Hollow carbon nanostructures obtained from hydrothermal carbonization of
lignocellulosic biomass
JOURNAL OF MATERIALS SCIENCE, 49 (2):
665-672 (2014)DOI: 10.1007/s10853-013-7747-1
Abstract
Here we describe a new method for obtaining carbon nanocages at
relatively low temperatures using a low-cost lignocellulosic waste
material as carbon precursor. Coconut coir dust has been submitted to
hydrothermal carbonization in the presence of clays minerals such as
sepiolite, attapulgite, and montmorillonite followed by a
demineralization step. Just after hydrothermal treatment, the samples
prepared in the absence of the clays presented a sponge-like morphology
as typically described for hard-plant tissues submitted to this
treatment while the samples heated in the presence of clays were
fundamentally heterogeneous. After chemical etching with hydrofluoric
acid, the sample free from clays exhibited irregular round-shaped
particles with poorly defined cavities. For samples containing clays, on
the other hand, the chemical etching lead to well-defined carbon
nanocages as long as the particles were successfully etched such as
attapulgite and montmorillonite. For sepiolite, however, the presence of
residual inorganic particles was observed along with irregularly shaped
hollow nanostructures. Finally, Raman measurements revealed the typical
features of amorphous carbons.