II International Symposium on Carbon for Catalysis ABSTRACTS

PP-I-7
groups and remove the catalyst. Textural and surface chemistry properties of carbon
nanofibers were characterised by adsorption isotherms of N 2 , scanning electronic microscopy
(SEM) and temperature programmed desorption (TPD).
Pt was deposited on the CNFs after the different oxidative treatments. An aqueous solution of
Pt(NH 3 ) 4 Cl 2 (Alfa Aesar) was mixed with the CNFs and stirred overnight. Under these
conditions, Pt is exchanged with the protons of the functional groups of the CNFs.
Subsequently, the catalyst was reduced with H 2 . The as-prepared catalysts have been
characterized by ICP-OES, TEM and CO chemisorption to study the impact of the surface
chemistry on the Pt loading and dispersion.
Results and discussion
The textural properties of carbon nanofibers were analyzed by means of N 2 -physisorption and
SEM. Furthermore, the carbon burn-off percentage after acid treatments was measured. Oxidation
treatment of the carbon nanofibers resulted in a weight loss of about 6–10%, whereas oxidized
carbon nanofibers in HNO 3 -H 2 SO 4 showed a considerable weight loss of 23%.
BET surface area of carbon nanofibers was over 100 m 2 /g and increased up to 150 m 2 /g after
oxidation treatments. The micropore volume was negligible in all samples. Therefore, carbon
nanofibers were mesoporous materials with a bimodal distribution of pore sizes.
The SEM images of oxidized samples were very similar to the SEM image of non-oxidized
one, hence the carbon nanofibers maintain their structure after the oxidation treatment.
However, the weight loss as well as the SEM images after the treatment in 1:1 HNO 3 -H 2 SO 4
indicate a partial destruction of the carbon nanofibers.
TPD experiments were used to determine the number of surface oxygen groups created during
the oxidation treatments. These experiments demonstrated that an increase in oxidation
severity results in an increase in the number of surface oxygen groups. The ongoing research
is focusing on the characterization of the Pt catalyst.
Acknowledgements
This research was supported by the MCyT, through Project NAN2004-09333-C05-01, and by
the Aragon Government, by means of the recognition as Consolidated Research Group. L.
Calvillo is indebted to CSIC for her I3P-postgrado grant.
References
[1] F. Yuan, H.K. Yu, H. Ryu. Electrochimica Acta 50 (2004) 685-691.
[2] T.G. Ros, A.J. van Dillen, J.W. Geus, D.C. Koningsberger. Chem. Eur. J. 8 (2002) 1151-
1162.
132