Structure of nanoporous carbon produced from titanium carbide and carbonitride

Article abstract of DOI:10.1134/S1070427208100066

Scanning electron microscopy, X-ray diffraction and adsorption structural analyses, and helium pycnometry were used to study the structure of nanoporous carbon produced by chlorination of powdered titanium carbide and carbonitride and of titanium carbide

Full text of DOI:10.1134/S1070427208100066

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 10, pp. 1733–1739. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © A.E. Kravchik, Yu.A. Kukushkina, V.V. Sokolov, G.F. Tereshchenko, E.A. Ustinov, 2008, published in Zhurnal Prikladnoi Khimii,
2
008, Vol. 81, No. 10, pp. 1605–1612.
PHYSICOCHEMICAL STUDIES
OF SYSTEMS AND PROCESSES
Structure of Nanoporous Carbon Produced from Titanium
Carbide and Carbonitride
A. E. Kravchik, Yu. A. Kukushkina, V. V. Sokolov, G. F. Tereshchenko, and E. A. Ustinov
Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg, Russia
Received June 3, 2008
Abstract—Scanning electron microscopy, X-ray diffraction and adsorption structural analyses, and helium
pycnometry were used to study the structure of nanoporous carbon produced by chlorination of powdered
titanium carbide and carbonitride and of titanium carbide synthesized by chemical-vapor deposition.
The results obtained were used to make suggestions about the type of organization of the nanoporous
structure of these materials. The evolution of the structure of nanoporous carbon was analyzed in
relation to the chlorination temperature. The effect of the chlorination temperature on the structure of
the nanoporous carbon obtained and on its pore volume was examined.
DOI: 10.1134/S1070427208100066
–
3
Nanoporous carbon (NPC) produced by chlorina-
sity 4.87 g cm , carbon content 19.5 wt %) by chlo-
rination at temperatures of 400, 600, 800, 1000, 1300,
and 1800°C; pyrolytic TiC (in the form of tubes 8 mm
in diameter and wall thickness of up to 1.5 mm) pro-
duced by chemical vapor deposition (CVD) (pycno-
tion of carbides is widely used in various fields of sci-
ence and technology [1–9]. Structural studies of NPC
synthesized from various carbide and carbonitride ma-
terials in the form of powders and a compact material
at various thermochemical treatment (TCT) tempera-
tures are of particular scientific and practical interest.
–
3
metric density 4.84 g cm , carbon content 19.8 wt %);
and powdered titanium carbonitride of composition
TiC0.44N0.48 (specific surface area 1.5 m g , pycnomet-
2
–1
In this study, NPC produced from powdered TiC,
TiC0.44N0.48 and pyrolytic TiC (CVD) was examined.
The structure of NPC produced from TiC powder was
studied in [10–13]. In [10], NPC produced from powders
at chlorination temperatures of 200–1200°C was exam-
ined. It was shown that amorphous carbon with a narrow
pore size distribution is formed at T = 400–600°C. Rais-
ing the synthesis temperature to above 800°C leads to a
broader pore size distribution. It was shown in [11–13]
that the structure of carbon produced from TiC strongly
depends on synthesis temperature and presence of cata-
lytically active metals, such as nickel, cobalt, and iron, in
the reaction medium. Addition of an insignificant amount
of a metal leads to formation of a turbostratic structure at
temperatures as low as 800–900°C.
–
3
ric density 5.42 g cm , carbon content 8.82 wt %, and
nitrogen content 11.35 wt %), produced by by chlori-
nation at 800°C. Titanium carbide and carbonitride
were charged into an electric furnace with a graphite
heater directly heated by passing a current in the at-
mosphere of argon; chlorine was fed into the reactor
heated to a prescribed temperature. The thermochemi-
cal treatment was performed in the flow-through mode
[
14] to complete removal of titanium from the tita-
nium carbide lattice, as indicated by X-ray diffraction
analysis (XRD) and elemental analysis by scanning
electron microscopy (SEM). No residual amounts of
the TiC phase and elementary titanium were found in
NPC. To remove the re-sidual content of titanium chlo-
ride and chlorine, NPC was additionally dechlorinated
at a temperature of 800°C in H for 1 h.
2
EXPERIMENTAL
The shape and size of powder particles of TiC and
TiC0.44N0.48 and of NPC synthesized from powdered
TiC and compact material (tube of pyrolytic TiC and
NPC produced from pyrolytic TiC) was determined
NPC samples were synthesized from the follow-
ing starting materials: titanium carbide powder (spe-
cific surface area by BET 1.3 m g , pycnometric den-
2
–1
1
733

1
734
KRAVCHIK et al.
Fig. 1. Fractograms of lateral fractured surface of (a) tube composed of TiC(CVD) and (b) NPC produced from TiC(CVD).
and an elemental analysis was performed with a Quan-
ta 200 scanning electron microscope. The structure
was examined by XRD on a DRON-4 X-ray diffratom-
eter with CoKα radiation. The pycnometric density was
measured by gas pycnometry (pycnometric gas He) with
a Quantachrome Ultrapycnometer 1000 device. An ad-
sorption-structural analysis (ASA) (measurement of
the adsorption–desorption of nitrogen) was performed
at liquid-nitrogen temperature (–196°C) on a Micro-
meritics ASAP 2020 installation.
used to obtain compact NPC with a monodisperse
structure. Figure 1 shows fractograms of a fractured
lateral surface of tubes composed of pyrolytic TiC be-
fore chlorination (Fig. 1a) and NPC tubes produced
from pyrolytic TiC after chlorination (Fig. 1b). As can
be seen from these images, the shape, size, and struc-
ture of compact NPC before and after chlorination are
the same. The pycnometric densities of NPC produced at
4
00–800°C from TiC and TiC N powders and pyro-
x y
–3
lytic TiC fall within the range 2.19–2.25 g cm , which
–3
SEM studies demonstrated that powders of
the starting carbide and powders subjected to thermo-
chem-ical treatment at various temperatures have ?the
same size and shape of particles?. The pyrolytic TiC
has no porosity, which is indicated by results of
pycnometric and metallographic studies, and, there-
is close to the theoretical density of graphite (2.265 g cm ).
At TCT temperatures T ≥ 1000°C, the pycnometric den-
sity gradually decreases (Table 1), with the pore volume
for nitrogen simultaneously becoming smaller. This indi-
cates that pores inaccessible to nitrogen (to a greater ex-
tent) and helium (to a lesser extent) are formed.
Table 1. Structural parameters of NPC produced from a TiC powder at various temperatures*
d
002
L
a
Δa
nm
L
c
Δd
–
3
TТCT, °C
α, deg
q, %
p
ρ , g cm
4
6
8
00
00
00
34
28
16
11
8
–
–
0.9
1.1
1.2
6.4
8.1
8.6
0.005
0.005
0.004
0.002
0
–
–
2.19
2.25
2.25
2.02
1.97
1.71
18
21
38
63
100
0.372
0.370
0.343
0.340
0.337
–
–
5.8
11.3
14.2
16.4
0.011
0.009
0.008
0.007
1
1
1
000
300
800
0
0
*
α is the slope of the X-ray diffraction curve at front diffraction angles, which gives the fraction of carbon atoms in the amorphous
state; q, number of hexagonal carbon monolayers in microlayers; d002, average interlayer spacing between hexagonal monolayers in a
microlayer; L
a
, average length of a rectilinear portion of a carbon monolayer; L
c
, average thickness of a microlayer; ∆a and ∆d, average
defectiveness of monolayers in the directions a and c, respectively; and ρ
p
, pycnometric density.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 81 No. 10 2008

STRUCTURE OF NANOPOROUS CARBON PRODUCED FROM TITANIUM CARBIDE
1735
The structural parameters of NPC were deter-
mined using methods described in [15, 16]. An XRD
analysis of the structure of NPC synthesized from TiC
demonstrated that, as the TCT temperature increases,
the structure of the material rather gradually changes
from amorphous to paracrystalline and further to tur-
bostratic (Table 1). It should be noted that, in the case
of NPC synthesized at 400°C, hexagonal carbon
monolayers do not combine into microlayers. The X-
ray diffraction pattern of this material contains no
(
002) reflection (Fig. 2a). As the TCT temperature is
raised, the fraction of the amorphous phase decreases
to zero. At a TCT temperature of 1800°C, the NPC
structure becomes turbostratic, with all carbon
monolayers combined into microlayers (q = 100%)
(
Fig. 2b). The spacing between hexagonal monolayers
in microlayers steadily decreases as the TCT tempera-
ture is raised and reaches a value of 0.337 nm. The
Fig. 2. X-ray diffraction patterns of NPC obtained at
(a) 400 and (b) 1800°C from TiC (Co ). (θ) Diffraction
angle.
average length L of rectilinear portions of carbon
a
K
α
monolayers increases from 0.9 to 8.6 nm. For NPC
powders produced from TiC (1800°C), in which all
monolayers are combined into microlayers, the pa-
bon monolayers (q = 0–38%). Consequently, a pre-
dominantly paracrystalline structure is formed, mostly
constituted by single carbon monolayers bound to each
other by linear carbine chains. Therefore, it can be
stated that the pore structure of NPC synthesized at
these temperatures is generated by carbon monolayers.
rameter L acquires a meaning of the length of the rec-
a
tilinear portion of a carbon microlayer. As the TCT
temperature is raised, the defectiveness of monolayers
in the direction a decreases from 0.05 nm to zero at a
temperature of 1300°C. This means that there is no
curvature of carbon monolayers across a length La.
The length and width of these layers, L = 0.9–1.2 nm.
a
For NPC powders produced from TiC and sub-
jected to TCT at 400 and 600°C, there are no (002) and
At TCT temperatures above 1300°C, the fraction
of the amorphous phase decreases to zero, linear car-
bine chains almost disappear, and a turbostratic carbon
structure is formed, with the fraction of monolayers
combined into microlayers ranging from 63 to 100%.
The pore structure of NPC synthesized from TiC at
above 1300°C can be for the most part represented by
slits formed between carbon microlayers, and, there-
fore, a decrease in the specific surface area and
pycnometric density is observed for these materials
(
004), and (004) reflections, respectively. Therefore, it
is impossible to determine L and ∆d. The thickness
c
Lc of microlayers is 5.8 nm in NPC produced from TiC
(800°C) and increases to 16.4 nm for NPC from TiC
(
1800°C). The defectiveness of monolayers in the di-
rection c substantially exceeds that in the direction a
and decreases from 0.011 to 0.007 nm as the TCT tem-
perature is raised.
(
Table 1). The average sizes of the rectilinear regions
The structural parameters of NPC produced from
powdered TiC0.44N0.48 and compact pyrolytic TiC at
of microlayers in NPC produced at a TCT temperature
of 1800°C are as follows (nm): L = 8.6 and L = 16.4.
a
c
8
00°C coincide, to within experimental error, with
those of NPC synthesized from TiC powders also at
00°C, and, therefore, these data are not presented in
It is apparent that an intermediate structure is formed
at TCT temperatures of 1000 to 1300°C. This structure
contains pores formed both by carbon monolayers and
by intersection of carbon microlayers.
8
Table 1. The structure of NPC produced from TiC var-
ies with the TCT temperature similarly to that of NPC
from B C [14]. Therefore, a model suggested for NPC
A study of the structure of NPC produced from
TiC by high-resolution transmission electron micros-
copy (HRTEM) demonstrated that the structure of the
material is constituted by hexagonal carbon monolay-
ers produced at low chlorination temperatures (Fig. 3a)
4
produced from B C can be adopted for NPC produced
4
from TiC. The NPC synthesized from TiC powders at
4
00–1000°C contain a large amount of amorphous car-
bon (α = 34°–11°) with a considerable fraction of car-
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 81 No. 10 2008

1
736
KRAVCHIK et al.
Fig. 3. HRTEM micrographs of NPC produced from α-SiC at TTCT of (a) 600 and (b) 1800°C.
and by carbon microlayers formed at high chlorination the original theory, the adsorbate within a limited vol-
temperatures (Fig. 3b).
ume of a pore was understood as a gas or vapor experi-
encing the action of an external field created by the
adsorbent. In the new variant, the adsorbent is not any
more a thermodynamically inert, external with respect
to the adsorbate, body whose only role is to create an
adsorption field. Previously, the NLDFT has been only
applied to gases, vapors, or fluids. In the NLDFT ver-
sion developed in this study, a common procedure is
used for the binary system constituted by a solid and a
gas (vapor). Even in the case when pores have a slit-
like shape, the model suggested here better describes
the adsorption isotherm because of the presence of de-
fects in the hexagonal structure of mono- and mi-
crolayers.
Titanium carbide has a face-centered cubic (fcc)
structure and belongs to interstitial phases formed by
introduction of carbon atoms into interstitial positions
of the fcc sublattice of titanium atoms. Metal atoms are
arranged in densely packed layers, between which car-
bon layers lie. The lattice constant of TiC is 0.4328
nm. The TCT of carbides is a topochemical reaction,
i.e., reaction that occurs in a narrow localized zone at
the interface between a solid reagent (carbide in the
case in question) and a solid product (NPC), with grad-
ual shift of the reaction front into the carbide and its
conversion into carbon. This suggestion was confirmed
in chlorination of TiC produced by CVD. With ac-
count of the initial structure of TiC and of the chemical
Particular attention was given to the inversion
nature of the process, an NPC structure with slit-like method used to find the differential pore distribution
pores should be formed.
function from the adsorption isotherm. This problem
belongs to the class of ill-posed problems because the
results of analysis are rather sensitive to experimental
errors. Accidental nonsignificant peaks or dips on the
distribution curves are suppressed using the regulariza-
tion (smoothing) method developed by Tikhonov [20].
A careful choice of the regularization parameter and of
the type of the stabilizing functional made it possible
to elucidate fine details of the porous structure and the
effect of technological parameters on this structure.
The pore width H is defined in this study as the dis-
tance between the centers of carbon atoms situated on
the opposite walls. It is noteworthy that the effective
pore width H–∆ (where ∆ is the distance between
neighboring graphenes in the graphite lattice, 0.335
The structure of the NPC samples under study
was determined by the ASA method, using the nonlo-
cal density functional theory (NLDFT) adapted to ad-
sorption of nitrogen on amorphous surfaces [17–19].
The surface of ungraphitized carbon black with ad-
sorbed nitrogen served as a reference system. It is
noteworthy that the NLDFT variant developed for
crystalline surface has been used until now, with
graphitized carbon black chosen as a reference system
in the case of activated carbons. As a rule, this choice
resulted in an insufficiently accurate description of ex-
perimental isotherms of nitrogen adsorption on activated
carbon and distorted the pore size distribution [18].
The suggestion that the pore wall surface has an nm) is used in the literature and software for instru-
amorphous (defective) structure considerably improves ments analyzing the porous structure by the adsorption
the descriptive capacity of the NLDFT and gives a method. Such a definition has been accepted in order
more adequate pore size distribution. The working to take into account only pores with width exceeding
principle of the approach developed consists in that the ∆, accessible to gas molecules. If, in particular, the
adsorbent and adsorbed nitrogen are represented as pore wall is composed of only a single graphene, its
components of a binary system and the global similar- wall thickness is considered to be equal to ∆, rather
ity of these components is in their disordered state. In than to zero. In this study, the definition was only used
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 81 No. 10 2008

STRUCTURE OF NANOPOROUS CARBON PRODUCED FROM TITANIUM CARBIDE
1737
Table 2. Porous structure parameters of NPC synthesized from TiC at various temperatures*
V
Σ
V
1
V
2
V
3
S
Σ
S
1
S
2
S
3
H
1
H
2
H
3
TТCT,°C
3
–1
2
–1
cm g
m g
nm
4
6
8
00
00
00
0.392
0.445
0.538
0.523
0.293
0.290
0.329
0.362
0.338
0.072
0.014
0.003
0.063
0.083
0.200
0.103
0.042
0.009
–
1935
2012
2100
1021
171
1829
1819
1679
375
69
106
193
421
326
44
–
0.696
0.734
0.735
0.734
0.715
0.734
1.314
–
–
–
–
–
1.092
1.064
0.981
2.548
2.483
–
–
1
000
300
800
0.348
0.237
0.278
320
58
39
1.713
11.54
18.10
1
1
62
15
8
*
V
Σ
, V
1
, V
2
, and V
3
are the total pore volume and volumes of the 1st, 2nd, and 3rd groups of pores; S
Σ
, S
1 2 3
, S , and S , the total specific
surface area and specific surface areas of the 1st, 2nd, and 3rd groups of pores; H , H , and H , widths of the 1st, 2nd, and 3rd groups of
1 2 3
pores, respectively.
to calculate the pore volume, because just the volume ples synthesized at 400, 600, and 800°C show no
accessible to molecules of the substance being ad- hysteresis loop characteristic of mesoporous systems
sorbed is conventionally understood as the pore vol- and are similar to type-I isotherms, which describe
ume. However, the concept of the true, geometric pore microporous systems in accordance with the IUPAC
width was used as the most adequate characteristic classification. A hysteresis loop appeared on the iso-
when analyzing the pore size distribution function.
therm for the NPC produced at 850°C, with the frac-
tion of mesopores equal to 21% of the total pore vol-
ume.
The isotherms of nitrogen adsorption on the nano-
porous carbon materials studied are shown in Fig. 4.
A study of the ASA results demonstrated that, as the
The pore size distribution varies with the chlori-
TCT temperature increases, the porous structure of nation temperature At a chlorination temperature of
NPC changes from microporous with high specific 400–800°C, only pores smaller than 2 nm in size (mi-
surface area to coarsely mesoporous with low specific cropores) are present in NPC; at NPC synthesis temper-
surface area (Fig. 5, Table 2). For example, the iso- atures of 850–1200°C, a bidisperse structure (micro-
therms of nitrogen adsorption-desorption on NPC sam-
mesoporous) is formed; whereas chlorination at tem-
Fig. 4. Adsorption isotherms of nanoporous carbons ob-
tained at different temperatures. (A) Amount of adsorbed
N
(
[
2
, and (P/P
2) 1300, (3) 800 (TiC0.44
TiC (CVD)], (7) 800, and (8) 1800.
0
) relative pressure. Temperature (°C): (1) 400,
Fig. 5. Pore size distribution for NPC in relation to the TCT
N0.48), (4) 600, (5) 100, (6) 800
temperature. (d
V/dlog H) Change in the pore volume,
(H) pore width, and (T) temperature.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 81 No. 10 2008

1
738
KRAVCHIK et al.
Table 3. Porous structure parameters of NPC synthesized from TiC and TiC0.44
N
0.48 at 800°C
V
Σ
V
1
V
2
V
3
S
Σ
S
1
S
2
S
3
H
1
H
2
H
3
Starting
material
3
–1
2
–1
cm g
m g
nm
TiC
0.538
0.541
1.228
0.338
0.319
0.162
0.200
0.094
0.526
–
2100
2230
1225
1679
1710
684
421
270
477
–
0.735
0.715
0.956
1.064
1.008
2.008
–
1.314
10.10
TiC (CVD)
0.128
0.540
250
64
TiC0.44N
0.48
peratures T ≥ 1300°C yields a mesoporous structure. pores show the same tendency. For example, the total
2
–1
The isotherms of nitrogen adsorption-desorption on specific surface area first increases to 2100 m g at
NPC samples synthesized at 1000, 1300, and 1800°C 800°C and then decreases as the temperature is raised
and NPC produced from TiC0.44N0.48 show a hysteresis further. At a TTCT of 1300°C, a mesoporous NPC
loop, which indicates that mesopores are present. For structure appears. For TCT at T ≥ 1300°C, the peaks in
NPC powders produced from TiC at 400–800°C, two the region of micropores are negligible. There is a
groups of micropores are observed, with the following broad peak in the region of mesopores (Fig. 5) and the
2
–1
sizes (nm): 1st group, 0.70–0.74; 2nd group, 1.06–1.31 specific surface area decreases to 62 m g . These
Fig. 5, Table 2). In the temperature range specified, NPC materials can be attributed to materials with a meso-
(
the volumes and specific surface areas of these two porous structure.
groups of micropores in the NPC obtained change only
The results obtained show a good correlation with
the results of XRD and refine these data. This gives
slightly.
The NPC obtained at 1000°C has already three reason to believe that, at TCT temperatures of 400–
groups of pores, with the sizes of the first two groups of 800°C, carbon monolayers form a microstructure with
pores remaining nearly the same, and the average size two characteristic sizes: 0.70–0.74 and 1.06–1.31 nm
of pores of the third group equal to 1.71 nm (Fig. 5). (on the assumption of a slit-like model). At a TCT
The volume of micropores passes through a maximum temperature of 1000°C, carbon microlayers start to be
3
–1
(
0.54 cm g ) for the NPC obtained at 800°C. Raising formed, with the fraction of pores formed by monolay-
the temperature further, to above 800°C, leads to a de- ers becoming smaller and there appearing a new type
crease in the volume of micropores and to a pro- of pores formed by spaces between microlayers. At
nounced development of mesopores. The total specific TCT temperatures T ≥ 1300°C, micropores formed by
surface area and the specific surface area of micro- carbon monolayers disappear and mesopores formed
by carbon microlayers remain. This yields NPC with a
mesoporous structure (Fig. 5).
In this study, NPC produced from TiC powder,
compact pyrolytic TiC, and TiC0.44N0.48 powder at a
chlorination temperature were examined. For TiC
powder and compact pyrolytic TiC, the data almost
coincide (Table 3, Fig. 6). It can be stated on the basis
of the results obtained that the structures of NPC pro-
duced under identical conditions are independent of
the dispersity of the starting carbide, being the same
even for a compact material.
The structure of the NPC produced from
TiC0.44N0.48 is similar to that of the NPC synthesized
from TiC (1000°C) (Figs. 5, 6). A small single peak
with an average pore size of 0.96 nm is observed in the
region of micropores, and two peaks (~2 and 10 nm),
in the region of mesopores. The main difference be-
tween these two materials is in the volume and specific
Fig. 6. Pore size distribution for NPC produced from
(
a) TiC0.44N0.48, (b) TiC (CVD), and (c) TiC (powder) in
relation to the TCT temperature. (dV/dlog H) Change in
the pore volume, and (H) pore width.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 81 No. 10 2008

STRUCTURE OF NANOPOROUS CARBON PRODUCED FROM TITANIUM CARBIDE
1739
surface area of mesopores (whose size exceeds 2 nm in
accordance with the international classification by IU-
PAC). For example there are no mesopores at all in
NPC produced from TiC (1000°C), and the volume
and specific surface area of mesopores in NPC pro-
duced from TiC0.44N0.48 are 0.94 cm g and 351 m g ,
respectively. The total pore volume in NPC synthe-
sized from TiC0.44N0.48 is twice that in NPC produced
from TiC (1000°C) (Tables 2, 3). This effect can be
attributed to removal of titanium and nitrogen atoms
from TiC0.44N0.48 by TCT. This yields lager pores.
support to the Russian Foundation for Basic Research
(grant no. 06-03-62 268).
REFERENCES
3
–1
2
–1
1. Fedorov, N.F., Ivakhnyuk, G.K., and Gavrilov, D.N.,
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2
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4
. Fedorov, N.F., Ivakhnyuk, G.K., and Gavrilov, D.N.,
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It should also be noted that the majority of pores
in NPC produced from TiC0.44N0.48 are formed by hex-
agonal carbon layers (q = 20%), whereas in NPC syn-
thesized from TiC (1000°C), a substantial part of
mesopores are formed by carbon microlayers (q = 38%).
The fraction of micropores in NPC produced from
TiC0.44N0.48 is 24%, and that in NPC synthesized from
TiC (1000°C), 100%. This suggests that NPC pro-
duced from TiC0.44N0.48 belongs to materials with pre-
dominantly mesoporous structure, and NPC synthe-
sized from TiC (1000°C), to materials with micropor-
ous structure.
5. Kravchik, A.E., Kritich. Tehnol., Membrany, 2003,
no. 3 (19), pp. 3–12.
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(
1) Analysis of the effect of the thermochemical
treatment temperature on the structure of nanoporous
carbon produced from TiC powders shows that the
structure varies from paracrystalline to turbostratic.
Depending on the thermochemical treatment tempera-
ture, the porous structure of nanoporous carbon varies
from microporous (thermochemical treatment tempera-
ture 400–800°C) to mesoporous (thermochemical
treatment temperature 1300–1800°C).
1
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(
2) The structures of nanoporous carbon produced
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nanoporous carbon produced from TiC0.44N0.48 is pre-
dominantly mesoporous, with a large total volume of
pores, including mesopores, which twice exceeds the
total pore volume of nanoporous carbon synthesized
from TiC.
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ACKNOWLEDGMENTS
2
The study was in part supported by the Russian
Federal Agency for Science and Innovations (grant
no. 9085.2006.2). E.A.U. is grateful for the financial
2
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 81 No. 10 2008