Content uploaded by Dr. Alaa F. Abd El-Rehim
Author content
All content in this area was uploaded by Dr. Alaa F. Abd El-Rehim on Feb 07, 2024
Content may be subject to copyright.
CORRECTED PROOF
Sensors & Actuators: B. Chemical xxx (xxxx) 135451
Contents lists available at ScienceDirect
Sensors & Actuators: B. Chemical
journal homepage: www.elsevier.com/locate/snb
Natural grape juice assisted synthesis of metal oxide nanoparticles:
Evaluation of microstructural, vibrational and colloidal stability analysis for
Liquified Petroleum Gas (LPG) sensor applications
S. Sindhu Kavia, V. Susithraa, A.F. Abd El-Rehimb, E. Ranjith Kumar a,⁎
aDepartment of Physics, KPR Institute of Engineering and Technology, Coimbatore 641 407, Tamilnadu, India
bPhysics Department, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 64113, Saudi Arabia
ARTICLE INFO
Keywords:
Green synthesis
Nanoparticles
Microstructural analysis
Colloidal stability
Vibrational analysis
Gas sensor
ABSTRACT
The current study used simple and cost-effective methods to generate Fe3O4, ZnO, NiO, and Co3O4nanoparticles.
Grape juice was chosen as a sustainable fuel along with metal nitrates. Green synthesised metal oxide nanoparti-
cles' microstructure and colloidal stability were characterised using several methods. Metal oxide nanoparticle
lattices and crystallite sizes were examined using X-ray diffraction. It shows that many metal oxide nanoparticles
have 20–30 nm crystallite diameters. TEM captured metal oxide nanoparticle form and size. Additionally, these
nanoparticles' particle size was determined and compared positively to XRD. Metal oxide nanoparticles have
spherical, cubical, and plate-like exteriors. Absorption bands from O-H, N-O, C-H, N-O, and M-O bond stretching,
bending, and lengthening were visible in the FTIR spectrum. Zeta potential tests demonstrate nanoparticle col-
loidal stability. Each of four metal oxide nanoparticles has a positive Zeta potential. Fe3O4nanoparticles are more
stable than other metal oxide nanoparticles (−58.7 mV). Metal oxide nanoparticles sensed many test gases well.
Fe3O4and ZnO nanoparticles have good LPG and ethanol detecting capabilities. The response-recovery time
demonstrates that the produced metal oxide nanoparticles are appropriate materials for the ethanol gas sensor.
1. Introduction
Nanostructured materials have garnered significant attention and
investigation in recent times due to their potential applications in vari-
ous aspects of everyday life. The resolution of highly complex issues can
be achieved through the utilization of sophisticated nanotechnology,
which encompasses a wide range of nanostructured materials such as
nanoparticles, nanotubes, nanowires, and nanodots. Nanostructured
materials possess a diverse range of dimensions, which contribute to
their extensive utilization in many fields such as biosensors, photocatal-
ysis, antibacterial agents, gas sensors, energy storage devices, and envi-
ronmental monitoring [1–6]. The synthesis method is a significant fac-
tor in determining the structural properties and appropriate applica-
tions of the materials. Researchers commonly employ these extensive
synthesis processes to produce a diverse range of nanostructured mate-
rials. Currently, researchers are demonstrating a keen interest in the
production of nanostructured materials using environmentally friendly
synthesis methods. These methods involve the utilization of various
green energy sources such as leaf extracts, fruit juice seed extracts, and
fruit peels [7–10]. The investigation of nanomaterials synthesized
through green methods has been conducted to explore their diverse
properties and potential applications. Green synthesis is an auspicious
alternative approach to chemical synthesis, aimed at mitigating the
deleterious effects caused by the release of products during conven-
tional chemical synthesis [11,12]. Sayed Zia Mohammadi et al. [13]
synthesized Co3O4nanoparticles using walnut green skin extract as a re-
ducing agent. The researchers optimized synthesis using the response
surface approach. SEM, XRD, FTIR, and vibrating sample magnetome-
try were used to analyze the nanoparticles. SEM showed that the
nanoparticles were 60–80 nm in size. A magnetic study showed no co-
ercivity and reversible hysteresis in superparamagnetic behavior. Sharif
et al. [14] synthesized Fe3O4nanoparticles from spirogyra hyaline and
Ajuga bracteosa. The researchers next tested these nanoparticles' an-
timicrobial properties. Many analytical methods were used to study
biofabricated nanoparticles. Plant-based nanoparticles have stronger
antibacterial activity than algal nanoparticles, according to studies.
Due to phytochemicals in the plant-based extract, efficiency differs.
Poonguzhali et al. [15] synthesized Co3O4nanoparticles from lemon
essence. The researchers then examined these nanoparticles' gas-
sensing capacities for hazardous chemicals. Crystallite size increased
⁎Corresponding author.
E-mail address: ranjueaswar@gmail.com (E.R. Kumar).
https://doi.org/10.1016/j.snb.2024.135451
Received 16 January 2024; Received in revised form 1 February 2024; Accepted 2 February 2024
0925-4005/© 20XX
Note: Low-resolution images were used to create this PDF. The original images will be used in the final composition.
CORRECTED PROOF
S.S. Kavi et al. Sensors & Actuators: B. Chemical xxx (xxxx) 135451
during annealing and their gas-detecting abilities were promising. Hus-
sain et al. [16] synthesized nickel oxide nanoparticles from Acacia
nilotica leaf extract and examined their electrochemical and biological
properties. After producing aqueous and ethanol extracts, XRD, SEM,
and TGA were used to characterize them. The water extract nanoparti-
cles had smaller crystallite sizes than the ethanol extract ones. Electro-
chemistry showed that the ethanol extract was electrochemically sta-
ble. Sabouri et al. [17] synthesized NiO nanoparticles via egg white-
mediated green synthesis. Researchers then tested these nanoparticles'
cytotoxicity and photocatalytic performance. XRD, SEM, EDX, and TGA
were examined. Research shows that particle size increases with tem-
perature. Thus, calcination below 400 ℃is suitable for NiO nanoparti-
cle production. The photocatalytic degradation of MB dye under UVA
irradiation was also examined. Fakhari et al. [18]. produced zinc oxide
nanoparticles using L. nobilis leaf extract, zinc nitrate, and zinc acetate
salts. XRD, EDX, FT-IR, and UV-Vis characterization methods were ex-
amined. The nanoparticles' hexagonal wurtzite crystal structure
showed exceptional purity. Faisal et al. [19] synthesized zinc oxide
nanoparticles from Myristica fragrans aqueous fruit extracts. The re-
searchers next examined these nanoparticles' properties and possible bi-
ological and environmental applications. Zinc oxide nanoparticles were
synthesized from M. fragrans fruit extract. XRD analysis assessed purity
and particle size. Additional characterization methods were used. Many
biological and environmental applications are possible using ZnO
nanoparticles. Ananthi et al. [20] presented a green synthesis of Fe3O4
nanoparticles using natural tannic acid (green tea) for gas sensor appli-
cation. The physicochemical properties of Fe3O4nanoparticles were an-
alyzed. The prepared nanoparticles showed a better response to ethanol
gas than the other gases. Nanoparticles produced by biological ap-
proaches or green technology exhibit a wide range of characteristics, in-
cluding enhanced stability and optimal dimensions, owing to their syn-
thesis via a streamlined, single-step procedure. The objective of the pre-
sent study is to employ the green combustion approach for the synthesis
of diverse metal oxide nanoparticles, including Fe3O4, ZnO, NiO, and
Co3O4.Vitis vinifera, often known as grape juice, has been utilized as a
source of fuel in conjunction with metal nitrates to facilitate a combus-
tion reaction. Fresh grape juice is a unique fruit beverage that exhibits a
tartaric acid content ranging from 40 % to 80 %. This high concentra-
tion of tartaric acid renders the juice suitable for initiating a combus-
tion process, hence facilitating the production of nanoparticles. The
physicochemical features of four metal oxide nanoparticles were inves-
tigated using various characterization methods. The analysis included
investigating the effects of varied operation temperatures, gas concen-
trations, test gases, and response times. This paper presents a compre-
hensive examination of diverse methods employed in the synthesis of
nanoparticles, along with an analysis of their respective properties.
2. Experimental procedure
2.1. Method of synthesis
A simple combustion method has been selected to prepare a variety
of metal oxide nanoparticles. Grape juice (Vitis vinifera) has been uti-
lized as a fuel to perform combustion reactions along with metal ni-
trates. Analytical-grade metal nitrates [Fe(NO3)3·9H2O],
[Zn(NO3)2·6H2O], [Ni(NO3)2·6H2O] and [Co(NO3)2·6H2O] were taken
to prepare 0.5 M of solution with 50 ml of double-distilled water. The
metal nitrate solution was stirred continuously for 30 min with 50 ml of
double-distilled water. The metal nitrate solution was stirred continu-
ously for 30 min, and 50 ml of freshly extracted natural tartaric acid
(C4H6O6) (grape juice) was added to the metal nitrate solution. The
mixed solution is stirred again for 30 min to make a clear solution. The
mixed clear solution was heat treated at 160 ℃on a hot plate. The ef-
fect of heat treatment on the mixed solution performs a combustion re-
action, and a large amount of heat and flames evolve during the com-
bustion reaction. The final product was collected in the form of ash and
crushed into a fine powder using mortar. The ground fine powder was
dried at 100 ℃and the final product was subjected to various charac-
terization techniques.
2.2. Characterization techniques
The X-ray diffraction patterns were obtained under ambient condi-
tions using a PANalytical X′pert-PRO X-ray powder diffractometer
equipped with a CuKα1 (λ= 1.5406 Å) source. The transmission elec-
tron micrographs were generated using the Philips-TEM (CM20) instru-
ment. The stability of colloidal nanoparticles was assessed using the
Horiba SZ100 Zeta Potential analyser. FTIR analysis was conducted us-
ing the Thermo Nicolet IR200 spectrometer, covering the spectral range
of 400 –4000 cm−1.
2.3. Sensor fabrication and measurements
This section aims to present a comprehensive overview of the proce-
dure involved in the construction of a sensor and its subsequent appli-
cation within experimental settings. Fig. 1 depicts the schematic depic-
tion of the equipment utilized in the conducted experiments [21]. The
production of a sensor involved the grinding of four distinct metal oxide
nanoparticles utilizing a mortar and pestle. A suspension comprising of
Fig. 1. illustrates the schematic representation of the experimental setup used for testing the response of the gas sensor.
2
CORRECTED PROOF
S.S. Kavi et al. Sensors & Actuators: B. Chemical xxx (xxxx) 135451
finely pulverized particles and de-ionized water is introduced into an
aluminum cylinder with dimensions of 10 mm in length, an internal di-
ameter of 3 mm, and an external diameter of 5 mm. A set of silver (or
platinum) electrodes are situated within the tube, with a separation dis-
tance of 6 mm between them. To maintain the sensor's temperature, a
Ni-Cr coil heater is attached to the tube. The implementation of a
chromel-alumel thermocouple is employed to measure the operational
temperature of the sensor, which is attached to the heater. The assess-
ment of sensor performance and sensitivity entails the quantification of
sensor resistance across various gaseous conditions. To optimize the
sensor threshold response, modifications are implemented to both the
operational temperature and gas concentration. As illustrated in Fig. 1,
the load resistor RL is subsequently connected to the sensitive element
A. The sensor response (S) mentioned above can be modified by manip-
ulating the resistance of the sensor in the test gas (Rg) and in the air
(Ra).
(1)
3. Results and discussion
3.1. Structural analysis
The XRD was performed to investigate the structural and phase
properties of metal oxide nanoparticles (namely Fe3O4, ZnO, NiO, and
Co3O4) produced from Vitis vinifera (grape juice). The XRD spectra of
different metal oxide nanoparticles are shown in Fig. 2. All diffraction
Fig. 2. Structural analysis of metal oxide nanoparticles synthesized by green
combustion method.
peaks are identified and listed in accordance with the standard JCPDS
card dates. The detected peaks support the crystal structure of the metal
oxide nanoparticles produced using a green technique. These nanopar-
ticles have cubic and hexagonal configurations, which match the crystal
forms specified in the JCPDS card database [22–25]. The relative peak
integrated intensity (RPII) of NiO in the mixed phase is calculated as
INiO/(INiO + INi), where I denotes the peak integrated intensity of the
main peak of NiO(200) and Ni(200) [26,27]. The hkl plane orientation
in ZnO nanoparticles confirms the hexagonal structure, as demon-
strated by the lattice constants a= 3.248 Å and c= 5.320. The cubic
shapes of the other metal oxide nanoparticles match the standard data
well. The crystallite size of the metal oxide nanoparticles was calcu-
lated using the standard equation [28], and the results demonstrate that
the generated metal oxide nanoparticles lie inside the nanoscale range.
Table 1 shows the lattice parameter and crystallite size statistics, as well
as the crystal structure for each.
3.2. TEM analysis
The particle size and shape of the metal oxide nanoparticles gener-
ated using a green method have been documented using transmission
electron microscopy (TEM). Fig. 3(a-d) presents transmission electron
microscopy (TEM) pictures of several metal oxide nanoparticles,
namely Fe3O4, ZnO, NiO, and Co3O4. The TEM images of Fe3O4(Fig. 3a)
and ZnO (Fig. 3b) nanoparticles reveal a spherical morphology, with
particles exhibiting a limited size distribution and agglomeration
within the range of 18 nm to 25 nm. The transmission electron mi-
croscopy (TEM) images reveal that the nanoparticles of NiO (Fig. 3c)
and Co3O4(Fig. 3d) exhibit predominantly spherical and plate-like
shapes, respectively. These nanoparticles are shown to be agglomer-
ated, forming clusters with an average size ranging from 30 to 35 nm.
Both aggregation and agglomeration are forms of nanoparticle assem-
blies,
wherein the cohesive and compact groupings of particles are com-
monly known as aggregation. Agglomeration refers to the process
through which particles are loosely joined together and can be easily
disintegrated through mechanical forces [29]. The process of agglomer-
ation may be observed through the examination of transmission elec-
tron microscopy (TEM) pictures depicting the four metal oxide
nanoparticles that were generated using a green synthesis method. The
size fluctuation of the metal oxide nanoparticles exhibited a strong cor-
relation with the crystallite size determined using X-ray diffraction
(XRD) analysis.
3.3. Colloidal stability analysis
The surface charge and colloidal stability of metal oxide nanoparti-
cles are significant factors that impact the performance and suitability
of these nanoparticles in diverse applications. The Zeta potential values
of the green synthesized metal oxide nanoparticles were analyzed using
a Zeta potential analyzer and are presented in Table 1.Fig. 4 displays
the Zeta potential analysis of the four metal oxide nanoparticles. The
Zeta potential measurements provide evidence of the colloidal stability
of the nanoparticles that were synthesized. These measurements indi-
Table 1
Crystal parameters of metal oxide nanoparticles.
Sample Crystallite
Size
(nm)
Crystal
Structure
Lattice Parameters
Å
Particle
Size
(nm)
Zeta
Potential
mV
a b c
Fe3O420.8 Cubic 8.394 24 -58.7
ZnO 22.4 Hexagonal
Wurtzite
3.248 5.320 28 -30.1
NiO 27.5 Cubic 4.1778 34 48.4
Co3O430.6 Cubic 8.084 35 38.4
3
CORRECTED PROOF
S.S. Kavi et al. Sensors & Actuators: B. Chemical xxx (xxxx) 135451
Fig. 3. Displays the TEM images of metal oxide nanoparticles: (a) Fe3O4, (b) ZnO, (c) NiO and (d) Co3O4nanoparticles.
cate that the nanoparticles possess both negative and positive surface
charges. The nanoparticles of Fe3O4and ZnO exhibit negatively
charged surfaces, as indicated by their respective Zeta potential values
of −58.7 mV and −30.1 mV. This finding provides confirmation that
both of these metal oxides exhibit characteristics of n-type semiconduc-
tors. Simultaneously, the p-type nanoparticles of NiO and Co3O4exhibit
positive Zeta potential values of approximately 48.4 mV and 38.4 mV,
respectively. Nanoparticles exhibiting a zeta potential ranging from
−10 to +10 mV are often regarded as being close to electrically neutral.
Conversely, nanoparticles possessing zeta potentials exceeding +30
mV or falling below −30 mV are deemed to be strongly cationic and
strongly anionic, respectively. All four metal oxide nanoparticles ex-
hibit favorable Zeta potential values. Fe3O4nanoparticles have superior
stability compared to other metal oxide nanoparticles, as seen by their
high Zeta potential value, which closely aligns with the reported value
[30–32].
3.4. FT-IR analysis
Fourier Transform Infrared (FTIR) spectra were obtained in the solid
phase using the KBr pellet technique within the spectral range of
3500–400 cm−1. The Fourier-transform infrared (FTIR) spectra of iron
oxide (Fe3O4), zinc oxide (ZnO), nickel oxide (NiO), and cobalt oxide
(Co3O4) nanoparticles are presented in Fig. 5. The Fourier-transform in-
frared (FTIR) spectra of the metal oxide nanoparticles, namely Fe3O4,
ZnO, NiO, and Co3O4, revealed vibrations within the range of 400–600
cm−1. These vibrations can be ascribed to the oscillations of the metal
(M)−oxygen (O) bonds, where M represents Fe, Zn, Ni, and Co. This ob-
servation provides confirmation of the synthesis of Fe3O4, ZnO, NiO,
and Co3O4nanoparticles. The presence of a faint band at approximately
1560 cm−1in Fe3O4and ZnO can be ascribed to the N-O stretching of ni-
tro compounds. The current results are consistent with the values docu-
mented in the existing body of research [33–36].
3.5. Gas sensor analysis
Numerous metal oxides have favorable characteristics for the detec-
tion of flammable, reducing, or oxidizing gases by conductive measure-
ments. Gas sensor applications are commonly employed for metal oxide
nanoparticles due to their distinct features. Currently, there is a signifi-
cant amount of research being conducted on the gas-sensing properties
of various metal oxide nanoparticles in order to detect a range of poten-
tially harmful gases present in the surrounding environment [37–40].
There is a nascent technological development in the field of environ-
mental monitoring, wherein a novel memory device with gas sensing
capabilities, referred to as a 'gasistor', is being introduced [41]. The pre-
sent investigation centers on the preparation of appropriate nanomate-
rials for gas-sensing purposes prior to their proposed integration into
the memory device. Four distinct metal oxide nanoparticles were pro-
duced using green methods, and their characteristics were subsequently
examined for potential use in gas sensor applications. The present study
focused on the examination of gas sensor readings and the comprehen-
sive analysis of their sensing performances using various approaches.
i) Variation of sensor resistance with respect to operating
temperature
4
CORRECTED PROOF
S.S. Kavi et al. Sensors & Actuators: B. Chemical xxx (xxxx) 135451
Fig. 4. Colloidal stability and Zeta potential analysis of metal oxide nanoparticles.
ii) Sensor response vs. different gas concentrations for fixed
optimum temperature
iii) Sensor response vs. different test gases for fixed optimum
temperature and 1000 ppm gas concentration
iv) Variation of sensor resistance with respect to response-recovery
time
Fig. 6 depicts several gas sensor analyses conducted on nanoparti-
cles of metal oxides, including Fe3O4, ZnO, NiO, and Co3O4. The experi-
mentation involved testing the sensor resistance at various operating
temperatures, and the resulting plot depicting the resistance variation
is presented in Fig. 6a. This finding provides confirmation that the op-
erating temperature significantly influences the gas sensor analysis
process. The resistance of the sensor is evaluated at different opera-
tional temperatures in the presence of a test gas with randomly chosen
parts per million (ppm) concentrations. This is done to determine the
operating temperature of the sensor for four distinct metal oxide
nanoparticles. The plot demonstrates that the resistance of the sensor
exhibits variation across a range of operating temperatures, with lower
temperatures corresponding to lower resistance and higher tempera-
tures corresponding to higher resistance. The resistance of sensor mate-
rials typically varies based on the chemical reaction between the gener-
ated oxygen ions and the test gas. As the temperature increases, the
oxygen molecules adsorbed on the surface of the sensor material be-
come thermally activated and undergo a process where they acquire
electrons from the band gap of the sensor material, resulting in the for-
mation of oxygen anions. The process of converting oxygen anions is as
follows.
O2+ e-→O2-(2)
O-2+ e-→2O-(3)
At lower operating temperatures, the thermal energy possessed by
the input gas is insufficient to facilitate a reaction with the O-ions. Con-
sequently, the sensor exhibits increased resistance. As the temperature
rises, the thermal energy reaches a level at which it enables a chemical
reaction to occur between O-ions and generate conduction electrons.
The electrons engage in a reaction with oxygen molecules that are ab-
sorbed on the surface, resulting in an enhancement of the conductivity
of the materials used in the sensor.
The findings of this investigation indicate that the sensor materials,
specifically Fe3O4and ZnO nanoparticles, exhibit a confirmed working
temperature of 230 ℃, while NiO and Co3O4nanoparticles demonstrate
a confirmed operating temperature of 250 ℃. The enhanced gas sensor
response of metal oxide nanoparticles towards LPG gas can be attrib-
uted to their low sensor resistance value and high conductivity, as de-
picted in Fig. 6a. The sensor resistance gradually decreases and reached
to a minimum value at sensor operating temperature (SOT) and again
increases. It is ascribed to the reaction rate of test gas with the conduc-
tion electrons generated on the surface of sensor film. Generally, the
conduction electrons are generated on the surface of the sensor film
based on the mechanism O2–→2O––e–. Initially, the thermal energy of
test gas in not high enough to react with the electron. Therefore, the
conductivity is low showing the higher resistance. As temperature
raises, the thermal energy of test gas cope up the reaction with gener-
ated electrons showing the conductivity resulting to decrease of resis-
tance and then reaches to minimum value at SOT. Further rise in tem-
perature, the mobility of electrons increases over the thermal energy of
test gas. As a result of increase in mobility struggling of exothermic re-
action of gas absorption increases resulting decrease of conductivity.
Therefore, the sensor resistance increases with raise in temperature
above SOT. Among the four metal oxide nanoparticles examined, it was
observed that Fe3O4exhibited a superior sensor response compared to
the other metal oxide nanoparticles. The operational temperature for
5
CORRECTED PROOF
S.S. Kavi et al. Sensors & Actuators: B. Chemical xxx (xxxx) 135451
Fig. 5. Shows FT-IR spectra of various metal oxide nanoparticles.
Fe3O4and ZnO nanoparticles in the sensor is set at a constant value of
230 ℃in order to conduct more gas sensing experiments. The nanopar-
ticles of NiO and Co3O4exhibited their maximum sensor response at a
low resistance value when operated at a temperature of 250 ℃. The
greater working temperature of these two nanoparticles, NiO and
Co3O4, may be attributed to their P-type semiconducting characteris-
tics. Fig. 6b illustrates the sensor response of the metal oxide nanoparti-
cles at their respective optimal operating temperatures (230 ℃for
Fe3O4and ZnO, and 250 ℃for NiO and Co3O4) in relation to varying
quantities of LPG gas. The sensor's reaction has a positive correlation
with the concentration of gas, whereby an increase in gas concentration
leads to a rise in sensor response. The sensor's response reaches its peak
at a gas concentration of 1000 parts per million (ppm). The sensor re-
sponse of all four metal oxide nanoparticles exhibits its peak value at a
concentration of 1000 parts per million (ppm), when operated at their
respective optimal sensor operating temperatures. The Fe3O4nanopar-
ticles have a superior sensor response compared to other metal oxide
nanoparticles. The Fe3O4nanoparticles exhibit a greater sensor re-
sponse compared to other nanoparticles due to their low resistance at
low working temperatures. Ananthi et al. [42] conducted a study in
which they described a method for synthesizing Fe3O4nanoparticles us-
ing tannic acid derived from green tea.
The synthesized nanoparticles were utilized for the development of
an ethanol gas sensor. The results confirm a greater sensor response at a
concentration of 1000 parts per million (ppm) when the sensor is oper-
ating at its designated temperature. Various test gases, including LPG,
Ethanol, H2, CO2, and Acetone, were subjected to experimentation us-
ing four distinct metal oxide nanoparticles. These tests were conducted
at the sensor's designated operating temperature (230 ℃for Fe3O4&
ZnO and 250 ℃for NiO & Co3O4), with a consistent gas concentration
of 1000 ppm. Throughout the process of evaluating a variety of test
gases, the gas concentration remains constant (1000 ppm). The results
of these experiments can be observed in Fig. 6c. The results indicate
that the sensor had a maximum response of 0.96 or 96 % specifically to-
wards LPG gas, surpassing the responses seen for the other test gases.
Simultaneously, the metal oxide nanoparticles exhibited a discernible
response rate towards ethanol gas. The metal oxide nanoparticles
elicited responses from all other gases, albeit without a discernible pat-
tern of increasing magnitude. The observed high sensor response for
LPG can perhaps be attributed to the presence of conduction electrons.
C3H8+ 10O→-3CO2+ 4H2O + 10e-(4)
C4H10 + 13O→-4CO2+ 5H2O + 13e-(5)
The conductivity of the sensor material can be influenced by the cas-
cading of O-ions resulting from the accumulation of electron concentra-
tion on the surface. The response and recovery times are crucial ele-
ments to consider while building a gas sensor. The reaction time refers
to the duration necessary for the application of the test gas and subse-
quent attainment of 90 % conductivity in relation to the equilibrium
value [43–46]. The recovery time refers to the duration necessary for
the sensor to attain its initial air conductivity. Fig. 6d illustrates the
graph depicting the resistance fluctuation of the sensors for the four
metal oxide nanoparticles when exposed to a gas concentration of 1000
ppm LPG at their respective operating temperatures (230 ℃for Fe3O4&
ZnO and 250 ℃for NiO & Co3O4). The experimental results indicate
that Fe3O4and ZnO nanoparticles have a response time of 50 s, while
NiO and Co3O4nanoparticles exhibit a response time of 60 s. The rapid
reaction and recovery time of the produced metal oxide nanoparticles
validate their potential as attractive materials for gas sensor applica-
tions aimed at environmental monitoring.
4. Conclusion
In the current research, several different types of metal oxide
nanoparticles, including Fe3O4, ZnO, NiO, and Co3O4, were produced in
a straightforward and economical manner. Vitis vinifera juice, in com-
bination with metal nitrates, was selected as a sustainable fuel source.
In order to investigate the microstructure and colloidal stability of
green-synthesized metal oxide nanoparticles, a number of different
methods of characterization were utilized. X-ray diffraction was uti-
lized so that we could investigate the lattice properties and crystallite
sizes of metal oxide nanoparticles. This demonstrates that a significant
number of metal oxide nanoparticles have crystallite diameters ranging
from 20 to 30 nm. The transmission electron microscope was used to
record the shape and size of metal oxide nanoparticles. In addition, the
particle size of these nanoparticles was determined, and the results of
the XRD experiment were a good match for it. Nanoparticles composed
of metal oxide can have an external morphology that is either spherical,
cubical, or plate-like. The p-type nanoparticles of NiO and Co3O4ex-
hibit positive Zeta potential values of 48.4 mV and 38.4 mV, respec-
tively. Fe3O4nanoparticles showed highest negative colloidal stability
−58.7 mV than the other metal oxide nanoparticles. The analysis fo-
cused on the stretching vibrations of the synthesised nanoparticles and
their corresponding functional groups. The presence of metal-oxygen
(M-O) stretching vibrations, such as Fe-O, Zn-O, Ni-O, and Co-O, was
verified through analysis of the Fourier-transform infrared (FT-IR) spec-
trum within the wavenumber range of 400–600 cm−1. The physico-
chemical properties of the metal oxide nanoparticles show that the syn-
thesised nanoparticles have a fast response and recovery time, making
them attractive for gas sensor applications.
6
CORRECTED PROOF
S.S. Kavi et al. Sensors & Actuators: B. Chemical xxx (xxxx) 135451
Fig. 6. Sensor behavior of green synthesized metal oxide nanoparticles: (a) Variation of sensor resistance vs operating temperature; (b) Sensor response vs different
gas concentrations; (c) Sensor response for various test gases; (d) Variation of sensor resistance vs response-recovery time.
CRediT authorship contribution statement
Ranjith Kumar Easwaran: Conceptualization. El-Rehim A.F. Abd:
Investigation. Kavi S. Sindhu: Conceptualization.
Declaration of Competing Interest
There is no Conflict of Interest.
Data availability
Data will be made available on request.
Acknowledgment
The authors extend their appreciation to the Deanship of Scientific
Research at King Khalid University for funding this work through large
group Research Project under grant number RGP2/325/44.
References
[1] Sana Batool, Murtaza Hasan, Momina Dilshad, Ayesha Zafar, Tuba Tariq, Ziqian
Wu, Renxiang Chen, et al., Green synthesis of Cordia myxa incubated ZnO, Fe2O3,
and Co3O4nanoparticle: characterization, and their response as biological and
photocatalytic agent, Adv. Powder Technol. 33 (11) (2022) 103780.
[2] Nazmi Sedefoglu, Characterization and photocatalytic activity of ZnO
nanoparticles by green synthesis method, Optik 288 (2023) 171217.
[3] Adnan H. Alrajhi, Naser M. Ahmed, Green Synthesis of Zinc Oxide Nanoparticles
Using Salvia officinalis Extract. Handbook of Green and Sustainable
Nanotechnology: Fundamentals, Developments and Applications, Springer
International Publishing, Cham, 2023, pp. 1–21.
[4] V.P. Aswathi, S. Meera, C.G.Ann Maria, M. Nidhin, Green synthesis of
nanoparticles from biodegradable waste extracts and their applications: a critical
review, Nanotechnol. Environ. Eng. 8 (2) (2023) 377–397.
[5] Lemma Tirfie Zegebreal, Newayemedhin A. Tegegne, Fekadu Gashaw Hone,
Recent progress in hybrid conducting polymers and metal oxide nanocomposite for
room-temperature gas sensor applications: a review, Sens. Actuators A: Phys.
(2023) 114472.
[6] Siyuan Wang, Ding Chen, Qiu Hong, Ying Gui, Yucheng Cao, Guanlin Ren, Zhao
Liang, Surface functionalization of metal and metal oxide nanoparticles for
dispersion and tribological applications-a review, J. Mol. Liq. (2023) 122821.
[7] Abril Freire, Eduardo Chung, Ian Mendoza, Juan Antonio Jaén, Green synthesis
of iron oxide nanoparticles using Caesalpinia coriaria (Jacq.) Willd. fruits extract,
Hyperfine Interact. 244 (1) (2023) 6.
[8] Kiran Kenchappa Somashekharappa, Ramesh Basavapattna Halappa, Shashanka
Rajendrachari, Green Chemistry Applications in Electrochemical Sensors. Recent
Developments in Green Electrochemical Sensors: Design, Performance, and
Applications, American Chemical Society, 2023, pp. 23–37.
[9] Biplab Kumar Mandal, Rahul Mandal, Suranjan Sikdar, Sidananda Sarma,
Ananthakrishnan Srinivasan, Subhajit Roy Chowdhury, Bhaskar Das, Rahul Das,
Green synthesis of NiO nanoparticle using Punica granatum peel extract and its
characterization for methyl orange degradation, Mater. Today Commun. 34 (2023)
105302.
[10] Qudsiya Y. Tamboli, Sunil M. Patange, Yugal Kishore Mohanta, Rohit Sharma,
Kranti R. Zakde, Green synthesis of cobalt ferrite nanoparticles: an emerging
material for environmental and biomedical applications, J. Nanomater. 2023
(2023).
[11] V.P. Aswathi, S. Meera, C.G.Ann Maria, M. Nidhin, Green synthesis of
7
CORRECTED PROOF
S.S. Kavi et al. Sensors & Actuators: B. Chemical xxx (xxxx) 135451
nanoparticles from biodegradable waste extracts and their applications: a critical
review, Nanotechnol. Environ. Eng. 8 (2) (2023) 377–397.
[12] Kiran Kenchappa Somashekharappa, Ramesh Basavapattna Halappa, Shashanka
Rajendrachari, Green Chemistry Applications in Electrochemical Sensors. Recent
Developments in Green Electrochemical Sensors: Design, Performance, and
Applications, American Chemical Society, 2023, pp. 23–37.
[13] Sayed Zia Mohammadi, Batoul Lashkari, Azita Khosravan, Green synthesis of
Co3O4nanoparticles by using walnut green skin extract as a reducing agent by
using response surface methodology, Surf. Interfaces 23 (2021) 100970.
[14] Muhammad Shakeeb Sharif, Hajra Hameed, Abdul Waheed, Muhammad Tariq,
Afshan Afreen, Asif Kamal, Eman A. Mahmoud, Hosam O. Elansary, Saddam Saqib,
Wajid Zaman, Biofabrication of Fe3O4nanoparticles from Spirogyra hyalina and
ajuga bracteosa and their antibacterial applications, Molecules 28 (8) (2023) 3403.
[15] R.Vandamar Poonguzhali, E.Ranjith Kumar, Ch Srinivas, Mubark Alshareef,
Meshari M. Aljohani, Ali A. Keshk, Nashwa M. El-Metwaly, N. Arunadevi, Natural
lemon extract assisted green synthesis of spinel Co3O4nanoparticles for LPG gas
sensor application, Sens. Actuators B: Chem. 377 (2023) 133036.
[16] Shabbir Hussain, Muazzam Ali Muazzam, Mahmood Ahmed, Muhammad
Ahmad, Zeeshan Mustafa, Shahzad Murtaza, Jigar Ali, Muhammad Ibrar,
Muhammad Shahid, Muhammad Imran, Green synthesis of nickel oxide
nanoparticles using Acacia nilotica leaf extracts and investigation of their
electrochemical and biological properties, J. Taibah Univ. Sci. 17 (1) (2023)
2170162.
[17] Zahra Sabouri, Alireza Akbari, Hasan Ali Hosseini, Mehrdad Khatami, Majid
Darroudi, Egg white-mediated green synthesis of NiO nanoparticles and study of
their cytotoxicity and photocatalytic activity, Polyhedron 178 (2020) 114351.
[18] Shabnam Fakhari, Mina Jamzad, Hassan Kabiri Fard, Green synthesis of zinc
oxide nanoparticles: a comparison, Green. Chem. Lett. Rev. 12 (1) (2019) 19–24.
[19] Faisal, Shah, Hasnain Jan, Sajjad Ali Shah, Sumaira Shah, Adnan Khan,
Muhammad Taj Akbar, Muhammad Rizwan, et al., Green synthesis of zinc oxide
(ZnO) nanoparticles using aqueous fruit extracts of Myristica fragrans: their
characterizations and biological and environmental applications, ACS Omega 6
(14) (2021) 9709–9722.
[20] Mahesh Vahini, Sivakumar Sowmick Rakesh, Rajakannu Subashini, Settu
Loganathan, Dhakshinamoorthy Gnana Prakash, In vitro biological assessment of
green synthesized iron oxide nanoparticles using Anastatica hierochuntica (Rose of
Jericho), Biomass Convers. Biorefinery (2023) 1–11.
[21] T. Pushpagiri, E. Ranjith Kumar, A. Ramalingam, A.F. Abd El-Rehim, Ch Srinivas,
Effect of doping concentration on structural, vibrational, morphological and
colloidal stability of Zn doped NiO nanoparticles for gas sensor applications,
Ceram. Int. (2023).
[22] Mostafa Yusefi, Kamyar Shameli, Ong Su Yee, Sin-Yeang Teow, Ziba
Hedayatnasab, Hossein Jahangirian, Thomas J. Webster, Kamil Kuča, Green
synthesis of Fe3O4nanoparticles stabilized by a Garcinia mangostana fruit peel
extract for hyperthermia and anticancer activities, Int. J. Nanomed. (2021)
2515–2532.
[23] K. Karthik, M. Shashank, V. Revathi, Tetiana Tatarchuk, Facile microwave-
assisted green synthesis of NiO nanoparticles from Andrographis paniculata leaf
extract and evaluation of their photocatalytic and anticancer activities, Mol. Cryst.
Liq. Cryst. (2019).
[24] Tu. Uyen Doan Thi, Trung Thoai Nguyen, Y.Dang Thi, Kieu Hanh Ta Thi, Bach
Thang Phan, Kim Ngoc Pham, Green synthesis of ZnO nanoparticles using orange
fruit peel extract for antibacterial activities, RSC Adv. 10 (40) (2020)
23899–23907.
[25] K. Kombaiah, J.Judith Vijaya, L.John Kennedy, K. Kaviyarasu, R.Jothi
Ramalingam, Hamad A. Al-Lohedan, Green synthesis of Co3O4nanorods for highly
efficient catalytic, photocatalytic, and antibacterial activities, J. Nanosci.
Nanotechnol. 19 (5) (2019) 2590–2598.
[26] Sodky Hamed Mohamed, Synthesis, structural and ellipsometric evaluation of
oxygen-deficient and nearly stoichiometric zinc oxide and indium oxide
nanowires/nanoparticles, Philos. Mag. 91 (27) (2011) 3598–3612.
[27] S.H. Mohamed, Kh.M. Al-Mokhtar, Characterization of Cu2O/CuO nanowire
arrays synthesized by thermal method at various temperatures, Appl. Phys. A 124
(2018) 493.
[28] M. Deepty, Srinivas Ch, P.N. Ramesh, N.Krishna Mohan, Meena Sher Singh, C.L.
Prajapat, Amit Verma, D.L. Sastry, Evaluation of structural and dielectric properties
of Mn2+-substituted Zn-spinel ferrite nanoparticles for gas sensor applications,
Sens. Actuators B: Chem. 316 (2020) 128127.
[29] Anthony Cartwright, Kyle Jackson, Christina Morgan, Anne Anderson, David W.
Britt, A review of metal and metal-oxide nanoparticle coating technologies to
inhibit agglomeration and increase bioactivity for agricultural applications,
Agronomy 10 (7) (2020) 1018.
[30] C.Arun Paul, E.Ranjith Kumar, J. Suryakanth, A.F. Abd El-Rehim, Structural,
microstructural, vibrational, and thermal investigations of NiO nanoparticles for
biomedical applications, Ceram. Int. (2023).
[31] C.Arun Paul, E. Ranjith Kumar, J. Suryakanth, A.F. Abd El-Rehim, Analysis and
characterization of structural, morphological, thermal properties and colloidal
stability of CuO nanoparticles for various natural fuels, Ceram. Int. 49 (19) (2023)
31193–31209.
[32] V. Praveenkumar, E. Janarthanan, E. Ranjith Kumar, B. Ranjithkumar, S.
Sathiyaraj, H.B. Ramalingam, Salman S. Alharthi, Effect of fuel concentration on
structural, vibrational, morphological properties and particle stability of NiO
nanoparticles, Ceram. Int. 48 (24) (2022) 37027–37031.
[33] Parvaneh Esmaeilnejad-Ahranjani, Marzieh Lotfi, Surfactant-assisted combustion
synthesis of agglomerated-free, size-and shape-controlled magnetic iron oxide
nanoparticles for biomedical applications, Ceram. Int. (2023).
[34] Azza Al-Ghamdi, T. Indumathi, E. Ranjith Kumar, Green synthesized zinc oxide
nanoparticles: effect of polyethylene glycol and chitosan on structural, optical and
morphological analysis, Ceram. Int. 48 (13) (2022) 18324–18329.
[35] Siranjeevi Ravichandran, Prabhu Sengodan, Jeyalakshmi Radhakrishnan,
Evaluation of biosynthesized nickel oxide nanoparticles from Clerodendrum
phlomidis: a promising photocatalyst for methylene blue and acid blue dyes
degradation, Ceram. Int. 49 (8) (2023) 12408–12414.
[36] Paul, C. Arun, E. Ranjith Kumar, A.F. Abd El-Rehim, and G. Yang. "Cobalt oxide
nanoparticles for biological applications: Synthesis and physicochemical
characteristics for different natural fuels." Ceramics International (2023).
[37] Yonghui Deng, Sensing mechanism and evaluation criteria of semiconducting
metal oxides gas sensors. Semiconducting Metal Oxides for Gas Sensing, Springer
Nature Singapore, Singapore, 2023, pp. 33–74.
[38] Neeraj Goel, Kishor Kunal, Aditya Kushwaha, Mahesh Kumar, Metal oxide
semiconductors for gas sensing, Eng. Rep. 5 (6) (2023) e12604.
[39] Yonghui Deng, Understanding semiconducting metal oxide gas sensors.
Semiconducting Metal Oxides for Gas Sensing, Springer Nature Singapore,
Singapore, 2023, pp. 1–32.
[40] Yonghui Deng, Applications of semiconducting metal oxide gas sensors,
Semicond. Met. Oxides Gas. Sens. (2023) 325–385.
[41] Doowon Lee, Min Ju Yun, Kyeong Heon Kim, Sungho Kim, Hee-Dong Kim,
Advanced recovery and high-sensitive properties of memristor-based gas sensor
devices operated at room temperature, ACS Sens. 6 (11) (2021) 4217–4224.
[42] S. Ananthi, M. Kavitha, E.Ranjith Kumar, A. Balamurugan, Y. Al-Douri, Hanan K.
Alzahrani, Ali A. Keshk, Turki M. Habeebullah, Shams H. Abdel-Hafez, Nashwa M.
El-Metwaly, Natural tannic acid (green tea) mediated synthesis of ethanol sensor
based Fe3O4nanoparticles: investigation of structural, morphological, optical
properties and colloidal stability for gas sensor application, Sens. Actuators B:
Chem. 352 (2022) 131071.
[43] Reshma Prakshale, Sachin Bangale, Mahesh Kamble, Sanjay Sonawale, Synthesis,
study and characterization of spinel CoFe2O4 for the ethanol gas-sensing
applications, J. Mater. Sci.: Mater. Electron. 34 (27) (2023) 1852.
[44] S. Ananthi, M. Kavitha, A. Balamurugan, E. Ranjith Kumar, G. Magesh, A.F. Abd
El-Rehim, Ch Srinivas, P. Anilkumar, J. Suryakanth, C. Sharmila Rahale, Synthesis,
analysis and characterization of Camellia sinensis mediated synthesis of NiO
nanoparticles for ethanol gas sensor applications, Sens. Actuators B: Chem. 387
(2023) 133742.
[45] N.M.A. Hadia, Meshal Alzaid, Bandar Alqahtani, Mohammed Al-Shaghdali, W.S.
Mohamed, Mohammed Ezzeldien, Mohamed Shaban, et al., Enhancement of
optical, electrical and sensing characteristics of ZnO nanowires for optoelectronic
applications, J. Mater. Sci.: Mater. Electron. 34 (5) (2023) 456.
[46] N.M.A. Hadia, Mohammed S. Alqahtani, S.H. Mohamed, WO 3 nanowires for
optoelectronic and gas sensing applications, Appl. Phys. A 119 (2015) 1261–1267.
Ms. S. Sindhu Kavi is doing her research in the field of materials science under the guid-
ance of Dr. E. Ranjith Kumar. Her current areas of interest in study are low-dimensional
materials, metal oxides, magnetic materials, nanocomposites, and biomaterials for use in
a variety of applications, including energy storage devices, gas sensors, biosensors, an-
tibacterial, and fungal agents.
Ms. V. Susithra is doing her research in the field of materials science under the guid-
ance of Dr. E. Ranjith Kumar. Her current areas of interest in study are low-dimensional
materials, metal oxides, magnetic materials, nanocomposites, and biomaterials for an-
tibacterial and fungal agents.
8
CORRECTED PROOF
S.S. Kavi et al. Sensors & Actuators: B. Chemical xxx (xxxx) 135451
Prof. Dr. A.F. Abd El-Rehim obtained MSc and PhD in Physics (Materials Science) in
2000 and 2004 from Ain Shams University, Egypt. He attended the School of Materials,
University of Manchester, UK, on June 2013 as a Visiting Postdoctoral Researcher. Whilst
in attendance, He has been an integral member of the LATEST2 research project (Light Al-
loys towards Environmentally Sustainable Transport: 2nd Generation) and he has fully
participated in all group work. He has held research or/and academic positions at UOM
(UK), PSMCHS (KSA), Sanaa University (Yemen), ASU (EGYPT), KKU (KSA). Research in-
terests are Nanostructures & Nanomaterials, Microstructure, Optical Properties, Thin
Films Technology.
Dr. E. Ranjith Kumar, has been working as an Associate Professor of Physics at KPR In-
stitute of Engineering and Technology, since August 2020. He received his Ph.D. degree
in Physics from Bharathiyar University in 2014. His current areas of interest in study are
low-dimensional materials, metal oxides, magnetic materials, nanocomposites, and bio-
materials for use in a variety of applications, including energy storage devices, gas sen-
sors, biosensors, antibacterial, and fungal agents. He is an expert in analyzing Rietveld re-
finements of XRD and FITR spectroscopic data. He has published 125 articles in Q1&Q2
journals. Elsevier BV and Stanford University, USA have consistently recognized him for
the past TWO YEARS (2021 & 2022) as top 2 % of the World Scientist in the field of Mate-
rial Science. He is working as a reviewer for many journals from Elsevier, Springer, RSC,
ACS, ASP and AIP.
9
