2012 Vol. 27, No. 05

Recent progress in the preparation of ordered mesoporous carbons using a self-assembled soft template
HUANG Zheng-hong
2012, 27(05): 321-336.
Abstract(2027) PDF(10337)
Abstract:
The preparation of self-assembled ordered mesoporous carbons (SA-OMCs) using a soft template method has many advantages, such as low cost, ease of preparation and control. This paper review the development periods, the basic principles and preparation procedures with an emphasis on the control of morphology and multi-level pore structure of OMCs based on SA-OMCs. And suggest that further research in this area can be focused on expanding the scope of the precursor, improving the flexibility and conductivity of the shaped products, such as fibers and membranes.
Thermal properties of nanoporous carbons prepared by a template method using different polymeric and organic precursors
Magdalena Sobiesiak
2012, 27(05): 337-343. doi: 10.1016/S1872-5805(12)60019-5
Abstract(1756) PDF(1387)
Abstract:
Six nanoporous carbons were prepared by a hard-template method using furfuryl alcohol (FA), 4,4’-bismaleimidediphenyl methane (BM), its copolymer with divinylbenzene (BM-DVB), and sucrose as carbon precursors, and two silica gels as templates. The influence of the templates and precursors on the properties of the synthesized porous carbons was studied. Other factors affecting the porous structure of the final products, such as surface activators and the final carbonization temperature, were also investigated. Results indicated that the specific surface areas and total pore volumes of the samples with micropores were in the range of 836-1 785 m2 · g-1 and 0.9-2.0 cm3 · g-1, respectively. The highest surface area was obtained for the systems when sulphosalicylic or/and phosphoric acids were used as surface activators. The porous carbons were mesoporous when benzene vapor was present during carbonization under argon atmosphere. An increase in final carbonization temperature resulted in an increase in total pore volume. The influence of carbon precursors on the properties of nanoporous carbons was not that obvious. The presence of nitrogen atoms in the precursors (BM and BM-DVB) improved the thermal stability of the product.
A comparison of microstructure and adsorption characteristics of activated carbons by CO2 and H3PO4 activation from date palm pits
K. Suresh Kumar Reddy,  Ahmed Al Shoaibi,  C. Srinivasakannan
2012, 27(05): 344-351. doi: 10.1016/S1872-5805(12)60020-1
Abstract(1665) PDF(1725)
Abstract:
This work attempts to compare the texture and the adsorption capacity of porous carbons prepared from date palm pits using CO2 and H3PO4 activation. The activation conditions were chosen based on the optimized parameters reported in the literature. The microstructure of the activated carbons was assessed based on nitrogen adsorption, SEM, and FT-IR, while the adsorption capacity was estimated using methylene blue (MB) adsorption. CO2 activation resulted in a microporous carbon with a yield of 44% and a BET surface area of 666 m2 · g-1, H3PO4 activation resulted in a mesoporous carbon with a yield of 14.8% and a BET surface area of 725 m2 · g-1. The average pore diameter of the activated carbons was estimated to be 1.51 and 2.91 nm for CO2 and H3PO4 activation respectively. The equilibrium adsorption isotherms for MB were fitted by the Langmuir and Freundlich models. The monolayer adsorption capacity of CO2 and H3PO4 activated carbons for MB from the Langmuir model were 110 and 345 mg · g-1 respectively under the optimized conditions. A highest MB adsorption capacity of 455 mg · g-1 was found for the H3PO4 activated carbon with a highest BET surface area.
Synthesis of carbon nanotubes on carbon fibers by modified chemical vapor deposition
HU Zhi-hui1, 2,  DONG Shao-ming1,  HU Jian-bao1,  WANG Zhen1
2012, 27(05): 352-361. doi: 10.1016/S1872-5805(12)60021-3
Abstract(1789) PDF(1494)
Abstract:
Carbon nanotubes (CNTs) were synthesized on carbon fibers by a modified thermal chemical vapor deposition (CVD) method. The fibers were first treated at a temperature of 973 K and then treated by a mixture of sulfur acid and nitric acid with a volume ratio of 1∶3 to improve the dispersion of catalyst precursor Fe(NO3)3 · 9H2O on the surface before impregnation with a catalyst solution. The carbon fibers then underwent simultaneous catalyst reduction and CNT growth to decrease the contact time between the transition metal and the carbon fiber surface, and a uniform and thick CNT forest could be obtained with no significant decrease of the mechanical strength of the carbon fibers compared with those produced by traditional thermal CVD. An in-depth analysis shows that the process parameters have a great influence on the CNT growth rate, such as the type of solvent, concentration of Fe(NO3)3 · 9H2O, the ratio of H2 to C2H2, and the growth time. It was revealed that a better CNT forest could be obtained when the catalyst solvent is ethanol, the Fe concentration is 100 mmol/L, the ratio of H2/C2H2 is 4/1, the temperature is 1 023 K and the growth time is 30 min.
Preparation and mechanical properties of MWCNT and carbon fiber reinforced bismaleimide resin composite
QIU Jun1, 2
2012, 27(05): 362-369.
Abstract(1351) PDF(1277)
Abstract:
Bismaleimide reinforced with both MWCNTs and carbon fibers was prepared by mold-pressing carbon fiber paper stacks impregnated with a bismaleimide acetone solution containing MWCNTs grafted with ethylene diamine. The MWCNTs were oxidized by concentrated HNO3 to form carboxyl groups before grafting. Results show that the flexural modulus, flexural strength and impact strength of composite with a 0.5 mass% of MWCNTs is 43.85 GPa, 1 160.62 MPa and 28.50 kJ/m2, which represent increases of 49.56%, 17.41% and 19.65% respectively compared with the carbon fiber/BMI composite.
Functionalized graphene oxide with ethylenediamine and 1,6-hexanediamine
YAN Jia-lin
2012, 27(05): 370-376. doi: 10.1016/S1872-5805(12)60022-5
Abstract(3008) PDF(4753)
Abstract:
Graphene oxide (GO) obtained by Hummers method was functionalized by ethylenediamine (EA) and 1,6-hexanediamine (HA) in N, N-dimethyl formamide using 1, 1, 3, 3-tetramethy-luronium hexafluorophosphate as a coupling agent. The functionalized GO was characterized by elemental analysis, FT-IR, XRD, XPS, TGA, SEM and TEM. Results showed one carbon atom in nine to ten of the carbon atoms in GO was functionalized by an amine group. The thermal stability of the GO functionalized by HA was much higher than the one functionalized by EA. However, the former was less dispersible in N, N-dimethyl formamide than the latter.
Preparation and properties of graphene oxide-carbon fiber/phenolic resin composites
LIU Yan-zhen1| LI Yong-feng2| YANG Yong-gang1| WEN Yue-fang3| WANG Mao-zhang1
2012, 27(05): 377-384.
Abstract(1798) PDF(2510)
Abstract:
Graphene oxide-carbon fiber/phenolic resin, chemically-reduced graphene oxide-carbon fiber/phenolic resin, and thermally-reduced graphene oxide-carbon fiber/phenolic resin composites were prepared by blending a graphene oxide suspension in an ethanol solution of phenolic resin with carbon fibers, followed by vacuum drying and hot pressing. The effects of the type of graphene oxide on structure, compressive performance and friction properties of the composites were investigated. Results showed that the compressive properties of the composites were greatly improved with a 0.1 mass graphene oxide % loading compared with the pure carbon fiber/phenolic resin composite. The compressive strength and modulus of the thermally-reduced graphene oxide/phenolic resin/carbon fiber composites were increased by 178.9%, 129.5%, respectively, and the highest energy storage modulus of the chemically-reduced graphene oxide/phenolic resin/carbon fiber composite was increased by 75.2% compared with the pure carbon fiber/phenolic resin composite. The glass transition temperatures of all the composites containing graphene oxide decreased.
The antimicrobial properties of carboxylated graphene oxide decorated with La particles
WANG Xiao-dan1, ,  ZHOU Ning-lin1, 3,  WANG Wei-yan1, 2
2012, 27(05): 385-392.
Abstract(1866) PDF(1254)
Abstract:
      Graphene oxide (GO) was functionalized by acetyl chloride to form carboxylated graphene oxide (GO-COOH). GO-COOH decorated with La particles with diameters between 0.2 and 1 μm was prepared by the sonication of a LaCl3 aqueous solution with GO-COOH. The La-decorated GO-COOH was characterized by FT-IR, TGA and TEM, and its antibacterial properties were characterized by bacteria growth kinetics. Results showed that the La3+ ions were coordinated on edges and corrugated parts of the GO-COOH by physical and chemical bonding. The La-decorated GO-COOH had a good inhibitory efficiency of 96.4% on the E.coli when its concentration was 0.5 mg/mL. It also had inhibitory effects on S.aureus and the P.Aeruginosa. The better antibacterial effect of the La-decorated GO-COOH than the corresponding La-decorated GTO was ascribed to the higher amount of La particles incorporated on the GO-COOH.
Influence of graphite powder on the properties of carbon paper for proton-exchange membrane fuel cells
LIANG Yi-li1, 2
2012, 27(05): 392-400.
Abstract(1519) PDF(1253)
Abstract:
A PAN-based carbon fiber paper preform prepared by a dry casting method was impregnated with phenolic resin mixed with graphite powder, which was mold-pressed, cured, carbonized and graphitized to prepare carbon paper for proton-exchange membrane fuel cells (PEMFCs). The effect of graphite powder content on the properties of the carbon paper was investigated. Results showed that the thickness, porosity, permeability and conductivity of the carbon paper increased with increasing content of graphite powder while its density and tensile strength exhibited a maximum. The carbon paper has an optimum performance for PEMFCs with a graphite addition of 5 mass%. The optimized properties of the carbon paper are as follows: thickness 0.23 mm, density 0.53 g · cm-3, resistivity 2.6 mΩ · cm-1, tensile strength 19.4 MPa, porosity 66%, gas permeability 2 080 mm · cm-2 · h-1 · mmAq-1. The output voltage of a single cell with this paper loaded with 0.5 mg Pt/cm2 was 0.65 V with a current density of 800 mA · cm-2 under atmospheric pressure and 65 ℃ using a H2/air pair.