INDIAN JOURNAL OF SCIENCE AND TECHNOLOGY
RESEARCH ARTICLE
OPEN ACCESS
Electrochemical Activity of TiO2
Nanoparticles in NaOH Electrolyte via
Green Synthesis Using Calotropis gigantea
Plant Leaf Extract
Received: 01.08.2021
P Naresh Kumar Reddy1,2 , Dadamiah P M D Shaik3 , D Nagamalleswari2 ,
Accepted: 05.10.2021
K Thyagarajan4 , P Vishnu Prasanth2 ∗
Published: 25.10.2021
Citation: Naresh Kumar Reddy P,
Shaik DPMD, Nagamalleswari D,
Thyagarajan K, Vishnu Prasanth P
(2021) Electrochemical Activity of
TiO2 Nanoparticles in NaOH
Electrolyte via Green Synthesis
Using Calotropis gigantea Plant Leaf
Extract. Indian Journal of Science
and Technology 14(34): 2766-2772.
https://doi.org/
10.17485/IJST/v14i34.1424
∗
Corresponding author.
vishnuprasanthp@gmail.com
Funding: None
Competing Interests: None
Copyright: © 2021 Naresh Kumar
Reddy et al. This is an open access
article distributed under the terms
of the Creative Commons
Attribution License, which permits
unrestricted use, distribution, and
reproduction in any medium,
provided the original author and
source are credited.
Published By Indian Society for
Education and Environment (iSee)
ISSN
Print: 0974-6846
Electronic: 0974-5645
1 Research Scholar, Department of Physics, JNTUA, Anantapuramu, 515002, India
2 Department of Physics, Sree Vidyanikethan Engineering College, A. Rangampet, 517102,
India
3 Department of Physics, Lords Institute of Engineering and Technology, Hyderabad, 500091,
India
4 Department of Physics, JNTUA College of Engineering, Pulivendula, 516390, India
Abstract
Objectives: Green synthesis of Titanium dioxide (TiO2 ) nanoparticles using
Calotropis gigantea (CG) plant leaf extract. Methods: Environmental ecofriendly green approach is used to synthesize nanostructured TiO2 nanoparticles by using TiCl4 as a precursor and C. gigantea plant leaf extract as a catalyst. The secondary metabolites in the CG plant leaf extract help to transform
the Ti4+ ions to TiO2 nanoparticles. The detailed structural properties are studied using X-ray diffraction (XRD), Field emission scanning electron microscopy
(FESEM), and high-resolution transmission electron microscopy (HRTEM). The
phase formation and chemical state of the prepared samples are examined
by Raman and Energy Dispersive X-ray spectroscopy (EDX). The vibrational frequencies between the bonds of atoms are studied with Fourier Transform InfraRed spectroscopy (FTIR). The electrochemical properties of green synthesized
nanoparticles using cyclic voltammetry (CV) technique in aqueous electrolyte.
Findings: XRD data conform to the tetragonal structure of TiO2 in the rutile
phase with P42/mnm space group and crystallite size is also found to be 9.84
nm. The SEM and TEM images show that the non-uniform spherical and flowerlike shape of grains with an average grains size of 100 nm. The specific capacitance of the sample is estimated to be 238 F g-1 at a scan rate of 1 mV s-1 with
good reversibility. Novelty: The novelty of this research lies in the fabrication
of the electrode material with TiO2 3D nanostructures for supercapacitor applications. This kind of morphology certainly enhances the surface area and leads
to achieving better electrochemical performance.
Keywords: Titanium tetra chloride; TiO 2 nanoparticles; Green synthesis;
Calotropis gigantea (CG) Plant; 3D nanostructure; specific capacitance
https://www.indjst.org/
2766
Naresh Kumar Reddy et al. / Indian Journal of Science and Technology 2021;14(34):2766–2772
1 Introduction
Synthesis of high surface area 3D nanostructures is an important task to improve the electrochemical performance of an energy
storage devices (1,2) . The high surface area 3D nanostructures have more active cites compared to normal 2D nanomaterials. Now
the 21st century researchers have planned various processes for the synthesis of 3D nanostructure metal oxides (NMOs) which
have contributed in the development of energy storage devices (3) . Synthesis of NMOs using plant leaf extract is compatible with
the green chemistry principles. Green synthesis of NMOs makes use of environmental friendly, non-toxic and safe reagents.
NMOs synthesized using biological techniques or green technology have diverse natures, with greater stability and appropriate
dimensions since they are synthesized using a one-step procedure. NMOs can be synthesized using a variety of methods
including chemical, physical, biological, and hybrid techniques. Physical methods including plasma arching, ball milling,
thermal evaporate, spray pyrolysis, ultrathin film, pulsed laser desorption, lithographic techniques, sputter deposition, layer
by layer growth, molecular beam epitasis, and diffusion flame synthesis of NMOs. Similarly, chemical methods are used to
synthesize NPs by electrodeposition, sol–gel process, chemical solution deposition, chemical vapour deposition soft chemical
method, Langmuir Blodgett method, catalytic route, hydrolysis co-precipitation method, and wet chemical method (4–7) .
Chemical and Physical methods have been using high radiation and highly concentrated reductants and stabilizing agents that
are harmful for the environmental and to human health. Hence, biological synthesis of NMOs is a single-step bio-reduction
method and less energy is used to synthesize eco-friendly.
So far, various transition metal oxides have been used as the electrode materials for supercapacitors, such as RuO2 , Co3 O4 ,
NiO, CuO, SnO2 , and manganese based oxides like MnO, Mn3 O4 , Mn2 O3 , and MnO2 (8–11) . Among these transition metal
oxides, RuO2 was the most widely studied metal oxide due to its high conductivity and high specific capacitance as well as its
excellent chemical stability. However, due to its less abundance and high cost regarding the usage of Ruthenium, there were
major limitations to its practical applications. Titanium Dioxide (TiO2 ) become alternate and promising electrode materials
for supercapacitors due to their extraordinary properties like hydrophobic nature, non-wet ability, high energy bandgap,
thermally stable, outstanding structure stability, chemical stability, potential oxidation strength; hence it can be used in different
types of applications such as self-cleaning, gas sensors, solar cell, photo catalysis, charge spreading devices, chemical sensors,
microelectronics, electrochemistry, anti-bacterial products, textiles and promising electrode material for lithium-ion batteries
and Supercapacitors (12–16) . Moreover, TiO2 has attractive advantages like high relative abundance and resistance to corrosion,
low cost, better safety, and environmental friendliness due to non-flammable and non-toxicity.
Quite a few reports are available on the green synthesis of TiO2 nanoparticles using various plant extracts like Nyctanthes
arbor-tristis, Solanum trilobatum, Annona squamosa, Catharanthus roseus, Jatropha curcas, Cucurbita pepo, Eclipta prostrata, C.
gigantea, and Ocimum basilicum (Ocimum tenuiflorum) (17–28) . C. gigantea is a well-known medicinal plant belongs to the
Asclepiadaceous family, this plant is widely used as a scent through which it netted its title Queen (basileus) of aromatic
herbs (29) . The present study focused on the preparation of Titanium dioxide (TiO2 ) nanoparticles with CG plant leaf extract
using the green synthesis method. This plants leaf extract is the source of various biologically active compounds, including
glycosides, tannins, alkaloids, flavanols, saponins, sterols and triterpenoids and many proteins among others contain which
helps to reducing Ti4+ ions to TiO2 nanoparticles and at the same time which stabilize and capping those nanoparticles (30) .
Further, the powders were systematically characterized and their electrochemical properties were studied.
2 Experimental method and materials
To synthesize TiO2 NMOs, a simple green approach is used. In this method TiCl4 which is bought from the organization
Merck co. with ≥99.0% purity (used without further purification) used as precursor and CG plant leaf extract as catalyst. In
the synthesis process first, the good and healthy leaves of the CG plant were collected and cleaned thoroughly with RO purified
water, distilled water, and double-distilled (DD) water a few times to remove the dust particles and other unnecessary materials
on the leaves. A 100 g of CGP leaves were cut into tiny pieces and directly taken into the single neck round base boiling flask
contains 500 ml of DD water and heated for 2 hours at 90 ◦ C with the help of heating mantle. After three hours, the solutions
of CGP leaf extricate was filtered using filter paper with pore size 2.5 µ m. The final solution is directly utilized as a reducing
agent to obtain TiO2 nanoparticles at various reaction times.
Finally, in the round bottom flask, 1.0 N Titanium tetrachloride solution was prepared using 100 ml of DD water and 25 ml
of CGP leaf extract was included dropwise under continuous stirring at room temperature. After being stirred for 24 hours, the
pH of the final solution was recorded in the range of 2.0-2.4. The plant leaf extract usually contains a high level of secondary
metabolites like polyphenols, flavonoids, alkaloids, terpenoids, and peptides has hydroxyl and ketonic groups which helps in
reducing Ti4+ ions to TiO2 state and at the same time which stabilize and capping those nanoparticles. The obtained TiO2
nanoparticles were washed several times with double distilled water and ethanol up to the pH of the solution reached to 7. The
https://www.indjst.org/
2767
Naresh Kumar Reddy et al. / Indian Journal of Science and Technology 2021;14(34):2766–2772
white TiO2 nanoparticles was dried at 100 ◦ C for overnight. Finally, the product was calcined at 200 ◦ C for 5 hours to remove any
evaporable impurities and obtain pure TiO2 nanoparticles. The collected nanoparticles were utilized to study different material
characterization for supercapacitor applications.
2.1 Material Characterization
X-ray diffraction data and Raman scattering data of TiO2 nanoparticles were recorded by Seifert X-ray diffractometer using
CuKα radiation (λ =0.154 nm) and Horiba Jobin Yvon Lab RAM HR800UV Raman Spectrometer using 532 nm wavelength
He-Ne laser source to study the structural properties. The Scanning electron microscope (Carl ZEISS-Model EVO MA15)
was used to investigate the surface morphology and elemental composition of TiO2 nanoparticles in high vacuum condition.
The High Resolution Transmission Electron Microscope (HR-TEM) images were captured by Tecnai. G2 20 Twin. The Energy
Dispersive Analysis of X-ray (EDAX) spectrum was recorded using BRUKER instrument. The electrochemical properties of
TiO2 nanoparticles were studied using CHI 608C electrochemical workstation.
2.2 Preparation of electrode
The working electrode was prepared using 80% of TiO2 nanoparticles, 10% of carbon black and 10% of Poly Vinylidene Fluoride
(PVdF). The combination was grinded for one and half an hour and N-methyl-2-pyrrolidone was added to obtain homogeneous
slurry. Finally, the slurry was coated uniformly on a chemically cleaned nickel foam and dried at 100 ◦ C for 2h.
2.3 Preparation of electrochemical work station
The electrochemical work station was prepared using TiO2 as working electrode, Ag/AgCl as reference electrode, platinum foil
as counter electrode and 1M Na2 SO4 as aqueous electrolyte to record Cyclic voltammetry (CV) data of TiO2 nanoparticles.
3 Results and discussion
X-ray powder diffraction spectrum of TiO2 nanoparticles synthesized with CG plant extract was recorded in the 2θ range of
20o -70o is as shown in Figure 1a. The XRD pattern exhibited (110) predominant orientation peak at 2θ = 27.52◦ with other
different characterization peaks (101), (200), (111), (210), (211), (220), (002), (310) and (301) at 36.21◦ , 39.24◦ , 41.28◦ , 44.03◦ ,
54.45◦ , 56.77◦ , 62.99◦ , 63.86◦ , and 69.21◦ respectively. All the diffraction peaks were indexed to the tetragonal structure of rutile
phase TiO2 with P42 /mnm, density = 4.25 g/cm2 space group (JCPDS card No. 88-1172) (31) . The estimated lattice parameters
are a=b=4.566 Å and c = 2.948 Å which are good agreement with previous literature reports. The broad and high intensity
of diffraction peaks indicate the smaller crystallite size and high crystallinity. The coherent length (Lc) which corresponds to
the crystallite size of the sample was calculated and found to be 9.84 nm from the predominant (110) diffraction peak using
Debye-Scherrer’s formula (3)
D=
kλ
β cos θ
The obtained powder was characterized by Raman spectroscopy, which is a very sensitive technique to atomic arrangements
and vibrations. The Raman spectra of TiO2 nanoparticles synthesized with CG plant extract were recorded in the range 2001000 cm−1 and the results are shown in Figure 1b. The Raman spectroscopy allows clear identification of the different TiO2
crystalline phases rutile exhibits four Raman-active modes, namely the B1g , Eg and A1g . The Raman frequencies for rutile
structures are 250 (B1g ), 443 (Eg ) and 608 (A1g ) cm−1 (32) . The vibrational studies of TiO2 nanoparticles synthesized CG plant
extract sample has been studied by FTIR within the wave number range of 4000–400 cm−1 in order to know the chemical bonds
present in the TiO2 sample as shown in Figure 1c. The observed transmittance bands of the samples in the range 800–400 cm-1
are accredited to Ti–O/Ti–O–Ti stretching bonds. The spectroscopic band is observed at around 3034 cm-1 is due to the O-H
stretching vibration bonds. The absorption peaks identified at 2098, 1886 and 1617 cm-1 corresponds to the C-H stretching
vibrations, C=O and C=C bonds respectively (33) .
https://www.indjst.org/
2768
Naresh Kumar Reddy et al. / Indian Journal of Science and Technology 2021;14(34):2766–2772
Fig 1. XRD (b) Raman (c) FTIR Spectrum of TiO2 nanoparticles
The effective surface area of the materials mainly depends on the size and shape of the nanoparticles which is very important
for supercapacitor applications (34) . The TiO2 nanoparticles synthesized with CG plant extracts sample morphology recorded
from SEM is shown in Figure 2a. The SEM images showed that the non-uniform spherical and flower-like shape of grains with
an average grains size of 100 nm and crystallite size around 11 nm. Figure 2b shows the SEM image at different magnification.
The TEM image from Figure 2c shows the flower-like morphology with an average grains size of 100 nm and crystallite size
around 10 nm which is a coincidence with SEM results. Finally the SEM and TEM results are good agreement with XRD results.
The EDS spectrum of TiO2 nanoparticles is displayed in the Figure 2d which clearly indicates the presence of Ti and O binding
energy peaks indicate the chemical purity of the sample.
Fig 2. (a, b) SEM micrographs (c) HRTEM images (d) EDS spectrumof TiO2 nanoparticles
https://www.indjst.org/
2769
Naresh Kumar Reddy et al. / Indian Journal of Science and Technology 2021;14(34):2766–2772
Electrochemical Properties
The electrochemical properties of TiO2 nanoparticles was studied using a three-electrode system includes working, reference,
and counter electrode in 1M NaOH aqueous electrolyte. The cyclic voltametric (CV) curves of the TiO2 at different reaction
times were measured in the potential window of -0.4 to 0.4 V (vs. Ag/AgCl) at different scan rates from 1 to 100 mVs-1 .
As revealed in Figure 3a, the TiO2 show redox peaks at about 0.2 V, and thus their capacitance mainly results from pseudo
capacitance of Ti ions. In Figure 3a, the CV curves of the sample showed similar profiles under different scan rates, indicate
good reversibility with minor shirt in the redox peaks. It can be seen that the current under curve increases with an increase
in scan rate and in turn results in a decrease in capacitance. It is well known that the voltametric current is always directly
proportional to the scan rate (7) . The specific capacitance of the sample was measured using the following formula
C=
∫
I (V ) dV
(2m ∆V (V2 −V1 ))
∫
Where, C is the specific capacitance in Fg-1 , I(V) is the instantaneous current in A, I (V ) dV is total voltametric charge in
C, ∆V is the scan rate in Vs-1 , and (V2 - V1 ) is the potential window range in V. The value of specific capacitance decrease
from 238 F g-1 to 92 F g-1 with increase in scan rate form 1 to 100 mV s-1 . The decrease in specific capacitance with scan rate
is due the electrolyte ions do not find sufficient time to avail all active sites of the electrode (35) . At a low scan rate, the ions
from the electrolyte can utilize all the available sites in the active electrode material. The rich in specific capacitance of the
sample is owing to the beautiful flower-like structure with the clear formation of petals. The Charge-discharge curves of TiO2
nanoparticles were shown in Figure 3b. The figure shows the slight bump in the charge and discharge at around 0.2 V, indicate
the redox reactions which further supports the CV results. The obtained specific capacitance results are compared with the
previous reports listed in Table 1. The cycling stability of the 3D TiO2 nanostructures was evaluated under GCD conditions at
2 A g-1 current density[Figure 3c]. The sample showed 85% of specific capacitive retention even after 1000 cycles. The greater
performance of the TiO2 sample is due to outstanding dispersion and formation of 3D nanostructure demonstrates that the
electrolyte ions can easily diffuse through the active electrode material.
Fig 3. (a). CV (b) Charge-discharge curves of TiO2 nanoparticles (c) Specific capacitance with cycle number
https://www.indjst.org/
2770
Naresh Kumar Reddy et al. / Indian Journal of Science and Technology 2021;14(34):2766–2772
Sl.
No.
1
2
3
4
5
6
7
8
Material
The porous anatase TiO2
nanoparticles
TiO2 /rGO/TiO2
TiO2 /Cu2 O
TiO2 /C3 N4
TiO2 /reduced
graphene
oxide
TiO2 Nanoflakes
Flower like TiO2
TiO2 3D Nanostructures
Table 1. Comparative study of specific capacitance of TiO2 .
Preparation Method
Electrolyte
Specific Capacitance
Hydrothermal method 1 M LiPF6
48.6 F g-1
Scan rate/ Current
density
100 mA g-1
Sol preparation
Electrochemical
doping
approach
using a facile cyclic
voltammetry method
–
Sol-gel method
1 M KOH
0.5 M Na2 SO4
83.7 F g-1
98.7 F g-1
5 mV s-1
100 mV s-1
2 M KOH
1 M LiPF6
125.1 F g-1
150 F g-1
1 A g−1
20 mV s-1
Sol-gel method
Green Synthesis
Green Synthesis
1 M Na2 SO4
1 M Na2 SO4
1 M NaOH
164 F g-1
224 F g-1
238 F g-1
5 mV s-1
0.5 A g−1
1 mV s-1
Reference
(36)
(37)
(38)
(39)
(40)
(41)
(42)
This work
4 Conclusion
3D nanostructure TiO2 particles have been successfully synthesized by a simple green synthesis method using Calotropis
gigantea plant (CGP) extract at room temperature. XRD and Raman data was confirmed the tetragonal structure of TiO2 in
the rutile phase with P42 /mnm space group and crystallite size was found to be 9.84 nm. The SEM and TEM images showed
that the non-uniform spherical and flower-like shape of grains with an average grains size of 100 nm. The EDS spectra confirmed
the high purity of the samples. The vibrational modes of the samples were studied using FTIR. The electrochemical studies of
TiO2 exhibited a specific capacitance of 238 F g-1 at a scan rate of 1 mV s-1 with good reversibility.
References
1) Reddy PNK, Shaik DPMD, Ganesh V, Nagamalleswari D, Thyagarajan K, Prasanth PV. High electrochemical activity of 3D flower like nanostructured
TiO2 obtained by green synthesis. Applied Surface Science. 2021;561(150092). Available from: https://dx.doi.org/10.1016/j.apsusc.2021.150092.
2) Gonçalves RA, Toledo RP, Joshi N, Berengue OM. Green Synthesis and Applications of ZnO and TiO2 Nanostructures. Molecules. 2021;26(8):2236.
Available from: https://dx.doi.org/10.3390/molecules26082236.
3) Yadav MS. Metal oxides nanostructure-based electrode materials for supercapacitor application. Journal of Nanoparticle Research. 2020;22(12):367.
Available from: https://dx.doi.org/10.1007/s11051-020-05103-2.
4) Dubey RS. Temperature-dependent phase transformation of TiO2 nanoparticles synthesized by sol-gel method. Materials Letters. 2018;215:312–317.
doi:10.1016/j.matlet.2017.12.120.
5) Wang D, Xie K, Wang Y, Cheng S. A Non-aqueous Hybrid Supercapacitor with Porous Anatase TiO2 Nanoparticles Anode and Activated Carbon Cathode.
International Journal of Electrochemical Science. 2016;11:9776–9782. Available from: http://www.electrochemsci.org/papers/vol11/111209776.pdf.
6) Zikriya M, Nadaf YF, Bharathy PV, Renuka CG. Luminescent characterization of rare earth Dy3+ ion doped TiO2 prepared by simple chemical coprecipitation method. Journal of Rare Earths. 2019;37(1):24–31. Available from: https://dx.doi.org/10.1016/j.jre.2018.05.012.
7) Lee DH, Swain B, Shin D, Ahn NK, Park JR, Park KS. One-pot wet chemical synthesis of fluorine-containing TiO2 nanoparticles with enhanced
photocatalytic activity. Materials Research Bulletin. 2019;109:227–232. Available from: https://dx.doi.org/10.1016/j.materresbull.2018.09.027.
8) Shaik DPMD, Kumar MVS, Reddy PNK, Hussain OM. High electrochemical performance of spinel Mn3O4 over Co3O4 nanocrystals. Journal of Molecular
Structure. 2021;1241:130619. Available from: https://dx.doi.org/10.1016/j.molstruc.2021.130619.
9) Prakash NG, Dhananjaya M, Narayana AL, Shaik DP, Rosaiah P, Hussain OM. High Performance One Dimensional α -MoO3 Nanorods for Supercapacitor
Applications. Ceramics International. 2018;44(8):9967–9975. Available from: https://dx.doi.org/10.1016/j.ceramint.2018.03.032.
10) Dhananjaya M, Prakash NG, Narayana AL, Hussain OM. Microstructural and supercapacitive properties of one-dimensional vanadium pentoxide
nanowires synthesized by hydrothermal method. Applied Physics A. 2018;124(2):185. Available from: https://dx.doi.org/10.1007/s00339-017-1522-0.
11) Shaik DP, Pitcheri R, Qiu Y, Hussain OM. Hydrothermally synthesized porous Mn3O4 nanoparticles with enhanced electrochemical performance for
supercapacitors. Ceramics International. 2019;45(2):2226–2233. Available from: https://dx.doi.org/10.1016/j.ceramint.2018.10.135.
12) Mathew S, Victório CP, S JSM, H BTB. Biosynthesis of silver nanoparticle using flowers of Calotropis gigantea (L.) W.T. Aiton and activity against
pathogenic bacteria. Arabian Journal of Chemistry. 2020;13(12):9139–9144. Available from: https://dx.doi.org/10.1016/j.arabjc.2020.10.038.
13) Alexpandi R, Gopi CVVM, Durgadevi R, Kim HJ, Pandian SK, Ravi AV. Metal sensing-carbon dots loaded TiO2-nanocomposite for photocatalytic
bacterial deactivation and application in aquaculture. Scientific Reports. 2020;10(1):12883. Available from: https://dx.doi.org/10.1038/s41598-020-69888x.
14) Jin SE, Jin HE. Synthesis, Characterization, and Three-Dimensional Structure Generation of Zinc Oxide-Based Nanomedicine for Biomedical Applications.
Pharmaceutics. 2019;11(11):575. Available from: https://dx.doi.org/10.3390/pharmaceutics11110575.
15) Saeed M, Usman M, Muneer M, Akram N, ul Haq A, Tariq M, et al. “Synthesis of ag-fe3o4 nanoparticles for degradation of methylene blue in aqueous
medium”. Bulletin of the Chemical Society of Ethiopia. 2020;34(1):123–134. Available from: https://dx.doi.org/10.4314/bcse.v34i1.11.
https://www.indjst.org/
2771
Naresh Kumar Reddy et al. / Indian Journal of Science and Technology 2021;14(34):2766–2772
16) Thakur PK, Verma V. A Review on Green Synthesis, Characterization and Anticancer Application of Metallic Nanoparticles. Applied Biochemistry and
Biotechnology. 2021;10:1–22. Available from: https://dx.doi.org/10.1007/s12010-021-03598-6.
17) Yadav LSR, Manjunath K, Kavitha C, Nagaraju G. Investigation of Hydrogen generation and Antibacterial activity by Ionic liquid aided synthesis of TiO2
nanoparticles”. Journal of Science: Advanced Materials and Devices. 2018. Available from: 10.1016/j.jsamd.2018.03.002.
18) Abisharani JM, Devikala S, Kumar RD, Arthanareeswari M, Kamaraj P. Green synthesis of TiO2 Nanoparticles using Cucurbita pepo seeds extract.
Materials Today: Proceedings. 2019;14(2):302–307. Available from: https://dx.doi.org/10.1016/j.matpr.2019.04.151.
19) Saeed M, Siddique M, Ibrahim M, Akram N, Usman M, Aleem MA, et al. Calotropis gigantea leaves assisted biosynthesis of ZnO and Ag@ZnO
catalysts for degradation of rhodamine B dye in aqueous medium. Environmental Progress & Sustainable Energy. 2020;39(4):e13408. Available from:
https://doi.org/10.1002/ep.13408.
20) Saeed M, Muneer M, Mumtaz N, Siddique M, Akram N, Hamayun M. Ag-Co 3 O 4 : Synthesis, characterization and evaluation of its photo-catalytic
activity towards degradation of rhodamine B dye in aqueous medium. Chinese Journal of Chemical Engineering. 2018;26(6):1264–1269. Available from:
https://dx.doi.org/10.1016/j.cjche.2018.02.024.
21) Venkatesan P, Remya N. Synthesis of TiO2 using Calotropis gigantea for Visible light Excitation and Degradation of pollutants. Toxic, and Radioactive
Waste. 2021;25:4. Available from: https://doi.org/10.1061/(ASCE)HZ.2153-5515.0000632.
22) Prashanth V, Priyanka K, Remya N. Solar photocatalytic degradation of metformin by TiO2 synthesized using Calotropis gigantea leaf extract. Water
Science and Technology. 2021;83(5):1072–1084. Available from: https://dx.doi.org/10.2166/wst.2021.040.
23) Patil SP. Calotropis gigantea assisted green synthesis of nanomaterials and their applications: a review. Beni-Suef University Journal of Basic and Applied
Sciences. 2020;9(1):14. Available from: https://doi.org/10.1186/s43088-020-0036-6.
24) Bekele ET, Gonfa BA, Sabir FK. Use of Different Natural Products to Control Growth of Titanium Oxide Nanoparticles in Green Solvent Emulsion,
Characterization, and Their Photocatalytic Application. Bioinorganic Chemistry and Applications. 2021;2021(6626313):1–17. Available from: https:
//dx.doi.org/10.1155/2021/6626313.
25) Bahria SS, Haruna Z, Hubadillahb SK, Norhayati W, Sallehc W, Rosmanc N, et al. Noor Hasliza Kamaruddina , Faiz Hafeez Azhara , Norsuhailizah
Sazalia , Raja Adiba Raja Ahmada and Hatijah Basri. “Review on recent advance biosynthesis of TiO2 nanoparticles from plant-mediated materials:
characterization, mechanism and application. IOP Conf Series: Materials Science and Engineering. 2021;p. 1142. doi:10.1088/1757-899X/1142/1/012005.
26) Nadeem M, Tungmunnithum D, Hano C, Abbasi BH, Hashmi SS, Ahmad W, et al. The current trends in the green syntheses of titanium oxide nanoparticles
and their applications. Green Chemistry Letters and Reviews. 2018;11(4):492–502. Available from: https://dx.doi.org/10.1080/17518253.2018.1538430.
27) Haldar KK, Banerjee B, Saha M, Ahmed I, Mete S, Patil RA, et al. Green Approach for the Fabrication of Au/ZnO Nanoflowers: A Catalytic Aspect. J Phys
Chem C. 2021;125(12):6619–6631. Available from: https://doi.org/10.1021/acs.jpcc.0c10149.
28) Kantheti P, Alapati P. Green synthesis of TIO2 nanoparticles using Ocimum basilicum extract and its characterization. International Journal of Chemical
Studies. 2018;6(4):670–674. Available from: http://krishi.icar.gov.in/jspui/handle/123456789/24553.
29) Gharge VG, Yadav A. ”Study of Methanolic Extract of Leaves Calotropis gigantea (L.) As an Anti-Solar”. Advances in Complementary & Alternative
Medicine. 2018;1(4). Available from: 10.31031/ACAM.2018.01.000518.
30) Singh R, Dutta S. Synthesis and characterization of solar photoactive TiO 2 nanoparticles with enhanced structural and optical properties. Advanced
Powder Technology. 2018;29(2):211–219. Available from: https://dx.doi.org/10.1016/j.apt.2017.11.005.
31) Nwankwo U, Bucher R, Ekwealor ABC, Khamlich S, Maaza M, Ezema FI. Synthesis and characterizations of rutile-TiO2 nanoparticles derived from chitin
for potential photocatalytic applications. Vacuum. 2019;161:49–54. Available from: https://dx.doi.org/10.1016/j.vacuum.2018.12.011.
32) Ekoi EJ, Gowen A, Dorrepaal R, Dowling DP. Characterisation of titanium oxide layers using Raman spectroscopy and optical profilometry: Influence of
oxide properties. Results in Physics. 2019;12:1574–1585. Available from: https://dx.doi.org/10.1016/j.rinp.2019.01.054.
33) Sarkar A, Khan GG. The formation and detection techniques of oxygen vacancies in titanium oxide-based nanostructures. Nanoscale. 2019;11(8):3414–
3444. Available from: https://dx.doi.org/10.1039/c8nr09666j.
34) Ojha DP, Poudel MB, Kim HJ. Investigation of electrochemical performance of a high surface area mesoporous Mn doped TiO2 nanoparticle for a
supercapacitor. Materials Letters. 2020;264:127363. Available from: https://dx.doi.org/10.1016/j.matlet.2020.127363.
35) Parveen N, Cho MH. Self-Assembled 3D Flower-Like Nickel Hydroxide Nanostructures and Their Supercapacitor Applications. Scientific Reports.
2016;6(1):27318. Available from: https://dx.doi.org/10.1038/srep27318.
36) Wang D. A Non-aqueous Hybrid Supercapacitor with Porous Anatase TiO2 Nanoparticles Anode and Activated Carbon Cathode. International Journal
of Electrochemical Science. 2016;11:9776–9782. doi:10.20964/2016.12.15.
37) Agharezaei P, Abdizadeh H, Golobostanfard MR. Flexible supercapacitor electrodes based on TiO2/rGO/TiO2 sandwich type hybrids. Ceramics
International. 2018;44(4):4132–4141. Available from: https://dx.doi.org/10.1016/j.ceramint.2017.11.214.
38) Qin Y, Zhang J, Wang Y, Shu X, Yu C, Cui J, et al. Supercapacitive performance of electrochemically doped TiO2 nanotube arrays decorated with Cu2O
nanoparticles. RSC Advances. 2016;6(53):47669–47675. Available from: https://dx.doi.org/10.1039/c6ra08891k.
39) Zhao Y, Xu L, Huang S, Bao J, Qiu J, Lian J, et al. Facile preparation of TiO2/C3N4 hybrid materials with enhanced capacitive properties for high
performance supercapacitors. Journal of Alloys and Compounds. 2017;702:178–185. Available from: https://dx.doi.org/10.1016/j.jallcom.2017.01.125.
40) Kim H, Cho MY, Kim MH, Park KY, Gwon H, Lee Y, et al. A Novel High-Energy Hybrid Supercapacitor with an Anatase TiO2-Reduced Graphene
Oxide Anode and an Activated Carbon Cathode. Advanced Energy Materials. 2013;3(11):1500–1506. Available from: https://dx.doi.org/10.1002/aenm.
201300467.
41) Anandhia P, Kumar V, Harikrishnan S. Enhanced Capacitive Characteristics of TiO2 Nanoflakes Based Electrode Material For Supercapacitor”. Journal
of Electrical Engineering. 2017;1:252–258.
42) Reddy PNK, Shaik DP, Ganesh V, Nagamalleswari D, Thyagarajan K, Prasanth PV. Structural, optical and electrochemical properties of TiO2 nanoparticles
synthesized using medicinal plant leaf extract. Ceramics International. 2019;45(13):16251–16260. Available from: https://dx.doi.org/10.1016/j.ceramint.
2019.05.147.
https://www.indjst.org/
2772