Formation of cluster structures on thermoexfoliated graphite by electrochemical method
Nickel-plating thermoexfoliated graphite particles were prepared by cathodic polarization of three-dimensional electrodes in diluted nickel sulphate aqueous solutions. X-ray photoelectron spectroscopy and X-ray diffraction techniques were employed for analysis of the particles surface. It has been f...
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Інститут хімії поверхні ім. О.О. Чуйка НАН України
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| Zitieren: | Formation of cluster structures on thermoexfoliated graphite by electrochemical method / I.G. Sidorenko, V.M. Ogenko, G.M. Zagorovsky, G.P. Prikhod’ko // Поверхность. — 2002. — Вип. 7-8. — С. 96-101. — Бібліогр.: 11 назв. — англ. |
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irk-123456789-1263562017-11-21T03:02:48Z Formation of cluster structures on thermoexfoliated graphite by electrochemical method Sidorenko, I.G. Ogenko, V.M. Zagorovsky, G.M. Prikhod’ko, G.P. Surface properties of inorganic materials Nickel-plating thermoexfoliated graphite particles were prepared by cathodic polarization of three-dimensional electrodes in diluted nickel sulphate aqueous solutions. X-ray photoelectron spectroscopy and X-ray diffraction techniques were employed for analysis of the particles surface. It has been found that oxidation process of the electrodeposited nickel clusters occurs due to their high reactivity. The presence of essential amounts of bound oxygen on surface of thermoexfoliated graphite particles was demonstrated by cyclic voltammetry and X-ray photoelectron spectroscopy methods. The role of oxygen-containing groups on the surface of thermoexfoliated graphite in the processes of adsorption and subsequent reduction of nickel ions at cathodic polarization as well as the behaviour in neutral aqueous solutions of natural graphite electrodes, intercalated with sulfuric acid and thermoexfoliated, are discussed. 2002 Article Formation of cluster structures on thermoexfoliated graphite by electrochemical method / I.G. Sidorenko, V.M. Ogenko, G.M. Zagorovsky, G.P. Prikhod’ko // Поверхность. — 2002. — Вип. 7-8. — С. 96-101. — Бібліогр.: 11 назв. — англ. XXXX-0106 http://dspace.nbuv.gov.ua/handle/123456789/126356 en Поверхность Інститут хімії поверхні ім. О.О. Чуйка НАН України |
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Surface properties of inorganic materials Surface properties of inorganic materials |
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Surface properties of inorganic materials Surface properties of inorganic materials Sidorenko, I.G. Ogenko, V.M. Zagorovsky, G.M. Prikhod’ko, G.P. Formation of cluster structures on thermoexfoliated graphite by electrochemical method Поверхность |
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Nickel-plating thermoexfoliated graphite particles were prepared by cathodic polarization of three-dimensional electrodes in diluted nickel sulphate aqueous solutions. X-ray photoelectron spectroscopy and X-ray diffraction techniques were employed for analysis of the particles surface. It has been found that oxidation process of the electrodeposited nickel clusters occurs due to their high reactivity. The presence of essential amounts of bound oxygen on surface of thermoexfoliated graphite particles was demonstrated by cyclic voltammetry and X-ray photoelectron spectroscopy methods. The role of oxygen-containing groups on the surface of thermoexfoliated graphite in the processes of adsorption and subsequent reduction of nickel ions at cathodic polarization as well as the behaviour in neutral aqueous solutions of natural graphite electrodes, intercalated with sulfuric acid and thermoexfoliated, are discussed. |
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Sidorenko, I.G. Ogenko, V.M. Zagorovsky, G.M. Prikhod’ko, G.P. |
| author_facet |
Sidorenko, I.G. Ogenko, V.M. Zagorovsky, G.M. Prikhod’ko, G.P. |
| author_sort |
Sidorenko, I.G. |
| title |
Formation of cluster structures on thermoexfoliated graphite by electrochemical method |
| title_short |
Formation of cluster structures on thermoexfoliated graphite by electrochemical method |
| title_full |
Formation of cluster structures on thermoexfoliated graphite by electrochemical method |
| title_fullStr |
Formation of cluster structures on thermoexfoliated graphite by electrochemical method |
| title_full_unstemmed |
Formation of cluster structures on thermoexfoliated graphite by electrochemical method |
| title_sort |
formation of cluster structures on thermoexfoliated graphite by electrochemical method |
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Інститут хімії поверхні ім. О.О. Чуйка НАН України |
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2002 |
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Surface properties of inorganic materials |
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http://dspace.nbuv.gov.ua/handle/123456789/126356 |
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Formation of cluster structures on thermoexfoliated graphite by electrochemical method / I.G. Sidorenko, V.M. Ogenko, G.M. Zagorovsky, G.P. Prikhod’ko // Поверхность. — 2002. — Вип. 7-8. — С. 96-101. — Бібліогр.: 11 назв. — англ. |
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Поверхность |
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AT sidorenkoig formationofclusterstructuresonthermoexfoliatedgraphitebyelectrochemicalmethod AT ogenkovm formationofclusterstructuresonthermoexfoliatedgraphitebyelectrochemicalmethod AT zagorovskygm formationofclusterstructuresonthermoexfoliatedgraphitebyelectrochemicalmethod AT prikhodkogp formationofclusterstructuresonthermoexfoliatedgraphitebyelectrochemicalmethod |
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2025-07-09T04:50:04Z |
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2025-07-09T04:50:04Z |
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1837143537763745792 |
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96
FORMATION OF CLUSTER STRUCTURES
ON THERMOEXFOLIATED GRAPHITE
BY ELECTROCHEMICAL METHOD
I.G. Sidorenko, V.M. Ogenko, G.M. Zagorovsky, and G.P. Prikhod`ko
Institute of Surface Chemistry, National Academy of Sciences
Gen. Naumov Str. 17, 03680 Kyiv-164, UKRAINE
Abstract
Nickel-plating thermoexfoliated graphite particles were prepared by cathodic
polarization of three-dimensional electrodes in diluted nickel sulphate aqueous solutions.
X-ray photoelectron spectroscopy and X-ray diffraction techniques were employed for
analysis of the particles surface. It has been found that oxidation process of the
electrodeposited nickel clusters occurs due to their high reactivity. The presence of essential
amounts of bound oxygen on surface of thermoexfoliated graphite particles was demonstrated
by cyclic voltammetry and X-ray photoelectron spectroscopy methods. The role of
oxygen-containing groups on the surface of thermoexfoliated graphite in the processes of
adsorption and subsequent reduction of nickel ions at cathodic polarization as well as the
behaviour in neutral aqueous solutions of natural graphite electrodes, intercalated with sulfuric
acid and thermoexfoliated, are discussed.
Introduction
At transition from macrostructure to microstructures, which sizes lay in the nanometer
range, properties of substance essentially vary. Metal nanoclusters in the condensed state have
another parameters of crystal lattice, melting point and electrical conductivity as compared
with the appropriate macrocrystals. Besides, they have new optical, magnetic and electronic
characteristics [1]. Presence of dimensional effects in the electronic and structural properties
of nanostructures means that their reactivity differs as against of the massive metal. Therefore
the dispersed materials with particles, covered with the clusters of metals, represent a
significant interest as highly-effective catalysts of various chemical reactions. The properties
of the nanoclusters, prepared by the method of sedimentation on a matrix, differ from those of
the clusters, prepared by other methods, due to isolation each from other by a matrix. Catalytic
properties of the deposited particles essentially differ from those of the massive metals and
change depending on size distribution of the particles [2]. At industrial synthesis of the
supported metal catalysts (it includes stages of the carrier granules impregnation by a solution
of active metal compound with following incandescence and reduction) the integration of
particles is observed in consequence of sintering.
There are some routes of the given problem solution, for example modification of the
carrier with the intention to create of enough amount of germ centres for metal particles
formation, selection of the materials, which ensure epitaxial growth of the nanoparticles due to
structural conformity of the crystal lattices parameters, use of the carriers with original pores
geometry, etc. One of the methods ensuring uniformity of system is realization of synthesis in
the controlled kinetic conditions, and in particular by electrodeposition. For application of this
method the matrix must exhibit an electronic conductivity and advanced surface area. Carbon
fibres and graphite are suited to these requirements. Last years the interest of the researchers
to such materials tends to widen because of an opportunity of their use in the electrochemical
97
reactors with three-dimensional electrodes intended for non-ferrous metals extraction from
industrial waste water [3, 4].
The process of non-ferrous metals electrodeposition onto the thermoexfoliated graphite
particles surface is of obvious interest because its conductivity are comparable with that of a
carbon fiber, however the former have more advanced surface area. In the present work, the
process of nickel clusters electrodeposition onto plate and three-dimensional electrodes of
thermoexfoliated graphite was investigated.
Experimental
Thermoexfoliated graphite with the filling density of 4-5 g×dm-3 was prepared by fast
heating in the previously warmed up to 900°С the electric furnace of natural graphite GAK-2
intercalated with sulfuric acid using (NH4)2S2O8 as an oxidizer.
The voltammograms were obtained using three electrode glass cells with the
potentiostate PI-50-1.1 with rate of potential scanning of 5 mV×s-1. The graphite plate with the
sizes of 40´10´3 mm served as an auxiliary electrode. The potential value was referred to the
silver chloride electrode saturated with KCl. Electrodeposition of nickel on the surface of
thermoexfoliated graphite particles was carried out in a flowing type glass electrochemical
reactor. The techniques of investigation have been described in more detail in [5]. The
analytical grade reagents were used for the working solutions preparation. The specific surface
area was determined by the standard technique of argon adsorption at liquid nitrogen boiling
temperature.
The X-ray diffractometer DRON–3M with CuKa radiation was used to measure the
Bragg refraction from the powder patterns of thermoexfoliated graphite with nickel plating.
The X-ray photoelectron spectra were obtained with the spectrometer XPS SERIES-800
(Kratos Analytical), using AlKa X-ray source (1486.6 еV).
Results and discussion
As it is known, the first stage of electrochemical reaction is adsorption of the ions,
discharged on an electrode when electrical current passes through an electrolyte. The process
of adsorption does not proceed on entire surface of a solid but only on some active sites. On
the carbon materials the oxygen-containing groups of such sites, which be able to absorb the
non-ferrous metal ions, have acidic or basic character. The concentration of these groups may
be determined by traditional methods of chemical analysis [6] or by more effective method of
cyclic voltammetry that was applied for research of electrical oxidation process of the carbon
fibers [7]. The mechanism of surface anodic oxidation of graphite carbon in aqueous
electrolytes is complex and depends in a large extent on the kind of an electrolyte. A simple
secondary oxidation of carbon with reactive oxygen species formed in the primary
electrochemical step is common assumed but it is true only for alkaline solutions. Surface
anodic oxidation in the diluted alkaline solutions (0.01 N) is at least 20 times more effective
than that in the concentrated ones (0.5 N).
Mechanism of carbon materials oxidation in neutral and acidic aqueous solutions is
considerably more complicated. Various kinds of oxides arise obviously here and in particular
bulk oxides are formed as result of the “graphite salt” hydrolysis. Anodic intercalation of
anions into graphite is observed even in the very diluted acids. Cyclic voltammetry indicates
on the formation of short-lived intercalation compounds even in neutral aqueous electrolytes
such as 1М Na2SO4 what may be related with the fact that the anode surface becomes acidic
because of electrolysis of water. As may be inferred from the Fig. 1, at anodic polarization of
natural graphite electrode (curve 1) at potential +0.6 V referred to saturated silver chloride
electrode the formation of surface oxides is observed.
98
Fig. 1. Cyclic voltammograms of: (1) natural graphite; (2) graphite intercalated with sulfuric
acid; (3) thermoexfoliated graphite electrodes in 0.01 N Na2SO4 solution.
The conclusion that the process of “surface oxides” formation proceeds on surface of
natural graphite electrode rather than that of sulfuric acid intercalation in bulk of graphite
occurs is confirmed by the fact of hydrosulfate-ions inculcation into the crystal lattice of
graphite, as it was noted in previous investigations [8, 9]. This process begins at higher
potentials, and on the curves of the opposite direction potential scanning the process of
deintercalation is not noticed (Fig. 1, curve 2). Moreover, identical voltammograms were
obtained in 0.01 N solution of potassium chloride without ions HSO4
-, which be able to form
the intercalation compounds with graphite.
As it is seen in Fig. 1, voltammogram of the thermoexfoliated graphite electrode
essentially differs from the curves of another forms of graphite electrodes. It is caused
substantially by oxidation of thermoexfoliated graphite surface. Presence of essential amounts
of oxygen on the surface of thermoexfoliated graphite is confirmed by the results of X-ray
photoelectron spectroscopy study (Fig. 2).
Although there are no peaks of the surface oxides reduction on voltammograms of
thermoexfoliated graphite electrodes, when these electrodes were cathode-polarized in
Na2SO4 solution under potentiostatic regime (-1 V), the current decrease was observed. This
phenomenon is connected with slowing of surface oxides reduction process [10].
With cathodic polarization of thermoexfoliated graphite electrode in 1 N nickel
sulphate solution on the surface of particles, instead of the metal clusters, the unbroken nickel
film is formed. Therefore based on the results of our previous investigations, the process of
nickel electrodeposition on particles of thermoexfoliated graphite was carried out in 0.01 N
solution. Wide scan spectra within the binding energy range of 200-900 eV were used to
identify the presence of the surface elements. A representative XPS wide scan spectrum for
thermoexfoliated graphite with nickel platting is shown in Fig. 3. The spectrum shows three
distinct peaks representing the major constituents: carbon, oxygen and nickel. No other
elements were detected on the surface of the samples. It is follows from results of these
researches that coating particles of island type are formed on the surface of thermoexfoliated
graphite.
-500 0 500 1000
50
m
kA
I 3
2
1
E, mV
99
9 0 0 7 5 0 6 0 0 4 5 0 3 0 0
0
2 0 0 0
4 0 0 0
6 0 0 0
8 0 0 0
1 0 0 0 0
O
C
In
te
ns
ity
(c
ou
nt
s)
B in d in g E n erg y (e V )
Fig. 2. X-ray photoelectron spectrum of thermoexfoliated graphite.
9 0 0 7 5 0 6 0 0 4 5 0 3 0 0
0
1 0 0 0
2 0 0 0
3 0 0 0
4 0 0 0
5 0 0 0
N i
O
C
In
te
ns
ity
(c
ou
nt
s)
B in d i n g E n e r g y ( e V )
Fig. 3. Wide scan XPS spectrum of thermoexfoliated graphite with nickel platting.
Fig. 4 shows an XPS narrow scan spectrum of the Ni 2p region at 860 eV. The
intensive peak at binding energy range 852.5 eV belongs to non-oxidized nickel. The peak of
oxidized nickel is energetically heterogeneous that specifies in the presence of nickel at
several oxidized forms: Ni(OH)2, Ni2O3 and NiO. These results correlate with the data of
work [11].
100
8 8 0 8 7 0 8 6 0
0
5 0 0
1 0 0 0
1 5 0 0
2 0 0 0
In
te
ns
ity
(c
ou
nt
s)
B in d in g E n e rg y (e V )
Fig. 4. Narrow XPS scan spectrum of thermoexfoliated graphite with nickel platting.
In Fig. 5 the X - ray diffraction powder patterns of thermoexfoliated graphite with
nickel platting is shown.
10 20 30 40 50 60 70
0
500
1000
In
te
ns
ity
(a
rb
. u
ni
ts)
2q (degrees)
Fig. 5. X - ray diffraction powder patterns of thermoexfoliated graphite
with nickel platting.
The spectrum is complex. More than 20 peaks are manifested in it. The most intensive
peak belongs to graphite. Appearance of other peaks is connected with the presence of nickel
and its above-mentioned compounds.
101
Conclusion
The presence on the surface of thermoexfoliated graphite particles essential amounts of
oxygen-containing functional groups, which be able to absorb the non-ferrous metals ions,
was shown by the cyclic voltammetry and Х-ray photoelectron spectroscopy techniques. It
was demonstrated that when the electrode of thermoexfoliated graphite is anode-polarized the
process of the surface oxidizing does not proceed unlike that of the natural and intercalated
with sulphuric acid graphite electrodes.
It was shown by the X-ray photoelectron spectroscopy and x-ray diffraction techniques
that clusters electrodeposited on the surface of thermoexfoliated particles nickel undergo to
particular oxidizing due to their high reactivity.
References
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(In Russian).
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Khim. - 2001. - V.74, N3. - P.416–418.
11. Gaevskaya T.V. and Tsybulskaya L.S. Reserch of surface layers electroplating nickel-
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FORMATION OF CLUSTER STRUCTURES
ON THERMOEXFOLIATED GRAPHITE
BY ELECTROCHEMICAL METHOD
BY ELECTROCHEMICAL METHOD
BY ELECTROCHEMICAL METHOD
Gen. Naumov Str. 17, 03680 Kyiv-164, UKRAINE
Abstract
Introduction
Experimental
Results and discussion
Results and discussion
Conclusion
References
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