Hierarchically porous carbon aerogels with high specific surface area prepared from ionic liquids via salt templating method
관리자2018-11-06조회 3974
High surface carbon aerogels with hierarchical and tunable pore structure were prepared
using ionic liquid as carbon precursor via a simple salt templating method. The as-prepared
carbon aerogels were characterized by nitrogen sorption measurement and scanning electron
microscopy. Through instant visual observation experiments, it was found that salt eutectics
not only serve as solvents, porogens, and templates, but also play an important role of foaming
agents in the preparation of carbon aerogels. When the pyrolyzing temperature rises from
800 to 1000°C, the higher temperature deepens the carbonization reaction further to form
a nanoporous interconnected fractal structure and increase the contribution of super-micropores
and small mesopores and improve the specific surface area and pore volume, while
having few effects on the macropores. As the mass ratio of ionic liquid to salt eutectics drops
from 55% to 15%, that is, the content of salt eutectics increases, the salt eutectics gradually
aggregate from ion pairs, to clusters with minimal free energy, and finally to a continuous
salt phase, leading to the formation of micropores, uniform mesopores, and macropores,
respectively; these processes cause BET specific surface area initially to increase but subsequently
to decrease. With the mass ratio of ionic liquids to salts at 35% and carbonization
temperature at 900°C, the specific surface area of the resultant carbon aerogels reached 2309
m2 g–1. By controlling the carbonization temperature and mass ratio of the raw materials,
the hierarchically porous architecture of carbon aerogels can be tuned; this advantage will
promote their use in the fields of electrodes and adsorption.
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