42
4 Cathodic Exfoliation of Graphite in Molten Salt Electrolytes
Fig. 4.5 TEM micrographs of the carbon nanostructures including multiwall carbon nanotubes and
nanoparticles produced by the molten salt cathodic erosion of a graphite rod (d = 1.5 mm) under
a cell current and voltage of 5 A and 8–10 V, respectively. The duration of the electrolysis process
was 3 min at 820 °C, reproduced from Ref. [15], copyright 2019, with permission from Elsevier
pseudo-reference electrode immersed in molten salt. The counter electrode was either
the graphite crucible used as the molten salt container (Fig. 4.6b) or a graphite rod
immersed in the salt. The current applied (about 4.7 A) was equal to a cathode current
density of about 2 A cm
−2 . This was found to be the threshold current density for
the high yield formation of CNTs in the conditions specified above. Despite that,
the molten salt procedure depicted above could only be retained for a brief amount
of time. This amount of time was commonly lower than 10 min, bringing about the
fabrication of typically less than 500 mg carbon nanomaterials [23].
Essentially, it was found that alumina-shielded graphite cathodes exposed to the
molten salt are fragmented into numerous pieces in the first few minutes of the
process. Subsequently, this brings on the failure of the electrolysis cell. The collapse
of the graphite electrode was presumed to be because of the maintenance of a high
current density of 2 A cm
−2 on a small area at the bottom of the electrode, lowering
the scalability of the process.
Afterward, it was discovered that the threshold cathode current density for the
preparation of CNTs in molten LiCl can be markedly decreased to around 1 A cm
−2
by using the electrolysis cell portrayed in Fig. 4.6c. Here, an entire length of a 15mm diameter graphite electrode immersed in the LiCl melt was being used as the
cathode. This time, regardless of a high electric current of 33 A applied, no failure
of the graphite cathode was detected even at prolonged electrolysis periods. This is
due to the smaller values of the electric current density at the cathode/electrolyte
interface [3].
4 Cathodic Exfoliation of Graphite in Molten Salt Electrolytes
Fig. 4.5 TEM micrographs of the carbon nanostructures including multiwall carbon nanotubes and
nanoparticles produced by the molten salt cathodic erosion of a graphite rod (d = 1.5 mm) under
a cell current and voltage of 5 A and 8–10 V, respectively. The duration of the electrolysis process
was 3 min at 820 °C, reproduced from Ref. [15], copyright 2019, with permission from Elsevier
pseudo-reference electrode immersed in molten salt. The counter electrode was either
the graphite crucible used as the molten salt container (Fig. 4.6b) or a graphite rod
immersed in the salt. The current applied (about 4.7 A) was equal to a cathode current
density of about 2 A cm
−2 . This was found to be the threshold current density for
the high yield formation of CNTs in the conditions specified above. Despite that,
the molten salt procedure depicted above could only be retained for a brief amount
of time. This amount of time was commonly lower than 10 min, bringing about the
fabrication of typically less than 500 mg carbon nanomaterials [23].
Essentially, it was found that alumina-shielded graphite cathodes exposed to the
molten salt are fragmented into numerous pieces in the first few minutes of the
process. Subsequently, this brings on the failure of the electrolysis cell. The collapse
of the graphite electrode was presumed to be because of the maintenance of a high
current density of 2 A cm
−2 on a small area at the bottom of the electrode, lowering
the scalability of the process.
Afterward, it was discovered that the threshold cathode current density for the
preparation of CNTs in molten LiCl can be markedly decreased to around 1 A cm
−2
by using the electrolysis cell portrayed in Fig. 4.6c. Here, an entire length of a 15mm diameter graphite electrode immersed in the LiCl melt was being used as the
cathode. This time, regardless of a high electric current of 33 A applied, no failure
of the graphite cathode was detected even at prolonged electrolysis periods. This is
due to the smaller values of the electric current density at the cathode/electrolyte
interface [3].