THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE
Two- and three-phase compositions of mesoporous nanocrystalline TiO2 (meso-nc-TiO2) were obtained from sol-gel reaction mixtures (ZGRM) using dibenzo-18-crown-6 (DВ18С6) as a structure-directing agent and titanium tetrabutoxide (TBOT) as a source of titanium in the presence of HCl with (or without)...
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| Date: | 2024 |
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| Format: | Article |
| Language: | English |
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V.I.Vernadsky Institute of General and Inorganic Chemistry
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| Online Access: | https://ucj.org.ua/index.php/journal/article/view/626 |
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Ukrainian Chemistry Journal| _version_ | 1871466011918598144 |
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| author | Ermokhina, Natalia Shvalagin, Vitalii Korzhak, Anna Grebennikov, Volodymyr Romanovska, Natalia Shulzshenko , Alexander Shcherbatyuk , Mykola Klymchuk , Dmytro Manoryk , Petro |
| author_facet | Ermokhina, Natalia Shvalagin, Vitalii Korzhak, Anna Grebennikov, Volodymyr Romanovska, Natalia Shulzshenko , Alexander Shcherbatyuk , Mykola Klymchuk , Dmytro Manoryk , Petro |
| author_institution_txt_mv | [
{
"author": "Natalia Ermokhina",
"institution": "Інститут фізичної хімії ім. Л. В. Писаржевського НАН України"
},
{
"author": "Vitalii Shvalagin",
"institution": "Інститут фізичної хімії ім. Л. В. Писаржевського НАН України"
},
{
"author": "Anna Korzhak",
"institution": "Інститут фізичної хімії ім. Л. В. Писаржевського НАН України "
},
{
"author": "Volodymyr Grebennikov",
"institution": "Інститут фізичної хімії ім. Л. В. Писаржевського НАН України"
},
{
"author": "Natalia Romanovska",
"institution": "Інститут фізичної хімії ім. Л. В. Писаржевського НАН України"
},
{
"author": "Alexander Shulzshenko ",
"institution": "Інститут фізичної хімії ім. Л. В. Писаржевського НАН України"
},
{
"author": "Mykola Shcherbatyuk ",
"institution": "Інститут ботаніки ім. М. Г. Холодного НАН України"
},
{
"author": "Dmytro Klymchuk ",
"institution": "Інститут ботаніки НАН України"
},
{
"author": "Petro Manoryk ",
"institution": "Інститут фізичної хімії ім. Л. В. Писаржевського НАН України"
}
] |
| author_sort | Ermokhina, Natalia |
| baseUrl_str | https://ucj.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-22T08:23:53Z |
| description | Two- and three-phase compositions of mesoporous nanocrystalline TiO2 (meso-nc-TiO2) were obtained from sol-gel reaction mixtures (ZGRM) using dibenzo-18-crown-6 (DВ18С6) as a structure-directing agent and titanium tetrabutoxide (TBOT) as a source of titanium in the presence of HCl with (or without) subsequent hydrothermal treatment (HTT) and calcination at 500 oC.
It has been shown that the addition of a small amount of dodecyldimethylethylammonium bromide (DDMEABr) and/or lanthanum salts in ZGRM, as well as HTT, has a significant effect on the phase composition and texture of the samples. It was established that the use of HTT before calcination of samples significantly increases their photocatalytic activity (PhA) in the reaction of photocatalytic hydrogen release from an aqueous-ethanol mixture mainly due to changes in their phase composition.
The hydrothermally treated sample of the anatase (85%)/rutile (4%)/brookite (11%) phase composition shows the highest photocatalytic activity, which is 2.5 times higher than the corresponding characteristic for the commercial Evonik P25 photocatalyst. It is shown that the size of the specific surface area of the sample is not the dominant factor influencing the photocatalytic activity of the obtained mixed-phase meso-nc-TiO2 samples in the process of hydrogen release from the aqueous-ethanol mixture. |
| doi_str_mv | 10.33609/2708-129X.89.12.2023.88-109 |
| first_indexed | 2025-09-24T17:43:54Z |
| format | Article |
| fulltext |
88 ISSN 2708-129X. Укр. хім. журн., 2023
УДК 541.145 doi: 10.33609/2708-129X.89.12.2023.88-109
THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE
MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY
IN THE REACTION OF HYDROGEN EVOLUTION FROM
AN AQUEOUS-ETHANOL MIXTURE.
N. I. Ermokhina1, V.V. Shvalagin 1, G. V. Korzhak1, V. N. Grebennikov1*, N. I. Romanovska1,
A. V. Shulzshenko1, М. М. Shcherbatyuk2, D. O. Klymchuk2, P. A. Manorik1
1 Pisarzhevskii Institute of Physical Chemistry of the National Academy of Sciences of Ukraine,
31 Ave. Science, 03028 Kyiv, Ukraine
2 Institute of Botany of the National Academy of Sciences of Ukraine,
2 Tereshchenkivska St., 01601 Kyiv, Ukraine
*e-mail: vng@ukr.net
Two- and three-phase compositions of mesoporous nanocrystalline TiO2 (meso-nc-TiO2)
were obtained from sol-gel reaction mixtures (ZGRM) using dibenzo-18-crown-6 (DВ18С6)
as a structure-directing agent and titanium tetrabutoxide (TBOT) as a source of titanium in
the presence of HCl with (or without) subsequent hydrothermal treatment (HTT) and calci-
nation at 500 oC.
It has been shown that the addition of a small amount of dodecyldimethylethylammonium
bromide (DDMEABr) and/or lanthanum salts in ZGRM, as well as HTT, has a significant
effect on the phase composition and texture of the samples. It was established that the use of
HTT before calcination of samples significantly increases their photocatalytic activity (PhA)
in the reaction of photocatalytic hydrogen release from an aqueous-ethanol mixture mainly
due to changes in their phase composition.
The hydrothermally treated sample of the anatase (85%)/rutile (4%)/brookite (11%) phase
composition shows the highest photocatalytic activity, which is 2.5 times higher than the
corresponding characteristic for the commercial Evonik P25 photocatalyst. It is shown that
the size of the specific surface area of the sample is not the dominant factor influencing the
photocatalytic activity of the obtained mixed-phase meso-nc-TiO2 samples in the process of
hydrogen release from the aqueous-ethanol mixture.
Keywords: sol-gel synthesis, mesoporous TiO2 anatase-rutile-brookite compositions,
H2 release.
89https://ucj.org.ua
N. I. Ermokhina, V.V. Shvalagin, G. V. Korzhak, V. N. Grebennikov, N. I. Romanovska, A. V. Shulzshenko, М. М. Shcherbatyuk, D. O. Klymchuk, P. A. Manorik UCJ № 12 / Vol. 89
INTRODUCTION. The need to ensure the
sustainable development of post-industrial so-
ciety, the rapid deepening of planetary energy
and environmental problems require obtain-
ing new materials for modern equipment and
technologies. In particular, such materials in-
clude electrode materials for solar cells, photo-
catalysts for cleaning the environment (water
and air) from various pollutants using sunlight
energy, etc. [1, 2]. Today, in the field of sem-
iconductor photocatalytic technology, mate-
rials based on TiO2 occupy a leading position
both in terms of demand and research inten-
sity due to the unique properties of TiO2 and,
above all, non-toxicity, chemical stability and
commercial availability [1–17].
One of the most advanced methods of ob-
taining TiO2 and other mesoporous oxides
today remains the sol-gel method, which in-
volves the use of a template [10, 13, 14, 18].
Combining it with the widely used method of
solvo(hydro)thermal treatment of an interme-
diate product allows controlling the processes
of formation of unique TiO2 materials with a
given phase composition, morphology and
texture at the nano-level [19, 20]. To achieve
the full catalytic potential of the obtained TiO2
materials, they usually require calcination at a
temperature of about 500 oC [21, 22].
The efficiency of the TiO2 photocatalyst
depends on a number of factors, in particular
the degree of crystallinity and crystallite size,
phase composition, morphology of nanopar-
ticles, textural characteristics, etc. [1, 2, 6, 7].
The main ways to increase the efficiency of
TiO2 photocatalysts are to expand their spec-
tral range of light absorption into the visible
region by doping with nonmetals, metals, sen-
sitization with dyes, obtaining nanocompos-
ites with nanoparticles, obtaining heterostruc-
tures with other semiconductors, etc. [1, 2, 7].
At the same time, for example, in the case of
nanocomposites and heterostructures, an ad-
ditional increase in the PhA of TiO2 photoca
talysts is achieved due to the suppression of the
recombination of photogenerated charge car-
riers [1, 2, 7].
Among the three main crystalline forms
of TiO2 (anatase, rutile, and brookite), ana-
tase usually has the highest photocatalytic
activity (PhA) [23]. However, a number of
experimental facts indicate that TiO2 nano-
structures in which several TiO2 crystalline
phases are combined [11, 12, 15, 24–28] show
a higher PhA than the corresponding sin-
gle-phase nanostructures. A classic example
of such mixed-phase structures is Degussa
P25 Evonik P25, which consists of anatase
(75%) and rutile (25%), and which is used as
a standard in studies of the photocatalytic ac-
tivity of materials [29]. The results obtained
in studies of two- and three-phase TiO2 poly
morphs sometimes lead to contradictory
conclusions when comparing the photocata-
lytic activity of compositions of TiO2 phases
in various redox processes [2, 24–31]. At the
same time, taking into account the fact that
the preparation of heterostructures from se
veral semiconductors, which differ in the band
gap, is one of the effective ways to increase the
PhA of photocatalysts [1, 2, 7], and that there
are no fundamental differences between such
heterostructures and mixed phases of TiO2,
which have different widths of the band gap,
the search for conditions for the synthesis of
such mixed-phase materials based on titani-
um dioxide, which can provide a controlled
variation of the phase composition of the ob-
tained materials, and, accordingly, their PhA,
seems very promising.
90 ISSN 2708-129X. Укр. хім. журн., 2023
THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY
IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE.PHISICAL CHEMISTRY
Earlier [28] we proposed an approach to
obtaining mixed-phase TiO2 nanostructures
(anatase/brookite) with increased PhA. How-
ever, due to the chemical features of the com-
ponents of the sol-gel reaction mixture, this
approach does not allow varying the phase
composition of the obtained material with-
in wide limits. It was also proposed to obtain
mesoporous nanocrystalline TiO2 (meso-nc-
TiO2) with a pure anatase structure by combin-
ing sol-gel synthesis with HTT of an interme-
diate product [32–36]. TiO2 samples calcined
at 500°C after HTT at 175°C had a significantly
more developed porous structure compared
to untreated hydrothermally treated samples.
It was shown that the introduction of small ad-
ditions of cationic surfactant (DDMEABr) and
(or) lanthanum salt into the reaction mixture
has a significant effect on the degree of crys-
tallization, morphology and texture of meso-
nc-TiO2 (anatase) samples and their photo-
catalytic activity. Practically all the obtained
samples were highly efficient photocatalysts
for the processes of water reduction, gas-phase
oxidation of alcohol and benzene [34–38]. This
approach can be used to vary the phase com-
position of mixed-phase TiO2 materials over a
wide range.
This paper considers the influence of vary-
ing the synthesis conditions of meso-nc-TiO2
samples on their phase composition, as well as
the influence of the phase composition of me-
so-nc-TiO2 samples both in the form of pure
anatase and various mixed-phase composi-
tions (anatase-brookite-rutile), which consist
of two or three phases, on their photocataly
tic properties in the reaction of the release of
molecular hydrogen from a aqueous-ethanol
mixture.
EXPERIMENT AND RESULTS DISCUS-
SION. The work used titanium tetrabutoxide
(IV), dodecyldimethylethylammonium bro-
mide, dibenzo-18-crown-6 ("Fluka"), HCl,
n-butanol, LaCl3•7H2O, CuCl2, NaCl, ethanol
(96%), TiO2 Evonik P25.
Samples of meso-nc-TiO2 with different
contents of rutile anatase and brookite were
obtained using the modified sol-gel method
similarly [32, 33]. Hydrolysis of titanium
tetrabutoxide was carried out in butanol in the
presence of HCl using as a structure-directing
agent the complex of sodium with dibenzo-18-
crown-6 [Na(DB18C6)]Cl in the presence (or
without) of small additions of the surfactant
DDMEABr and a lanthanum salt. The calcu-
lated amounts of reagents were successively
dissolved in butanol. TBOT was added drop-
wise with vigorous stirring. The reaction mix-
ture was left under a glass cap in air at room
temperature (without stirring) until the forma-
tion of the gel stopped. The obtained product
was subjected to HTT at 175 oC for 24 hours
followed by annealing at 500 oC in air for
4 hours.
The meso-nc-TiO2 samples obtained under
different conditions are denoted as Ti n and Ti
nН, where n is the sample number and H is the
hydrothermal treatment. The molar composi-
tion of the reaction mixture, which was used
for the synthesis of meso-nc-TiO2 samples, is
given in Table 1.
The X-ray diffraction (XRD) patterns of
the samples was performed on a DRON-3M
(CuKα) diffractometer. The average size of
TiO2 crystallites was calculated from the width
of the diffraction peak of anatase (101) at
2θ = 25.4o according to the well-known Scher-
rer formula.
91https://ucj.org.ua
N. I. Ermokhina, V.V. Shvalagin, G. V. Korzhak, V. N. Grebennikov, N. I. Romanovska, A. V. Shulzshenko, М. М. Shcherbatyuk, D. O. Klymchuk, P. A. Manorik UCJ № 12 / Vol. 89
Table 1.
Synthesis conditions of meso-nc-TiO2 sam-
ples ([TBOT]:[Na(DB18C6)]Cl = 1.0:0.02).
Sampler
Additive
BuOH H2O HCl
Surfactant** La3+
Ti1 - - 78 3 0,4
Ti1Н - - 78 3 0,4
Ti2 0,02 - 78 3 0,4
Ti2Н 0,02 - 78 3 0,4
Ti3 - 0,01 78 3 0,4
Ti3 Н - 0,01 78 3 0,4
Ti4 0,02 0,01 117 3 0,4
Ti4Н 0,02 0,01 117 3 0,4
Ti5 0,02 0,01 78 3 0,4
Ti5Н 0,02 0,01 78 3 0,4
Ti6 Н 0,02 0,01 57 3 0,4
Ti7 Н 0,02 0,01 26 7 0,7
Ti(MS1) * - - 78,0 - -
Ti(MS1)H* - - 78,0 - -
Ti(MS2)* - - 78,0 3,0 -
Ti(MS2)H* - - 78,0 3,0 -
* meso-nc-TiO2 samples (microspheres) [36];
** surfactant – DDMEABr.
The morphology of the samples was studied
by transmission (TEM) and scanning (SEM)
electron microscopy using JEM 1230 and JSM-
6060LA ("JEOL") microscopes, respectively.
In some cases, the samples were pretreated for
5 min using an ultrasonic disperser UZDN-A
(130 W).
N2 adsorption/desorption isotherms were
recorded at –196 oC on a gas-adsorption ana-
lyzer Autosorb-6 (Quantachrome). Before ad-
sorption, the sample was pumped at 200 oC for
20 hours. The specific surface area (SBET) and
the average pore diameter (Dp) were deter-
mined by the ВЕТ та ВJН methods, respec-
tively. The pore size distribution was calculated
from the desorption branch of the isotherm
using the NLDFT method using a cylindrical
pore model. The total amount of N2 adsorbed
at p/p0 = 0.997 was used to determine the total
pore volume (Vtot).
The photocatalytic activity of the obtained
meso-nc-TiO2 samples was studied in a model
reaction of photocatalytic hydrogen evolution
from an aqueous-ethanol mixture. The reac-
tion conditions were similar to those described
in [39]. The TiO2 samples were irradiated with
UV light (λ = 310–390 nm) in a system con-
taining a aqueous-ethanol mixture (4 vol. %
H2O) and CuCl2 (2∙10-4 mol/l). Commercial
photocatalyst TiO2 Evonik P25 was used as a
comparison sample.
Samples of meso-nc-TiO2 with different
contents of anatase, rutile and brookite were
obtained by a simple modification of our pre-
viously proposed approach [32, 33] - changing
the conditions of TBOT hydrolysis, namely, by
switching from a neutral to an acidic medium,
using a well-known acid catalyst - hydrochlo-
ric acid [38, 39] (Table 1). The main concept
of such optimization of the former synthetic
approach is to combine the influence of fac-
tors: HTT, small additives of surfactant and
(or) lanthanum salt, as well as the concentra-
tion of reagents in the reaction mixture in the
presence of HCl on the phase composition of
meso-nc-TiO2 materials.
Previously [32-36] samples of thermally sta-
ble meso-nc-TiO2 with a well-defined spheri-
cal morphology (microspheres of size from 0.6
to 3 μm with a pure anatase structure) were
92 ISSN 2708-129X. Укр. хім. журн., 2023
THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY
IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE.PHISICAL CHEMISTRY
obtained under conditions of neutral hydro
lysis, characterized by different textures. Mi-
crospheres are formed by primary spherical
particles (anatase crystallites about 10 nm in
size), which are tightly packed into spherical
mesoaggregates 30–70 nm in size (secondary
particles), which form a mesopore system. Ta-
ble 1 and 2 shows examples of synthesis condi-
tions and textural characteristics of such TiO2
microstructures.
Table 2.
Textural characteristics of meso-nc-TiO2 samples, as well as their photocatalytic pro
perties in the reaction of H2 release from an aqueous-ethanol mixture.
Sample SBET,
m2/g
Vp ,
cm3/g
Dtot,
nm
Crystallite
Size
А, nm
Phase composition **
H2∙107,
mol/minА R B
Ti1 39 0,14 14,5 9,8 29 39 32 2,5
Ti1H 61 0,29 18,9 10,4 34 14 52 3,0
Ti2 48 0,23 13,0 7,2 22 60 18 0,4
Ti2H 33 0,21 17,4 9,4 16 70 14 0,7
Ti3 83 0,21 9,4 7,1 55 21 24 1,8
Ti3H 64 0,30 17,3 8,2 43 28 29 2,9
Ti4 122 0,31 9,4 8,3 97 3 - 3,7
Ti4H 96 0,28 11,3 9,5 85 4 11 5,5
Ti5 98 0,18 7,0 7,4 88 - 12 2,0
Ti5H 132 0,46 13,9 7,0 100 - - 3,0
Ti6H 90 0,44 17,3 9,1 90 - 10 2,8
Ti7H 100 0,30 12,3 10,2 25 45 30 4,7
Ti(MS1)* 61 0,14 9,0 10,5 100 - - 3,8
Ti(MS1)
H* 84 0,33 15,5 11,0 100 - - 6,6
Ti(MS2)* 97 0,30 12,3 8,7 100 - - 4,0
Ti(MS2)
H* 116 0,50 17,3 10,0 100 - - 5,0
P25 50 - - 25 70 30 - 2,2
* [36]; **A – anatase, R – rutile, B – brookite.
93https://ucj.org.ua
N. I. Ermokhina, V.V. Shvalagin, G. V. Korzhak, V. N. Grebennikov, N. I. Romanovska, A. V. Shulzshenko, М. М. Shcherbatyuk, D. O. Klymchuk, P. A. Manorik UCJ № 12 / Vol. 89
In Fig. 1 presents the diffraction patterns
of meso-nc-TiO2 (Ti1, Ti1H, and Ti4, Ti4H)
samples obtained in an acidic environment
in the presence of HC1. The phase content of
the compositions in the samples was deter-
mined by the main diffraction peaks of anatase
(JCPDS-PDF, No. 21–1272), rutile (JCPDS-
PDF, No. 21–1276), and brookite (JCPDS-
PDF, No. 29–1360), marked respectively as
( 101), (110) and (121) reflexes using known
calculation methods. According to the XRD,
pattern of Ti4 sample contain low-intensity
narrow peaks at 32o and 45.5o (2θ), which can
be attributed to NaCl occluded in the synthe-
sis process [33]. The calculated average sizes of
anatase crystallites in the samples range from
7.0 to 10.4 nm (Table 2). The most important
samples are Ti1 (9.8 nm) and Ti1H (10.4 nm),
obtained without additives of sulfactant or lan-
thanum salt.
6
10 20 30 40 50 60
А
А А
А
B
B
АА
А
А
А
R
R
R
R
R
R
R
R
R
R
R
R
Ti4H
Ti4
Ti1HIn
te
ns
ity
(a
.u
.)
, degree
Ti1
R
Fig. 1 XRD patterns of meso-nc-TiO2: Ti1, Ti1H and Ti4, Ti4H samples, obtained in various synthetic
conditions; A – anatase, R – rutile, B – brookit.
In Fig. 2 presents N2 adsorption/desorption isotherms and pore size distribution for meso-nc-
TiO2 samples. All isotherms belong to type IV (according to the IUPAC classification) with H1 and
H2 hysteresis loops located at values of relative pressure p/p0 above 0.6, which indicates the
formation of mesopores in the obtained samples.
Textural characteristics and phase composition of meso-nc-TiO2 samples are shown in Table
2. All of them contain anatase phase, the proportion of which covers a wide range from 16 to 100%.
At the same time, the content of rutile ranges from 0 to 70%, and brookite from 0 to 52%. The
average size of anatase crystallites in the samples is about 10 nm. Most of the meso-nc-TiO2 samples
are three-phase compositions. In samples that contain two TiO2 phases (anatase with rutile or
brookite), the anatase phase predominates (88–97%) and one sample contains only anatase.
As can be seen from Fig. 1 and Table 2, the phase composition of the meso-nc-TiO2 samples is
affected by both the presence of DDMEABr surfactant additives, lanthanum salt, and the concentration
of reagents in the reaction mixture during synthesis and the mode of heat treatment (use or absence of
HTT before calcination) of the samples. Thus, the addition of DDMEABr leads to a decrease in the
content of anatase and brookite and an increase in the content of rutile (sample Ti1), and the differences
dramatically deepen in the case of HTT of these samples (sample Ti1H). It is the presence of the
surfactant additive that makes it possible to obtain a Ti2H sample with the highest content of the rutile
phase – 70%.
Fig. 1 XRD patterns of meso-nc-TiO2: Ti1, Ti1H and Ti4, Ti4H samples, obtained in various synthetic
conditions; A – anatase, R – rutile, B – brookit.
In Fig. 2 presents N2 adsorption/desorpti
on isotherms and pore size distribution for
meso-nc-TiO2 samples. All isotherms belong
to type IV (according to the IUPAC classifica-
tion) with H1 and H2 hysteresis loops locat-
ed at values of relative pressure p/p0 above 0.6,
which indicates the formation of mesopores in
the obtained samples.
Textural characteristics and phase compo-
sition of meso-nc-TiO2 samples are shown in
Table 2. All of them contain anatase phase, the
proportion of which covers a wide range from
16 to 100%. At the same time, the content of
rutile ranges from 0 to 70%, and brookite from
0 to 52%. The average size of anatase crystal-
lites in the samples is about 10 nm. Most of the
meso-nc-TiO2 samples are three-phase com-
positions. In samples that contain two TiO2
94 ISSN 2708-129X. Укр. хім. журн., 2023
THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY
IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE.PHISICAL CHEMISTRY
phases (anatase with rutile or brookite), the
anatase phase predominates (88–97%) and one
sample contains only anatase.
As can be seen from Fig. 1 and Table 2,
the phase composition of the meso-nc-TiO2
samples is affected by both the presence of
DDMEABr surfactant additives, lanthanum
salt, and the concentration of reagents in the
reaction mixture during synthesis and the
mode of heat treatment (use or absence of
HTT before calcination) of the samples. Thus,
the addition of DDMEABr leads to a decrease
in the content of anatase and brookite and
an increase in the content of rutile (sample
Ti1), and the differences dramatically deepen
in the case of HTT of these samples (sample
Ti1H). It is the presence of the surfactant ad-
ditive that makes it possible to obtain a Ti2H
sample with the highest content of the rutile
phase – 70%.
7
Fig. 2 N2 adsorption/desorption isotherms and pore size distribution (obtained by the NLDFT method) of
meso-nc-TiO2 samples: Ti1 and Ti1H (a, b), Ti4 and Ti4H (c, d).
The addition of lanthanum salt contributes to an increase in the content of anatase and a
decrease in the content of brookite regardless of the use of HTT of the samples (samples Ti1, Ti1H
and Ti3, Ti3H), while without the use of HTT the content of rutile decreases (samples Ti1 and Ti3),
and when using HTT (samples Ti1H and Ti3H) increases. In the case of the samples obtained with
the simultaneous presence of DDMEABr and lanthanum salts (Ti1, Ti1H and Ti5, Ti5H, T6H) in the
ZGRM, a three-fold increase in the content of anatase is observed against the background of a sharp
drop in the content of brookite and the complete disappearance of the rutile phase. The phase
composition of the samples undergoes especially profound changes when using HTT (samples Ti1H
and Ti5H), as a result of which the three-phase composition is transformed into a single-phase anatase
(Fig. 1, Table 2).
Dilution of the original ZGRM in the presence of lanthanum salt additive (samples Ti3, Ti3H
and Ti4, Ti4H) causes a two-fold increase in the amount of anatase with a simultaneous decrease in the
content of brookite and rutile phases. So, for example, sample Ti3 consists of anatase (55%), rutile
(21%) and brookite (24%), and the corresponding sample Ti4 consists of anatase (97%) and rutile (3%).
1 10 100
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
Ti1H
dV
/d
lo
g(
D
)
D (nm)
Ti1
b
0,0 0,2 0,4 0,6 0,8 1,0
0
50
100
150
200
Ti1H
V
ad
(c
m
3 /g
)
P/Po
Ti1
a
0,0 0,2 0,4 0,6 0,8 1,0
0
50
100
150
200
Ti4
V
ad
(c
m
3 /g
)
P/Po
Ti4H
c
1 10 100
0,0
0,5
1,0
1,5
2,0
2,5
Ti4H
dV
/d
lo
g(
D
)
D (nm)
Ti4
d
7
Fig. 2 N2 adsorption/desorption isotherms and pore size distribution (obtained by the NLDFT method) of
meso-nc-TiO2 samples: Ti1 and Ti1H (a, b), Ti4 and Ti4H (c, d).
The addition of lanthanum salt contributes to an increase in the content of anatase and a
decrease in the content of brookite regardless of the use of HTT of the samples (samples Ti1, Ti1H
and Ti3, Ti3H), while without the use of HTT the content of rutile decreases (samples Ti1 and Ti3),
and when using HTT (samples Ti1H and Ti3H) increases. In the case of the samples obtained with
the simultaneous presence of DDMEABr and lanthanum salts (Ti1, Ti1H and Ti5, Ti5H, T6H) in the
ZGRM, a three-fold increase in the content of anatase is observed against the background of a sharp
drop in the content of brookite and the complete disappearance of the rutile phase. The phase
composition of the samples undergoes especially profound changes when using HTT (samples Ti1H
and Ti5H), as a result of which the three-phase composition is transformed into a single-phase anatase
(Fig. 1, Table 2).
Dilution of the original ZGRM in the presence of lanthanum salt additive (samples Ti3, Ti3H
and Ti4, Ti4H) causes a two-fold increase in the amount of anatase with a simultaneous decrease in the
content of brookite and rutile phases. So, for example, sample Ti3 consists of anatase (55%), rutile
(21%) and brookite (24%), and the corresponding sample Ti4 consists of anatase (97%) and rutile (3%).
1 10 100
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
Ti1H
dV
/d
lo
g(
D
)
D (nm)
Ti1
b
0,0 0,2 0,4 0,6 0,8 1,0
0
50
100
150
200
Ti1H
V
ad
(c
m
3 /g
)
P/Po
Ti1
a
0,0 0,2 0,4 0,6 0,8 1,0
0
50
100
150
200
Ti4
V
ad
(c
m
3 /g
)
P/Po
Ti4H
c
1 10 100
0,0
0,5
1,0
1,5
2,0
2,5
Ti4H
dV
/d
lo
g(
D
)
D (nm)
Ti4
d
7
Fig. 2 N2 adsorption/desorption isotherms and pore size distribution (obtained by the NLDFT method) of
meso-nc-TiO2 samples: Ti1 and Ti1H (a, b), Ti4 and Ti4H (c, d).
The addition of lanthanum salt contributes to an increase in the content of anatase and a
decrease in the content of brookite regardless of the use of HTT of the samples (samples Ti1, Ti1H
and Ti3, Ti3H), while without the use of HTT the content of rutile decreases (samples Ti1 and Ti3),
and when using HTT (samples Ti1H and Ti3H) increases. In the case of the samples obtained with
the simultaneous presence of DDMEABr and lanthanum salts (Ti1, Ti1H and Ti5, Ti5H, T6H) in the
ZGRM, a three-fold increase in the content of anatase is observed against the background of a sharp
drop in the content of brookite and the complete disappearance of the rutile phase. The phase
composition of the samples undergoes especially profound changes when using HTT (samples Ti1H
and Ti5H), as a result of which the three-phase composition is transformed into a single-phase anatase
(Fig. 1, Table 2).
Dilution of the original ZGRM in the presence of lanthanum salt additive (samples Ti3, Ti3H
and Ti4, Ti4H) causes a two-fold increase in the amount of anatase with a simultaneous decrease in the
content of brookite and rutile phases. So, for example, sample Ti3 consists of anatase (55%), rutile
(21%) and brookite (24%), and the corresponding sample Ti4 consists of anatase (97%) and rutile (3%).
1 10 100
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
Ti1H
dV
/d
lo
g(
D
)
D (nm)
Ti1
b
0,0 0,2 0,4 0,6 0,8 1,0
0
50
100
150
200
Ti1H
V
ad
(c
m
3 /g
)
P/Po
Ti1
a
0,0 0,2 0,4 0,6 0,8 1,0
0
50
100
150
200
Ti4
V
ad
(c
m
3 /g
)
P/Po
Ti4H
c
1 10 100
0,0
0,5
1,0
1,5
2,0
2,5
Ti4H
dV
/d
lo
g(
D
)
D (nm)
Ti4
d
7
Fig. 2 N2 adsorption/desorption isotherms and pore size distribution (obtained by the NLDFT method) of
meso-nc-TiO2 samples: Ti1 and Ti1H (a, b), Ti4 and Ti4H (c, d).
The addition of lanthanum salt contributes to an increase in the content of anatase and a
decrease in the content of brookite regardless of the use of HTT of the samples (samples Ti1, Ti1H
and Ti3, Ti3H), while without the use of HTT the content of rutile decreases (samples Ti1 and Ti3),
and when using HTT (samples Ti1H and Ti3H) increases. In the case of the samples obtained with
the simultaneous presence of DDMEABr and lanthanum salts (Ti1, Ti1H and Ti5, Ti5H, T6H) in the
ZGRM, a three-fold increase in the content of anatase is observed against the background of a sharp
drop in the content of brookite and the complete disappearance of the rutile phase. The phase
composition of the samples undergoes especially profound changes when using HTT (samples Ti1H
and Ti5H), as a result of which the three-phase composition is transformed into a single-phase anatase
(Fig. 1, Table 2).
Dilution of the original ZGRM in the presence of lanthanum salt additive (samples Ti3, Ti3H
and Ti4, Ti4H) causes a two-fold increase in the amount of anatase with a simultaneous decrease in the
content of brookite and rutile phases. So, for example, sample Ti3 consists of anatase (55%), rutile
(21%) and brookite (24%), and the corresponding sample Ti4 consists of anatase (97%) and rutile (3%).
1 10 100
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
Ti1H
dV
/d
lo
g(
D
)
D (nm)
Ti1
b
0,0 0,2 0,4 0,6 0,8 1,0
0
50
100
150
200
Ti1H
V
ad
(c
m
3 /g
)
P/Po
Ti1
a
0,0 0,2 0,4 0,6 0,8 1,0
0
50
100
150
200
Ti4
V
ad
(c
m
3 /g
)
P/Po
Ti4H
c
1 10 100
0,0
0,5
1,0
1,5
2,0
2,5
Ti4H
dV
/d
lo
g(
D
)
D (nm)
Ti4
d
Fig. 2 N2 adsorption/desorption isotherms and pore size distribution (obtained by the NLDFT me
thod) of meso-nc-TiO2 samples: Ti1 and Ti1H (a, b), Ti4 and Ti4H (c, d).
95https://ucj.org.ua
N. I. Ermokhina, V.V. Shvalagin, G. V. Korzhak, V. N. Grebennikov, N. I. Romanovska, A. V. Shulzshenko, М. М. Shcherbatyuk, D. O. Klymchuk, P. A. Manorik UCJ № 12 / Vol. 89
The addition of lanthanum salt contributes
to an increase in the content of anatase and a
decrease in the content of brookite regardless
of the use of HTT of the samples (samples Ti1,
Ti1H and Ti3, Ti3H), while without the use of
HTT the content of rutile decreases (samples
Ti1 and Ti3), and when using HTT (samples
Ti1H and Ti3H) increases. In the case of the
samples obtained with the simultaneous pre
sence of DDMEABr and lanthanum salts (Ti1,
Ti1H and Ti5, Ti5H, T6H) in the ZGRM, a
three-fold increase in the content of anatase
is observed against the background of a sharp
drop in the content of brookite and the com-
plete disappearance of the rutile phase. The
phase composition of the samples undergoes
especially profound changes when using HTT
(samples Ti1H and Ti5H), as a result of which
the three-phase composition is transformed
into a single-phase anatase (Fig. 1, Table 2).
Dilution of the original ZGRM in the pre
sence of lanthanum salt additive (samples Ti3,
Ti3H and Ti4, Ti4H) causes a two-fold increase
in the amount of anatase with a simultaneous
decrease in the content of brookite and rutile
phases. So, for example, sample Ti3 consists of
anatase (55%), rutile (21%) and brookite (24%),
and the corresponding sample Ti4 consists of
anatase (97%) and rutile (3%). Increasing the
concentration of reagents in ZGRM contain-
ing DDMEABr additives and lanthanum salts
(samples Ti5H, Ti6H, and Ti7H) makes it
possible to obtain one-, two-, and three-phase
compositions of TiO2 (Fig. 1, Table 2). An in-
crease in the concentration of Н2О and НС1
in the ZGRM in the case of sample Ti7H sig-
nificantly affects the phase composition of this
sample in comparison with samples Ti5Н and
Ti6Н. The mode of heat treatment obviously
in all cases significantly affects the phase com-
position of meso-nc-TiO2 (samples Ti1 and
Ti1H, Ti2 and Ti2H, Ti3 and Ti3H, Ti4 and
Ti4H, Ti5 and Ti5H). So, for example, sample
Ti1, which was subjected only to calcination, is
a composition of anatase (29%), rutile (39%)
and brookite (32%), and sample Ti1H (which
was previously subjected to HTT before an-
nealing) contains anatase (34%), respectively ),
rutile (14%) and brookite (52%). It should be
noted that among all the meso-nc-TiO2 sam-
ples, the Ti1H sample (obtained without addi-
tives) contains the largest amount of brookite.
The presence of a surfactant additive in
ZGRM (Table 2) leads to a slight increase in
the value of SBET. in the case of calcined sam-
ples Ti1 (39 m2/g) and Ti2 (48 m2/g). At the
same time, in the case of Ti1H (61 m2/g) and
Ti2H (33 m2/g) samples, which were previous-
ly subjected to HTT, on the contrary, there is
an almost two-fold decrease in the value of SBET.
However, the surfactant practically does not
affect the size of the diameter of the specified
pores pairs of samples. The introduction of the
lanthanum salt additive in the ZGRM provides
a significant increase in SBET. So, for example,
the value of SBET for sample Ti3 (89 m2/g) in-
creases by 2 times compared to Ti1 (39 m2/g),
which is probably due to an increase (doubled)
in the content of the anatase phase, the nano-
particles of which form mesopores.
When diluting ZGRM by ~1.5 times, the
specific surface area increases by the same
amount (samples Ti3, Ti3H and Ti4, Ti4H),
while the pore diameter decreases (samples
Ti3H and Ti4H), which may be associated with
the formation of these samples contain more
anatase with smaller crystallites. This assump-
tion is consistent with the results obtained for
the Ti5H sample (Table 2). This sample, which
contains the smallest crystallites among the
96 ISSN 2708-129X. Укр. хім. журн., 2023
THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY
IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE.PHISICAL CHEMISTRY
studied samples and consists of 100% anatase,
has the highest value of SBET (132 m2/g) and
volume Vpor (0.46 cm3/g) (Table 2). It should be
noted that this sample, like Ti5H, was obtained
with the simultaneous introduction of sur-
factant additives and La3+ ions into the ZGRM,
which leads to a drastic increase in Sp. of
meso-nc-TiO2 samples compared to the sam-
ples obtained only in the presence of surfactant
additives (Ti2 and Ti2H samples) or La3+ ions
(Ti3 and Ti3H samples). The reason for this
may be the dominance of the anatase phase in
Ti5 and Ti5H, the crystallite sizes of which are
the smallest among the studied samples (Ta-
ble 2). This assumption is consistent with the
results of a comparison of the textural charac-
teristics of the Ti5H sample with the T6H sam-
ple, which was obtained using higher concen-
trations of reagents in ZGRM than for Ti5H
(Table 1, Table 2). Thus, an increase in the
concentration of initial reagents in the ZGRM
leads to a one-and-a-half-fold decrease in SBET.,
a significant increase in Dp (~25%) with an
unchanged pore volume and a significant in-
crease in the average size of anatase crystallites
(from 7.0 to 9.1 nm).
A comparison of the textural characteristics
of samples Ti2 and Ti2H (obtained in the pre
sence of a surfactant additive), Ti3 and Ti3H,
Ti4 and Ti4H (obtained in the presence of a
lanthanum salt additive) shows that the pre-
vious HTT calcination leads to a decrease in
SBET (~20–30%) and a significant increase in
Dp (~20-80%). A significant change in the
pore volume (an increase of almost 1.5 times)
occurs only in the case of the Ti3H sample. In
the case of Ti5 and Ti5H samples (obtained
with the simultaneous presence of La3+ ions
and surfactant additives), on the contrary, the
Ti5H sample, which underwent hydrothermal
treatment before calcination, compared to the
simply calcined Ti5 sample, shows an increase
in SBET (~35%) with a simultaneous increase of
~ 2.5 times Vtot and 2 times Dp, probably due
to an increase in the content of anatase and a
decrease in the size of crystallites.
In Fig. 3(b, d, e, h) shows examples of SEM
images of meso-nc-TiO2 microphase samples,
which were obtained in the presence of HCl.
As can be seen, there are no microspheres in
samples Ti1 and Ti1H, Ti2 and Ti2H obtained
with and without HTT. Obviously, hydro-
chloric acid prevents the formation of micro-
spheres. All meso-nc-TiO2 samples obtained
in an acidic environment are amorphous ag-
gregates of various sizes from 100 to 500 nm.
During ultrasonic treatment of samples, these
aggregates disintegrate into uniform nanosized
secondary particles (40–100 nm) of spherical
or spheroidal shape.
According to the results of TEM data (Fig. 3
(a, c, d, g) and Fig. 4(a - g)), all samples of me-
so-nc-TiO2, with the exception of sample T7H
(Fig. 4g), have homogeneous, spherical forms
of primary particles (anatase phase). The sizes
of anatase crystallites in the samples slightly
exceed the corresponding values calculated ac-
cording to Scherrer's formula (Table 2). Samples
Ti1, Ti1H (Fig. 3(a, c)) and samples Ti2, Ti2H,
Ti3, Ti3H (Fig. 4(a – d)), in which the percen
tage content of rutile and brookite phases is
the highest, demonstrate the presence of crys-
tallites in the form of various according to the
size of plates having the shape of hexagons and
quadrilaterals. Samples Ti1 and Ti1H contain
the largest number of such particles, and the
number of hexagons dominates (Fig. 3(a, c)).
For samples Ti1 and Ti1H, the average sizes
of hexagons are 80x30 nm, 110x50 nm, and
85x35 nm, 110x40 nm, and the average sizes of
97https://ucj.org.ua
N. I. Ermokhina, V.V. Shvalagin, G. V. Korzhak, V. N. Grebennikov, N. I. Romanovska, A. V. Shulzshenko, М. М. Shcherbatyuk, D. O. Klymchuk, P. A. Manorik UCJ № 12 / Vol. 89
quadrilaterals are 70x40 nm, 50x50 nm, and
80x60. In the Ti2 and Ti2H samples (Fig. 4(a,
b)), on the contrary, square-shaped particles
with an average size of 50x40 nm and 65x45 nm
dominate, and the average size of hexagons is
100x45 nm and 90x50 nm. Ti3 and Ti3H sam-
ples (Fig. 4(c, d)) are significantly inferior in
the number and size of hexagons (average size
75x30 nm and 80x25 nm), and tetragons (ave
rage size 60x35 nm) are present in small quan-
tities only in the Ti3H sample. Samples Ti4 and
Ti4H (Fig. 3(d, g)) have the smallest hexagons
(50x20 nm and 65x30 nm). Samples Ti5, Ti5H,
and T6H, which do not contain the rutile phase
(Fig. 4(d - g)), consist only of spherical parti-
cles. The Ti7H sample (Fig. 4h) with a close
content of three phases (Table 2) differs from
other samples by the indistinct shapes of dis-
torted particles, both spherical and polygonal
in shape.
10
4(d - g)), consist only of spherical particles. The Ti7H sample (Fig. 4h) with a close content of three
phases (Table 2) differs from other samples by the indistinct shapes of distorted particles, both
spherical and polygonal in shape.
TEM SEM
Fig. 3 TEM and SEM images of meso-nc-TiO2 samples: Ti1 (a, b), Ti1H (c, d – after ultrasonic treatment),
Ti4 (e, f), Ti4H (g, h – after ultrasonic treatment).
h g
f e
d c
b
б
а
Fig. 3 TEM and SEM images of me-
so-nc-TiO2 samples: Ti1 (a, b), Ti1H (c,
d – after ultrasonic treatment), Ti4 (e, f),
Ti4H (g, h – after ultrasonic treatment).
98 ISSN 2708-129X. Укр. хім. журн., 2023
THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY
IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE.PHISICAL CHEMISTRY
Fig. 4 TEM images of meso-nc-TiO2
samples: Ti2 (a), Ti2H (b), Ti3 (c), Ti3H
(d), Ti5 (e), Ti5H (f), Ti6H (g), Ti7H (h).
11
Fig. 4 TEM images of meso-nc-TiO2 samples: Ti2 (a), Ti2H (b), Ti3 (c), Ti3H (d), Ti5 (e), Ti5H (f), Ti6H
(g), Ti7H (h).
Thus, within the framework of one approach to sol-gel synthesis, a number of meso-nc-TiO2
samples with different phase composition (anatase - rutile - brookite) were obtained in the presence of
HCl in ZGRM. It is shown that small additions of surfactant and (or) lanthanum salts, HTT, as well as
the concentration of reagents in the ZGRM affect the phase composition and texture of meso-nc-TiO2
materials. This allows for a reliable comparative analysis of the obtained data on the photocatalytic
activity of TiO2 samples and to optimize the process of forming new photocatalysts with high activity.
b
d c
f e
g h
Thus, within the framework of one approach
to sol-gel synthesis, a number of meso-nc-TiO2
samples with different phase composition (ana-
tase - rutile - brookite) were obtained in the
presence of HCl in ZGRM. It is shown that
small additions of surfactant and (or) lantha-
num salts, HTT, as well as the concentration of
reagents in the ZGRM affect the phase compo-
sition and texture of meso-nc-TiO2 materials.
This allows for a reliable comparative analysis of
the obtained data on the photocatalytic activity
of TiO2 samples and to optimize the process of
forming new photocatalysts with high activity.
The photocatalytic activity of meso-nc-TiO2
samples of different phase composition (ana-
tase - rutile - brookite) was studied in the mod-
el reaction of photocatalytic release of H2 from
an aqueous-ethanol mixture.
Earlier [42], we showed that samples of
mesoporous TiO2 (anatase) modified with Ni,
99https://ucj.org.ua
N. I. Ermokhina, V.V. Shvalagin, G. V. Korzhak, V. N. Grebennikov, N. I. Romanovska, A. V. Shulzshenko, М. М. Shcherbatyuk, D. O. Klymchuk, P. A. Manorik UCJ № 12 / Vol. 89
Ag, and Cu nanoparticles exhibit photocataly
tic activity in the process of releasing H2 from
aqueous-ethanol mixtures. In these systems,
photochemically deposited metal nanopar
ticles are co-catalysts that accept photoge
nerated electrons in the TiO2 conduction zone
and accelerate their transfer to the H2O mole-
cule. It was established [42] that copper nano-
particles are the most active co-catalyst. At the
same time, the holes in the TiO2 valence band
are filled with the help of electron transfer
from ethanol molecules. Under similar con-
ditions, upon irradiation of the obtained me-
so-nc-TiO2 samples with different phase com-
position, a rapid photodeposition process of
copper nanoparticles occurs, which is visually
recorded as a change in the color of the TiO2
sample from white to dark brown. During the
entire measurement period, the rate of H2 re-
lease remains unchanged.
In Fig. 5a, as an example, kinetic depen
dences for samples Ti1H and Ti4H are given.
At the same time, the commercial photocata-
lyst Evonik P25 shows much lower photocata-
lytic activity. As can be seen from Table 2, the
rate of H2 release in the presence of Evonik P25
is almost 1.5 and 2.5 times lower than the in-
dicators of the above samples, respectively. The
photocatalytic activity of Evonik P25, which
consists of a mixture of nanocrystalline phases
of anatase (~70%) and rutile (~30%) and has
SBET = 50 m2/g and a particle size of 20-25 nm,
is associated [31] with the possibility of spatial
separation of photogenerated different charge
carriers between anatase and rutile nanocrys-
tals due to a small difference in the value of the
conduction band potential of these TiO2 phases.
Histograms and kinetic dependences pre-
sented in Fig. 5(a, b) show that most of the
meso-nc-TiO2 samples (Table 2) are signi
ficantly more active than Evonik P25 photo-
catalysts in the reaction of releasing H2 from
a aqueous-ethanol mixture Ti1, Ti3 and Ti5
are close in activity to sample P25, and Ti2H
and Ti2 samples are significantly inferior by 3
and 5 times, respectively. The first two places
in terms of photocatalytic activity are occupied
by hydrothermally treated samples Ti4H and
Ti7H. The highest activity in the case of sam-
ples Ti4H (1st place) and Ti4 (3rd place) can
obviously be explained by the synergistic effect
of anatase and rutile phases [12, 15], which is
due to the combination of these phases in the
mixed-phase compositions of Ti4H samples
(anatase (85%) – rutile (4%) – brookite (11%))
and Ti4 (anatase (97%) – rutile (3%)). More-
over, even 2% of rutile in the composition of
anatase – rutile causes an increase in the pho-
tocatalytic activity of such a photocatalyst [44].
A significant increase in the photocatalytic
activity of anatase compositions with a small
amount of rutile can be associated, as in the
case of Evonik P25, with a different position
of energy levels in anatase and rutile [12, 15,
31], which leads to a spatial separation of pho-
togenerated charges between the components
of the composition and accordingly, a decrease
in electron-hole recombination. In the case of
sample T7H (2nd place), high activity may be
a consequence of the influence of the concen-
tration conditions of the reagents used in the
synthesis of this sample. The effect of HTT on
increasing the photocatalytic activity of Ti1H-
Ti5H samples (compared to Ti1-Ti5) is possi-
bly a consequence of an increase in the size of
the pore diameter in the treated samples. All
samples, which are obtained in the presence
of La3+ ion additives, are ahead of sample P25
in terms of activity. The only exception is sam-
ple Ti1 (close in activity to P25). This may be
100 ISSN 2708-129X. Укр. хім. журн., 2023
THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY
IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE.PHISICAL CHEMISTRY
related to the large value of the diameter of the
pores of the sample Ti1 (14.5 nm). It is inte
resting to note the fact that the specific surface
area of the studied meso-nc-TiO2 samples and
their phase composition are not key factors af-
fecting their photocatalytic activity. For exam-
ple, samples Ti4 and Ti5H have the maximum
content of the anatase phase (97% and 100%, re-
spectively) and the maximum value of SBET (122
m2/g and 132 m2/g), and in the range of activity
they occupy only 3 and 5 places, respectively.
Mixed-phase Ti1 and Ti1H samples con-
sisting of anatase, rutile, brookite (Table 2) are
significantly inferior in terms of activity ob-
tained earlier [38] to samples of microspheres
(anatase) Ti(MS1), Ti(MS2) and Ti(MS1)H,
Ti(MS2)H, probably due to the fact that the
special morphology of the microspheres pro-
vides much more efficient absorption of light
quanta. The Ti(MS2)H sample outperforms
both the Ti5H sample consisting of 100% ana-
tase and all mixed-phase meso-nc-TiO2 sam-
ples obtained in the presence of HCl in terms
of photocatalytic activity (Table 2).
13
separation of photogenerated charges between the components of the composition and accordingly,
a decrease in electron-hole recombination. In the case of sample T7H (2nd place), high activity may
be a consequence of the influence of the concentration conditions of the reagents used in the synthesis
of this sample. The effect of HTT on increasing the photocatalytic activity of Ti1H-Ti5H samples
(compared to Ti1-Ti5) is possibly a consequence of an increase in the size of the pore diameter in the
treated samples. All samples, which are obtained in the presence of La3+ ion additives, are ahead of
sample P25 in terms of activity. The only exception is sample Ti1 (close in activity to P25). This may
be related to the large value of the diameter of the pores of the sample Ti1 (14.5 nm). It is interesting
to note the fact that the specific surface area of the studied meso-nc-TiO2 samples and their phase
composition are not key factors affecting their photocatalytic activity. For example, samples Ti4 and
Ti5H have the maximum content of the anatase phase (97% and 100%, respectively) and the
maximum value of SBET (122 m2/g and 132 m2/g), and in the range of activity they occupy only 3 and
5 places, respectively.
Mixed-phase Ti1 and Ti1H samples consisting of anatase, rutile, brookite (Table 2) are
significantly inferior in terms of activity obtained earlier [38] to samples of microspheres (anatase)
Ti(MS1), Ti(MS2) and Ti(MS1)H , Ti(MS2)H, probably due to the fact that the special morphology
of the microspheres provides much more efficient absorption of light quanta. The Ti(MS2)H sample
outperforms both the Ti5H sample consisting of 100% anatase and all mixed-phase meso-nc-TiO2
samples obtained in the presence of HCl in terms of photocatalytic activity (Table 2).
The results of a comparison of histograms for the processes of H2 release from an aqueous-
ethanol mixture (Fig. 5b) and gas-phase oxidation of ethanol [43] (Fig. 5c) in the presence of mixed-
phase meso-nc-TiO2 samples are interesting. According to the histograms, in the process of ethanol
oxidation, the most active samples Ti4, Ti4H, and Ti5H occupy 1, 2, and 3 places, and in the series of
activity for the process of H2 release, these samples occupy 3, 1, and 5 places, respectively. A similar
picture is observed when comparing the histograms of these processes using meso-nc-TiO2 (anatase)
samples with the morphology of microspheres and nanopowders containing La3+ as photocatalysts
[36-38].
0 20 40 60 80 100 120 140 160
0,0
2,0x10-5
4,0x10-5
6,0x10-5
8,0x10-5
P25
Ti1H
Ti4H
n
(H
2),
m
ol
t, min
a
14
Fig. 5 Kinetic dependencies of the photocatalytic hydrogen evolution from a aqueous-ethanol mixture in the
presence of samples: Ti1H, Ti4H and TiO2 Evonik P25 (a); rate of photocatalytic evolution H2 from a
aqueous-ethanol mixture (b) and the corresponding ethanol oxidation initial rates (c) [43] in the system with
the participation of the of meso-nc-TiO2 samples with different phase composition (anatase- rutile - brookite)
obtained under various conditions for the synthesis.
According to the results shown in Table 2, the PhA of all three-phase samples that underwent
preliminary HTT before calcination and differ significantly both in terms of textural characteristics
and crystallite sizes is higher than that of Evonik P25, with the exception of the sample. Based on this,
it can be assumed that all three phases (anatase, brookite and rutile) are responsible for the
manifestation of photocatalytic activity. This assumption is especially clearly confirmed when
comparing Ti4H and Ti5 samples, which are characterized by almost identical specific surface values
(respectively 96 and 98 g/m2) and have a close phase composition A/R/B (respectively 85/4/11 and
88/- /12). Here, the PhA of the Ti4H sample, which additionally contains 4% brookite, is 2.5 times
higher than the PhA of the two-phase Ti5 sample, which does not contain brookite. This is probably
due to the synergistic effect of three TiO2 phases, the energy of the valence band and the conduction
band of which are different, which contributes to the effective spatial separation of photogenerated
charge carriers and, as a result, to the growth of the photocatalytic activity of mixed-phase samples.
However, as can be seen from the results for Ti7H (Table 2), a significant increase in the content of
the rutile and brookite phases and a decrease in the content of the anatase phase in the three-phase
sample in comparison with, for example, the Ti4H sample leads to a decrease in the rate from 5.5 to
4.7 H2∙107 mol/min, probably due to a decrease in the content of the anatase phase, which is the main
source of photogenerated charge carriers. As can be seen from the results shown in Table 2, the three-
phase samples are more efficient photocatalysts than the two-phase samples.
CONCLUSIONS. It was established that the variation of the synthesis conditions, namely the
introduction of a small amount of dodecyldimethylethylammonium bromide (DDMEABr) and/or
lanthanum salt into ZGRM, containing dibenzo-18-crown-6 (DВ18С6) as a structure-directing
agent and titanium tetrabutoxide (HTT) as a source of titanium. Decreasing or increasing the
1 2 3 4 5 6 7 8 9 10 11 12 13
0,0
1,0
2,0
3,0
4,0
5,0
6,0
H
2
10
7 (м
ол
ь/
хв
.)
The number of the place of the sample among the activityі
Ti4H
Ti7H
Ti4
Ti1H Ti5H Ti3H Ti6H
Ti1
P25 Ti5
Ti3
Ti2H
Ti2
b Тi4
Тi4Н
Тi5НТi6Н
Тi5
Тi3 Тi3НТi7Н Тi2 Тi2Н
Тi1Н
Тi1
Р-25
Òi4
Тi4Н
Тi3 Тi3НТi7Н Тi2 Тi2Н
Тi1Н
Тi1
Р-25
1 2 3 4 5 6 7 8 9 10 11 12 13
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
R
(m
m
ol
/m
in
)
The number of the place of the sample among the activityі
c
14
Fig. 5 Kinetic dependencies of the photocatalytic hydrogen evolution from a aqueous-ethanol mixture in the
presence of samples: Ti1H, Ti4H and TiO2 Evonik P25 (a); rate of photocatalytic evolution H2 from a
aqueous-ethanol mixture (b) and the corresponding ethanol oxidation initial rates (c) [43] in the system with
the participation of the of meso-nc-TiO2 samples with different phase composition (anatase- rutile - brookite)
obtained under various conditions for the synthesis.
According to the results shown in Table 2, the PhA of all three-phase samples that underwent
preliminary HTT before calcination and differ significantly both in terms of textural characteristics
and crystallite sizes is higher than that of Evonik P25, with the exception of the sample. Based on this,
it can be assumed that all three phases (anatase, brookite and rutile) are responsible for the
manifestation of photocatalytic activity. This assumption is especially clearly confirmed when
comparing Ti4H and Ti5 samples, which are characterized by almost identical specific surface values
(respectively 96 and 98 g/m2) and have a close phase composition A/R/B (respectively 85/4/11 and
88/- /12). Here, the PhA of the Ti4H sample, which additionally contains 4% brookite, is 2.5 times
higher than the PhA of the two-phase Ti5 sample, which does not contain brookite. This is probably
due to the synergistic effect of three TiO2 phases, the energy of the valence band and the conduction
band of which are different, which contributes to the effective spatial separation of photogenerated
charge carriers and, as a result, to the growth of the photocatalytic activity of mixed-phase samples.
However, as can be seen from the results for Ti7H (Table 2), a significant increase in the content of
the rutile and brookite phases and a decrease in the content of the anatase phase in the three-phase
sample in comparison with, for example, the Ti4H sample leads to a decrease in the rate from 5.5 to
4.7 H2∙107 mol/min, probably due to a decrease in the content of the anatase phase, which is the main
source of photogenerated charge carriers. As can be seen from the results shown in Table 2, the three-
phase samples are more efficient photocatalysts than the two-phase samples.
CONCLUSIONS. It was established that the variation of the synthesis conditions, namely the
introduction of a small amount of dodecyldimethylethylammonium bromide (DDMEABr) and/or
lanthanum salt into ZGRM, containing dibenzo-18-crown-6 (DВ18С6) as a structure-directing
agent and titanium tetrabutoxide (HTT) as a source of titanium. Decreasing or increasing the
1 2 3 4 5 6 7 8 9 10 11 12 13
0,0
1,0
2,0
3,0
4,0
5,0
6,0
H
2
10
7 (м
ол
ь/
хв
.)
The number of the place of the sample among the activityі
Ti4H
Ti7H
Ti4
Ti1H Ti5H Ti3H Ti6H
Ti1
P25 Ti5
Ti3
Ti2H
Ti2
b Тi4
Тi4Н
Тi5НТi6Н
Тi5
Тi3 Тi3НТi7Н Тi2 Тi2Н
Тi1Н
Тi1
Р-25
Òi4
Тi4Н
Тi3 Тi3НТi7Н Тi2 Тi2Н
Тi1Н
Тi1
Р-25
1 2 3 4 5 6 7 8 9 10 11 12 13
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
R
(m
m
ol
/m
in
)
The number of the place of the sample among the activityі
c
Fig. 5 Kinetic dependencies of the
photocatalytic hydrogen evolution
from a aqueous-ethanol mixture in
the presence of samples: Ti1H, Ti4H
and TiO2 Evonik P25 (a); rate of pho-
tocatalytic evolution H2 from a aque-
ous-ethanol mixture (b) and the cor-
responding ethanol oxidation initial
rates (c) [43] in the system with the
participation of the of meso-nc-TiO2
samples with different phase compo-
sition (anatase- rutile - brookite) ob-
tained under various conditions for
the synthesis.
101https://ucj.org.ua
N. I. Ermokhina, V.V. Shvalagin, G. V. Korzhak, V. N. Grebennikov, N. I. Romanovska, A. V. Shulzshenko, М. М. Shcherbatyuk, D. O. Klymchuk, P. A. Manorik UCJ № 12 / Vol. 89
The results of a comparison of histograms
for the processes of H2 release from an aque-
ous-ethanol mixture (Fig. 5b) and gas-phase
oxidation of ethanol [43] (Fig. 5c) in the pre
sence of mixed-phase meso-nc-TiO2 samples
are interesting. According to the histograms, in
the process of ethanol oxidation, the most ac-
tive samples Ti4, Ti4H, and Ti5H occupy 1, 2,
and 3 places, and in the series of activity for the
process of H2 release, these samples occupy 3,
1, and 5 places, respectively. A similar picture
is observed when comparing the histograms of
these processes using meso-nc-TiO2 (anatase)
samples with the morphology of microspheres
and nanopowders containing La3+ as photoca
talysts [36-38].
According to the results shown in Table 2,
the PhA of all three-phase samples that under-
went preliminary HTT before calcination and
differ significantly both in terms of textural
characteristics and crystallite sizes is higher
than that of Evonik P25, with the exception of
the sample. Based on this, it can be assumed
that all three phases (anatase, brookite and
rutile) are responsible for the manifestation
of photocatalytic activity. This assumption is
especially clearly confirmed when comparing
Ti4H and Ti5 samples, which are characte
rized by almost identical specific surface va
lues (respectively 96 and 98 g/m2) and have a
close phase composition A/R/B (respectively
85/4/11 and 88/- /12). Here, the PhA of the
Ti4H sample, which additionally contains 4%
brookite, is 2.5 times higher than the PhA of
the two-phase Ti5 sample, which does not con-
tain brookite. This is probably due to the sy
nergistic effect of three TiO2 phases, the energy
of the valence band and the conduction band
of which are different, which contributes to the
effective spatial separation of photogenerated
charge carriers and, as a result, to the growth of
the photocatalytic activity of mixed-phase sam-
ples. However, as can be seen from the results
for Ti7H (Table 2), a significant increase in the
content of the rutile and brookite phases and a
decrease in the content of the anatase phase in
the three-phase sample in comparison with, for
example, the Ti4H sample leads to a decrease
in the rate from 5.5 to 4.7 H2∙107 mol/min,
probably due to a decrease in the content of
the anatase phase, which is the main source of
photogenerated charge carriers. As can be seen
from the results shown in Table 2, the three-
phase samples are more efficient photocata-
lysts than the two-phase samples.
CONCLUSIONS. It was established that the
variation of the synthesis conditions, namely
the introduction of a small amount of dode-
cyldimethylethylammonium bromide (DD-
MEABr) and/or lanthanum salt into ZGRM,
containing dibenzo-18-crown-6 (DВ18С6) as
a structure-directing agent and titanium tetra
butoxide (HTT) as a source of titanium. De-
creasing or increasing the concentrations of the
main reagents in the ZGRM, using HTT before
calcining the samples has a significant effect on
the phase composition and texture of the sam-
ples when standard heat treatment conditions
are used (HTT at 175°C for 24 hours and an-
nealing in air at 500 °C for 4 hours). This makes
it possible to vary within fairly wide limits both
the qualitative and quantitative composition of
mixed-phase samples, their textural characte
ristics and photocatalytic activity.
It is shown that the use of HTT before calci-
nation of samples significantly increases their
photocatalytic activity in the reaction of pho-
tocatalytic release of hydrogen from an aque-
ous-ethanol mixture due to changes in their
phase composition. In general, the obtained
102 ISSN 2708-129X. Укр. хім. журн., 2023
THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY
IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE.PHISICAL CHEMISTRY
three-phase meso-nc-TiO2 samples are more
effective photocatalysts than the two-phase
samples. The PhA of all three-phase samples
that underwent preliminary HTT before cal-
cination and differ significantly both in terms
of textural characteristics and crystallite sizes
is higher than that of Evonik P25. Probably, all
three phases (anatase, brookite and rutile) are
responsible for the final value of photocatalytic
activity due to the manifestation of the syner-
gistic effect of three TiO2 phases, the energy
of the valence band and conduction band of
which are different, which contributes to the
effective spatial separation of photogenerated
charge carriers and, as a result, the growth of
photocatalytic activity mixed-phase samples.
However, a significant increase in the content
of the rutile and brookite phases and, accord-
ingly, a decrease in the content of the anatase
phase in the three-phase sample leads to a de-
crease in PhA, probably due to a decrease in
the content of the anatase phase, which is the
main source of photogenerated charge carriers.
The three-phase anatase (85%) rutile (4%) –
brookite (11%) sample shows the highest pho-
tocatalytic activity among the studied samples,
the PhA of which in the reaction of photocata-
lytic release of hydrogen from a aqueous-etha-
nol mixture exceeds the activity of the Evonik
P25 sample by 2.5 times.
It was established that the use of HTT before
calcination of the samples significantly increas-
es their photocatalytic activity in the reaction
of photocatalytic release of hydrogen from the
aqueous-ethanol mixture mainly due to chang-
es in their phase composition. At the same time,
it is shown that the size of the specific surface
of the sample is not the dominant factor affect-
ing the photocatalytic activity of the obtained
mixed-phase meso-nc-TiO2 samples.
ACKNOWLEDGEMENT. The work
was carried out within the framework
of the state budget topic: "Composites
based on doped TiO2 nanostructures
and coordination polymers: synthesis,
phase composition, morphology and
functional properties (state registra-
tion number: 0120U102376
ВПЛИВ ФАЗОВОГО СКЛАДУ ЗМІШАНО-
ФАЗОВОГО МЕЗОПОРИСТОГО TiO2 НА ЙОГО
ФОТОКАТАЛІТИЧНУ АКТИВНІСТЬ У РЕАКЦІЇ
ВИДІЛЕННЯ ВОДНЮ З ВОДНО-ЕТАНОЛЬНОЇ
СУМІШІ
Н. І. Єрмохіна1, В. В. Швалагін1,
Г. В. Коржак1, В. М. Гребенніков1*,
Н. І. Романовська1, О. В. Шульженко1,
М. М. Щербатюк2, Д. О. Климчук2,
П. А. Манорик1
1Інститут фізичної хімії ім. Л. В. Писар-
жевського НАН України;
просп. Науки, 31, Київ 03028, Україна
2Інститут ботаніки ім. М. Г. Холодного
НАН України;
вул. Терещенківська, 2, Київ 01601, Україна
*e-mail:_vng@ukr.net
Дво- і трифазові композиції мезопо-
ристого нанокристалічного TiO2 (meso-
nc-TiO2) було отримано із золь-гель-реак-
ційних сумішей (ЗГРС) із використанням
дибензо-18-краун-6 (DВ18С6) як структу-
роспрямовуючого агента і тетрабутокси-
ду титану (ТВОТ) як джерела титану за
присутності HCl із (або без) подальшим
гідротермальним обробленням (ГТО) і
103https://ucj.org.ua
N. I. Ermokhina, V.V. Shvalagin, G. V. Korzhak, V. N. Grebennikov, N. I. Romanovska, A. V. Shulzshenko, М. М. Shcherbatyuk, D. O. Klymchuk, P. A. Manorik UCJ № 12 / Vol. 89
прожарюванням за 500 оС. Показано, що
добавляння невеликої кількості додецил-
диметилетиламонію броміду (DDMEABr)
та/або солі лантану в ЗГРС, а також ГТО
справляють істотний вплив на фазовий
склад та текстуру зразків. Встановлено, що
використання ГТО перед кальцинуванням
зразків суттєво підвищує їхню фотоката-
літичну активність (ФА) в реакції фотока-
талітичного виділення водню з водно-ета-
нольної суміші головним чином завдяки
змінам їхнього фазового складу. Найбільшу
фотокаталітичну активність виявляє гідро
термально оброблений зразок фазового
складу анатаз (85%)/рутил (4%)/ брукіт
(11%), яка у 2,5 рази перевищує відповідну
характеристику для комерційного фотока-
талізатора Evonik P25. Показано, що вели-
чина питомої поверхні зразка не є доміную-
чим фактором впливу на фотокаталітичну
активність одержаних змішано-фазових
зразків meso-nc-TiO2 в процесі виділення
водню з водно-етанольної суміші.
Ключові слова: золь-гель-синтез, мезо-
пористий TiO2 анатаз-рутил-брукіт-компо-
зиції, виділення Н2.
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Cтаття надійшла 15.12.2023.
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| id | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-626 |
| institution | Ukrainian Chemistry Journal |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-23T01:11:09Z |
| publishDate | 2024 |
| publisher | V.I.Vernadsky Institute of General and Inorganic Chemistry |
| record_format | ojs |
| resource_txt_mv | ucjorgua/7d/3a4498a99c58ea3b6d6c58c4280f837d.pdf |
| spelling | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-6262026-07-22T08:23:53Z THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE Ermokhina, Natalia Shvalagin, Vitalii Korzhak, Anna Grebennikov, Volodymyr Romanovska, Natalia Shulzshenko , Alexander Shcherbatyuk , Mykola Klymchuk , Dmytro Manoryk , Petro sol-gel synthesis, mesoporous TiO2anatase-rutile-brookite compositions, H2 release. Two- and three-phase compositions of mesoporous nanocrystalline TiO2 (meso-nc-TiO2) were obtained from sol-gel reaction mixtures (ZGRM) using dibenzo-18-crown-6 (DВ18С6) as a structure-directing agent and titanium tetrabutoxide (TBOT) as a source of titanium in the presence of HCl with (or without) subsequent hydrothermal treatment (HTT) and calcination at 500 oC. It has been shown that the addition of a small amount of dodecyldimethylethylammonium bromide (DDMEABr) and/or lanthanum salts in ZGRM, as well as HTT, has a significant effect on the phase composition and texture of the samples. It was established that the use of HTT before calcination of samples significantly increases their photocatalytic activity (PhA) in the reaction of photocatalytic hydrogen release from an aqueous-ethanol mixture mainly due to changes in their phase composition. The hydrothermally treated sample of the anatase (85%)/rutile (4%)/brookite (11%) phase composition shows the highest photocatalytic activity, which is 2.5 times higher than the corresponding characteristic for the commercial Evonik P25 photocatalyst. It is shown that the size of the specific surface area of the sample is not the dominant factor influencing the photocatalytic activity of the obtained mixed-phase meso-nc-TiO2 samples in the process of hydrogen release from the aqueous-ethanol mixture. V.I.Vernadsky Institute of General and Inorganic Chemistry 2024-01-26 Article Article Physical chemistry Физическая xимия Фізична xімія application/pdf https://ucj.org.ua/index.php/journal/article/view/626 10.33609/2708-129X.89.12.2023.88-109 Ukrainian Chemistry Journal; Vol. 89 No. 12 (2023): Ukrainian Chemistry Journal; 88-109 Украинский химический журнал; ##issue.vol## 89 ##issue.no## 12 (2023): Ukrainian Chemistry Journal; 88-109 Український хімічний журнал; Том 89 № 12 (2023): Ukrainian Chemistry Journal; 88-109 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/626/312 Copyright (c) 2024 Natalia Ermokhina, Vitalii Shvalagin, Anna Korzhak, Volodymyr Grebennikov, Natalia Romanovska, Alexander Shulzshenko , Mykola Shcherbatyuk , Dmytro Klymchuk , Petro Manoryk https://creativecommons.org/licenses/by-nc/4.0 |
| spellingShingle | Ermokhina, Natalia Shvalagin, Vitalii Korzhak, Anna Grebennikov, Volodymyr Romanovska, Natalia Shulzshenko , Alexander Shcherbatyuk , Mykola Klymchuk , Dmytro Manoryk , Petro THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE |
| title | THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE |
| title_full | THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE |
| title_fullStr | THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE |
| title_full_unstemmed | THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE |
| title_short | THE INFLUENCE OF THE PHASE COMPOSITION OF MIXED-PHASE MESOPOROUS TiO2 ON ITS PHOTOCATALYTIC ACTIVITY IN THE REACTION OF HYDROGEN EVOLUTION FROM AN AQUEOUS-ETHANOL MIXTURE |
| title_sort | influence of the phase composition of mixed-phase mesoporous tio2 on its photocatalytic activity in the reaction of hydrogen evolution from an aqueous-ethanol mixture |
| topic_facet | sol-gel synthesis mesoporous TiO2anatase-rutile-brookite compositions H2 release. |
| url | https://ucj.org.ua/index.php/journal/article/view/626 |
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