ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 10, pp. 1643−1649. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © V.K. Varentsov, V.I. Varentsova,
2015, published in Zhurnal Prikladnoi Khimii, 2015, Vol. 88, No. 10, pp. 1460−1466.
AND CORROSION PROTECTION OF METALS
Electrochemical Oxidative Modiﬁ cation of Nanocarbon Materials
in Aqueous Electrolyte Solutions
V. K. Varentsov and V. I. Varentsova
Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch, Russian Academy of Sciences,
ul. Kutateladze 18, Novosibirsk, 630128 Russia
Received September 30, 2015
Abstract—The effect exerted by electrochemical oxidative modiﬁ cation of carbon nanoﬁ bers and nanotubes by
anodic and successive cathodic and anodic polarization in aqueous solutions of electrolytes H
] on the structure and morphology of the ﬁ bers constituting the nano-
materials, on the composition of surface groups, on the stationary electrode potential of carbon nanoﬁ bers, and
on properties of epoxy–carbon composites was studied. The results of the electrochemical modiﬁ cation were
compared to the results of chemical modiﬁ cation of carbon nanoﬁ bers in a 6.0 M HNO
solution and of carbon
nanotubes in a mixture of concentrated acids H
The use of carbon nanoﬁ bers (CNFs) and nanotubes
(CNTs) in composite materials is largely determined
by the condition of the surface of their microﬁ bers, in
particular, by the presence of oxygen-containing groups.
Because the initial nanomaterials are hydrophobic in
accordance with their preparation process, their surface
should be modiﬁ ed (functionalized). Various methods,
usually chemical methods involving treatment with
oxidants in the gas phase or aqueous solution, are used
for this purpose: treatment with acids or surfactants,
high-temperature oxidation, etc. [1–5]. Such treatment
results in oxidation with the formation of functional
oxygen-containing groups (carboxy, phenol, etc.) on the
surface of carbon nanomaterial ﬁ bers.
An essential point in modiﬁ cation of carbon
nanoﬁ bers and nanotubes is choosing a method and
an oxidant that would not destroy the initial structure
of the nanocarbon material and would ensure high
concentration of functional groups on the nanoﬁ ber
surface. One of such methods is electrochemical method.
By varying the electrolyte composition and electrolysis
conditions (current, hydrodynamic conditions), it is
possible to signiﬁ cantly inﬂ uence the surface properties
of carbon materials (CMs), in particular, the formation of
intercalation compounds, and to control the modiﬁ cation
of CM properties [1, 2, 6–8].
This study deals with oxidative modiﬁ cation of the
surface of nanocarbon materials by the electrochemical
method in aqueous solutions of indifferent electrolytes.
Electrochemical modiﬁ cation experiments were
performed with nanoﬁ bers and nanotubes. Carbon
nanoﬁ bers were prepared by methane decomposition
using 90% Ni + 10% Al
catalyst . Carbon
nanotubes were prepared using Fe catalyst at the
Institute of Inorganic Chemistry, Siberian Branch,
Russian Academy of Sciences. The conditions under
which nanoﬁ bers and nanotubes were subjected to
oxidative modiﬁ cation in some cases differed essentially.
Therefore, the results of experiments with each of these
materials will be considered separately.
The installation and electrochemical cell in which
the electrochemical treatment of nanomaterials was
performed are similar to those described in [6–8].