期刊
CARBON
卷 50, 期 12, 页码 4424-4431出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.carbon.2012.05.020
关键词
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资金
- Smart Mix Program of the Netherlands Ministry of Economic Affairs
- Netherlands Ministry of Education, Culture and Science
Oxygen containing groups were introduced, onto carbon nanofibers (CNFs) that were previously loaded with palladium, using HNO3 vapor. Using traditional liquid-phase oxidations this is not possible due to severe metal leaching. For the samples oxidized using HNO3 vapor temperature programmed desorption and X-ray photoelectron spectroscopy revealed the presence of two major classes of oxygen containing groups, i.e. carboxylic acid groups which are thermally stable up to 300 degrees C and less acidic (e.g. phenol) and basic groups which were stable up to 700 degrees C. The amount of acidic oxygen containing groups introduced by this gas-phase treatment ranged from 0.1 to 0.3 mmol/g, as determined by titration. The latter amount is comparable to that introduced by traditional liquid-phase treatment in 65% HNO3 on bare CNFs. Transmission electron microscopy and H-2-chemisorption measurements show a gradual increase of the average metal particle size from 2.1 nm for the starting Pd/CNF to 4.5 nm for Pd/CNF treated for 75 h in HNO3 vapor indicating that the extent of sintering with gas-phase treatment is limited. Elemental analysis showed that no leaching occurred upon gas-phase oxidation, whereas 90% of the metal was lost with a liquid-phase reflux HNO3 treatment. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.
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