Different Forms Of Carbon Research Articles

Properties of Functional Materials on Basis of Hybrid Polymer Composites with Nano-Carbon Additives

Исследованы полимерные композиты на основе различных форм наноуглерода: углеродные нанотрубки, графены и терморасширенный графит. В качестве полимерных матриц при получении композитов были использованы эпоксидная смола, полиметилметакрилат, поливинилацетат и биоразлагаемый сополимер стирол-акрилата (SAC). Разработана модель, описывающая формирование электромагнитного отклика многостенных нанотрубок как конечной, так и бесконечной длины в микроволновой области частот. На основе модели получено выражение для эффективной диэлектрической проницаемости разориентированного неупорядоченного композита из углеродных нанотрубок. Разработаны и экспериментально опробованы методы функционализации углеродных нанотрубок путем прививки аминогрупп и эпоксидных групп. Разработаны методики селективного модифицирования графена и углеродных нанотрубок наночастицами меди, кобальта и оксида железа. Получены экспериментальные данные в микроволновом частотном диапазоне (26-37 ГГц) и в низкочастотной области (20 Гц - 1 МГц) и проведен сравнительный анализ электромагнитного отклика полимерных композитов с различными формами углерода в качестве наполнителя. Экспериментально получены функционализированные углеродные материалы и изучены их ЭМ-свойства. Показано, что композиты на основе нанопластинок графена с наночастицами оксида железа формируют в магнитном поле тонкопленочные структуры со значительно большей площадью поверхности, чем без поля. Созданы полимерные композитные материалы на основе электропроводных полимеров полиэтилендиокситиофена и полистиролсульфоната (PEDOT:PSS) с малыми добавками графена, модифицированного наночастицами меди, кобальта или оксида железа. Такие материалы образуют стабильные пленки со свойствами, определяемыми наполнителем (электропроводные или магнитные).

Thermo-mechanical properties of graphite-reinforced high-density polyethylene composites and its structure–property corelationship

Composite prepared by mixing of different forms of carbon or other reinforcing fillers with polymer, is one of the possible ways to enhance the performance of polymeric materials. The present work focuses on the study of viscoelastic, thermal, electrical and mechanical properties of graphite flake-reinforced high-density polyethylene composites. The composites are processed by melt mixing using vertical twin-screw micro-compounder followed by final sample preparation via micro injection moulding. The reinforcing filler, graphite flake, is varied from 0 to 50 vol.% with respect to the polymer matrix. Dynamic mechanical thermal analysis reveals an increase in the storage modulus (E′) as well as loss modulus (E″) throughout the temperature range; however, damping (tan δ) shows a mixed behaviour. There is 550% and 479% increase of E′ and E″ in the rubbery region. Degree of entanglement, reinforcement efficiency and C factor are also calculated and correlated with the mechanical properties. On comparison, high-density polyethylene /graphite flake composite having 50 vol.% graphite flake with pure high-bcdensity polyethylene shows 52% increase in melt viscosity, whereas bulk density increases by 38%. This graphite flake is also responsible for the increase in the thermal stability (shift in the onset degradation temperature of ∼7℃ and the degradation temperature is more than 400℃), thermal conductivity (175% improvement) and electrical conductivity (∼6125% improvement, as the conductivity of pristine high-density polyethylene is ∼9.67 E-08 S/m). Mechanical properties determined by tensile and flexural tests show an initial increase and then a slight decrease in the tensile and flexural strength. Therefore, the graphite flake-reinforced high-density polyethylene composite with improved thermal conductivity, electrical conductivity, heat stability, viscoelastic behaviour and flexural modulus can be a promising as well as suitable composite material for making of various electronic and electrical accessories including bipolar plate for fuel cell applications.

Characterization of x-ray imaging crystal spectrometer for high-resolution spatially-resolved x-ray Thomson scattering measurements in shock-compressed experiments

We have proposed, designed and built a dual-channel x-ray imaging crystal spectrometer (XICS) for spectrally- and spatially-resolved x-ray Thomson scattering (XRTS) measurements in the Matter in Extreme Conditions (MEC) end station at the Linac Coherent Light Source (LCLS). This spectrometer employs two spherically-bent germanium (Ge) 220 crystals, which are combined to form a large aperture dispersive element with a spectral bandwidth of ~300eV that enables both the elastic and inelastic x-ray scattering peaks to be simultaneously measured. The apparatus and its characterization are described. A resolving power of ~1900 was demonstrated and a spatial resolution of ~12μm was achieved in calibration tests. For XRTS measurements, a narrow-bandwidth (ΔE/E<0.003) LCLS x-ray free electron laser (XFEL) beam at 5.07keV was used to probe a dense carbon plasma produced in shock-compressed samples of different forms of carbon. Preliminary results of the scattering experiments from Pyrolytic Graphite samples that illustrate the utility of the instrument are presented.

New Electrocatalyst for PEM Fuel Cell Application Based on Platinum Supported on Mwcnts and Few Graphene Layers

Carbon blacks supporting Pt, currently widely used as electrocatalysts in Polymer Electrolyte Membrane Fuel Cells (PEMFC) are thermochemically unstable in PEMFC operating conditions. This is especially true at the cathode side where, on top of relatively elevated temperature (80°C) and acidic conditions, both the potential and the relative humidity may be high. The resulting carbon oxidation is partially responsible for the PEMFC performance decrease observed over time. Hence, long term durability still needs to be improved in order to consider PEMFC as credible alternatives to conventional power sources for automotive, stationary or portable applications. Much effort have been directed to identify and synthesize alternative carbon materials as catalyst supports for PEMFCs. One strategy to decrease carbon support corrosion is to use carbon with high extent of graphitization, which is supposed to decrease defect sites on the carbon structure, where carbon oxidation starts [1], [2]. However high graphitic content of carbon can be a brake for particle nucleation and dispersion. Among the different forms of carbon, graphene and carbon nanotubes have attracted tremendous interest materials for various energy applications [3], [4]. We will show how the combination of their high surface area, high conductivity and high chemical stability makes these 1D and 2D materials promising candidates for cathode catalyst support in PEMFCs. In this work, platinum and bimetallic (PtM, M=Co or Ni) nanoparticles catalysts have been prepared on N-doped Multi-Walled Carbon Nanotubes (MWCNTs) (home synthetized and commercial) and Few Graphene Layers (FGLs) using three synthetic routes: polyol route [5], impregnation and reduction under H2 [6] and SBH reduction [7]. The Platinum loading, the dispersion and size of metallic nanoparticles were analyzed by UV, XRD, SEM. Our materials showed good dispersion on nanostructured support and size of metallic particles reached 2 nm (figure 1). We investigated the properties of 2D FGLs/1D MWCNTs Pt and PtM catalysts for electrocatalysis of oxygen reduction. By comparing the electrochemical properties of these hybrid materials with a commercial Pt/C catalyst using carbon blacks as carbon support, it is found that this hybrid material demonstrated an enhancement of electro-catalyst performances in RDE tests. Moreover accelerated stress tests in half cell and fuel-cell setup demonstrated that the use of this hybrid FGLs/MWCNTs support can be promising in effectively reducing the carbon corrosion and then increase lifetime of the cell. This work is funded by the FP7 NANOCAT European program (SP1-JTI-FCH.2012.1.5) and French region Midi-Pyrénées. REFERENCES [1] Xin Wang , Wenzhen Li , Zhongwei Chen , Mahesh Waje , Yushan Yan, “Durability investigation of carbon nanotube as catalyst support for proton exchange membrane fuel cell”, Journal of Power Sources, 2006, 158, pp 154–159 [2] D. Bom, R. Andrews, D. Jacques, J. Anthony, B. Chen, M. S. Meier, John P. Selegue , “Thermogravimetric Analysis of the Oxidation of Multiwalled Carbon Nanotubes: Evidence for the Role of Defect Sites in Carbon Nanotube Chemistry”, Nano Letters, 2002, 2, pp 615-619 [3] Yingwen Cheng, Songtao Lu, Hongbo Zhang, Chakrapani V. Varanasi⊥, and Jie Liu, “Synergistic Effects from Graphene and Carbon Nanotubes Enable Flexible and Robust Electrodes for High-Performance Supercapacitors”, Nano Letters, 2012, 12 (8), pp 4206–4211 [4] Zhou, X., Qiao, J., Yang, L. and Zhang, J ”A Review of Graphene-Based Nanostructural Materials for Both Catalyst Supports and Metal-Free Catalysts in PEM Fuel Cell Oxygen Reduction Reactions”, Adv. Energy Mater., Vol. 4, (2014) p.1301523 [5] Yongjie Li, Wei Gao, Lijie Ci, Chunming Wang, Pulickel M. Ajayan “Catalytic performance of Pt nanoparticles on reduced graphene oxide for methanol electro-oxidation”, Carbon (2010), 48, 1124-1130. [6] S. M. Choi, M. H. Seo, H. J. Kim, W. B. Kim, “Synthesis and characterization of graphene-supported metal nanoparticles by impregnation method with heat treatment in H2 atmosphere”, Synthetic Metals 161 (2011) 21–22, 2405–2411. [7] D. Wang et al., Nature Materials, “Synthesis and characterization of Cocore–Ptshell electrocatalyst prepared by spontaneous replacement reaction for oxygen reduction reaction” 2013, 12, 81-87. Figure 1

Brazing techniques for the fabrication of biocompatible carbon-based electronic devices

Prototype electronic devices have been critical to the discovery and demonstration of the unique properties of new materials, including composites based on carbon nanotubes (CNT) and graphene. However, these devices are not typically constructed with durability or biocompatibility in mind, relying on conductive polymeric adhesives, mechanical clamps or crimps, or solders for electrical connections. In this paper, two key metallization techniques are presented that employ commercially-available brazing alloys to fabricate electronic devices based on diamond and carbonaceous wires. Investigation of the carbon—alloy interfacial interactions was utilized to guide device fabrication. The interplay of both chemical (“adhesive”) and mechanical (“cohesive”) forces at the interface of different forms of carbon was exploited to fabricate either freestanding or substrate-fixed carbonaceous electronic devices. Elemental analysis in conjunction with scanning electron microscopy of the carbon—alloy interface revealed the chemical nature of the Ag alloy bond and the mechanical nature of the Au alloy bond. Electrical characterization revealed the non-rectifying nature of the carbon—Au alloy interconnects. Finally, electronic devices were fabricated, including a Au circuit structure embedded in a polycrystalline diamond substrate.

Densimetric fractionation of organic matter in an agricultural chronosequence in no-till areas in the Cerrado region, Brazil

Mineralization of organic residues deposited on the soil surface in a no-till system (NT) maintains a continuous flow of different forms of carbon (C), which might interfere with densimetric fractions of soil organic matter (SOM). Currently, there are few studies on variations in these fractions in NT areas with different deployment times in the Cerrado region. Thus, the objective of this study was to evaluate the total C, nitrogen (N), and 13C in the soil, as well as to quantify the mass and contents of C, N, and 13C in the light and heavy fractions of SOM extracted using different solutions (water, sodium iodide [NaI], and sodium polytungstate [SPT]) in areas of Cerrado, pastures, and NT with different deployment times with Distroferric Red Latosol soil. The study areas are located in Montividiu, Goiás (GO), Brazil: (1) pasture of Brachiaria decumbens (PA); (2) NT with three years of deployment with soybean in summer and fallow instead of a second crop (NT3); (3) NT with 15 years of deployment with soybean in the summer and maize/sorghum as the second crop (NT15); and (4) NT with 20 years of deployment with soybean in the summer and maize as the second crop (NT20). These areas were compared to an area of native Cerrado sensu stricto (CE). The NT according to the deployment time showed an increase in the contents of C (0-0.05 m) and N (0-0.2 m) in the soil. The origin of C in the soil of the NT areas is associated with C4 plants; however, in up to 0.2 m of the soil profile, the 13C contents reduced according to NT deployment years. Extraction of light-fraction organic matter (LFOM) with SPT better represents this SOM fraction quantitatively and qualitatively than extraction of LFOM with water and NaI. This pattern is evident because of a greater consistency in the mass, C, N, and 13C contents of the LFOM extracted with SPT among the evaluated areas and the lower C content in residual particulate organic matter among the extractants.

Electrochemical Characterization of Ordered Mesoporous Carbon Screen-Printed Electrodes

Screen-printed electrodes have become an essential tool in the development of electrochemical sensors and biosensors. Among the materials used for the fabrication, the most employed are the different forms of carbon. In this work, the electrochemical characterization of ordered mesoporous carbon screen-printed electrodes is carried out. The results show that the surface area is enhanced and the resistance to the electron transfer is highly reduced in comparison to graphite screen-printed electrodes. Although a lower limit of detection is obtained for screen-printed graphite, ordered mesoporous carbon electrodes showed a better voltammetric selectivity.

The Distribution of Carbon Stable Isotopes as an Indicator of Temporal and Spatial Dynamic and Distribution of Autochtonic and Allochtonic Organic Matter in a Shallow Estuarine Lagoon

Physical and chemical parameters were measured in a mostly freshwater estuarine lagoon in the SE Baltic. Present paper demonstrates an attempt to trace the sources and analyse the seasonal and spatial patterns of distribution of POC, DIC and DOC in the Curonian lagoon mostly by the isotopic content in different forms of carbon. Samples were collected in 2012-2014 in 9 stations in the Curonian lagoon including riverine and marine input/output stations. Riverine inputs and summarizing outflow to the Baltic sea locations (Nemunas river delta and Klaipeda channel stations were sampled monthly, while POC, DIC and DOC samples in other stations were collected on a seasonal basis. The observed results allow easily differentiate between estuarine and riverine POM samples, while the differences in DOC δ13C content between sampling stations were found to be not statistically reliable. The high biological productivity of the Nemunas river along with the minor contribution of the Baltic Sea inflows to the overall hydrodynamics of the lagoon explain similarity of content between riverine and estuarine material in the spring and autumn. However, the δ13C content of DIC and DOC could serve as indicator of external inputs only in connection with seasonal water residence variations. DOI: 10.15181/csat.v3i1.1132

Burial fluxes and source apportionment of carbon in culture areas of Sanggou Bay over the past 200 years

In this study, we assessed the burial fluxes and source appointment of different forms of carbon in core sediments collected from culture areas in the Sanggou Bay, and preliminarily analyzed the reasons for the greater proportion of inorganic carbon burial fluxes (BFTIC). The average content of total carbon (TC) in the Sanggou Bay was 2.14%. Total organic carbon (TOC) accounted for a small proportion in TC, more than 65% of which derived from terrigenous organic carbon (C t), and while the proportion of marine-derived organic carbon (C a) increased significantly since the beginning of large-scale aquaculture. Total inorganic carbon (TIC) accounted for 60%–75% of TC, an average of which was 60%, with a maximum up to 90% during flourishing periods (1880–1948) of small natural shellfish derived from seashells inorganic carbon (Shell-IC). The TC burial fluxes ranged from 31 g/(m2·a) to 895 g/(m2·a) with an average of 227 g/(m2·a), which was dominated by TIC (about 70%). Shell-IC was the main source of TIC and even TC. As the main food of natural shellfish, biogenic silica (BSi) negatively correlated with BFTIC through affecting shellfish breeding. BFTIC of Sta. S1, influenced greatly by the Yellow Sea Coastal Current, had a certain response to Pacific Decadal Oscillation (PDO) in some specific periods.

Multivariate Auger Feature Imaging (MAFI) - a new approach towards chemical state identification of novel carbons in XPS imaging

The clear identification of allotropes and similar chemical states of carbon in XPS imaging can be made difficult because of the subtle differences observed in spectra, particularly when varying from sp2 to sp3 hybridised carbon. By shifting focus from the commonly analysed C1s region in XPS spectra to the often ignored C KVV region, we utilise the so-called D-Parameter to identify different forms of carbon in a surface. When this methodology is applied to XPS imaging, the result is a powerful and unambiguous tool for the chemical state identification of carbon in XPS images. Further enhancement by multivariate statistics improves XPS spectral and image quality, and we call this technique Multivariate Auger Feature Imaging. Herein, we have applied this technique to clearly identify in XPS imaging a graphite film mounted on carbon tape. Copyright © 2015 John Wiley & Sons, Ltd.

Distribution of carbon and nitrogen forms in Histosols of headwater areas – a case study from the valley of the Kamienna Creek (northern Poland)

The aim of the study was to recognize the vertical variability in the content of different forms of carbon and nitrogen in Histosols of a forest spring niche located in the upper course of the Kamienna Creek (the Slupia River catchment). Soil samples were taken from three profiles and analyzed with standard methods used in the soil science. Analyses included the degree of peat mass decomposition, content of soil organic matter, pH, content of total organic carbon (TOC), total nitrogen (TN) and forms of carbon and nitrogen after sequential extraction in 0.25 mol KCl dm -3 , 0.25 mol H 2 SO 4 dm -3 and 2.5 mol H 2 SO 4 dm -3 . The following fractions were isolated: nonhydrolyzable carbon (NHC) and nitrogen (NHN), weakly hydrolyzable carbon (WHC) and nitrogen (WHN), easy hydrolyzable carbon (EHC) and nitrogen (EHN), dissolved organic nitrogen (DON), and its ammonium (NH 4 -N) and nitrate (NO 3 -N) form. The Histosols were t up to 0.9 m hick. The degree of peat mass decomposition was 3-9. The content of organic matter ranged from 317.3 to 829.0 g kg-1, and TOC from 162.2 to 459.5 g kg -1 . The soils were acid at pH H2O equal 5.6-6.5. The NHC form predominated in TOC. The content of the form was 117.3-399.7 g kg -1 , and contribution in TOC 72.3-89.2%. Soils contained 17.1-41.7 g kg -1 of WHC (4.5-10.6% in TOC), and 27.3-62.2 g kg -1 EHC (6.4-17.2% in TOC). The soils were rich in total nitrogen (TN), whose content was 11.1-33.6 g kg-1. The content of NHN was 5.50-18.89 g kg-1 (37.18-69.84% in TN), WHN 4.28-14.17 g kg-1 (21.23-43.72 in TN), EHN 1.16-8.02 g kg -1 (8.06-24.32% in TN), and DON ranged from 0.029-0.394 g kg -1 (0.10-1.20% in TN). The concentration of NH4-N was 0.043-0.337 g kg -1 , and NO3-N 0.003-0.012 g kg -1 . Similar regularities in the vertical distribution of the investigated forms of carbon and nitrogen were observed in every soil profile. In general, an increase in the nonhydrolyzable forms of carbon and nitrogen and a decrease in EHC, EHN, DON and NH 4 -N were observed with depth. The maximum concentration of EHC, EHN, DON and NH 4 -N found in bog horizons is probably an

Effect of land use on the carbon and nitrogen forms in humic horizons of Stagnic Luvisols

The aim of the study was to assess the effect of land use on the forms of carbon and nitrogen in humic horizons of Stagnic Luvisols located in the area of Slawienska Plain (northern Poland). Soil samples were collected form six stands with different land uses located in the same soil complex: more than 100-year-old beech-oak forest (BOF), meadow (M), arable field (AF), fallow (F), secondary afforestation with 15- year-old birch trees (SAB) and secondary afforestation with 30-year-old alder trees (SAA). In every stand, soils were sampled in five replications and analyzed with standard methods used in soil science. The content of different forms of carbon and nitrogen was analyzed after sequential extraction in 0.25 mol KCl dm-3, 0.25 mol H 2 SO 4 dm-3 and 2.5 mol H 2 SO 4 dm-3 (Becher, KalemBasa 2011). Different land uses were reflected in the properties of humic horizon of the investigated soils. Particularly large differences were observed between the forest soils never used for agriculture, and arable or post-arable soils. Tillage caused the increase of the A horizon depth from 9.2 to 26.4-35.6 cm, and the increase of its volumetric density. The highest content of soil organic matter (SOM), total organic carbon (TOC) and total nitrogen (TN) as well as the highest TOC:TN ratio were observed in BOF stand. Statistically significant differences were observed between the stands in the content of carbon forms. Nonhydrolyzable carbon was dominat in the soils (55.98-68.11% of TOC), and dissolved organic carbon (DOC) had the smallest contribution (1.43-3.70% in TOC). In general, higher contribution of DOC in TOC was observed in arable and post-arable soils than in soils under forest. The content of mineral nitrogen (NO 3 -N + NH 4 -N) in the studied soils ranged from 0.028 to 0.053 g kg -1 , and NH 4 -N dominated in the pool. The lowest concentration of mineral nitrogen was observed in arable soils, and significantly higher in the soils under forest and fallow. Easily hydrolyzable nitrogen (EHN), weakly hydrolyzable nitrogen (WHN) and nonhydrolyzable nitrogen (NHN) were the main forms of the element in the studied soils and their content was closely related to the content of SOM. The highest concentration of the forms was noticed in BOF stand. There were differences between the stands in DOC:DON, EHC:EHN, WHC:WHN and NHC:NHN ratios, which indicate varied biological activity of the soils under different uses.

Development of Cost-Efficient Silicon-Carbon Anode Materials Based on Existing Mass-Production of Silicon and Carbon at Elkem

Elkem is one of the world’s leading companies for environment-friendly production of metals and materials. Among its principal products are metallurgical silicon, solar grade silicon, and different forms of carbon. For the coming generation of Li-ion batteries, silicon is a very attractive candidate to replace graphite as anodic material due to its remarkable energy density (3.6 Ah/g) and volumetric capacity (8.3 Ah/ccm). To tackle the massive cracking and degradation typically observed during electrochemical cycling of silicon anodes, we are developing composite nanostructured materials based on existing production of silicon and carbon at Elkem. The goal is to use silicon of optimum purity and doping w.r.t. production costs and performance mixed with carbon materials through milling techniques in a commercially viable way resulting in a product that can be used as anode material in Li-ion batteries.Results show that performance can be substantially improved by using appropriate milling methods. The current presentation focuses on silicon-carbon nanostructures obtained by high-energy ball-milling in argon atmosphere. Silicon-carbon composites showed improved cycle life-time with ball-milling time, though usually accompanied with a loss of initial capacity due to high-surface area and extensive SEI formation. More pronounced improvements were achieved by co-milling silicon with graphite. Further enhancements were obtained by using additives in the electrolyte and by controlling the delithiation step during cycling.The electrochemical performance was tested in half cells where typically the working electrode was made by mixing a silicon-carbon composite powder with an organic binder in an aqueous slurry and coated on a Cu-foil. Lithium metal was used as the counter electrode. Structural properties and degradation mechanisms were examined by electron microscopy (SEM, FIB-SEM, TEM) and XRD.Figure txt: A) Charge (delithiation) capacity retention for selected Si-C based materials. The electrodes were cycled with C/20 rate for the three first and the last cycle. Other cycles were performed at C/10 rate (C-rate was based on the mass of Si assuming full capacity of 3.6 Ah/gSi). The curves labeled 1 was for materials only treated by low-energy milling of Si. A rapid decrease in capacity is seen already from cycle one. This is in contrast to composite materials made by mixed milling of graphite and silicon by high-energy ball milling (curves labeled 2 represents material milled for 20 minutes at 800 rpm, curves labeled 3 were milled at 5 minutes) where a rapid degradation zone appears first after ca. 10 cycles. FIB-SEM cross-sectional images of the cycled electrodes (cycle 8 – just before rapid degradation sets in, cycle 15 – middle of rapid degradation zone, and “dead” electrode after 55 cycles) show that the electrodes gradually become clogged both by SEI formation and Si-intergrowth and lose porosity. This is accompanied with a thickness increase, most dramatically seen after the rapid degradation zone. B) Discharge-charge characteristics for a composite Si+C electrode restricting the charge capacity to 1200 mAh/gSi pr. cycle (material: 80wt.% Si and 20wt.% graphite ball-milled for 5 minutes at 800 rpm). All electrodes were tested as half-cells with a Li-counter electrode and consisted of 60wt.% silicon, 30wt.% graphite, 2 wt.% carbon black and 8wt.% CMC. Typical loading of the active material was 0.8-1.0 mg/cm2.

Novel Co-Precipitation Method for Synthesis of Carbon-Free LiFePO4

Lithium iron phosphate (LiFePO4) is an important alternative cathode material to LiCoO2, which applications are limited by resource availability and safety issues. However, the full potential of the material is sometimes difficult to achieve due to its limited electrical conductivity and low rate of Li+ ion diffusion that together may limit the battery performance. One strategy is to manufacture LiFePO4 particles coated with a conductive phase, such as carbon, which improves the electronic contact between the LiFePO4 particles. However, the carbon seems to modulate not only the electric conductivity but also the reduce crystallite sizes and thus reduces the distance for Li+ transport in the LiFePO4 structure. Furthermore, carbon may improve the phase purity of the final product because during high temperature synthesis, carbon acts as a reducing agent and thus minimizes the likelihood of oxidation of Fe2+ to Fe3+. Despite these advantages, the role of different forms of carbon on the synthesis of LiFePO4 and the electrochemical performance of the materials is yet to be fully understood. This could be because the synthetic methods reported in the literature employ carbon containing precursors or solvents and therefore the LiFePO4 product always contain some form of residual carbon. This complicates the analysis of the effect of a specific carbon type on the electrochemical performance of the cathode material.Carbon-free LiFePO4 material has been synthesised by a novel single-step co-precipitation method from aqueous solutions of LiOH∙H2O, NH4H2PO4 and FeSO4.7H2O precursors. The precipitation sequence and methodology, reaction atmosphere and the role of intermediate phases on the purity of LiFePO4 product has been investigated. The mechanism of formation of phase-pure carbon free LiFePO4 is also investigated and the role of synthesis atmosphere on the phase transformations and the effect of evolving gaseous species on the likelihood of oxidation of Fe2+ to Fe3+ are discussed. The lowest temperature to synthesise phase pure carbon-free LiFePO4 is 550 oC which remains phase pure during further heating up to 750 oC. The novel carbon-free method is suitable for investigation of the effect various forms of carbon (carbon black, nanotubes, meso-porous carbons, etc.) on the electrochemical performance of the cathodes containing LiFePO4.

Effect of carbon on the beneficiation of OSCOM ilmenite by carbonitrothermy

Ilmenite (FeO·TiO2) and rutile (TiO2) are well-known minerals for titanium. Ilmenite is far more abundant than rutile in nature. However, ilmenite contains iron oxides and the TiO2 content of ilmenite is considerably less than rutile. Hence it is necessary to upgrade (enhance TiO2 content) Ilmenite by removing iron before it could be processed for recovery of pure TiO2. Compared to the other grades of ilmenite in India, OSCOM grade from Chatrapur, Orissa has the lowest content of TiO2. Hence beneficiation of such a grade of ilmenite is highly challenging and cost intensive. The present work explores the possibility of beneficiation of ilmenite by a carbonitrothermic process using three different forms of carbon namely, petroleum coke, carbon black and graphite. The thermogravimetry results of carbonitrothermic reduction of ilmenite and rutile and the residue analysis are presented in detail to determine whether the form of carbon has any role in this beneficiation process.

Direct writing on graphene ‘paper’ by manipulating electrons as ‘invisible ink’

The combination of self-assembly (bottom up) and nano-imprint lithography (top down) is an efficient and effective way to record information at the nanoscale by writing. The use of an electron beam for writing is quite a promising strategy; however, the ‘paper’ on which to save the information is not yet fully realized. Herein, graphene was selected as the thinnest paper for recording information at the nanoscale. In a transmission electron microscope, in situ high precision writing and drawing were achieved on graphene nanosheets by manipulating electrons with a 1 nm probe (probe current ∼2 × 10−9 A m−2) in scanning transmission electron microscopy (STEM) mode. Under electron probe irradiation, the carbon atom tends to displace within a crystalline specimen, and dangling bonds are formed from the original sp2 bonding after local carbon atoms have been kicked off. The absorbed random foreign amorphous carbon assembles along the line of the scanning direction induced by secondary electrons and is immobilized near the edge. With the ultralow secondary electron yield of the graphene, additional foreign atoms determining the accuracy of the pattern have been greatly reduced near the targeting region. Therefore, the electron probe in STEM mode serves as invisible ink for nanoscale writing and drawing. These results not only shed new light on the application of graphene by the interaction of different forms of carbon, but also illuminate the interaction of different carbon forms through electron beams.

A system dynamic modeling of carbon cycle from mangrove litter to the adjacent Hooghly estuary, India

Hooghly-Matla estuarine system receives a major load of carbon from adjacent mangrove forest in the form of litterfall throughout the year. Keeping in view, the crucial role of carbon, a seven compartment model has been proposed to study the dynamics of carbon in this estuarine system. Different forms of carbon present in soil (as soil organic carbon (SOC), soil inorganic carbon (SIC)) and in water (as dissolved inorganic carbon (DIC), dissolved carbon dioxide (DCO2), dissolved bicarbonate (DBC), dissolved organic carbon (DOC) and particulate organic carbon (POC)) are taken as state variables. Litter biomass, dissolved oxygen, primary productivity, community respiration, temperature of water, pH of water and soil, air–water exchange of carbon dioxide and conversion rates among different forms of carbon are considered as graph time functions. The data used in the present model are collected for over two years from our own field works and experiments. Other sensitive rate parameters which are not possible to collect from survey or experiment, calibrated following standard procedure. Sensitivity analysis is performed along with calibration. Model simulation results are validated with observed data. Results show seasonal variations of litterfall and which is the main source of SOC pool and ultimately transported to the estuary. Other than litterfall, the death of organisms in soil and water enriches the SOC and POC respectively. pH of water is governing factor and depending on this factor, DIC is converted to DCO2 and DBC, which are taken up by phytoplankton during photosynthesis. Mineralization rate of SOC to SIC and uptake rate of DCO2 and DBC are the sensitive parameters.

Organic matter in the universe

1. History and introduction 2. The chemistry of organic matter 2.1 families of organic molecules 2.2 different forms of carbon 2.3 chains and rings 2.4 molecules of biological significance 3. Techniques of detecting organic molecules in space 3.1 Electronic structure of molecules 3.2 Rotational transitions 3.3 Vibrational transitions 3.4 Electronic transitions 3.5 Nuclear spin and hyperfine lines 3.6 Radical and molecular ions 3.7 Ground-based observations and spectroscopic observations from space 4. Organic molecules in the diffuse interstellar medium 5. Organic compounds in galaxies 6. Synthesis of organic compounds in the late stages of stellar evolution 6.1 nucleosynthesis of carbon 6.2 stellar winds and the late stages of stellar evolution 6.3 synthesis of gas-phase molecules and the condensation of solids 6.4 physical conditions of the stellar wind and chemical pathways of synthesis 6.5 emergence of aliphatic and aromatic compounds and their ejection into the interstellar medium 7. Organic compounds in the Solar System 7.1 meteorites 7.2 interplanetary dust particles 7.3 comets 7.4 asteroids 7.5 planetary satellites 8. Organic compounds as carriers of unsolved astronomical phenomena 8.1 unidentified infrared emission features 8.2 diffuse interstellar bands 8.3 the 217 nm feature 8.4 extended red emission 8.5 the 21 and 30 micron emission features 9. Chemical structures of organic matter in space 9.1 polycyclic aromatic hydrocarbons 9.2 hydrogenated amorphous carbon and carbon nanoparticles 9.3 quenched carbonaceous composites 9.4 kerogen and coal 9.5 tholin and HCN polymers 10. Laboratory simulations of molecular synthesis 10.1 Miller-Urey experiment 10.2 Ultraviolet photolysis of ices 11. Delivery of organic compounds in the early history of the Earth 11.1 isotopic signatures and the existence of presolar grains 11.2 crater records and the heavy bombardment phase in the early history of the Earth 12. Origin of life on Earth 12.1 endogenous and exogenous theories of origin of life 12.2 organic compounds and the first emergence of life 13. Outlook for the future 13.1 future astronomical facilities 13.2 future Solar System exploration missions 14. References 15. Glossary 16. Subject index 17. Object index

Toward facile synthesizing of diamond nanostructures via nanotechnological approach: Lonsdaleite carbon nanofibers by electrospinning

Low cost synthesis of the diamond is a dream for the scientists. In this study, different forms of carbon were obtained due to utilizing of different cobalt-based catalytic materials in the graphitization of poly(vinyl alcohol) (PVA) electrospun nanofibers. The utilized cobalt-based catalysts were cobalt acetate tetrahydrate (CoAc), cobalt NPs, and CoAc/palladium NPs. Calcination in argon atmosphere of the polymeric nanofibers containing the aforementioned catalytic materials led to obtain different products. High yield and good nanofibrous morphology were obtained in case of CoAc-containing nanofibers, however cobalt nanoparticles destroyed the nanofibrous morphology and revealed low yield. Interestingly, diamond-like lonsdaleite carbon nanofibers were produced when CoAc–Pd NPs catalytic system was utilized; however normal graphite powder and nanofibers were obtained when Co NPs and CoAc have been used, respectively. The obtained Co-graphite and Co–Pd–lonsdaleite nanofibers could be also synthesized in the form of thin films supported on graphite disks when polyacrylonitrile disks were used as collectors. Calcination of the obtained disks with the attached electrospun nanofibers produced well affixed Co-graphite and Co–Pd–lonsdaleite nanofibers on graphite disks. Electrical properties study of the obtained films indicated that the Co–Pd–lonsdaleite nanofibers behave as semiconductor while Co-graphite nanofibers show ohmic conductivity. Magnetically, Pd has a negative impact on the magnetic properties of the cobalt.

Variable source and age of different forms of carbon released from natural peatland pipes

We used the carbon isotope composition (14C and δ13C) to measure the source and age of DOC, POC, dissolved CO2 and CH4 (δ13C only) released from three natural peat pipes and the downstream catchment outlet of a small peatland in northern England. Sampling under different hydrological extremes (high flows associated with storm events and low flows before or after storms) was used to explore variability in C sources as flow paths change over short periods of time. The δ13C composition of organic C differed (δ13C‐DOC −28.6‰ to −27.6‰;δ13C‐POC −28.1‰ to −26.1‰) from that of the dissolved gases (δ13C‐CO2 −20.5‰ to +1.1‰; δ13C‐CH4−67.7‰ to −42.0‰) and showed that C leaving the catchment was a mixture of shallow/deep pipe and non‐pipe sources. The isotopic composition of the dissolved gases was more variable than DOC and POC, with individual pipes either showing13C enrichment or depletion during a storm event. The 14C age of DOC was consistently modern at all sites; POC varied from modern to 653 years BP and evasion CO2 from modern to 996 years BP. Differences in the isotopic composition of evasion CO2 at pipe outlets do not explain the variability in δ13C and 14C at the catchment outlet and suggest that overland flow is likely to be an important source of CO2. Our results also show that the sources of CO2 and CH4 are significantly more variable and dynamic than DOC and POC and that natural pipes vent old, deep peat CO2 and POC (but not DOC) to the atmosphere.