electroless plating of co–fe on the surface of mwcnts

an amorphous solid with small grains at 550 �C. The intensity of

the diffraction peaks decreases and the values of the cell param-

eters a and cincrease with the deposition temperature. The as-

prepared crystalline films are silicon carbonitride with the crys-

talline structure of Si3N4 modified by replacing some of the Si

atoms with C atoms. The N atoms are mainly bonded to Si, and

C atoms are in the form of sp3C–N, sp2C@N and sp2C@C bonds.

Decreasing deposition temperature favors an increase of C atom

content and sp3C–N bond fraction.

[New Carbon Materials 2010;25(1):48–52].

doi:10.1016/j.carbon.2010.01.043

The effect of particle size on the interaction of Pt catalyst particles

with a carbon black support

Lin Gana,b, Hong-da Dua,b, Bao-hua Lib, Fei-yu Kanga

a Laboratory of Advanced Materials, Department of Materials Science

and Engineering, Tsinghua University, Beijing 100084, Chinab Institute of Advanced Materials, Graduate School at Shenzhen,

Tsinghua University, Shenzhen 518055, China

Pt catalysts with different average particle sizes (1.7, 3.0, and

5.0 nm) were supported on Vulcan XC-72 carbon black through

ethylene glycol reduction of H2PtCl6. Using transmission electron

microscopy, we found a geometric interaction between the

micropores on the surface of carbon black support and the sup-

ported Pt catalysts. Small Pt nanoparticles (with an average parti-

cle size of 1.7 nm) were found to be frequently incorporated into

the micropores, and thus appeared to be covered by a thin carbon

layer and embedded in the carbon matrix. However, such a phe-

nomenon was absent for Pt particles with larger average particle

sizes (3.0 and 5.0 nm), which generally showed an exposed clean

surface. The different interaction with the micropores therefore

induced an abnormal particle size effect of the supported Pt cat-

alysts on their electrochemically active surface area, and had an

influence on their mass electrocatalytic activity towards metha-

nol oxidation.


doi:10.1016/j.carbon.2010.01.044

The thermal expansion behavior of 3D C/C composites

Xiao-ling Liao, He-jun Li, Guo-dong Sun, Ke-zhi Li

Research Center of Carbon/Carbon Composites, State Key Laboratory of

Superhigh Temperature Composites, Northwestern Polytechnic

University, Xi’an 710072, China

Three dimensional braided carbon/carbon composites (3D C/C

composites) were fabricated by chemical vapor infiltration. The

thermal expansion behavior of these materials with various den-

sities before and after heat treatment was investigated. It is found

that PAN-based carbon fibers (CFs) have an obviously negative

coefficient of thermal expansion (CTE) after heat treatment at

1200 �C. The CTE of the 3D C/C composites is negative from room

temperature to 100 �C and is proportion to their density. In the

temperature range of 100–1000 �C, CTE vs. T curves have an

almost a constant slope and expansion behavior of the composite

is similar to that of pyrocarbon. When the temperature is above

1000 �C, a peak is found in the CTE vs. T curves, indicating that

expansion of the pyrocarbon is limited by CFs and the thermal

expansion behavior of the composites is determined by both

CFs and matrix.


doi:10.1016/j.carbon.2010.01.045

Electroless plating of Co–Fe on the surface of MWCNTs

Yan Zhao, Ya-juan Xue, Hao Zheng, Yue-xin Duan

School of Materials Science and Engineering, Beihang University, Beijing

100191, China

Multiwalled carbon nanotubes (MWCNTs) were electroless

plated with cobalt–iron (Co–Fe). Palladium-atom centers were

formed on the surface of MWCNTs by a pretreatment before the

plating. Three main parameters, the molar ratio of C2þCo : C2þ

Fe , the

concentration of complexing agent, and the temperature of plat-

ing bath, were changed to investigate their effects, whereas the

concentrations of metal salts and reducing agent and pH were

kept unchanged. A layer of metal deposited neatly with a Co–Fe

content above 90% was obtained when the molar ratio of

C2þCo : C2þ

Fe was 9:1, the concentration of complexing agent was

0.32 mol/L, and the temperature of plating bath was 60 �C. Metal

granules were obtained, or the content of Co–Fe was much less

in the other conditions investigated.


doi:10.1016/j.carbon.2010.01.046

Preparation and ablation behavior of carbon fiber reinforced

nitride composites

Bin Li, Chang-rui Zhang, Feng Cao, Si-qing Wang, Ying-bin Cao

State Key Laboratory of Advanced Ceramic Fibers and Composites,

College of Aerospace and Materials Engineering, National University of

Defense Technology, Changsha 410073, China

A hybrid precursor containing borazine and perhydropolysi-

lazane was synthesized and characterized, and used to produce

three-dimensional carbon fiber reinforced nitride matrix

composites (3D Cf/nitrides) through vacuum infiltration of the

precursor followed by pyrolysis under inert atmosphere. The

oxidation resistance and ablation behavior of the Cf/nitrides

were studied. Results showed that there were several bonds

such as B–N, B–H, Si–N, Si–H and N–H in the hybrid precursor

and the as-formed matrix had a good oxidation resistance.

The matrix weight did not change distinctly when the temper-

ature was increased from room temperature to 1000 �C. The

surface of the ablated composites was flat and the nitride

matrix had a much better ablation resistance than did the car-

bon fibers.


doi:10.1016/j.carbon.2010.01.047

C A R B O N 4 8 ( 2 0 1 0 ) 2 1 2 3 – 2 1 2 6 2125

electroless plating of co–fe on the surface of mwcnts

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