalysis, and sensing, for example. This review separates the methods into vapor-phase synthesis, solution-phase synthesis, template-based synthesis, and other approaches, such as lithography, electrospinning, and assembly. These methods are used to form a variety of heterojunctions, including segmented, core/shell, branched, or crossed, from different combinations of semiconductor, metal, carbon, and polymeric materials.
279 citations
TL;DR: This review paper summarizes the synthesis of various carbon nanomaterials via the chemical vapor deposition (CVD) method, including fullerenes, carbon nanotubes (CNTs), carbon nanofibers (CNFs), graphene, carbide-derived carbon (CDC), carbon nano-onion (CNO) and MXenes.
Abstract: Carbon nanomaterials have been extensively used in many applications owing to their unique thermal, electrical and mechanical properties. One of the prime challenges is the production of these nanomaterials on a large scale. This review paper summarizes the synthesis of various carbon nanomaterials via the chemical vapor deposition (CVD) method. These carbon nanomaterials include fullerenes, carbon nanotubes (CNTs), carbon nanofibers (CNFs), graphene, carbide-derived carbon (CDC), carbon nano-onion (CNO) and MXenes. Furthermore, current challenges in the synthesis and application of these nanomaterials are highlighted with suggested areas for future research.
262 citations
Cites background from "Carbide-Derived Nanoporous Carbon a..."
...In addition, CDC also been synthesized from other carbide forms including bulk, nano‐wires [188], and whiskers [189]....
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TL;DR: The porosity of carbide-derived carbon varied based on the initial carbide's structure and chemistry, such as the layered ternary carbides, which resulted in larger mesopore volumes as compared to more isotropic carbides such as TaC.
109 citations
TL;DR: In this paper, a simple template/catalyst-free chemical vapor reaction approach using Si−SiO2 mixture powder and CH4 as raw materials at relatively low temperatures of 1250−1200 °C.
Abstract: Novel SiC/SiO2 chainlike nanostructures have been synthesized via a simple template/catalyst-free chemical vapor reaction approach using Si−SiO2 mixture powder and CH4 as raw materials at relatively low temperatures of 1250−1200 °C. Digital camera, stereoscope, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and infrared spectroscopy demonstrate that large-scale blue products have been obtained on graphite substrate; the samples are composed of chainlike nanostructures having lengths up to several tens of micrometers, diameters of 20−30 nm single crystalline β-SiC nanowires, and 80−100 nm amorphous SiO2 periodic wrapping spheres, possessing [111] preferred growth direction with a high density stacking faults and twin defects. We suppose the formation of the nanostructure is induced by two-stage VS growth mechanism, especially because the defects within SiC nanowires are the critical factors for the second-stage formati...
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TL;DR: A critical review of adsorption methods that are currently used in the characterization of ordered organic−inorganic nanocomposite materials is presented in this paper, where the authors compare and evaluate the available methods for mesopore size analysis.
Abstract: A critical review of adsorption methods that are currently used in the characterization of ordered organic−inorganic nanocomposite materials is presented, and the adsorption methodology that is potentially useful for this characterization, but has not yet been applied, is discussed. The ordered organic−inorganic nanocomposites include surface-functionalized ordered mesoporous materials (OMMs) with siliceous frameworks (synthesized either via postsynthesis surface modification or via direct co-condensation method), periodic mesoporous organosilicas, and surfactant-containing OMMs. This review covers the methods for determination of the specific surface area and pore volume. The available methods for mesopore size analysis are critically compared and evaluated, with special emphasis on the recent developments related to the application of advanced computational methods for studying adsorption in porous media and to the direct modeling of adsorption using highly ordered surface-functionalized OMMs as model a...
2,987 citations
TL;DR: In this article, a method for producing a nanoporous carbide-derived carbon composition with a tunable pore structure and a narrow pore size is presented. But the method is not suitable for the use of nanoporous carbon.
Abstract: The present invention provides a method for producing a nanoporous carbide-derived carbon composition with a tunable pore structure and a narrow pore size. Also provided are compositions prepared by the method.
629 citations
TL;DR: A continuous 300-Myr record of stomatal abundance from Fossil leaves of four genera of plants that are closely related to the present-day Ginkgo tree is presented, supporting the role of water vapour, methane and CO2 in greenhouse climate warming over the past 300 Myr.
Abstract: To understand better the link between atmospheric CO2 concentrations and climate over geological time, records of past CO2 are reconstructed from geochemical proxies1,2,3,4. Although these records have provided us with a broad picture of CO2 variation throughout the Phanerozoic eon (the past 544 Myr), inconsistencies and gaps remain that still need to be resolved. Here I present a continuous 300-Myr record of stomatal abundance from fossil leaves of four genera of plants that are closely related to the present-day Ginkgo tree. Using the known relationship between leaf stomatal abundance and growing season CO2 concentrations5,6, I reconstruct past atmospheric CO2 concentrations. For the past 300 Myr, only two intervals of low CO2 ( 2,000 p.p.m.v.) concentrations. These results are consistent with some reconstructions of past CO2 (refs 1, 2) and palaeotemperature records7, but suggest that CO2 reconstructions based on carbon isotope proxies3,4 may be compromised by episodic outbursts of isotopically light methane8,9. These results support the role of water vapour, methane and CO2 in greenhouse climate warming over the past 300 Myr.
374 citations
TL;DR: An overview of various nanoindentation techniques, various measurement options, and data analysis is presented in this article, where data on elastic-plastic deformation behavior, hardness, elastic modulus, scratch resistance, film-substrate adhesion, residual stresses, time-dependent creep and relaxation properties, fracture toughness, and fatigue are presented.
Abstract: To measure nanomechanical properties of surface layers of bulk materials and thin films, depth-sensing nanoindentation measurement techniques are used commonly. The nanoindentation apparatus continuously monitors the load and the position of the indenter relative to the surface of the specimen (depth of an indent or displacement) during the indentation process. Indentation experiments can be performed at a penetration depth of as low as about 5 nm. This chapter presents an overview of various nanoindentation techniques, various measurement options, and data analysis. Data on elastic-plastic deformation behavior, hardness, elastic modulus, scratch resistance, film-substrate adhesion, residual stresses, time-dependent creep and relaxation properties, fracture toughness, and fatigue are presented.
374 citations
TL;DR: In this article, the micropore size distributions determined from experimental isotherms using such models usually show minima near two and three molecular diameters effective pore width, regardless of the simulation method used.
269 citations