Water-Ionic Liquid Binary Mixture Tailored Resorcinol-Formaldehyde Carbon Aerogels without Added Catalyst

The potential applications of mesoporous carbon aerogels are wide-ranging. These gels are often obtained from resorcinol-formaldehyde (RF) hydrogel precursors. The sol-gel method in this synthesis provides an efficient and versatile means of product control through systematic variation of process co...

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Bibliographic Details
Published in:Materials 2019-12, Vol.12 (24), p.4208
Main Authors: Nagy, Balázs, Bakos, István, Geissler, Erik, László, Krisztina
Format: Article
Language:English
Subjects:
Additives
Adsorption
Aerogels
Binary mixtures
Carbon
Catalysts
Electron micrographs
Formaldehyde
Hydrogels
Investigations
Ionic liquids
Ions
Low temperature
Moisture content
Morphology
Nitrogen
Pore size
Pyrolysis
Scanning electron microscopy
Sol-gel processes
Solvents
Stoichiometry
X-ray scattering
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Summary:The potential applications of mesoporous carbon aerogels are wide-ranging. These gels are often obtained from resorcinol-formaldehyde (RF) hydrogel precursors. The sol-gel method in this synthesis provides an efficient and versatile means of product control through systematic variation of process conditions, such as pH, stoichiometry, concentration, catalyst, further additives, etc., in addition to the drying and pyrolytic conditions. Here, a novel means of tuning the texture of carbon aerogels is proposed. Water-1-ethyl-3-methylimidazolium ethyl sulfate ([emim][EtSO ] mixtures constitutes a polycondensation medium that requires no added catalyst, thus yielding an intrinsically metal-free carbon aerogel after pyrolysis. We also show that the carbon morphology is tailored by the supramolecular structure of the aqueous ionic liquid. The results of scanning electron micrographs, low-temperature nitrogen adsorption/desorption isotherms, and small-angle X-ray scattering (SAXS) confirm that changing the initial water concentration from 9 to 55 wt % gives rise to systematic alteration of the mesopore size and volume, as well as of the bead size. The pore structure becomes consolidated only when the water content exceeds 25 wt %. When the water content reaches 55 wt %, the bead size increases by two orders of magnitude. The electrocatalytic performance, however, is compromised, most probably by structural defects.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma12244208