Temperature dependence of the thermal conductivity of individ-

ual pitch-derived carbon fibers

Jian-Li Wang a, Ming Gu a, Wei-gang Ma a, Xing Zhang a, Yan Song b

a Key Laboratory for Thermal Science and Power Engineering of Ministry

of Education, Department of Engineering Mechanics, Tsinghua

University, Beijing 100084, Chinab Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan

030001, China

The thermal conductivity of individual pitch-derived carbon

fibers was measured in the temperature range 100–400 K by a T

type method, in which a hot wire served both as a heating source

and thermometer, and the electrical and thermal properties of

the hot wire were measured by direct current heating. When a

tested carbon fiber was attached to the center position of the

hot wire, the thermal conductivity of the fiber was determined

by a comparison of the average temperature rise of the hot wire

with and without the fiber. Results show that the thermal con-

ductivity of the fiber was limited by boundary scattering below

300 K, and saturated around 350 K at a value of about 800 W/

(m � K). An unexpectedly high thermal conductivity of about

920 W/(m � K) was observed at around 400 K. The effect of the

thermal contact resistance on the measurement was estimated

by changing the length of the fiber in the same contact conditions

and the radiation effect was also discussed. The uncertainty of

the thermal conductivity was estimated to be ±13%.

[New Carbon Materials 2008;23(3):259–63.]

doi:10.1016/j.carbon.2008.09.023

Effects of precursor preoxidization on the structure and gas

separation properties of polyetherimide derived carbon

membranes

Tong-Hua Wang a, Li-Hong Hu a, Qing-Ling Liu a, Shi-Li Liu a, Zhen

Wang b, Meng-Xian Ding b

a Carbon Research Laboratory, State Key Laboratory of Fine Chemicals,

Dalian University of Technology, Dalian 116012, Chinab Changchun Institute of Applied Chemistry, Chinese Academy of

Sciences, Changchun 130022, China

Polyetherimide derived carbon membranes were prepared by

pretreating the precursor in air before carbonization at 700 �C.

The chemical structure, microstructure and gas separation prop-

erties of these membranes pretreated at 400, 460 and 480 �C were

characterized by FT-IR, elemental analysis, XRD and gas perme-

ation tests. The effects of preoxidization on their microstructure

and gas separation properties were investigated. Results show

that decomposition and oxidation-induced crosslinking reactions

occur during the pretreatment. The higher the preoxidization

temperature, the higher the degree of decomposition and the

degree of crosslinking. After carbonization, the pretreated mem-

branes have an amorphous structure. The differences in the

crosslinked structure generated in the pretreatment leads to dif-

ferences in the micropore structure of the membranes, which

can be used to tune gas separation properties. The permeability

of all gases investigated exhibits a maximum with a preoxidiza-

tion temperature at 460 �C., for which the O2 permeability is

8.2 � 10�13 (m3(STP) � cm)/(m2 � s � Pa) and the O2/N2 selectivity is

14.1.

[New Carbon Materials 2008;23(3):264–8.]

doi:10.1016/j.carbon.2008.09.024

Preparation and performance of activated carbon doped with

manganese oxide as an electrode for electrochemical capacitors

Lan-Ting Li a, Li-Na Hao a, Jun Zhang a, Guang-Chang Wang b,

Qiang Xie a

a School of Chemical and Environmental Engineering, China University

of Mining and Technology, Beijing 100083, Chinab Research Institute of Chemical Defence, Beijing 100083, China

A MnOx-doped mesoporous activated carbon (AC–MnOx) and

an activated carbon (AC) were prepared with and without Mn-

containing additives. The microstructure and properties, such

as pore volume, pore size distribution, iodine value and methy-

lene blue value, were determined. The electrochemical perfor-

mance of the two activated carbons as electrodes for

electrochemical capacitors were characterized by cyclic voltam-

metry, AC impedance and charge-discharge at a constant current.

Results show that the yield and iodine value of AC–MnOx are low-

ered by 28.9% and 12.4%, respectively compared to AC. The meth-

ylene blue value of AC-MnOx is increased by 19.8% compared to

AC. Moreover, AC-MnOx has more mesopores than does AC, espe-

cially in the range 3.4–4.2nm. The specific capacitance of an AC–

MnOx electrode is 93.8 F/g, which is 140% of that of an AC elec-

trode, indicating that energy density and pseudo-capacitance of

the AC–MnOx electrode are higher than those of AC electrode.

[New Carbon Materials 2008;23(3):269–74.]

doi:10.1016/j.carbon.2008.09.025

Activated carbon coated with polyaniline as an electrode material

in supercapacitors

Qin Wang a, Jian-Ling Li a, Fei Gao a, Wen-Sheng Li b,

Ke-Zhong Wu a, Xin-Dong Wang a

a Department of Physical Chemistry, University of Science and

Technology Beijing, Beijing 100083, Chinab Jinzhou Kaimei Energy Co. Ltd., Jinzhou 121000, China

The performance of activated carbons coated with polyaniline

(PANI-C) by polymerization of aniline using cyclic voltammetry

was investigated as an electrode for supercapacitors by scanning

electron microscopy, electrochemical impedance spectroscopy,

and constant current charge/discharge measurement. Results

showed that a PANI thin film was uniformly deposited on the sur-

face of the activated carbon, forming an interlinked porous net-

work. The PANI-C composite electrodes had better cycling

stability than PANI electrodes and the specific capacitance of

the composite electrodes was 587 F/g, which was much higher

than that of the pristine activated carbon (140 F/g), owing to the

faradic reaction of PANI with the electrolyte. The PANI electrode

was less stable than the PANI-C composite electrode with a

C A R B O N 4 7 ( 2 0 0 9 ) 3 5 0 – 3 5 4 353

capacitance decay from 513 to 334 F/g for the former and 415 to

385 for the latter, after 50 cycles.

[New Carbon Materials 2008;23(3):275–80.]

doi:10.1016/j.carbon.2008.09.026

Synthesis and electrocatalytic performance of ordered mesopor-

ous carbons produced by a hard templating method using phe-

nolic resol as carbon precursor

Xiu Chen, Jian-Ping He, Wang-Juan Dang, Jian-Hua Zhou, Tao

Wang, Chuan-Xiang Zhang, Gui-Wang Zhao

Department of Applied Chemistry, Nanjing University of Aeronautics

and Astronautics, Nanjing 210016, China

Ordered mesoporous carbons (OMC) were prepared by high

temperature carbonization of in-situ synthesized phenolic resol

from phenol and formaldehyde within ordered mesoporous silica

SBA-15 and of mixture of SBA-15 and phenolic resol prepared in

advance., These are denoted C1 and C2, respectively. Pt/C1, Pt/

C2 and Pt/CMK-5 (furfural as carbon precursor) electrocatalysts

were prepared by a microwave-assisted polyol process. The

microstructure of the samples was characterized by XRD, TEM

and nitrogen adsorption. The performance of Pt loaded samples

for methanol electrooxidation was characterized by cyclic vol-

tammetry (CV). Results show that C1 has an ordered hexagonal

(P6mm symmetry) mesoporous structure with a BET surface area

of 947 m2/g and a sharp pore size distribution around 4.5 nm. The

Pt nanoparticles are uniformly dispersed on C1 with an average

diameter of 3 nm, while for. C2 the pores are somewhat disor-

dered and the Pt nanoparticles are agglomerated. The CV curves

indicate that Pt/C1 exhibits a higher electrocatalytic activity for

methanol electrooxidation than do Pt/C2 and Pt/CMK-5 and a lit-

tle bit lower activity than does commercial E-TEK Pt/C. The elec-

trochemically active surface area of Pt/C1 is 54.2 m2/g.

[New Carbon Materials 2008;23(3):281–8.]

doi:10.1016/j.carbon.2008.09.027

354 C A R B O N 4 7 ( 2 0 0 9 ) 3 5 0 – 3 5 4