Herein, we have employed a novel microwave autoclave strategy,
which combines the advantages of high productivity and efficiency
with low temperature and risk. Most importantly, the
microwave autoclave strategy is environmentally friendly and energy
saving, successfully producing a composite material of wellorganized
a-Fe2O3 encapsulated in graphene sheets. In comparison
with the traditional hydrothermal method [31e36], the microwave
hydrothermal method can expedite the kinetics of
crystallization by causing rapid nucleation and growth, which can
dramatically decrease the reaction time from 10 h or even several
days via the conventional hydrothermal method to 15 min, as reported
here. Therefore it can save a large amount of energy and
offers great possibilities for large-scale reactions. Furthermore, the
microwave hydrothermal method can be used effectively and efficiently
for preparing various multifunctional nanomaterials with
intriguing morphologies, such as nanowires [37,38], nanoplates
[39], nanospheres [40], and nanoporous networks [41].