5.4 Electrochemical Erosion of Graphite Under Hydrogen-Containing Atmospheres
71
Fig. 5.4 Illustration of the
mechanism proposed for the
electrochemical exfoliation
of graphite into graphene in
LiCl melt. The intercalation
of hydrogen atoms in the
graphite lattice and their
subsequent combination
leads to the formation of
hydrogen molecules in the
interlayer space of graphite,
causing its exfoliation,
reproduced from Ref. [25],
copyright 2019, with
permission from RSC
Publishing
characteristics can make the graphene product attractive for many applications. It
will be discussed in Chap. 6.
5.5 Molten Salt Formation of Metal-Filled Carbon
Nanostructures
As discussed in Chaps. 4 and 5, the electrolysis of LiCl as the electrolyte with
graphite cathodes under dry Ar can produce carbon nanostructures including CNTs.
While no nanostructured carbon can be produced by the electrolysis of pure SnCl 2 ,
the electrolysis of LiCl–SnCl 2 mixture can produce Sn-filled carbon nanostructures.
These experimental observations are explainable by electrochemical measurements.
Figure 5.5a shows the cyclic voltammogram obtained using a molybdenum working electrode in the molten LiCl-4.5 wt%SnCl 2 at 625 °C conducted under a dry Ar
gas flow [6]. The anodic and cathodic events extracted from this voltammogram
provide important information about the mechanisms involved in the formation of
core-shell metal filled nanostructures, such as shown in Figs. 4.10 and 4.13. Accordingly, the cathodic peak A observed in Fig. 5.5a can be assigned to the deposition
of metallic Sn on the molybdenum working electrode. The cathodic peaks B, C and
D can be related to the formation of Li–Sn intermetallics such as Li 5 Sn 2 (Li 13 Sn 5 ),
Li 7 Sn 2 and Li 22 Sn 5 . The strong cathodic current E is due to the deposition of metallic lithium. The peak E 1 in the positive anodic scan is related to the dissolution of
71
Fig. 5.4 Illustration of the
mechanism proposed for the
electrochemical exfoliation
of graphite into graphene in
LiCl melt. The intercalation
of hydrogen atoms in the
graphite lattice and their
subsequent combination
leads to the formation of
hydrogen molecules in the
interlayer space of graphite,
causing its exfoliation,
reproduced from Ref. [25],
copyright 2019, with
permission from RSC
Publishing
characteristics can make the graphene product attractive for many applications. It
will be discussed in Chap. 6.
5.5 Molten Salt Formation of Metal-Filled Carbon
Nanostructures
As discussed in Chaps. 4 and 5, the electrolysis of LiCl as the electrolyte with
graphite cathodes under dry Ar can produce carbon nanostructures including CNTs.
While no nanostructured carbon can be produced by the electrolysis of pure SnCl 2 ,
the electrolysis of LiCl–SnCl 2 mixture can produce Sn-filled carbon nanostructures.
These experimental observations are explainable by electrochemical measurements.
Figure 5.5a shows the cyclic voltammogram obtained using a molybdenum working electrode in the molten LiCl-4.5 wt%SnCl 2 at 625 °C conducted under a dry Ar
gas flow [6]. The anodic and cathodic events extracted from this voltammogram
provide important information about the mechanisms involved in the formation of
core-shell metal filled nanostructures, such as shown in Figs. 4.10 and 4.13. Accordingly, the cathodic peak A observed in Fig. 5.5a can be assigned to the deposition
of metallic Sn on the molybdenum working electrode. The cathodic peaks B, C and
D can be related to the formation of Li–Sn intermetallics such as Li 5 Sn 2 (Li 13 Sn 5 ),
Li 7 Sn 2 and Li 22 Sn 5 . The strong cathodic current E is due to the deposition of metallic lithium. The peak E 1 in the positive anodic scan is related to the dissolution of