Solvothermal fusion of Ag- and N-doped LiTaO3 perovskite nanospheres for improved photocatalytic hydrogen production

Article abstract of DOI:10.1002/aoc.6207

Tantalate semiconductor photocatalyst has received significant attention as an alternative promising material to mitigate the globally increasing energy demand with the course of action of the produced hydrogen. In this report, an efficient enhancement in the hydrogen production under ultraviolet (UV) light by Ag- and N-doped LiTaO₃ via solvothermal strategy is proposed. The structural appearance and the spherical morphology are affirmed from the X-ray diffraction and field emission scanning electron microscopy (FESEM) analysis. The bandgap of the prepared photocatalysts is calculated as 5.12, 4.92, and 4.82 eV for undoped LiTaO₃, Ag, and N-doped LiTaO₃ nanoparticles using Tauc's plot. Moreover, the band position of the synthesized LiTaO₃ and also with its dopants is calculated by the Mulliken electro negativity method. The elemental composition of the synthesized photocatalyst is confirmed from the energy dispersive analysis (EDS). Photocatalytic water splitting results over Ag- and N-doped LiTaO₃ photocatalyst showed that the rate of H₂ evolution from formic acid aqueous solution was 240 and 123 μmolh^?1 with an apparent quantum yield of 3.11% and 1.59%, whereas for undoped LiTaO₃, the rate is quite lower to be 71 μmolh^?1. The reason behind the high catalytic activity of Ag-doped LiTaO₃ is explained by the fact that the higher electronegativity of Ag (1.93) as compared with Ta (1.5) resulted in quite transfer of photoexcited electrons from the conduction band of LiTaO₃ to the Ag species. Interestingly, up to the best of our knowledge, this is the first study regarding the photocatalytic hydrogen evolution for Ag- and N-doped LiTaO₃.

Full text of DOI:10.1002/aoc.6207

Received: 8 November 2020
DOI: 10.1002/aoc.6207
Revised: 23 January 2021
Accepted: 1 February 2021
F U L L P A P E R
Solvothermal fusion of Ag- and N-doped LiTaO perovskite
3
nanospheres for improved photocatalytic hydrogen
production
1
1
2
3
C.R. Kalaiselvi
| T.S. Senthil
| M.V. Shankar
| V. Sasirekha
1
Department of Physics, Erode
Sengunthar Engineering College,
Perundurai, India
Tantalate semiconductor photocatalyst has received significant attention as an
alternative promising material to mitigate the globally increasing energy
demand with the course of action of the produced hydrogen. In this report, an
efficient enhancement in the hydrogen production under ultraviolet (UV) light
2
Nanocatalysis and Solar Fuels Research
Laboratory, Department of Materials
Science and Nanotechnology, Yogi
Vemana University, Kadapa, India
by Ag- and N-doped LiTaO via solvothermal strategy is proposed. The struc-
3
3
Department of Physics, Avinashilingam
tural appearance and the spherical morphology are affirmed from the X-ray
diffraction and field emission scanning electron microscopy (FESEM) analysis.
The bandgap of the prepared photocatalysts is calculated as 5.12, 4.92, and
University, Coimbatore, India
Correspondence
T.S. Senthil, Department of Physics, Erode
Sengunthar Engineering College,
Perundurai 638057 Tamil Nadu, India.
Email: tssenthi@esec.ac.in
4
.82 eV for undoped LiTaO , Ag, and N-doped LiTaO nanoparticles using
3
3
Tauc's plot. Moreover, the band position of the synthesized LiTaO and also
3
with its dopants is calculated by the Mulliken electro negativity method. The
elemental composition of the synthesized photocatalyst is confirmed from the
energy dispersive analysis (EDS). Photocatalytic water splitting results over
Ag- and N-doped LiTaO photocatalyst showed that the rate of H evolution
3
2
from formic acid aqueous solution was 240 and 123 μmolh− with an apparent
1
quantum yield of 3.11% and 1.59%, whereas for undoped LiTaO , the rate is
3
−
1
quite lower to be 71 μmolh . The reason behind the high catalytic activity of
Ag-doped LiTaO is explained by the fact that the higher electronegativity of
3
Ag (1.93) as compared with Ta (1.5) resulted in quite transfer of photoexcited
electrons from the conduction band of LiTaO to the Ag species. Interestingly,
3
up to the best of our knowledge, this is the first study regarding the photo-
catalytic hydrogen evolution for Ag- and N-doped LiTaO3.
K E Y W O R D S
hydrogen production, perovskite, photocatalysis, spherical morphology
1
| INTRODUCTION
combustion reaction of it produces only water. Moreover,
it is the cheapest water splitting system and suitable to
have for large scale applications for H2 evolution.
Hence, hydrogen production by the way of photocatalytic
water splitting is the best choice. In this perspective, an
effort has been made for search in materials that are eco-
friendly and stable, and also it should afford for energy
[1]
The energy crisis has become one of the major concerns
in the 21st century owing to the fast development of the
global economy and population. Hydrogen, a most prom-
inent energy carrier, has laid for environment friendly
solution by photocatalytic water splitting because the
Appl Organomet Chem. 2021;35:e6207.
wileyonlinelibrary.com/journal/aoc
© 2021 John Wiley & Sons, Ltd.
1 of 9
https://doi.org/10.1002/aoc.6207

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KALAISELVI ET AL.
[
13]
insight in the future. In the family of lead-free perovskite
oxides such as titanates, tantalates, niobates, vanadates,
and ferrites, tantalates and niobates are being explored as
a captivating material with versatile properties for vari-
ous applications such as dielectrics, ferroelectrics, and
electro-optic waveguides and photocatalyst for water
activity for H evolution than LiTaO . Edalati et al.
2 3
measured the enhanced hydrogen evolution on CsTaO3
and LiTaO when they are subjected to severe plastic
strain using the high-pressure torsion (HPT) method.
3
[
14]
Zhou et al.
reported that LiTaO possessed the highest
3
photocatalytic ability on tree trunk derived alkali
tantalates. The authors also affirmed that the high photo-
catalytic performance of LiTaO3 is due to its higher
splitting to produce H or treatment of effluents in
2
[2,3]
water.
Moreover, inorganic semiconductors are found
to be a substitute because it had feasibility in the synthe-
reduction potential, which is more favorable for CO pho-
2
[4]
sis process, and also the production cost is low. Alkali
tantalate perovskites like LiTaO , NaTaO , and KTaO
3
toreduction despite its larger bandgap. A comparative
analysis is made with nobel metal free 1-D CdS core–
shell structure-based photocatalyst with its distinct
properties such as narrow bandgap, suitable band edge
position, and having admirable charge transfer finds its
application in photocatalytic hydrogen production with
3
3
have accepted significant consideration as they can disin-
tegrate water as H and O without the need of any
2
2
cocatalyst, whereas the water splitting process in TiO2
[5]
usually needs a cocatalyst such as Pt. In the titanates
−
1
group, for example, in the case of ZnTiO doped with Ag,
the rate of evolution of 7.6 μmolh with lactic acid as a
3
[
15–18]
nanoparticles played its dual aspect in the photocatalytic
dye degradation and also investigated for its antibacterial
sacrificial agent.
Tantalate photocatalysts are synthesized by numerous
methods such as a solid state reaction, sol–gel, and
hydrothermal method. Of all the methods, hydrothermal
synthesis is considered as a promising wet chemical pro-
cess as it generates output in a highly crystalline nature
with high purity and low aggregation. Moreover, it regu-
lates the morphology and crystalline structure of the final
[6]
activity.
Among photocatalytically active semiconductors, tan-
talate perovskites have been widely explored because
their electronic band structure fulfills the requirements
for water splitting, as it consists of three dimensional
framework consisting of TaO octahedra with their bot-
6
tom level of conduction bands consisting of Ta 5d located
products by adjusting the hydrothermal reaction condi-
+
[19]
at a more negative state of redox potential of H /H than
tions.
Hence, in the present work, we address the
2
[
7]
TiO (Ti 3d), the most prevalent material in this field.
simple solvothermal route for the synthesis of LiTaO3
perovskite for photocatalytic hydrogen evolution. More-
over, to enrich further, the discussion is being made on
the doping of Ag cations and N anions in to and also its
photocatalytic water splitting for the hydrogen produc-
tion was evaluated. This is the first report regarding the
2
Despite its significant advantage for water splitting with-
out cocatalyst, their main demerit is with its high
bandgap as 4.7 eV for LiTaO , 4.0 eV for NaTaO , and
3
3
3
.6 eV for KTaO , which reduces their photocatalytic
3
[8]
activity.
Therefore, the bandgap can be effectively
reduced with the addition of suitable dopants. Further-
more, the hydrogen generated by this process can be
directly used as a fuel in hydrogen fuel cells.
addition of dopants to LiTaO perovskite for the hydro-
gen evolution.
3
Among alkali tantalates, lithium tantalate (LiTaO ) is
3
one of the most admirable photocatalyst materials owing
to its impressive physical properties such as its piezoelec-
tric, pyroelectric, electro-optic, and photo-refractive
2 | EXPERIMENTAL DETAILS
2.1 | Preparation of LiTaO3
nanoparticles
[9]
properties.
It also spreads its wings for extensive
applications as an ultra-fast switchers, multiplexors
and demultiplexors, optical amplifiers, or waveguide
High analytical grade tantalum pentoxide and lithium
carbonate are used as a precursor for synthesizing lith-
[10]
lasers.
It is also being investigated as an effective
photocatalyst involved in the reaction process of
photocatalytic hydrogen evolution. Kato and Kudo
ium tantalate perovskite (LiTaO ). In this process, 0.13 M
3
[
11]
of Ta O is dispersed in 30-ml double distilled water and
2
5
described the photocatalytic water splitting ability into
H and O over the alkali tantalates (LiTaO , NaTaO ,
30-ml ethylene glycol under magnetic stirring. Then
1.62 M of Li CO is added into the Ta O suspension and
2
2
3
3
2
3
2 5
and KTaO ) processed by the conventional solid-state
method and also investigated the various factors affecting
the photocatalytic activities of various tantalates based on
again stirred well to attain a homogeneous solution. The
desired solution is then transferred into a Teflon-lined
stainless steel autoclave that is filled with the mixture to
nearly 80% of the total volume. The autoclave is kept at
200 C for a designed period of 15 h. The obtained precipi-
tate is centrifuged and washed three times with double
3
their crystal and energy structure. Photocatalytic H pro-
2
ꢀ
duction of La-doped alkali tantalate was studied by Fu
[12]
et al.,
and they reported that NaTaO exhibited higher
3

KALAISELVI ET AL.
3 of 9
distilled water and once with ethanol thoroughly in order
to remove impurities. Subsequently, the products are
ꢀ
dried at 120 C. Then it is grounded well to obtain a
perovskite structured LiTaO3 photocatalyst. The sche-
matic representation of the preparation of LiTaO is pres-
3
ented in Figure S1.
The above same procedure has to be followed with
the addition of 0.43 wt% of silver nitrate and 0.025 wt%
urea as a nitrogen source for anion doping into the
solution containing Ta O5 and Li CO3 such that we
2
2
have the incorporation of Ag and N into LiTaO3
nanoparticle. Then the synthesized perovskite photo-
catalysts are undergone for various characterization
techniques and also for photocatalytic H2 evolution
measurements.
The structural property of the photocatalyst is ana-
lyzed with X-ray diffractometer (XPERT-PRO PW3050)
adopting a Cu Kα radiation. The surface morphology is
learned through field emission scanning electron micro-
scope (FESEM, Zeiss supra 55Ve),s and the composition
of elements present in the sample is done by energy dis-
persive X-ray analysis (EDS). The optical properties of
the prepared photocatalyst are examined from the ultra-
violet (UV)–visible absorbance spectra recorded using a
spectrophotometer (JASCO V-570) in the range of
FIGURE 1 Powder X-ray diffraction (PXRD) pattern for
a) undoped LiTaO , (b) Ag-doped LiTaO , and (c) N-doped LiTaO
nanoparticles
(
3
3
3
2
00–800 nm. Photocatalytic hydrogen evolution measure-
ments are carried out using Shimadzu (GC-2014) gas
chromatograph equipped with a thermal conductivity
detector (TCD).
From the XRD pattern, it is inferred that only the inten-
sity of the peak slightly varies with the addition of Ag
and N dopants.
The crystallite size (D) of the particle is calculated
3
| RESULTS AND DISCUSSION
using Debye–Scherrer relation D = kλ/β cosθ, where λ is
ꢀ
the X-ray wavelength (1.54 A ), θ is the diffraction angle,
The crystalline structure of the LiTaO photocatalysts is
identified by X-ray diffraction (XRD) pattern as shown in
the Figure 1. It is confirmed that for our sample, the
β is the full width at half maximum (FWHM), and k is a
constant equal to 0.94. The average crystallite size is
found to be 8.18, 7.92, and 6.2 nm for undoped LiTaO3,
Ag-, and N-doped LiTaO3 nanoparticles, respectively.
Hence, we inferred that Ag- and N-doped LiTaO3
nanoparticles exhibited a smaller grain size than the
3
rhombohedral phase of LiTaO nanoparticle is attained,
3
which is in good agreement with the standard data
(
JCPDS Card No: 29-0836), and the lattice constants are
ꢀ
ꢀ
[20]
found to be a = 5.153 A and c = 13.755 A .
characteristic reflection peaks found at 2θ are 23.4 ,
3
5
The
ꢀ
undoped LiTaO , which accounts for high photocatalytic
3
activity.
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
2.03 , 34.31 , 37.25 , 40.13 , 44.54 , 46.50 , 46.68 ,
The morphology of the synthesized LiTaO and also
3
ꢀ
ꢀ
0.15 , 55.54 , 63.58 , and 71.02 , which are indexed as
with its dopants is examined by FESEM as shown in the
Figure 2a–c. It is examined that the undoped LiTaO3
nanoparticles exhibited a spherical morphology, and no
significant change in the morphology is noted in the case
(
(
012), (104), (110), (006), (113), (330), (024), (002), (082),
122), (300), and (010), correspond to LiTaO3 planes
ꢀ
whereas some additional peaks noted at 2θ are 21.27 ,
ꢀ
ꢀ
ꢀ
2
(
6.75 , 28.69 , and 30.69 , which are inscribed as (170),
061), (200), and (240) planes that inferred some
unreacted Ta O species exist in the crystal structure of
of Ag- and N-doped LiTaO , whereas the particle gets
3
agglomerated for the addition of dopants. The particle
size that lies in the range of 100–300 nm is noted whereas
the average crystallite size estimated as below 10 nm has
been confirmed from XRD analysis.
2
5
LiTaO that are verified with JCPDS card No: 71-0639.
3
ꢀ
Moreover, one more peak recorded at 59.96 referred to
the plane (116) related to the formation of Ta N as con-
firmed from the standard data (JCPDS card No: 89-5200).
EDS reveals the composition of elements present in
the synthesized photocatalyst. It is recorded in the range
2
5

4
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KALAISELVI ET AL.
FIGURE 2 (a) Field emission scanning
electron microscopy (FESEM) image of undoped
LiTaO , (b) Ag-, and (c) N-doped LiTaO
nanoparticles
3
3
FIGURE 3 (a) Energy
dispersive analysis (EDS) image of
undoped LiTaO
N-doped LiTaO
3
, (b) Ag-, and (c)
nanoparticles
3
from 0- to 20-keV binding energy region. Figure 3a
clearly shows the presence of elements such as Ta and O
for pure samples, and from Figure 3b,c, additionally, the
presence of Ag and N as doped materials is confirmed.
There is no signal regarding the presence of lithium been
noted since it has very low energy of characteristic
radiation not easy to detect. Table 1 showed the quantita-
tive analysis of elements present in the synthesized
photocatalyst. Further, it is confirmed that the
addition of dopants affects the composition of the
material.
crystallinity and morphology, the bandgap of the semi-
conductor is the primary concept in determining the effi-
[
21]
ciency of the photocatalyst.
Figure 4a showed the
optical absorption spectra for LiTaO with its dopants.
3
The high bandgap of LiTaO3 is reported due to an
ꢀ
increase in deviation from 180 of Ta–O–Ta bond angle
due to decreased conduction bandwidth. Figure 4b
showed the absorbance spectrum of LiTaO with its dop-
3
ants, and from that absorbance value, Tauc's relation is
used to probe the optical bandgap of the synthesized
photocatalyst as represented in the Equation 1.
UV–visible absorbance spectroscopy is used to charac-
terize the bandgap of the prepared photocatalyst. Next to
À
Á
n
ðαhγÞ = K hγ−Eg
ꢁꢁꢁ
ð1Þ

KALAISELVI ET AL.
5 of 9
TABLE 1 Elemental composition of LiTaO
3
with its dopants
where α refers to the absorption coefficient (α = 2.303A/I),
hγ denotes the photon energy, E denotes the optical
g
Atomic ratio (%)
bandgap value, K represents the energy independent con-
stant, and n for the occurence of nature of transition.
Using the above relation, the energy bandgap value is
Element composition
Undoped LiTaO
Ag-LiTaO
N-LiTaO
Li
-
Ta
O
Ag
N
3
3.11
7.36
4.87
96.89
91.37
94.52
-
-
found to be 5.12, 4.92, and 4.82 eV for undoped LiTaO3,
3
-
1.26
-
-
Ag-, and N-doped LiTaO nanoparticles as appeared in the
3
3
-
0.61
Figure 5b. Moreover, it is inferred from the analysis that
the bandgap value decreases with the addition of dopants.
FIGURE 4 (a) Absorbance spectra for
undoped LiTaO , Ag-, and N-doped LiTaO
nanoparticles, (b) Tauc's plot for undoped
LiTaO , Ag-, and N-doped LiTaO nanoparticles
3
3
3
3

6
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KALAISELVI ET AL.
+
−
to produce H by the equation 4H +4e ! 2H , it is
2
2
desirable to know the edge of valence and conduction
band for the fruitful activity of the photocatalyst. The
conduction and valence band position is calculated from
the formula ECB = X − E − 1/2E and E = E +E ,
c
g
VB
g
CB
where E is the energy of the free electrons of hydrogen
c
scale (1.23 eV) and ECB and EVB are the energy of con-
duction and valence band. The edges of the valence band
(
EVB) and conduction band (ECB) of LiTaO are deter-
3
mined to be 2.58 and −2.54 eV (vs. normal hydrogen elec-
trode, NHE) The valence band is more positive than the
.
oxidation potential of O whereas the conduction band is
2
[24]
more negative than the reduction potential of H2.
This
hampers the catalytic active sites to have surface interface
reactions.
The photocatalytic hydrogen production is carried out
in an air free closed gas system with a quartz reactor pro-
vided with the sealant at the top using rubber septum,
and a light source of 450-W Xe-Hg UV lamp is used for
irradiation. The gas evolved in this process is detected by
online analysis with a multichannel analyzer equipped
with TCD for the determination of the concentration of
[
25]
hydrogen.
In the present examination, the prepared
photocatalyst powder with 10 mg is dispersed in 38-ml
distilled water, and 12-ml formic acid serves as a sacrifi-
[26]
cial agent altogether taken in the quartz reactor.
it is subjected to sonication and followed by stirring for
0 min in order to attain a homogeneous solution.
Then
2
Finally, the quartz reactor is tightly closed with a rubber
septum and carried out for degassing in such a way to
evacuate the undesired gases inside the reactor, eventu-
FIGURE 5 (a) Amount of H
photocatalystand and (b) H production with the time of irradiation
for LiTaO photocatalyst with its dopants
2
generated for various
2
ally purged with ultra-pure N gas to have an inert atmo-
2
3
sphere setup. Photocatalytic experiments are functioned
with revealed to UV light radiation along with the
continuous stirring of the quartz reactor. The rate of H2
gas evolved is computed using a gas chromatograph
equipped with TCD detector.
Another significant parameter that determines the
water splitting capability of the photocatalyst is the loca-
tion of the bandgap. More precisely, the conduction-band
minimum (CBM) and valence-band maximum (VBM)
The photocatalytic hydrogen production measure-
+
must straddle the redox potentials of H /H and
ments were evaluated for undoped LiTaO and also for
2
3
O /H O. While the semiconductor surface is exhibited to
Ag- and N-doped LiTaO in formic acid and water mix-
2
2
3
the reaction solution in the photocatalytic reaction sys-
tem, the flat-band potential favors to shift along with the
ture under UV light. Figure 5a exhibits the comparison of
H evolution for undoped LiTaO and also with its Ag
2
3
[22]
potential of redox species in the solution.
Thus, there
and N dopants. The rate of H production for Ag-doped
2
−1
is a need to study the position of the band edge potential
LiTaO is found to be 240 μmolh , whereas for undoped
3
of the used photocatalyst (LiTaO ) by Mulliken electro
negativity method. Mulliken's definition of the electro-
negativity of a neutral atom is the arithmetic mean of the
and N-doped LiTaO , the rate of H production is
only 71 and 123 μmolh . The apparent quantum yield
3
3
2
−1
(A.Q.Y) for Ag-doped LiTaO is 3.11%, which is higher
3
atomic electron affinity (A ) and the first ionization
than that for undoped and N-doped LiTaO as 0.92% and
f
3
energy (I1). The absolute electronegativity (X) is
1.59%. When comparing the obtained A.Q.Y value with
other alkali tantalates such as NaTaO and KTaO , the
[23]
calculated for LiTaO and found to be 6.03.
As the
3
3
3
photocatalytic H generation reaction can be split into
value is quite lower than 7.22% and 4.87%. Figure 5b
showed the production rate at which H2 evolution
increases linearly for the time interval up to 4 h as
2
two portions: (i) oxidation for the evolution of O by the
2
+
−
equation H O ! 4H +4e +O and (ii) water reduction
2
2

KALAISELVI ET AL.
7 of 9
2
69 μmol for undoped LiTaO , whereas for Ag and N-
the photocatalytic performance whereas in the case of N
doping the catalytic activity is decreased due to the fact it
acts as a electron–hole recombination centers resulted in
low hydrogen production. The reason behind this is
explained by the fact that it showed higher electronega-
tivity of Ag (1.93) as compared with Ta (1.5), which
resulted in quite transfer of photoexcited electrons from
3
doped LiTaO , the rate is 956 and 505 μmol. There should
3
be noted that no addition of cocatalyst to avoid any dis-
turbance caused by the addition of cocatalyst. The lowest
photocatalytic activity observed may be due to the fact
ꢀ
that the bond angle of Ta–O–Ta is 143 which is too
small been responsible for the migration of UV light
excited charge carriers. Moreover from the structural
point of view, though the crystallite and particle size is
low, the spherical surface attributes to have an exposure
to the low surface area might be one of the reasons for
the low production output in hydrogen evolution.
The observed photocatalytic activity is compared with
the previous reported values that are presented in
Table 2.
the conduction band of LiTaO to the Ag species. This
3
hampers the rapid recombination of electron–hole pairs
leading to the high catalytic activity. Moreover, it is
possible for the Ag-doped LiTaO serves as active sites for
3
[
29]
proton reduction.
A possible mechanism is proposed
based on the obtained results in the form of an equation
from 2 to 7.
−
+
Ag−LiTaO3 + hγ ! e + h
ꢁꢁꢁ
ꢁꢁꢁ
ð2Þ
ð3Þ
4
| PROBABLE MECHANISM OF
+
+
_
LITAO FOR H EVOLUTION
3
2
H O + h ! H + OH
2
As viewed from the photocatalytic hydrogen evolution
measurements that Ag doped showed its improvement in
1
2
_
_
OH + OH ! H2O + O2
ꢁꢁꢁ
ð4Þ
2 3
TABLE 2 Comparison of the rate of photocatalytic H evolution for LiTaO with its various dopants
(μmolh−
1
)
Light source
Reference
Photocatalyst
LiTaO
Cocatalyst
Evolution of H
2
[
27]
3
NiO (0.10 wt%)
98
430
20
400-W Hg lamp
Kato and Kudo
-
[12]
La-LiTaO
3
Pt (0.2 wt%)
125-W Hg lamp
500-W Xe lamp
300-W Xe lamp
Fu et al.
Hagiwara et al.
[
28]
LiTaO
LiTaO
3
3
Pt (0.2 wt%)
4.3
10
[
13]
Before processed by HPT method
Edalati et al.
After processed by HPT method
27
LiTaO
3
-
-
-
`71
240
143
450-W
Present work
Ag-NaTaO
N-NaTaO
3
Xe-Hg
3
UV lamp
Abbreviations: HPT, high-pressure torsion; UV, ultraviolet.
FIGURE 6 Photocatalysis mechanism
3 2
involved in Ag-doped LiTaO for H production

8
of 9
KALAISELVI ET AL.
HCOOH ! HCOO― + H +
ꢁꢁꢁ
ð5Þ
ð6Þ
ð7Þ
ORCID
C.R. Kalaiselvi https://orcid.org/0000-0002-1788-4848
T.S. Senthil https://orcid.org/0000-0003-2376-9122
M.V. Shankar https://orcid.org/0000-0002-5284-1480
V. Sasirekha https://orcid.org/0000-0003-3584-1101
HCOO + 2h+ ! H + CO "
―
+
ꢁꢁꢁ
2
H + + 2e ! H2 "
−
2
ꢁꢁꢁ
REFERENCES
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UV light is absorbed by the Ag-doped LiTaO3
2016, 35, 1.
[
[
2] A. Kudo, Y. Miseki, Chem. Soc. Rev. 2009, 38, 253.
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photocatalyst and thereby electron–hole pairs created
(
Equation 2). The molecules of water present in the
+
[4] C. R. Kalaiselvi, N. Muthukumarasamy, D. Velauthapillai,
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•
radicals ( OH) by oxidation reaction (Equation 3).
[
The generated hydroxyl radicals produce molecular
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−
+
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equation (Equation 5). The photogenerated holes then
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2
[
entire process transferred to the doped Ag species
where the reduction process occurs with the genera-
tion of H2 in the last step of the entire process
2
[
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(Equation 7). Figure
6
signifies the mechanism
involved in the process of generation of hydrogen in
Ag-doped LiTaO3.
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5
| CONCLUSION
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In summary, Ag- and N-doped LiTaO3 photocatalysts
have been synthesized by solvothermal strategy. The
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5
resultant Ag-doped LiTaO showed its enhancement in
3
−
1
the rate of H evolution of 240 μmolh with formic acid
2
2
as a sacrificial agent with an A.Q.Y to be 3.11%, which is
[
[
quite higher than N-doped LiTaO . Compared with non-
3
2
metal (N) doping, noble metal (Ag) provides a favorable
route for the transfer of photoexcited electrons between
semiconductor and Ag nanoparticle. Further, this study
perhaps provided an effective path in designing LiTaO3
photocatalyst with other suitable dopants towards
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DATA AVAILABILITY STATEMENT
Data are available on request from the authors.
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2015, 7, 113.
[
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AUTHOR CONTRIBUTIONS
C.R. Kalaiselvi: Conceptualization; formal analysis;
investigation; methodology; validation; visualization.
T.S. SENTHIL: Conceptualization; investigation; super-
vision. M.V. SHANKAR: Methodology; project admin-
istration; validation. V. SASIREKHA: Data curation;
resources.
[
[
[29] T. Puangpetch, T. Sreethawong, S. Chavadej, Int. J. Hydrogen
Energy 2010, 35, 6531.

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SUPPORTING INFORMATION
Additional supporting information may be found online
in the Supporting Information section at the end of this
article.
How to cite this article: Kalaiselvi CR,
Senthil TS, Shankar MV, Sasirekha V.
Solvothermal fusion of Ag- and N-doped LiTaO3
perovskite nanospheres for improved
photocatalytic hydrogen production. Appl
Organomet Chem. 2021;35:e6207. https://doi.org/
10.1002/aoc.6207