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C, Volume 2, Issue 3 (September 2016)

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Research

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Open AccessFeature PaperArticle Thermochemistry of a Biomimetic and Rubisco-Inspired CO2 Capture System from Air
C 2016, 2(3), 18; doi:10.3390/c2030018
Received: 1 May 2016 / Revised: 28 May 2016 / Accepted: 21 June 2016 / Published: 1 July 2016
Cited by 1 | PDF Full-text (2931 KB) | HTML Full-text | XML Full-text
Abstract
In theoretical studies of chemical reactions the reaction thermochemistry is usually reported for the stoichiometric reaction at standard conditions (ΔG°, ΔH°, ΔS°). We describe the computation of the equilibrium concentrations of the CO2-adducts for the
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In theoretical studies of chemical reactions the reaction thermochemistry is usually reported for the stoichiometric reaction at standard conditions (ΔG°, ΔH°, ΔS°). We describe the computation of the equilibrium concentrations of the CO2-adducts for the general capture reaction CO2 + Capture System ⇆ CO2-adduct (GCR) and the rubisco-type capture reaction CO2 + Capture System ⇆ CO2-adduct + H2O (RCR) with consideration of the reaction CO2(g) ⇆ CO2(aq) via Henry’s law. The resulting equations are evaluated and graphically illustrated as a function of atmospheric CO2 concentration and as a function of temperature. The equations were applied to the thermochemistry of small molecule rubisco-model reactions and series of additional model reactions to illustrate the range of the Gibbs free enthalpy for the effective reversible capture and of the reaction entropy for economic CO2 release at elevated temperature. A favorable capture of free enthalpy is of course a design necessity, but not all exergonic reactions are suitable CO2 capture systems. Successful CO2 capture systems must allow for effective release as well, and this feature is controlled by the reaction entropy. The principle of using a two-pronged capture system to ensure a large negative capture entropy is explained and highlighted in the graphical abstract. It is hoped that the presentation of the numerical examples provides useful guidelines for the design of more efficient capture systems. Full article
(This article belongs to the Special Issue Materials and Processes for Carbon Dioxide Capture and Utilisation)
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Open AccessArticle Carbon Nanofibers Grown on Large Woven Cloths: Morphology and Properties of Growth
C 2016, 2(3), 19; doi:10.3390/c2030019
Received: 26 April 2016 / Revised: 6 June 2016 / Accepted: 13 June 2016 / Published: 4 July 2016
Cited by 2 | PDF Full-text (8832 KB) | HTML Full-text | XML Full-text
Abstract
The morphology and chemical composition of carbon nanofibers in situ grown on a large carbon-fiber woven fabric are studied using SEM measurements, X-ray Diffraction, X-ray Flourescence, and X-ray Photoelectron Spectroscopy. Results show that nanofibers can have a density and a morphology potentially advantageous
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The morphology and chemical composition of carbon nanofibers in situ grown on a large carbon-fiber woven fabric are studied using SEM measurements, X-ray Diffraction, X-ray Flourescence, and X-ray Photoelectron Spectroscopy. Results show that nanofibers can have a density and a morphology potentially advantageous for application in polymer-matrix composites. The fiber surface functional groups significantly change after the growth and this also potentially provides a better interfacial adhesion. These advantages can be controlled, e.g., by the catalyst loading and the type of solvent used for its deposition. Full article
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Open AccessFeature PaperArticle Simple Process for Sidewall Modification of Multi-Walled Carbon Nanotubes with Polymer Side Chain Radicals Generated by Ultraviolet-Induced C–Cl Bond Dissociation of Polystyrene Derivatives
C 2016, 2(3), 20; doi:10.3390/c2030020
Received: 30 May 2016 / Revised: 20 June 2016 / Accepted: 11 July 2016 / Published: 26 July 2016
Cited by 1 | PDF Full-text (3343 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this work, we investigated a simple one-step process for the formation of chemical bonds between multi-walled carbon nanotubes (MWCNTs) and benzyl-type side chain radicals generated by UV photolysis of polystyrene derivatives containing the chloromethyl (–CH2Cl) group. Poly(4-chloromethyl)styrene, or styrene/4-(chloromethyl)styrene random
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In this work, we investigated a simple one-step process for the formation of chemical bonds between multi-walled carbon nanotubes (MWCNTs) and benzyl-type side chain radicals generated by UV photolysis of polystyrene derivatives containing the chloromethyl (–CH2Cl) group. Poly(4-chloromethyl)styrene, or styrene/4-(chloromethyl)styrene random copolymer, was mixed with MWCNTs in 1-methyl-2-pyrrolidone and irradiated with ultraviolet (UV) light. Films of polymer/MWCNT mixtures before and after UV irradiation were fabricated, and then examined by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. According to the XPS analysis, the amount of Cl atoms in the mixture was found to decrease upon UV irradiation, indicating that the Cl atoms generated by photolysis of chloromethyl groups escaped from the reaction system in the form of gaseous Cl2. The structural change of CNTs after UV irradiation was also observed by comparing the G/D ratios (the intensity ratio of the G to D bands) of the Raman spectra obtained before and after UV irradiation. Similar phenomena were also confirmed in the case of the polymer/MWCNT mixture containing hydroxylammonium chloride as a dispersant of MWCNTs. These results confirmed the UV-induced covalent bond formation between polymer side chains and MWCNTs. Full article
(This article belongs to the Special Issue Surface Modification of Carbon Nanotubes)
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Open AccessArticle Synergetic Hybrid Aerogels of Vanadia and Graphene as Electrode Materials of Supercapacitors
C 2016, 2(3), 21; doi:10.3390/c2030021
Received: 7 April 2016 / Revised: 27 June 2016 / Accepted: 11 July 2016 / Published: 4 August 2016
PDF Full-text (2072 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The performance of synergetic hybrid aerogel materials of vanadia and graphene as electrode materials in supercapacitors was evaluated. The hybrid materials were synthesized by two methods. In Method I, premade graphene oxide (GO) hydrogel was first chemically reduced by L-ascorbic acid and then
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The performance of synergetic hybrid aerogel materials of vanadia and graphene as electrode materials in supercapacitors was evaluated. The hybrid materials were synthesized by two methods. In Method I, premade graphene oxide (GO) hydrogel was first chemically reduced by L-ascorbic acid and then soaked in vanadium triisopropoxide solution to obtain V2O5 gel in the pores of the reduced graphene oxide (rGO) hydrogel. The gel was supercritically dried to obtain the hybrid aerogel. In Method II, vanadium triisopropoxide was hydrolyzed from a solution in water with GO particles uniformly dispersed to obtain the hybrid gel. The hybrid aerogel was obtained by supercritical drying of the gel followed by thermal reduction of GO. The electrode materials were prepared by mixing 80 wt % hybrid aerogel with 10 wt % carbon black and 10 wt % polyvinylidene fluoride. The hybrid materials in Method II showed higher capacitance due to better interactions between vanadia and graphene oxide particles and more uniform vanadia particle distribution. Full article
(This article belongs to the Special Issue Graphene Aerogels)
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Open AccessArticle Flexible Carbon Aerogels
C 2016, 2(3), 22; doi:10.3390/c2030022
Received: 24 June 2016 / Revised: 17 August 2016 / Accepted: 18 August 2016 / Published: 6 September 2016
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Abstract
Carbon aerogels are highly porous materials with a large inner surface area. Due to their high electrical conductivity they are excellent electrode materials in supercapacitors. Their brittleness, however, imposes certain limitations in terms of applicability. In that context, novel carbon aerogels with varying
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Carbon aerogels are highly porous materials with a large inner surface area. Due to their high electrical conductivity they are excellent electrode materials in supercapacitors. Their brittleness, however, imposes certain limitations in terms of applicability. In that context, novel carbon aerogels with varying degree of flexibility have been developed. These highly porous, light aerogels are characterized by a high surface area and possess pore structures in the micrometer range, allowing for a reversible deformation of the aerogel network. A high ratio of pore size to particle size was found to be crucial for high flexibility. For dynamic microstructural analysis, compression tests were performed in-situ within a scanning electron microscope allowing us to directly visualize the microstructural flexibility of an aerogel. The flexible carbon aerogels were found to withstand between 15% and 30% of uniaxial compression in a reversible fashion. These findings might stimulate further research and new application fields directed towards flexible supercapacitors and batteries. Full article
(This article belongs to the Special Issue Graphene Aerogels)
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Review

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Open AccessFeature PaperReview Tuning CNT Properties for Metal-Free Environmental Catalytic Applications
C 2016, 2(3), 17; doi:10.3390/c2030017
Received: 30 May 2016 / Revised: 24 June 2016 / Accepted: 27 June 2016 / Published: 29 June 2016
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Abstract
The application of carbon nanotubes (CNTs) as metal-free catalysts is a novel approach for heterogeneous liquid phase catalytic systems. Textural and chemical modifications by liquid/gas phase or mechanical treatments, as well as solid state reactions, were successfully applied to obtain carbon nanotubes with
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The application of carbon nanotubes (CNTs) as metal-free catalysts is a novel approach for heterogeneous liquid phase catalytic systems. Textural and chemical modifications by liquid/gas phase or mechanical treatments, as well as solid state reactions, were successfully applied to obtain carbon nanotubes with different surface functionalities. Oxygen, nitrogen, and sulfur are the most common heteroatoms introduced on the carbon surface. This short-review highlights different routes used to develop metal-free carbon nanotube catalysts with enhanced properties for Advanced Oxidation Processes. Full article
(This article belongs to the Special Issue Surface Modification of Carbon Nanotubes)
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