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Leclere, M., Lejeune, M., Dupont, L., Barres, A.-L., Renault, S., Dolhem, F. & Poizot, P. (2014) Pyrolysis reaction of squaric acid: A one-step method for producing expanded foam of mesoporous carbon. Mater. Lett. 137 233–236.
Added by: Laurent Cournède (2016-03-10 21:01:54) |
| Type de référence: Article DOI: 10.1016/j.matlet.2014.08.148 Numéro d'identification (ISBN etc.): 0167-577X Clé BibTeX: Leclere2014 Voir tous les détails bibliographiques  |
Catégories: ST2E Mots-clés: carbon materials, Electrochemical properties, mesoporous carbon, Oxocarbon pyrolysis, Porous materials, Squaric acid Créateurs: Barres, Dolhem, Dupont, Leclere, Lejeune, Poizot, Renault Collection: Mater. Lett. |
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| Résumé |
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A template-free approach is described for the synthesis of expanded foams of mesoporous carbon exhibiting high surface areas ranging from 550 to 1100 m(2) g(-1). The procedure is based on the exceptional carbonization reaction that occurs with squaric acid (H2C4O4), a strained four-membered carbocycle belonging to the oxocarbon acids. Indeed the pyrolysis reaction proceeds just above 300 degrees C through an amazing one-step and sharp exothermic phenomenon coupled with a weight loss of 90\%, thereby promoting a porous structure. This massive gas release behaves also as a "fluid" template during the carbon production, which explains the formation of expanded foams. This particular thermal behaviour seems related to the phase transition that occurs in H2C4O4 crystals at T-c = 121 degrees C. Below T-c the planar squaric acid molecules exhibit a fully ordered structure in a monoclinic system whereas for T {>} T-c the structure undergoes a disordered tetragonal structure where all C-O bonds of squaric acid become statistically equivalent in a perfect square, making a discrete thermal decomposition reaction possible. (C) 2014 Elsevier B.V. All rights reserved.
Added by: Laurent Cournède |