新型炭材料

A review of the adsorption of organic pollutants on mesoporous carbons and carbon/silica hybrids

LIU Xian-bin1, 　XIE Xin-xin1, 　YAN Hong1, 　SUN Xiao-jun1

2013, 28(4)

Abstract(1607)

PDF(2467)

Abstract:
This paper gives a brief review of the adsorption of organic pollutants on mesoporous carbons and carbon/silica hybrids prepared using soft and hard templating methods. These adsorbents include both pristine and modified ones such as metal-loaded, ammonia-treated, KMnO₄-oxidized, CO₂-activated, and octyl-grafted carbons and hybrids. The adsorbates cover small-molecule pollutants such as phenol, nitrosamine, nitrobenzene, 4-nitrophenol and 4-chlorophenol, and large-molecule pollutants such as cationic, anionic and non-ionic dyes, bisphenol A, humic acids and rhodamine B. Their adsorption mechanism and kinetics are analyzed. Applications of these mesoporous materials in the adsorption of large-molecule organic pollutants are highlighted.

An efficient dye-sensitized solar cell using surfactant-modified mesoporous carbon film as a counter electrode

XU Shun-jian 1, 　LUO Yu-feng 1

2013, 28(4) doi: 10.1016/S1872-5805(13)60079-7

Abstract(1466)

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Abstract:
Mesoporous carbon (MC), prepared by the carbonization of phenol resin using ethylene glycol as a pore forming agent, was used as the catalyst of the counter electrode in dye-sensitized solar cells (DSCs) fabricated by a paste coating method at low temperature, where a non-ionic surfactant, Triton X100, was used as a modifier of the paste. Fractal dimensions (D_F) were used to evaluate the morphological difference of the MC films on the substrate with surfactant content. The efficiency of the DSCs using the MC modified by the surfactant reaches a maximum of 5.65% for 0.6g MC with 0.1 mL surfactant. This is 46.5% higher than that of DSCs using activated carbon as a catalyst in the counter electrode, and 95.4% of the value obtained using DSCs with a Pt counter electrode under the same conditions. The performance improvement of the surfactant-modified MC counter electrode is attributed to a uniform MC film with a low D_F value induced by adding the surfactant, a large average mesopore size of 34.6 nm that is favorable for mass transport, and a high-surface-area glassy carbon structure that has a high content of active sites.

The effect of the HClO₄ oxidization of petroleum coke on the properties of the resulting activated carbon for use in supercapacitors

DENG Mei-gen, 　WANG Ren-qing

2013, 28(4) doi: 10.1016/S1872-5805(13)60080-3

Abstract(1356)

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Abstract:
Petroleum coke (PC) was modified by HClO₄ oxidization. Activated carbons (ACs) were prepared using a mass ratio of KOH/modified PC of 3∶1 (denoted OAC-3) and a KOH/PC mass ratio of 4∶1 (denoted AC-4) for comparison. XRD, I₂ adsorption, N₂ adsorption and cyclic voltammograms were used to investigate the influence of HClO₄ oxidization on the structure of the PC and the performance of the resultant AC. Results indicated that HClO₄ oxidization increased the d₍002) of microcrystalline PC from 0.344 to 0.353 nm and decreased L_c from 2.34 to 1.75 nm. The specific surface areas of AC-4 and OAC-3 were 2 929 and 3 058 m²/g, respectively. AC-4 and OAC-3 had a specific gravimetric capacitances of 361.3 and 392.7 F/g at a scan rate of 0.5 mV/s, respectively. A supercapacitor based on OAC-3 possessed a better power performance than that based on AC-4.

Synthesis of a nitrogen-doped porous carbon monolith and its use for CO₂ capture

QIAN Dan

2013, 28(4)

Abstract(1519)

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Abstract:
Monolithic nitrogen-doped porous carbon was synthesized by the copolymerization of resorcinol and formaldehyde in the presence of L-lysine as the catalyst at the ambient conditions. The carbon is designated RFL. In order to increase the active nitrogen content, nitrogen-rich melamine was added, and the resulting material (RFLM) has more nitrogen-containing functional groups, and a higher specific surface area and pore volume than the original RFL. Glutamic acid was used to control the rate of polymerization, resulting in a porous carbon (RFLMG) with optimized texture properties. However, samples of RFLM and RFLMG show lower CO₂ adsorption capacities than do the RFL series, indicating that there is no explicit linear relationship between the nitrogen content and CO₂ adsorption capacity. This may be directly caused by the different form of the nitrogen-containing functional groups.

Classification schemes for carbon phases and nanostructures

Evgeny A Belenkov, 　Vladimir A Greshnyakov

2013, 28(4) doi: 10.1016/S1872-5805(13)60081-5

Abstract(1455)

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Abstract:
New schemes of structural classification for carbon phases and nanostructures have been proposed, which are based on the types of chemical bonds formed and the numbers of the nearest neighbors with which each atom forms covalent bonds. The classification schemes can describe not only the known phases, but also new phases and nanostructures. New phases can be derived by linking, superpositioning or cutting precursor structures. The classification scheme has been used to predict diamond polymorphs, yielding thirty diamond-like phases that consist of atoms in equivalent crystallographic positions and eighteen of which were predicted for the first time.

Growth of vertically aligned carbon nanotubes on a silicon substrate by a spray pyrolysis method

V S Angulakshmi1, 　K Rajasekar2, 　C Sathiskumar3, 　S Karthikeyan3

2013, 28(4) doi: 10.1016/S1872-5805(13)60082-7

Abstract(1379)

PDF(1288)

Abstract:
Vertically aligned carbon nanotubes on a silicon substrate were synthesized by a spray pyrolysis method using the methyl ester of Helianthus annuus oil as a carbon source, ferrocene as a catalyst precursor and argon as a carrier gas. Results show that Fe catalyst nanoparticles are formed from ferrocene in-situ on the silicon substrate. As-grown vertically aligned carbon nanotubes are well graphitized as shown by Raman spectra, transmission electron microscopy images and X-ray diffraction patterns. The diameter of the carbon nanotubes is around 10-30 nm and their wall thickness is around 10 nm. The content of catalyst in the products is negligible.

Preparation of ruthenium-loaded CNT-TiO₂ nanohybrids and their catalytic performance for the selective oxidation of benzyl alcohol

FAN Li-man

2013, 28(4)

Abstract(1423)

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Abstract:
CNT-TiO₂ nanohybrids were synthesized using CNTs as a substrate and isopropyl titanate as a titanium source by a hydrothermal method. The nanohybrids were characterized by SEM and XRD, and their dispersion ability as an emulsion was investigated by optical microscopy. Ruthenium was loaded onto TiO₂ and the nanohybrids by an impregnation method, and their catalytic performance was evaluated by the selective oxidation of benzyl alcohol to benzylaldehyde. The mechanism involved in the reaction was proposed. Results show that the dispersion ability of the CNT-TiO₂ nanohybrids, judged by the numbers of uniform oil droplets in water per unit liquid volume, is better than that of TiO₂. The catalytic activity and selectivity of the Ru/CNT-TiO₂ for the selective oxidation reactions are higher than for Ru/TiO₂, indicating that they are closely related to the dispersion ability of the catalysts as emulsions.

Growth of a cup-stacked carbon nanotube carpet with a superhydrophobic surface

LI Shi-sheng, 　HOU Peng-xiang, 　LIU Chang

2013, 28(4) doi: 10.1016/S1872-5805(13)60083-9

Abstract(1309)

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Abstract:
A carpet structure composed of high purity cup-stacked carbon nanotubes (CSCNTs) was synthesized by a catalytic chemical vapor deposition method. In a 15-min growth time, the CSCNT carpet with a height up to ~300 μm and carbon purity above 99.9 mass% was prepared. Transmission electron microscopy observations indicated that the CSCNTs with diameters ranging from 80 nm to 230 nm consist of truncated conical graphene layers. Based on the experimental results, a possible “base growth” mechanism was proposed for the CSCNTs. The CSCNT carpet is highly flexible and superhydrophobic, showing a contact angle of ~155^o. It can be easily harvested from the original growth substrate and be transferred to target substrates. It may therefore find applications as a water-proof and self-cleaning coating layer.

Tensile properties of 4D braided carbon/carbon composites produced from carbon fiber bundles and carbon rods

WU Xiao-jun1

2013, 28(4)

Abstract(1617)

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Abstract:
4D preforms woven with carbon fiber bundles and carbon rods were densified by repeated pitch impregnation, carbonization and high temperature treatment to obtain 4D-C/C composites. The tensile properties were investigated at room temperature when tension was applied in the carbon rod direction (Z direction). The strain and stress under tensile load were measured, and the surface morphologies of specimens after tensile failure were observed by scanning electron microscopy. Results indicate that the tensile strengths of the composite were controlled by interfacial shear strength between the carbon rod and the carbon matrix. The carbon rods were pulled out entirely from matrix after tensile failure, indicating that the material was not sufficiently reinforced by the carbon rods. Numerous micro-cracks were found on the surface of specimens after tensile failure. These were perpendicular to the load direction and equally spaced by a distance of about 2mm. The damage model of 4D-C/C is similar to that of 1D-C/C.

Preparation of carbon quantum dots in wood charcoal and their interaction with bovine serum albumin

LU Hua, 　SHAN Xiao-hui

2013, 28(4)

Abstract(1679)

PDF(2166)

Abstract:
Carbon quantum dots (CQDs) are a new fluorescent material with stable fluorescence, low toxicity and many other superior properties that make their applications in biology possible. CQDs in wood charcoal were created by a 5N HNO₃ solution using three different methods, reflux, microwave and ultrasound methods. Factors that determine the fluorescence quantum yield were examined and preparation conditions were optimized. Results indicated that the fluorescence quantum yield of CQDs prepared by the reflux method was highest among the three methods. The CQDs prepared by this method were modified by poly(ethylene glycol)2000 to increase the fluorescent lifetime and the quantum yield. The reaction of the modified CQDs with bovine serum albumin was investigated by ultraviolet absorption spectrometry and fluorescence spectrometry, which revealed a static quenching behavior.

Conductive and photoactive properties of polyethylene terephthalate fabrics treated with nano TiO₂/nano carbon blacks

A Ebrahimbeiki Chimeh1, 　M Montazer2, 　A Rashidi1

2013, 28(4) doi: 10.1016/S1872-5805(13)60084-0

Abstract(1277)

PDF(1456)

Abstract:
A polyethylene terephthalate (PET) fabric was pretreated by alkaline-hydrolyzation. Both the pristine and pretreated PETs were loaded with nano carbon blacks (CB1515 and CB156), mixtures of nano TiO₂ (NTO) and NCBs (CB1515 or CB156) using an impregnation method with sodium dodecyl sulfate as a dispersing agent. Citric acid (CA) and sodium hypophosphite (SHP) were also used as a cross-linking agent and a catalyst respectively in addition to the dispersant to load NTO+CB1515 and NTO+CB156 onto the PETs with and without pretreatment as comparisons. It is found that CB156 is more effective than CB1515 to decrease the electrical resistivity for all samples. The samples from the pristine PET have lower resistivities than those from the pretreated PET when NTO is added. However, this is reversed when NTO is not added. Use of CA and SHP can significantly lower the resistivity of samples in all cases by increasing the loading level and dispersion uniformity of NCBs and NTO in the fabrics. A synergistic effect of NCBs and NTO is found to increase UV absorption of the treated fabrics. The samples from the pristine PET loaded with NCBs and NTO were more active than those from the pretreated PET for the degradation of methylene blue. The activity can be increased by loading with NTO or by adding both CA and SHP and the former is more effective than the latter.

2013 Vol. 28, No. 4

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