C | March 2018 - Browse Articles

13 pages, 5844 KiB

Open AccessArticle

TEM Nano-Moiré Pattern Analysis of a Copper/Single Walled Carbon Nanotube Nanocomposite Synthesized by Laser Surface Implanting

by Jay F. Tu^1,2

¹ Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-8501, USA

² Department of Engineering Science, University West, 46129 Trollhättan, Sweden

C 2018, 4(1), 19; https://doi.org/10.3390/c4010019 - 20 Mar 2018

Cited by 16 | Viewed by 12611

Abstract

In our previous studies, we have developed a wet process to synthesize a copper-single walled carbon nanotube (Cu–SWCNT) metal nanocomposite with excellent mechanical properties. The nanostructure of this Cu–SWCNT composite was confirmed independently by energy-dispersive X-ray spectroscopy mapping, spectroscopy measurements, and Transmission Electron [...] Read more.

In our previous studies, we have developed a wet process to synthesize a copper-single walled carbon nanotube (Cu–SWCNT) metal nanocomposite with excellent mechanical properties. The nanostructure of this Cu–SWCNT composite was confirmed independently by energy-dispersive X-ray spectroscopy mapping, spectroscopy measurements, and Transmission Electron Microscope (TEM) images with discernable SWCNT clusters in nano sizes. However, TEM images with discernable nano-sized SWCNT clusters are rare. In this paper, we present analysis of indirect TEM image patterns, such as moiré fringes, to infer the existence of SWCNT clusters within the copper matrix. Moiré fringes or patterns in the TEM images of a Cu–SWCNT nanocomposite could be generated due to the overlapping of more than one thin crystals with similar periodic arrangements of atoms, promoted by SWCNT clusters. However, the presence of moiré patterns is not a sufficient or a necessary condition for the existence of SWCNT clusters. It was found that based on the overlapping angle of two periodic arrangements, it is feasible to distinguish the moiré fringes induced by SWCNT clusters from those by other factors, such as dislocations. The ability to identify SWCNTs within the copper matrix based on indirect TEM moiré patterns helps to widen the usability of TEM images. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy and Carbon Materials)

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14 pages, 798 KiB

Open AccessReview

Current Progress of Si/Graphene Nanocomposites for Lithium-Ion Batteries

by Yinjie Cen¹

, Richard D. Sisson¹, Qingwei Qin^2,* and Jianyu Liang^1,*

¹ Department of Mechanical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, USA

² The Key State Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China

C 2018, 4(1), 18; https://doi.org/10.3390/c4010018 - 19 Mar 2018

Cited by 27 | Viewed by 12408

Abstract

The demand for high performance lithium-ion batteries (LIBs) is increasing due to widespread use of portable devices and electric vehicles. Silicon (Si) is one of the most attractive candidate anode materials for next generation LIBs. However, the high-volume change (>300%) during lithium ion [...] Read more.

The demand for high performance lithium-ion batteries (LIBs) is increasing due to widespread use of portable devices and electric vehicles. Silicon (Si) is one of the most attractive candidate anode materials for next generation LIBs. However, the high-volume change (>300%) during lithium ion alloying/de-alloying leads to poor cycle life. When Si is used as the anode, conductive carbon is needed to provide the necessary conductivity. However, the traditional carbon coating method could not overcome the challenges of pulverization and unstable Solid Electrolyte Interphase (SEI) layer during long-term cycling. Since 2010, Si/Graphene composites have been vigorously studied in hopes of providing a material with better cycling performance. This paper reviews current progress of Si/Graphene nanocomposites in LIBs. Different fabrication methods have been studied to synthesize Si/Graphene nanocomposites with promising electrochemical performances. Graphene plays a key enabling role in Si/Graphene anodes. However, the desired properties of graphene for this application have not been systematically studied and understood. Further systematic investigation of the desired graphene properties is suggested to better control the Si/Graphene anode performance. Full article

(This article belongs to the Special Issue Batteries: Recent Advances in Carbon Materials 2017)

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15 pages, 8984 KiB

Open AccessArticle

Catalytic Growth of Carbon Nanotubes by Direct Liquid Injection CVD Using the Nanocluster [H_xPMo₁₂O₄₀⊂H₄Mo₇₂Fe₃₀(O₂CMe)₁₅O₂₅₄(H₂O)_98-y(EtOH)_y]

by Gibran L. Esquenazi¹, Bruce Brinson^1,2 and Andrew R. Barron^1,2,3,*

¹ Department of Chemistry, Rice University, Houston, TX 77005, USA

² Department of Materials Science and Nanoengineering, Rice University, Houston, TX 77005, USA

³ Energy Safety Research Institute, Swansea University Bay Campus, Swansea SA1 8EN, UK

C 2018, 4(1), 17; https://doi.org/10.3390/c4010017 - 2 Mar 2018

Cited by 5 | Viewed by 6141

Abstract

The growth of carbon nanotubes (CNTs) by direct liquid injection chemical vapor deposition (DLICVD) has been studied using the polyoxometalate cluster [H_xPMo₁₂O₄₀⊂H₄Mo₇₂Fe₃₀(O₂CMe)₁₅O₂₅₄(H₂O)_98-y [...] Read more.

The growth of carbon nanotubes (CNTs) by direct liquid injection chemical vapor deposition (DLICVD) has been studied using the polyoxometalate cluster [H_xPMo₁₂O₄₀⊂H₄Mo₇₂Fe₃₀(O₂CMe)₁₅O₂₅₄(H₂O)_98-y(EtOH)_y] (FeMoC) as the catalyst with either ethanol or toluene as the carbon source. In order to screen different growth conditions a single large batch of FeMoC is required in order to eliminate variation in the catalyst precursor. The preparation of 6 g of FeMoC is possible by scaling (10×) literature reagent ratios. DLICVD studies of the FeMoC derived carbon product were evaluated by Raman spectroscopy and scanning electron microscopy (SEM) to determine the quality (G:D ratio) and purity of CNT content. With the use of ethanol as the carbon source, increasing the temperature in the injection zone (aspiration temperature) above 250 °C increases the yield, and results in a slight increase in the G:D ratio. The maximum yield is obtained with a growth temperature of 900 °C, while the G:D ratio is the highest at higher temperatures. Faster solution injection rates increase yield, but with a significant decrease in G:D, in fact no CNTs are observed in the product for the highest injection rate (10 mL/h). An optimum catalyst concentration of 1.25 wt.% is found, which influences both the catalyst:C and catalyst:H ratios within the system. Growth at 800 °C is far more efficient for toluene as a carbon source than ethanol. The resulting “process map” allows for large quantities of CNTs to be prepared by DLICVD. Full article

(This article belongs to the Special Issue Carbon Nanotube and Applications)

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15 pages, 7817 KiB

Open AccessArticle

Silica Precursor Effect on the Physical and Chemical Properties of Cobalt Incorportated MCM-41 Catalysts and Their Performance towards Single Wall Carbon Nanotubes

by Frank Ramírez Rodríguez^1,*

, Luis Fernando Giraldo² and Betty Lucy Lopez¹

¹ Grupo de Investigación Ciencia de los Materiales, Universidad de Antioquia, Calle 70 N° 52-21, Medellín 050010, Colombia

² Laboratorio de Investigación en Polímeros, Universidad de Antioquia, Calle 70 N° 52-21, Medellín 050010, Colombia

C 2018, 4(1), 16; https://doi.org/10.3390/c4010016 - 22 Feb 2018

Cited by 1 | Viewed by 5461

Abstract

In this work, mesoporous silica (MCM-41) and a cobalt-incorporated catalyst (Co-MCM-41) were prepared using colloidal silica Cab-O-Sil, sodium silicate and tetraethylorthosilicate (TEOS) as the silica sources and cobalt nitrate as the cobalt source. Their physicochemical properties were analyzed, and their catalytic performance for [...] Read more.

In this work, mesoporous silica (MCM-41) and a cobalt-incorporated catalyst (Co-MCM-41) were prepared using colloidal silica Cab-O-Sil, sodium silicate and tetraethylorthosilicate (TEOS) as the silica sources and cobalt nitrate as the cobalt source. Their physicochemical properties were analyzed, and their catalytic performance for the synthesis of single-wall carbon nanotubes (SWCNT) during chemical vapor deposition (CCVD) of methane was evaluated. When Cab-O-Sil was used, it was possible to incorporate 3% (nominal) cobalt with a good dispersion and without losing mesoporosity, resulting in minimal formation of superficial cobalt oxide. In contrast, the other catalysts product superficial cobalt oxide, according to the temperature programmed reduction (TPR) analysis. Co-MCM-41 prepared using Cab-O-Sil showed the best performance during the formation of SWCNT with a good regularity and selectivity without forming multi-wall carbon nanotubes or amorphous carbon structures. Full article

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12 pages, 1470 KiB

Open AccessArticle

Electrical and Tensile Properties of Carbon Black Reinforced Polyvinyl Chloride Conductive Composites

by Iftekharul Islam¹, Shahin Sultana^2,*

, Swapan Kumer Ray², Husna Parvin Nur², Md. Tofazzal Hossain² and Walliullah Md. Ajmotgir¹

¹ Department of Chemistry, Dhaka College, Dhaka-1205, Bangladesh

² Fiber and Polymer Research Division, BCSIR Laboratories Dhaka, BCSIR, Dhaka-1205, Bangladesh

C 2018, 4(1), 15; https://doi.org/10.3390/c4010015 - 22 Feb 2018

Cited by 49 | Viewed by 10714

Abstract

Conductive polymer composites are becoming more important and useful in many electrical applications. This paper reports on the carbon black (CB) reinforced polyvinyl chloride (PVC) conductive composites. Conductive filler CB was reinforced with thermoplastic PVC by compression molding technique to make conductive composites. [...] Read more.

Conductive polymer composites are becoming more important and useful in many electrical applications. This paper reports on the carbon black (CB) reinforced polyvinyl chloride (PVC) conductive composites. Conductive filler CB was reinforced with thermoplastic PVC by compression molding technique to make conductive composites. The particle size of CB was measured, as it affects the electrical conductivity of the composites. Different types of CB-PVC compression-molded composites were prepared, using CB contents from 5 to 30 wt %. The electrical and tensile properties of these composites were studied and compared. Improved electrical properties were obtained for all CB-PVC conductive polymer composites compared to virgin PVC composite. However, the tensile properties of the CB-PVC composites increased up to 15 wt % CB loading, and then decreased, and elongation at break decreased with increasing CB loading. The structure of the CB, PVC and CB-PVC composites were studied by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic analysis. ATR-FTIR spectra provide evidence of the formation of CB-PVC composites. The microstructural analyses showed a good dispersion of CB in PVC matrix. Full article

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9 pages, 2532 KiB

Open AccessArticle

Mechanochemical Functionalization of Carbon Black at Room Temperature

by Desirée Leistenschneider¹, Katharina Zürbes¹, Christina Schneidermann¹, Sven Grätz¹

, Steffen Oswald², Karl Wegner¹, Benjamin Klemmed³, Lars Giebeler²

, Alexander Eychmüller³ and Lars Borchardt^1,*

¹ Department of Inorganic Chemistry, Technische Universität Dresden, Bergstraße 66, 01062 Dresden, Germany

² Institute for Complex Materials, Leibniz Institute for Solid State and Materials Research (IFW) Dresden e.V., Helmholtzstraße 20, 01069 Dresden, Germany

³ Physical Chemistry, Technische Universität Dresden, Bergstraße 66b, 01062 Dresden, Germany

C 2018, 4(1), 14; https://doi.org/10.3390/c4010014 - 13 Feb 2018

Cited by 18 | Viewed by 9647

Abstract

Carbon nanomaterials such as carbon blacks are intrinsically hydrophobic with limited wettability in aqueous media, thus restricting their potential applications. To improve their hydrophilicity, common methods tend to utilize harmful chemicals and conditions, such as a mixture of KMnO₄ and H₂ [...] Read more.

Carbon nanomaterials such as carbon blacks are intrinsically hydrophobic with limited wettability in aqueous media, thus restricting their potential applications. To improve their hydrophilicity, common methods tend to utilize harmful chemicals and conditions, such as a mixture of KMnO₄ and H₂SO₄ or a complex and expensive synthesis setup. In our work, we report a simple method to improve the wettability of these materials by a mechanochemical treatment completed within 1 h at room-temperature utilizing a NH₃ solution. Besides increasing the specific surface area of the carbon black from 67 m²·g⁻¹ up to 307 m²·g⁻¹, our process also incorporates nitrogen- and oxygen-containing functional groups into the carbon. This reduces the contact angle from 80° to 30°, confirming an enhanced wettability. Our work presents an easy, fast, and straightforward pathway towards the functionalization of carbon nanomaterials and can be of use in various applications where aqueous wettability is advantageous. Full article

(This article belongs to the Special Issue Functional Nanoporous Carbon-Based Materials)

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13 pages, 3504 KiB

Open AccessArticle

Phytosterol Recognition via Rationally Designed Molecularly Imprinted Polymers

by Lachlan J. Schwarz^†, Brenda K. Y. Leung, Basil Danylec, Simon J. Harris, Reinhard I. Boysen

and Milton T. W. Hearn^*

¹ Centre for Green Chemistry and Australian Centre for Research on Separation Science, School of Chemistry, Monash University, Melbourne, VIC 3800, Australia

^† Current Address: School of Agricultural and Wine Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.

C 2018, 4(1), 13; https://doi.org/10.3390/c4010013 - 12 Feb 2018

Cited by 7 | Viewed by 4958

Abstract

Molecularly imprinted polymers (MIPs) prepared via a semi-covalent imprinting strategy using stigmasteryl methacrylate as a polymerisable template have been evaluated by static binding methods for their ability to selectively capture other valuable phytosterol targets, including campesterol and brassicasterol. Design criteria based on molecular [...] Read more.

Molecularly imprinted polymers (MIPs) prepared via a semi-covalent imprinting strategy using stigmasteryl methacrylate as a polymerisable template have been evaluated by static binding methods for their ability to selectively capture other valuable phytosterol targets, including campesterol and brassicasterol. Design criteria based on molecular modelling procedures and interaction energy calculations were employed to aid the selection of the co-monomer type, as well as the choice of co-monomer:template ratios for the formation of the pre-polymerisation complex. These novel hybrid semi-covalently imprinted polymers employed N,N′-dimethylacryl-amide (N,N′-DMAAM) as the functional co-monomer and displayed specific binding capacities in the range 5.2–5.9 mg sterol/g MIP resin. Their binding attributes and selectivities towards phytosterol compounds were significantly different to the corresponding MIPs prepared via non-covalent procedures or when compared to non-imprinted polymers. Cross-reactivity studies using stigmasterol, ergosterol, cholesterol, campesterol, and brassicasterol as single analytes revealed the importance of the A-ring C-3-β-hydroxyl group and the orientational preferences of the D-ring alkyl chain structures in their interaction in the templated cavity with the N,N′-dimethylamide functional groups of the MIP. Finally, to obtain useful quantities of both campersterol and brassicasterol for these investigations, improved synthetic routes have been developed to permit the conversion of the more abundant, lower cost stigmasterol via a reactive aldehyde intermediate to these other sterols. Full article

(This article belongs to the Special Issue Molecularly Imprinted Polymers—Molecular Recognition)

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13 pages, 7054 KiB

Open AccessArticle

Electrostatic Adsorption of Platinum onto Carbon Nanotubes and Nanofibers for Nanoparticle Synthesis

by Ritubarna Banerjee, Jose L. Contreras-Mora, Susan K. McQuiston, Brandon Bolton, Bahareh Alsadat Tavakoli Mehrabadi and John R. Regalbuto^*

Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208, USA

C 2018, 4(1), 12; https://doi.org/10.3390/c4010012 - 11 Feb 2018

Cited by 3 | Viewed by 6215

Abstract

Strong Electrostatic Adsorption (SEA) has been demonstrated as a simple, scientific method to prepare well dispersed Pt nanoparticles over typical forms of carbon: activated, black, and graphitic carbons. Many varieties of specialty carbons have been invented in the last few decades including multi-walled [...] Read more.

Strong Electrostatic Adsorption (SEA) has been demonstrated as a simple, scientific method to prepare well dispersed Pt nanoparticles over typical forms of carbon: activated, black, and graphitic carbons. Many varieties of specialty carbons have been invented in the last few decades including multi-walled nanotubes, nanofibers, graphene nanoplatelets, etc. In this work, we explore whether SEA can be applied to these specialty carbons for the synthesis of Pt nanoparticles. Over a number of oxidized and unoxidized multiwalled nanotubes and nanofibers, the point of zero charge (PZC) was measured and the uptake of anionic Pt complexes (Pt hexachloride, [PtCl₆]²⁻, and cationic Pt complexes (platinum tetraammine, [Pt(NH₃)₄]²⁺) as functions of final pH were surveyed. Pt nanoparticles on the various supports were synthesized at the optimal pH and were characterized by x-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). The specialty carbons displayed volcano-shaped uptake curves typical of electrostatic adsorption for both Pt anions at low pH and Pt cations at high pH. However, the regimes of uptake often did not correspond to the measured PZC, probably due to surface impurities from the carbon manufacturing process. This renders the measured PZC of these specialty carbons unreliable for predicting anion and cation uptake. On the other hand, the anion and cation uptake curves provide an “effective” PZC and do indicate the optimal pH for the synthesis of ultrasmall nanoparticle synthesis. High resolution STEM imaging also showed that with SEA it is possible to disperse nanoparticles on the surface as well as the inner walls of the specialty carbons. Full article

(This article belongs to the Special Issue Smart Carbon Materials in Catalysis)

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15 pages, 3317 KiB

Open AccessArticle

Nitrogen-Doped Hollow Carbon Spheres with Embedded Co Nanoparticles as Active Non-Noble-Metal Electrocatalysts for the Oxygen Reduction Reaction

by Ruohao Xing^1,2, Yao Zhou¹, Ruguang Ma^1,*, Qian Liu^1,3,*, Jun Luo^2,3, Minghui Yang^4,* and Jiacheng Wang^1,3,*

¹ State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China

² School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China

³ Shanghai Institute of Materials Genome, Shanghai 200050, China

⁴ Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China

C 2018, 4(1), 11; https://doi.org/10.3390/c4010011 - 9 Feb 2018

Cited by 1 | Viewed by 6243

Abstract

Transition metal (Fe, Co, Ni) complexes on carbon nanomaterials are promising candidates as electrocatalysts towards the oxygen reduction reaction (ORR). In this paper, nitrogen-doped hollow carbon spheres with embedded Co nanoparticles were successfully prepared via a controllable synthesis strategy. The morphology characterization shows [...] Read more.

Transition metal (Fe, Co, Ni) complexes on carbon nanomaterials are promising candidates as electrocatalysts towards the oxygen reduction reaction (ORR). In this paper, nitrogen-doped hollow carbon spheres with embedded Co nanoparticles were successfully prepared via a controllable synthesis strategy. The morphology characterization shows that the hollow carbon spheres possess an average diameter of ~150 nm with a narrow size distribution and a shell thickness of ~14.5 nm. The content of N doping ranges from 2.1 to 6.6 at.% depending on the calcination temperature from 900 to 1050 °C. Compared with commercial Pt/C, the Co-containing nitrogen-doped hollow carbon spheres prepared at 900 °C (CoNHCS-900) as an ORR electrocatalyst shows a half-wave potential shift of only ∆E_1/2 = 55 mV, but a superior stability of about 90.2% maintenance after 20,000 s in the O₂-saturated 0.1 M KOH at a rotating speed of 1600 rpm. This could be ascribed to the synergistic effects of N-containing moieties, Co-N_x species, and Co nanoparticles, which significantly increase the density of active sites and promote the charge transfer during the ORR process. Full article

(This article belongs to the Special Issue Functional Nanoporous Carbon-Based Materials)

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19 pages, 9854 KiB

Open AccessArticle

Surface Observation and Magnetism of Oil-Extracted Botryococcus braunii Residues before and after Carbonization

by Aohan Wang¹, Mikihide Demura², Makoto M. Watanabe², Kotaro Ohara¹, Takanari Kashiwagi¹, Kazuo Kadowaki¹, Eiji Kita³, Jiuchao Dong¹ and Hiromasa Goto^1,*

¹ Division of Materials Science, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan

² Algae Biomass and Energy System R & D Center (ABES), University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan

³ Division of Applied Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan

C 2018, 4(1), 10; https://doi.org/10.3390/c4010010 - 2 Feb 2018

Cited by 3 | Viewed by 4808

Abstract

Microalgae is a promising next-generational energy. In this research, we focus on oil-extracted Botryococcus braunii residues collected by adding polysilicato-iron (PSI) as a flocculant followed by carbonization under argon atmosphere. We conducted carbonization at various temperatures as a first attempt to reveal the [...] Read more.

Microalgae is a promising next-generational energy. In this research, we focus on oil-extracted Botryococcus braunii residues collected by adding polysilicato-iron (PSI) as a flocculant followed by carbonization under argon atmosphere. We conducted carbonization at various temperatures as a first attempt to reveal the fundamental properties of the carbonization process of the microbes. The carbons thus obtained by heat treatment at 900 °C present a unique magnetic behavior due to reduced magnetite (Fe₃O₄) inclusion, which is produced from polysilicato iron (Fe₂O₃) during the heating process. Experimental results suggest that this carbonic material can be applied as a heavy metal-capturing carbon and magnetic porous substrate catalyst. The effective use of the waste may open a new avenue for an energy-microbiology-materials system. Full article

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17 pages, 4248 KiB

Open AccessArticle

Controlling the Incorporation of Phosphorus Functionalities on Carbon Nanofibers: Effects on the Catalytic Performance of Fructose Dehydration

by Sebastiano Campisi^1,*

, Felipe J Sanchez Trujillo², Davide Motta², Thomas E. Davies², Nikolaos Dimitratos² and Alberto Villa^1,*

¹ Dipartimento di Chimica, Università degli Studi di Milano, Milano 20133, Italy

² Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK

C 2018, 4(1), 9; https://doi.org/10.3390/c4010009 - 27 Jan 2018

Cited by 16 | Viewed by 5489

Abstract

Phosphorylated carbons have been reported to be effective catalysts in dehydration reactions for biomass valorization. The amount and the nature of P groups are a key parameter affecting the catalytic performances of functionalized materials. Herein, we investigate the role of structural and surface [...] Read more.

Phosphorylated carbons have been reported to be effective catalysts in dehydration reactions for biomass valorization. The amount and the nature of P groups are a key parameter affecting the catalytic performances of functionalized materials. Herein, we investigate the role of structural and surface properties of carbon-based materials, specifically carbon nanofibers, in determining the amount of P-functionalities. In order to incorporate P groups on carbon surfaces, various carbon nanofibers (CNFs) with different graphitization degrees have been functionalized through treatment with a H₃PO₄-HNO₃ mixture at 150 °C. The pristine materials, as well as the functionalization protocol, were properly selected to achieve an effective functionalization without drastically altering the morphology of the samples. Surface and structural properties of the synthesized functionalized materials have been investigated by means of transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The catalytic behavior of phosphorylated carbon nanofibers has been evaluated in the selective dehydration of fructose to hydroxymethylfurfural (HMF) to elucidate structure-activity relationships. Full article

(This article belongs to the Special Issue Smart Carbon Materials in Catalysis)

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17 pages, 7658 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

High-Performance Vanadium Redox Flow Batteries with Graphite Felt Electrodes

by Trevor J. Davies^* and Joseph J. Tummino

Department of Natural Sciences, University of Chester, Thornton Science Park, Pool Lane, Ince, Chester CH2 4NU, UK

C 2018, 4(1), 8; https://doi.org/10.3390/c4010008 - 25 Jan 2018

Cited by 52 | Viewed by 11131

Abstract

A key objective in the development of vanadium redox flow batteries (VRFBs) is the improvement of cell power density. At present, most commercially available VRFBs use graphite felt electrodes under relatively low compression. This results in a large cell ohmic resistance and limits [...] Read more.

A key objective in the development of vanadium redox flow batteries (VRFBs) is the improvement of cell power density. At present, most commercially available VRFBs use graphite felt electrodes under relatively low compression. This results in a large cell ohmic resistance and limits the maximum power density. To date, the best performing VRFBs have used carbon paper electrodes, with high active area compression pressures, similar to that used in fuel cells. This article investigates the use of felt electrodes at similar compression pressures. Single cells are assembled using compression pressures of 0.2–7.5 bar and tested in a VRFB system. The highest cell compression pressure, combined with a thin Nafion membrane, achieved a peak power density of 669 mW cm⁻² at a flow rate of 3.2 mL min⁻¹ per cm² of active area, more than double the previous best performance from a felt-VRFB. The results suggest that felt electrodes can compete with paper electrodes in terms of performance when under similar compression pressures, which should help guide electrode development and cell optimization in this important energy storage technology. Full article

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17 pages, 3375 KiB

Open AccessReview

Hybrid Carbon-Based Clathrates for Energy Storage

by Kwai S. Chan

Materials Engineering Department, Southwest Research Institute, San Antonio, TX 78238, USA

C 2018, 4(1), 7; https://doi.org/10.3390/c4010007 - 22 Jan 2018

Cited by 1 | Viewed by 6215

Abstract

Hybrid carbon–silicon, carbon–nitrogen, and carbon–boron clathrates are new classes of Type I carbon-based clathrates that have been identified by first-principles computational methods by substituting atoms on the carbon clathrate framework with Si, N, and/or B atoms. The hybrid framework is further stabilized by [...] Read more.

Hybrid carbon–silicon, carbon–nitrogen, and carbon–boron clathrates are new classes of Type I carbon-based clathrates that have been identified by first-principles computational methods by substituting atoms on the carbon clathrate framework with Si, N, and/or B atoms. The hybrid framework is further stabilized by embedding appropriate guest atoms within the cavities of the cage structure. Series of hybrid carbon–silicon, carbon–boron, carbon–nitrogen, and carbon-silicon-nitrogen clathrates have been shown to exhibit small positive values for the energy of formation, indicating that they may be metastable compounds and amenable to fabrication. In this overview article, the energy of formation, elastic properties, and electronic properties of selected hybrid carbon-based clathrates are summarized. Theoretical calculations that explore the potential applications of hybrid carbon-based clathrates as energy storage materials, electronic materials, or hard materials are presented. The computational results identify compositions of hybrid carbon–silicon and carbon–nitrogen clathrates that may be considered as candidate materials for use as either electrode materials for Li-ion batteries or as hydrogen storage materials. Prior processing routes for fabricating selected hybrid carbon-based clathrates are highlighted and the difficulties encountered are discussed. Full article

(This article belongs to the Special Issue Carbon Hybrid Materials)

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18 pages, 7928 KiB

Open AccessArticle

Mechanical and Electrical Characterization of Carbon Fiber/Bucky Paper/Zinc Oxide Hybrid Composites

by Suma Ayyagari^†, Marwan Al-Haik^*,† and Virginie Rollin

¹ Department of Aerospace Engineering, Embry-Riddle Aeronautical University, Daytona Beach, FL 32114, USA

^† These authors contributed equally to this work.

C 2018, 4(1), 6; https://doi.org/10.3390/c4010006 - 18 Jan 2018

Cited by 14 | Viewed by 6435

Abstract

The quest for multifunctional carbon fiber reinforced composites (CFRPs) expedited the use of several nano reinforcements such as zinc oxide nanorods (ZnO) and carbon nanotubes (CNTs). Zinc oxide is a semi-conductor with good piezoelectric and pyroelectric properties. These properties could be transmitted to [...] Read more.

The quest for multifunctional carbon fiber reinforced composites (CFRPs) expedited the use of several nano reinforcements such as zinc oxide nanorods (ZnO) and carbon nanotubes (CNTs). Zinc oxide is a semi-conductor with good piezoelectric and pyroelectric properties. These properties could be transmitted to CFRPs when a nanophase of ZnO is embedded within CFRPs. In lieu of ZnO nanorods, Bucky paper comprising mat of CNTs could be sandwiched in-between composite laminae to construct a functionally graded composite with enhanced electrical conductivities. In this study, different configurations of hybrid composites based on carbon fibers with different combinations of ZnO nanorods and Bucky paper were fabricated. The composites were tested mechanically via tensile and dynamic mechanical analysis (DMA) tests to examine the effect of the different nanoadditives on the stiffness, strength and the damping performance of the hybrid composites. Electrical resistivities of the hybrid composites were probed to examine the contributions of the different nanoadditives. The results suggest that there are certain hybrid composite combinations that could lead to the development of highly multifunctional composites with better strength, stiffness, damping and electrical conductivity. Full article

(This article belongs to the Special Issue Carbon Hybrid Materials)

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2 pages, 172 KiB

Open AccessEditorial

Acknowledgement to Reviewers of C in 2017

by C Editorial Office

MDPI AG, St. Alban-Anlage 66, 4052 Basel, Switzerland

C 2018, 4(1), 5; https://doi.org/10.3390/c4010005 - 12 Jan 2018

Viewed by 2917

Abstract

Peer review is an essential part in the publication process, ensuring that C (Journal of Carbon Research) maintains high quality standards for its published papers [...]
Full article

17 pages, 8633 KiB

Open AccessReview

Transmission Electron Microscopy of Carbon: A Brief History

by Peter J. F. Harris

Electron Microscopy Laboratory, Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AF, UK

C 2018, 4(1), 4; https://doi.org/10.3390/c4010004 - 12 Jan 2018

Cited by 40 | Viewed by 18572

Abstract

Transmission electron microscopy (TEM) has been used in the study of solid carbon since the 1940s. A number of important forms of carbon have been discovered through the use of TEM, and our understanding of the microstructure of carbon has largely been gained [...] Read more.

Transmission electron microscopy (TEM) has been used in the study of solid carbon since the 1940s. A number of important forms of carbon have been discovered through the use of TEM, and our understanding of the microstructure of carbon has largely been gained through the application of TEM and associated techniques. This article is an attempt to present an historical review of the application of TEM to carbon, from the earliest work to the present day. The review encompasses both graphitic carbon and diamond, and spectroscopic techniques are covered, as well as imaging. In the final section of the review, the impact of aberration-corrected TEM on current carbon research is highlighted. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy and Carbon Materials)

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14 pages, 2842 KiB

Open AccessArticle

Adsorption of Bovine Serum Albumin on Carbon-Based Materials

by Mykola Seredych¹

, Lyuba Mikhalovska²

, Sergey Mikhalovsky²

and Yury Gogotsi^1,*

¹ Department of Materials Science & Engineering and A.J. Drexel Nanomaterials Institute, Drexel University, Philadelphia, PA 19104, USA

² School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, UK

C 2018, 4(1), 3; https://doi.org/10.3390/c4010003 - 7 Jan 2018

Cited by 44 | Viewed by 10037

Abstract

The protein adsorption plays a very important role in biotechnology, biomolecular engineering and it is one of the main factors determining bio- and hemocompatibility of biomedical materials in medical applications, such as blood purification and wound healing. Here we report adsorption properties of [...] Read more.

The protein adsorption plays a very important role in biotechnology, biomolecular engineering and it is one of the main factors determining bio- and hemocompatibility of biomedical materials in medical applications, such as blood purification and wound healing. Here we report adsorption properties of two carbon-based materials, thermally expanded graphite (EGr) and graphene nanoplatelets (GnP), for bovine serum albumin (BSA), the most abundant blood plasma protein. The influence of the surface chemistry of expanded graphite on the mechanism of BSA adsorption was studied by using EGr modified with oxygen or nitrogen functionalities. Having low microporosity and the specific surface area in the range of 5 to 50 m²/g, the expanded graphite exhibits high protein adsorption capacity at high equilibrium concentrations, which makes this material a potential candidate for biomedical applications as a carrier for high molecular weight (HMW) drug delivery or adsorption of HMW metabolites. At low equilibrium concentrations, the effect of specific protein-surface functional groups interaction reveals the differences between the adsorption affinity of different surface modified EGr materials to BSA. The adsorption of BSA on GnP with a specific surface area of 286 m²/g and a developed micro-/mesoporous structure did not follow the same mechanism as seen with EGr materials. At low equilibrium concentration of BSA, GnP exhibits high adsorption efficiency. An important finding is that no release of nanoparticles from expanded graphite adsorbents was observed, which makes them potentially suitable for direct contact with blood and other tissues while very small nanoparticles were noticed in the case of graphene nanoplatelets. Full article

(This article belongs to the Special Issue Functional Nanoporous Carbon-Based Materials)

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17 pages, 3920 KiB

Open AccessArticle

One-Pot Synthesis of Graphene-Sulfur Composites for Li-S Batteries: Influence of Sulfur Precursors

by James Guo Sheng Moo^1,2,*

, Ahmad Omar², Tony Jaumann², Steffen Oswald², Juan Balach³, Sebastian Maletti²

and Lars Giebeler^2,*

¹ Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore

² Institute for Complex Materials, Leibniz Institute for Solid State and Materials Research (IFW), 01069 Dresden, Germany

³ Department of Chemistry, Universidad Nacional de Río Cuarto-CONICET, X5804ZAB Río Cuarto, Argentina

C 2018, 4(1), 2; https://doi.org/10.3390/c4010002 - 27 Dec 2017

Cited by 11 | Viewed by 9656

Abstract

Lithium-sulfur (Li-S) batteries are postulated as next-generation electrochemical energy storage devices due to their increased storage capabilities. However, challenges persist from the polysulfide-shuttle effect at the cathode. Soluble sulfur-based species in the cathode cross over to the lithium anode through the separator leading [...] Read more.

Lithium-sulfur (Li-S) batteries are postulated as next-generation electrochemical energy storage devices due to their increased storage capabilities. However, challenges persist from the polysulfide-shuttle effect at the cathode. Soluble sulfur-based species in the cathode cross over to the lithium anode through the separator leading to fading capacity with cycling. This has spurred continuous effort by the scientific community to develop novel cathodes where sulfur species can affix better. A conductive nanostructured graphene network is a suitable candidate that can serve as a scaffold for holding sulfur nanoparticles. Here, a one-pot synthesis of chemically reduced graphene oxide networks prepared from easily accessible graphene oxide is demonstrated. The solution-based method simply allows for impregnation of the graphene oxide network with sulfur nanoparticles through a careful manipulation of pH of the chemical environment. Two routes were chosen for the precipitation of such sulfur nanoparticles: firstly, the dissolution of sulfur in sodium hydroxide into polysulfides followed by acidification and secondly, the acidification of sodium thiosulfate from alkaline media into sulfur nanoparticles. Both graphene oxide materials from the two routes were treated with sodium borohydride to achieve conductive graphene. The second route, with the sulfur nanoparticles derived from the acidification of sodium thiosulfate with chemically reduced graphene oxide, demonstrated favorable electrochemical behavior, showing promise as electrode material for Li-S batteries. Full article

(This article belongs to the Special Issue Functional Nanoporous Carbon-Based Materials)

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11 pages, 8658 KiB

Open AccessArticle

Synthesis of Hybrid Silica-Carbon Tubular Structures by Chemical Vapor Deposition with Methane or Ethene

by Victor R. Sepulveda^*

and Betty L. López

Grupo de Investigación Ciencia de los Materiales, Instituto de Química, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, Calle 70 No. 52-21, Medellín 050010, Colombia

C 2018, 4(1), 1; https://doi.org/10.3390/c4010001 - 25 Dec 2017

Viewed by 4620

Abstract

Silica microtube and carbon nanotube hybrid structures have been synthesized by catalytic chemical vapor deposition using either methane or ethene as the carbon source, and cobalt-grafted or impregnated silica tubes (200–800 nm) as catalyst. The cobalt-grafted catalyst shows a high resistance to reduction [...] Read more.

Silica microtube and carbon nanotube hybrid structures have been synthesized by catalytic chemical vapor deposition using either methane or ethene as the carbon source, and cobalt-grafted or impregnated silica tubes (200–800 nm) as catalyst. The cobalt-grafted catalyst shows a high resistance to reduction (>1000 °C) and selectivity to single-wall carbon nanotubes (SWCNT). While ethene deposition produces more carbonaceous material, methane experiments show higher selectivity for SWCNT. After removing the silica with an excess of HF, the carbon nanostructure endured, resulting in a coaxial carbon nanostructure. The novel hybrid nanostructures obtained consist of a submicron-sized tube, with walls that are formed by a succession of carbon/silica/carbon layers to which multiwall (20–25 nm) and/or single-wall (0.6–2.0 nm) carbon nanotubes are attached. This synthesis approach combines the mechanical properties of carbon nanotubes and the thermal properties of silica tubes into a synergetic nanostructured material, opening further possibilities for polymer reinforcement and potential applications in catalysis. Full article

(This article belongs to the Special Issue Carbon Nanotube and Applications)

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C, Volume 4, Issue 1 (March 2018) – 19 articles

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