ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2011, Vol. 56, No. 11, pp. 1693–1697. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © A.V. Gorokhovsky, I.D. Kosobudskii, E.V. Tret’yachenko, G.Yu. Yurkov, L.V. Nikitina, A.I. Palagin, 2011, published in Zhurnal Neorganicheskoi Khimii,
2011, Vol. 56, No. 11, pp. 1775–1780.
SYNTHESIS AND PROPERTIES
OF INORGANIC COMPOUNDS
Potassium Polytitanates Intercalated with Nickel Ions
and Their Thermal Transformations
A. V. Gorokhovskya, I. D. Kosobudskiia, E. V. Tret’yachenkoa,
G. Yu. Yurkovb, L. V. Nikitinaa, and A. I. Palaginc
a Saratov State Technical University, ul. Universitetskaya 42, Saratov, 410601 Russia
b Baikov Institute of Metallurgy, Russian Academy of Sciences, Leninskii pr. 49, Moscow, 119991 Russia
c Science and Production Company Nanocomposite, Saratov, Russia
Received October 14, 2010
Abstract—The intercalation of nickel ions into the layered structure of ultradispersed amorphous potassium
polytitanate powder on treatment with an aqueous solution of nickel sulfate was studied. The limiting nickel
content that can be attained by intercalation is 12.8 wt %. The nickel ion intercalation results in a decrease in
the average particle size of potassium polytitanate and in the structural ordering. Heat treatment of the resulting
intercalate promotes the formation of a nanocomposite consisting of the solid solution K1.35(NixTi8 – x)O16 with
the hollandite structure, Ti2O3, and, depending on the treatment schedule, either NiO nanocrystals or Ni
metal.
DOI: 10.1134/S0036023611110088
THEORETICAL ANALYSIS
Thus alkali metal titanates with intercalated transiꢀ
tionꢀmetal ions have a number of advantages over the
titanium oxide–transition metal oxide composite sysꢀ
tems; localization of the positively charged transitionꢀ
metal ions in the interlayer space of the polyanions
formed by titanium–oxygen polyhedra brings about a
much broader pH range in which the stability of these
structures is maintained [8–10]. However, there are
only few works devoted to the use of intercalation synꢀ
thetic processes for the preparation of highꢀperforꢀ
mance catalytic systems in which layered titanates are
used as matrices. In particular, it was shown [11] that
During the last decade, particular interest is
aroused by the synthesis of mesoporous materials that
exhibit high adsorption properties in combination
with the catalytic activity [1–3]. The synthesis of
mesoporous transition metal oxides having a number
of advantages due to the high catalytic activity is hamꢀ
pered as a result of high rate of hydrolysis of transitionꢀ
metal ions and their tendency to form structures with
large coordination numbers [2].
A convenient method for solving this problem is
intercalation of transition metals into the structure of
layered minerals functioning as supports [4–7]. The nickel doping of hydrated titanium oxide increases its
use of layered titanium oxide modifications and its
derivatives for this purpose provides the possibility of
forming various types of structures with enhanced catꢀ
alytic activities: titanates intercalated with transitionꢀ
metal ions; doped titanates in which some titanium
atoms are replaced by transitionꢀmetal atoms; comꢀ
bined structures consisting of layers of a semiconducꢀ
tor with relatively wide band gap (titanium oxide) and
a semiconductor with a relatively narrow band gap
(transition metal oxide).
It should be borne in mind that titanates doped
with transition metals exhibit photocatalytic activity
in the visible region [4, 5, 7], which is especially
important, as the total intensity of solar radiation in
photocatalytic activity. The kinetics of ionꢀexchange
adsorption of nickel with hydrated titanium oxide was
measured [12]. In addition, it was noted [13] that iniꢀ
tial layered potassium tetratitanate has a higher cataꢀ
lytic activity in the photocatalytic reduction of Cr(VI)
to Cr(III) than protonated potassium tetratitanate.
The interlayer spacing in layered crystalline potasꢀ
sium titanates is relatively small; this hampers the penꢀ
etration of multicharged ions into it. Therefore, to
increase the sorption capacity with respect to transiꢀ
tionꢀmetal ions, it is necessary to intercalate first
larger organic cations [14]. Potassium polytitanates
look more attractive as matrix materials for intercalaꢀ
the UV region (the region of TiO2 photoactivity) is tion of transitionꢀmetal ions. The class of potassium
only 4–6%, whereas in the visible region it increases to
45% [8].
polytitanates having amorphous or highly distorted
crystal structure consisting of layers located far apart
was synthesized rather recently [15] and exhibited very
high sorption characteristics with respect to Pb(II)
On the other hand, each of the listed types of cataꢀ
lytic systems has its own advantages and drawbacks. ions [16].
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