Continuous Production of Graphite Nanosheets by Bubbling Chemical Vapor Deposition Using Molten Copper

We
report a bubbling chemical vapor deposition method for mass
production of high-quality graphite nanosheets using molten copper
as the catalyst for continuous growth. Bubbles containing precursor
gas (CH4 or natural gas) are produced by inserting an aerator
into molten copper. High-quality graphite nanosheets with a thickness
ranging from a few to 40 graphitic layers are grown on bubble surfaces
and carried to the copper surface. The production rate can be as high
as 9.4 g/h using a crucible with a volume of 3 L. The high quality
of the graphite nanosheets is demonstrated by composites with very
high conductivity. The highly conductive composite shows excellent
performance in an electromagnetic interference (EMI) shielding application
with an EMI effectiveness of >70 dB at X band. Moreover, except
for
precursor gases, the lack of other chemicals in the growth process
makes it an environmentally friendly approach. Natural gas can also
be used as the precursor, making it a low-cost production. In addition,
the naturally crumpled feature of the graphite nanosheets should allow
them to ber used in multiple applications, because restacking can
be prevented.