a b s t r a c t Polyaniline (PANI) loaded ordered mesoporous carbon (OMC) composites were prepared via different processes, involving the in situ polymerization of aniline in the presence of OMC or its precursor and the direct physical mixing method. On the basis of analyzing the morphologies and structures of these three OMC/PANI composites, the influence of compounding processes on the el…
A B S T R A C T AC and DC electrical measurements were made to better understand the thermal conversion of microcrystalline cellulose to carbon. This study identifies five regions of electrical conductivity that can be directly correlated to the chemical decomposition and microstructural evolution of cellulose during carbonization. In Region I (250–350 0C), a decrease in overall AC condu…
A B S T R A C T Thermophysical properties of carbon materials derived from microcrystalline cellulose have been studied under vacuum and compared with earlier measurements conducted under nitrogen to better understand the influence of porosity, composition, microstructure, and atmosphere effects. The effective thermal conductivity in vacuum is lower than that observed in nitrogen primarily…
a b s t r a c t In this study, activated carbons were prepared from sugar beet bagasse by chemical activation and the prepared activated carbons were used to remove nitrate from aqueous solutions. In chemical activation, ZnCl2 was used as chemical agent. The effects of impregnation ratio and activation temperature were investigated. The produced activated carbons were characterized by measu…
A B S T R A C T Activated carbons were prepared from durian shell by chemical activation with potassium hydroxide. In order to find the optimum pore characteristics, different KOH to durian shell ratio (0.25–1.0) and activation temperature (673–923 K) was employed. The adsorption isotherm of activated carbons produced within these range of temperature and impregnation ratio is a mixture…
a b s t r a c t Two samples of commercial multi-walled carbon nanotubes (Sigma–Aldrich and Sun Nanotech) and a sample of carbon black (Vulcan XC-72R) were investigated in raw state and after the activation in nitric and sulfuric acid by ultrasound agitation. Atomic force microscopy revealed that activated Sigma–Aldrich nanotubes are straight with corrugated walls (bamboo-like structure)…
Abstract. The renaissance of electrical/electrochemical double layer capacitors is occurring at a phenomenally high rate as the significant role of these power storage devices in traction, space flight technology, power electronics and other related fields is recognized. The needs of to-day’s computer world cannot be fulfilled by the conventional capacitors such as electrostatic and elect…
Abstract Ruthenium oxide/ordered mesoporous carbon composites materials were prepared by impregnating an ordered mesoporous carbon CMK-3 with RuCl3 Æ xH2O solution followed by annealing in nitrogen atmosphere from 80 to 400 C. The content of ruthenium oxide in the composites ranged from 10.0 to 30.7 wt.%. X-ray diffraction (XRD), thermogravimetric analysis (TGA), nitrogen adsorption measurem…
a b s t r a c t Composite electrodes for use in redox supercapacitors were prepared by electrochemical deposition of RuO2 or the co-deposition of Ru–Co mixed oxides on the surface of single-walled carbon nanotubes. Electrodes coated with the Ru–Co mixed oxide [Ru (13.13 wt%) and Co (2.89 wt%)] or RuO2, exhibited a similar specific capacitance (∼620Fg−1) at low potential scan rates (…
a b s t r a c t A simple and efficient way has been developed to decorate multiwalled carbon nanotubes (MWCNTs) withRuO2 nanoparticles for use of electrochemical supercapacitor. In thismethod,RuO2 nanoparticleswas directly synthesizedand attachedontoMWCNTs in the mixture withRuCl3 solution by microwave-assisted irradiation. Energy dispersive X-rays analysis (EDXA) elucidated the presence of…
a b s t r a c t Hydrous ruthenium oxide/activated carbon black (RuOx/ACB) composite was synthesized for the first time for supercapacitors by a chemical impregnation method. The RuOx/ACB composite is characterized by thermogravimetric analysis (TGA), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The results of TGA and TEM characterization s…
Abstract: Carbon/nano Ru composites were obtained by silica templating of dichlorobis (μ-chloro)bis [(1-3-η: 6-8-η)-2,7- dimethyloctadienediyl] diruthenium(IV), followed by pyrolysis. Carbon/RuO2·XH2O composites were obtained by electro-oxidation of carbon/nano Ru composites. It was found that the carbon/Ru composites had homogeneously dispersed Ru nanoparticles in the hierarchical pore str…
a b s t r a c t An asymmetric supercapacitor with improved energy and power density, relative to a symmetric Ru oxide device, has been constructed with anthraquinone-modified carbon fabric (Spectracarb 2225) as the negative electrode and Ru oxide as the positive electrode. The performance of the supercapacitorwas characterized by cyclic voltammetry and constant current discharging. Use of th…
Abstract Amorphous RuO2·xH2O and a VGCF/RuO2·xH2O nanocomposite (VGCF = vapour-grown carbon fibre) are prepared by thermal decomposition. The morphology of the materials is investigated by means of scanning electron microscopy. The electrochemical characteristics of the materials, such as specific capacitance and rate capability, are investigated by cyclic voltammetry over a voltage range of…
a b s t r a c t Active carbon–ceramic sphere as support of ruthenium catalysts were evaluated through the catalytic wet air oxidation (CWAO) of resin effluent in a packed-bed reactor. Active carbon–ceramic sphere and ruthenium catalysts were characterized by N2 adsorption and chemisorption measurements. BET surface area and total pore volume of active carbon (AC) in the active carbon–…
a b s t r a c t Composites consisting of ruthenium oxide particles deposited on amorphous carbon nanofibres are prepared by a repetitive impregnation procedure. The choice of amorphous carbon nanofibres as support of amorphous ruthenium oxide leads to composites in which the deposited oxide consists of aggregates of extremely small primary particles (1–1.5 nm-size) and showing high porosi…
a b s t r a c t A novel method based on spontaneous reduction of Ru(VI) and Ru(VII) is reported for the deposition of Ru oxide on multi-walled carbon nanotubes (MWCNT). Both purified and acid functionalized nanotubes (p-MWCNT and a-MWCNT) have been used to produce composite materials for use in high power aqueous supercapacitors. Specific capacitances of 213±16Fg−1 and 184±11Fg−1 were…
Abstract We reported an asymmetric supercapacitor technology where RuO2/TiO2 nanotube composite was used as positive electrode and the activated carbon as negative electrode in 1 mol/L KOH electrolyte solution. The electrochemical capacitance performance of the asymmetric supercapacitor was tested by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge …
Abstract The structural, surface morphological and optical properties of sprayed ruthenium oxide thin film were investigated using XRD, SEM and optical absorption measurements. The structural analysis from XRD pattern showed the formation of RuO2 in amorphous phase. The scanning electron micrographs revealed network-like morphology of ruthenium oxide. The optical studies showed a direct band g…
Abstract The effects of annealing in air and anodizing on the capacitive behavior of carbon–ruthenium (denoted as C–Ru) composites fabricated by wet impregnation were investigated in 0.1 M H2SO4 by cyclic voltammetry (CV) and chronopotentiometry (CP). The utilization of Ru species within the thick composites (-1000 lm) was greatly promoted by annealing in air at 240 -C for 8 h and anodizin…
Abstract In this study we report the pseudocapacitive behavior of multiwalled carbon nanotubes (MWNTs) functionalized with hydrous ruthenium oxide in 1 M sulfuric acid for supercapacitor applications.The entangled network of nanotubes which forms open mesopores and their chemical stability with a basal geometry makes them suitable for such applications.Oxidative treatment to generate oxygenate…
Abstract Hydrous ruthenium oxide was synthesized by a sol-gel method on the surface of activated carbon (AC). After heat treatment at 150°C, the RuO2/AC composite was used as a positive electrode material in an alkaline electrochemical capacitor. Several composites with different Ru contents were prepared and studied. It was found that the composite containing 30 w/% Ru had a specific capacit…
Abstract A simple and efficient route to decorate carbon nanotubes (CNTs) with nanocrystalline RuO2 has been developed. In this method, RuCl3.3H2O was oxidized into RuO2 by oxygen in supercritical diethyl amine, and the produced RuO2 deposited on CNTs, resulting in RuO2/CNT nanocomposites. The as-prepared composites were structurally and morphologically characterized by X-ray diffraction, X-ra…
Abstract The electrochemical storage of energy in various carbon materials (activated carbons, aerogels, xerogels, nanostructures) used as capacitor electrodes is considered. Different types of capacitors with a pure electrostatic attraction and/ or pseudocapacitance effects are presented. Their performance in various electrolytes is studied taking into account the different range of operating…
Abstract Ruthenium oxide (RuO2) thin films have been prepared using single step chemical method containing Ru(III) Cl3 solution in an aqueous medium at low temperature. The structural, morphological and optical properties have been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and optical absorption technique. The XRD stu…
Abstract Porous carbon materials were prepared using resorcinol and formaldehyde catalyzed by KOH in a sol–gel process followed by carbonization, during which the KOH serves as an activating agent and generates pores mainly located in the micropore range. With an increase of mass ratio of KOH to resorcinol from 1 to 4, both the specific surface area and the pore volume of the carbons increas…
Abstract Asymmetric capacitors composed of carbon electrodes with different pore size distributions (PSD) were constructed in order to study the fundamental relationship between the PSD of positive and negative carbon electrodes and the performance of electric double layer capacitors. The performance of asymmetric capacitors in a non-aqueous electrolyte solution (TEMA·BF4/PC) was found to be …
Abstract Fractal characteristics of mesoporous carbon electrodes were investigated with various pore structures using the N2 gas adsorption method and the transmission electron microscopy (TEM) image analysis method. The mesoporous carbons with various pore structures were prepared by imprinting mesophase pitch used as a carbonaceous precursor with different colloidal silica particles. All imp…
a b s t r a c t A series of porous carbon samples as electric double layer capacitor electrode materials were prepared by a pyrolysis process using phenol formaldehyde resin (PF) as precursors and KOH/ZnCl2 as activation agents. Porous carbon samples were characterized by thermogravimetric analysis, X ray diffraction, nitrogen adsorption/desorption isotherms and transmission electron microsc…
a b s t r a c t Microporous activated carbons were prepared by microwave heating petroleum coke with potassium hydroxide as activation agent.Microporous activated carbons were characterized by infrared spectro- scopy, X-raydiffraction and nitrogen adsorption/desorption isotherms. Electrochemical properties of an electric double layer capacitor using microporous activated carbonas electrode …
Abstract Two kinds of mesophase pitches with different softening points were prepared at different soaking times and directly acti-vated with KOH to study the effects of the softening point on the textural characteristics of the resulting activated carbons and their be-havior as electrodes in capacitors. Results show that the softening points of the two mesophase pitches are 280 and 330 °C, …
a b s t r a c t Polyfurfuryl alcohol (PFA) derived activated carbons were prepared by the acid catalysed polymerization of furfuryl alcohol, followed by potassium hydroxide activation. Activated carbons with apparent BET surface areas ranging from 1070 to 2600m2 g−1, and corresponding average micropore sizes between 0.6 and 1.6nm were obtained. The porosity of these carbons can be careful…
a b s t r a c t Supercapacitors have been known for over fifty years and are considered as one of the potential energy storage systems. Research into supercapacitors is presently based primarily on their mode of energy storage, namely: (i) the redox electrochemical capacitors and (ii) the electrochemical double layer capacitor. The commonly investigated classes of materials are transition m…
A B S T R A C T Electrical double layer capacitors (EDLCs) with activated sucrose-derived carbons (ASCs) as electrodes are reported. The carbons were prepared by the pyrolysis of sucrose followed by the activation with CO2 gas for 1–5 h at 900 -C to tune the pore size distribution and the specific surface area (SSA). The porosity of the ASCs has been characterized using N2 and CO2 adsorp…
A B S T R A C T The beneficial feature of the polymeric framework in a gel electrolyte is to assist ion transport via the segmental motion of the polymer chains. This feature was displayed by ac impedance analysis on an activated carbon capacitor assembled with a gel electrolyte, which consisted of poly(ethylene oxide)-copoly(propylene oxide) as a host, propylene carbonate (PC) as a plastici…
Abstract: Activated carbons (ACs) made from petroleum coke by KOH activation were further treated by microwaves to investigate the effect of microwave-treatment time on the pore structure, the surface properties (functional groups) and the electrochemical properties of the as-made ACs for electrochemical capacitors (ECs). Results show that the specific capacitance and the equivalent series re…
a b s t r a c t In this study, contributions of hemicellulose, cellulose and lignin to the mass and the porous roperties of chars and activated carbons from various lignocellulosic materials were studied. A predictive alculation was established using the experimental results obtained for the three components separately to evaluate the carbonization and activation yields and their respective co…
Abstract The influence of pre-carbonization of petroleum cokes on the properties of the activated carbon precursors and final carbons activated with KOH was investigated by using TG–DTG, FTIR, XRD, and BET techniques. TG–DTG study revealed the decomposition of volatile species and FTIR analysis identified the presence of C–O, C–O–C, C–O–H and some alkyl species on the surface of …
a b s t r a c t Equations routinely used to describe the properties of conventional symmetric electrochemical doublelayer capacitors (EDLCs) are expanded to develop straightforward mathematical functions that can effectively describe the performance characteristics of asymmetric supercapacitors based on electrically conducting polymer and activated carbon (ECP–AC) electrodes. Formulae are…
Abstract The present paper deals with the electrical conductivity of a number of carbonaceous powders undergoing a low compaction. It is shown that the contributions to the conductivity of such samples are too numerous and too complex to be solved exactly. Hence, several criteria are proposed in order to quantify the behaviour of moderately compressed powders, and thus derive several useful pa…
Abstract. High surface area, highly mesoporous carbon granules in the form of pellets were prepared by first mixing a solution of polymer (phenolic resin, cellulose, or PAN) with water and a chemical reagent (NaOH or ZnCl2). Carbon black powder was then added to form a mixture, followed by molding into a pellet, drying and activating at a given temperature. The pore structures of the porous ca…
Abstract. High conductivity and solubility of polypyrrole (PPy)/multi-walled carbon nanotubes (MWCNT) composites has been successfully synthesized by in situ chemical oxidation polymerization using various concentrations of cationic polyelectrolyte poly(styrenesulfonate) (PSS) and ammonium peroxodisulfate (APS). Raman spectroscopy, FTIR, EPR, FESEM and HRTEM were used to characterize their …
Abstract. Polyetherimide (PEI) and carbon nanofiber (CNF) composites have been developed successfully by using a Sigma high temperature internal mixer and then compression molded. The amount of carbon nanofibers used was 1–3 phr (parts per hundred of polymer), respectively. Thermal properties were characterized by using thermogravimetric analysis (TGA). Thermal conductivity was measured at t…
Abstract. Porous carbon/SiO2 composites were prepared by heating the compacts composed of the rice husk (RH) powders of small (
Abstract. Activated carbon pellets without a binder from cellulose microcrystals as a raw material were investigated. After compression of the raw materials, the thus obtained raw material pellets were slowly carbonized to 1073 K under nitrogen. To activate them, the carbon pellets were heated to 1173 K under carbon dioxide. The activated carbon pellet shape, after heat treatment, was columnar…
Abstract. Many interesting cathode materials, such as LiFePO4, LiMnPO4, LiFeBO3 or the recently discovered Li2FeSiO4 and Li2MnSiO4, exhibit extremely low electronic conductivity (
Abstract. Several macroscopic assemblies of carbon nanotubes(CNTs), consisting only of CNTs, have been developed for the maximum utilization of their characteristic properties for macroscale structures. These include bucky paper, freestanding films, and fibres. However, these materials have limited performance, because the CNTs are assembled via weak interactions, such as van der Waals for…
Abstract. Truck tire particles were pyrolysed at 490 °C at atmospheric pressure and under vacuum, respectively. The recovered pyrolytic carbon black (CBP) was heated in a post-pyrolysis process at temperatures ranging from 670 to 860 °C. The CBP were studied in comparison to a commercial tire carbon black by low-pressure nitrogen adsorption and surface spectroscopic methods (ESCA and SIM…
Abstract. Conductive carbon blacks from different manufacturers were studied in order to obtain some insight into the relation between their electrical conductivity and their surface properties. The surface chemistry was studied by X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectroscopy (SIMS), whereas the topology of the carbon black surface was investigated using lo…
Abstract. The electrical conductivity of cubic samples (monoliths) made of moderately compressed expanded graphite has been measured along two orthogonal directions, namely parallel and perpendicular to the pressing force. It is found that these highly porous materials exhibit a percolation behaviour, with a transition from insulator to conductor occurring at a very low critical density. Besi…