Photocatalytic, nitrite sensing and antibacterial studies of facile bio-synthesized nickel oxide nanoparticles

These results convey that the NiO nanoparticles modi ﬁed electrode can act as a novel non-enzymatic sensor in trace level quanti ﬁcation of nitrite.. 3.9.[r]

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Original Article

C.R Rajith Kumara, Virupaxappa S Betageria, G Nagarajub, G.H Pujarc, B.P Sumad, M.S Lathaa,*

aResearch Centre, Department of Chemistry, G M Institute of Technology, Davangere, Karnataka, 577006, India bEnergy Materials Research Laboratory, Department of Chemistry, SIT, Tumakuru, Karnataka, 572103, India cResearch Centre, Department of Physics, G M Institute of Technology, Davangere, Karnataka, 577006, India dDepartment of Chemistry, Bangalore University, Central College Campus, Bengaluru, 560001, India

a r t i c l e i n f o

Article history:

Received 15 October 2019 Received in revised form February 2020 Accepted 11 February 2020 Available online xxx

Keywords: NiO nanoparticles Calotropis gigantea Dye degradation Antibacterial activity Nitrite sensing

a b s t r a c t

In the present work, Nickel oxide nanoparticles (NiO NPs) were synthesized using leaves extract of C gigantea through a solution combustion method The NiO NPs were characterized through analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) The XRD results revealed rhombohedral structured crystallites with average size of 31 nm SEM and TEM images indicate that the nanoparticles are agglomerated with an asymmetrical shape The optical energy bandgap of 3.45 eV was estimated using UV-diffused reﬂectance spectroscopy (UV-DRS) The synthesized NiO NPs have shown superior photodegradation for methylene blue (MB) dye Further, the antibacterial activity of the pre-pared nanoparticles was tested against E.coli and S.aureus bacterial strains In addition, nanoparticles were utilized for electroanalytical applicability as a novel non-enzymatic sensor in the trace level quantiﬁcation of nitrite The proposed nitrite sensor showed wide linearity in the range 8e1700mM and good stability with a lower detection limit of 1.2mM

© 2020 The Authors Publishing services by Elsevier B.V on behalf of Vietnam National University, Hanoi This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

1 Introduction

Nanoscience and nanotechnology have acquired an excellent impetus in the rapidly growing technological era by covering the basic understanding of physicochemical and biological properties in atomic/sub-atomic levels with promising applications in various fields [1] In the last few years, various researchers investigated on transition metal oxide nanoparticles due to their increasing importance and potential applications [2] Among all, NiO an interesting p-type, wide direct bandgap semiconductor (3.4e4.0 eV), has caught more attention owing to its key applica-tions Indeed, nano-sized NiO materials have gained great interest with respect to bulk NiO because of their size quantization and large surface-area ratio [3] Due to their unique and remarkable properties NiO NPs gained significant importance in various fields,

as battery cathodes/anodes [4], catalysis [5], solar cells [6], mate-rials for sensors [7], electrochemical super capacitors [8] Various plants have been increasingly employed in the synthesis of nano-particles due to their ample advantages in elimination of elaborate processes of maintaining cell cultures, cost-effectiveness and easy scale up for large-scale synthesis During the bioproduction of NPs, plant extracts act as both reducing and stabilizing agents [9] Kumar et al [10], and Vidya et al [11], have reported about the synthesis of Ag NPs, and ZnO NPs using leaf extract of Calotropis gigantea In the present study, NiO NPs have been synthesized using leaves extracts of C gigantea plant The C gigantea, also called as Arka, Madara, etc., belongs to the family of Apocynaceae and is available throughout India, especially in the dry and vast land Various phytochemical constituents are present in different parts of the Calotropis plant, mainly in the leaves, which acts as a reducing and stabilizing agents during the synthesis of NPs

Highly toxic dyes play a major role in polluting water These, are frequently being used in the industries like textile, food, cosmetics, paper, plastics, etc., [12] The natural degradation of such dyes is very difﬁcult due to their complex structure However, recently,

* Corresponding author GM Institute of Technology Davangere, Karnataka, 577006, India

E-mail address:lathamschem97@gmail.com(M.S Latha)

Peer review under responsibility of Vietnam National University, Hanoi

Contents lists available atScienceDirect

Journal of Science: Advanced Materials and Devices j o u r n a l h o m e p a g e : w w w e l s e v i e r c o m / l o c a t e / j s a m d

https://doi.org/10.1016/j.jsamd.2020.02.002

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various semiconductor photocatalysts NiO, Cu2O, FeO, etc., have

been developed to degrade the organic pollutants [13,14] In the present study, the synthesized NiO NPs have been used to study the photocatalytic degradation of methylene blue dye Various nano-structure materials have shown good antibacterial activity against human pathogens [15] Earlier reports have demonstrated the possibility of utilization of metal oxide NPs, in particular, NiO NPs in biomedicines due to their unique therapeutic and biological prop-erties such as adsorbing and metal ion releasing ability, cytotoxic effects and surface-area ratio [16] Hence, the antibacterial activity of NiO NPs has been demonstrated in the present study

In the past decades, the highly sensitive detection of‘nitrite’ has caught increasing interest because of its harmful effect on both human health and global environment Further, ground water pollution is rapidly increasing by‘nitrates’ due to the anthropogenic activities [17] The World Health Organization (WHO) recommends, the maximum limit of‘nitrite’ should be mg/L in drinking water [18], hence, it is an important task of chemists to monitor the existing levels/limits of nitrite in water and environment Generally, the analysis of nitrites can be quantified by using various tech-niques such as chromatography, spectrophotometry/spectro-fluorimetry, electroluminescent and capillary electrophoresis techniques However, some of the above quantitative techniques lack sensitivity and, high detection limits and require extensive instrumentation In contrast, electrochemical methods give better precision quantification over all these methods in terms of sensi-tivity/selectivity [19] In a quantitative analysis, the thorough exploitation of CMEs within thefield of electrochemistry and sur-face manipulation with selective indicator moieties is desirable to achieve the tailored properties Such CMEs have found to be very sensitive, easy to fabricate and target specific in electrochemical applications [20] Here, the synthesized NiO NPs have been used as a modifier molecule in the fabrication of electrode The modifier electrode has been explored for its electroanalytical applicability as a novel non-enzymatic sensor in trace level quantification of nitrite Experimental section

2.1 Materials

All the chemicals (analytical grade) were purchased from SDeFine Chemicals Pvt Ltd and Hiemedia and used without any further puriﬁcation.

2.2 Instrumentation and experimental methods

The Crystalline nature and phase purity was identiﬁed with the aid of the X-ray diffractometer (Rigaku Smart Lab) The morphology and elemental composition of the material was examined using SEM and EDAX (Hitachi S3400n), respectively The HR-TEM with SAED (Jeol/JEM 2100) was used to measure shape and size of the nanoparticles, respectively The FT-IR spectrometer (Bruker alpha-P) was used to examine the functional groups Absorption spectra were recorded with the UVeVisible spectrophotometer (Agilent technology cary-60 spectrophotometer) The diffuse reﬂectance spectrum was measured using the Lab India UV 3092, UV-VIS spectrophotometer Electrochemical measurements were ach-ieved using the CH instrument

2.3 Synthesis of NiO NPs

Freshly collected leaves of C gigantea were washed, dried and grinded well The Soxhlet extractor with water as solvent was used for the extraction for h and the obtained extract was dried using a rotary evaporator The combustion synthesis method was used to

synthesize NiO NPs using Nickel nitrate hexahydrate (Ni (NO3)26H2O) as an oxidizer and C gigantea leaves extract as a fuel

In this process, gm of the extract dissolved in 100 mL of double distilled water was, constantly stirred for 10 to get a homog-enous solution Ni (NO3)26H2O of 0.5 M was dissolved in 10 mL of

C gigantea extract and was placed in a preheated mufﬂe furnace (400± 10C) A smouldering reaction takes place and the entire

process was completed within 10 The obtained NiO NPs were subjected for calcinations at 500C for h to eliminate the impu-rities Until further use, the obtained product was stored in an airtight container

2.4 Photo catalytic studies

The photocatalytic studies of NiO NPs were assessed by the degradation of cationic methylene blue (MB) dye in aqueous media using a 250 W UV-light irradiation source For the photocatalytic experiments, a visible annular photoreactor was used, which con-sists of cylindrical tubes with transparent interior to employ com-plete radiation In this process, 50 mg of NiO NPs as a photocatalyst was added to quartz tubes of 100 mL capacity, which contains 100 mL MB solution of concentration ppm The solution was continuously air bubbled for complete mixing of the MB dye and the photocatalyst Then, mL was taken out from the above solu-tion, theﬁrst time after 15 and then at regular intervals of 30 The percentage of degradation of the cationic MB dye has been calculated using the BeereLambert law as follows [21]: % of degradation¼Ci Cf

Ci 100 (1)

where, Ciand Cfare the initial andﬁnal concentration of the dye

solution, respectively 2.5 Antibacterial studies

The antibacterial activity of NiO NPs was screened against Gram positive bacteria NCIM-5022 and Gram negative bacteriaNCIM-5051 through the Agar well diffusion method [22] The bacteri-cidal activity of NiO NPs was tested in Nutrient Agar (NA) media, the NA plates were prepared using 28 gm of NA media Then, it was dissolved in 1000 mL of double distilled water and subjected to pasteurization at 121C with pressure of 15 lbs during 15e20 NA plates with 100ml of 24 h mature broth culture of each indi-vidual bacterial strains were prepared and swabbed using a sterile L-shaped glass rod In each petri - plate mm wells were made using a sterile cork bore The NiO NPs were dispersed in sterile double distilled water and loaded onto the well The zone of inhi-bition (ZOI) was measured after the incubation of NA plates for 24 h at 37C [23,24]

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electrode, a platinum disc electrode as a counter electrode and saturated Ag/AgCl electrode as a reference electrode [25]

3 Results and discussion

3.1 Structural and morphological analysis

The diffractogram of green synthesized NiO NPs is depicted in Fig (a)The XRD peaks coincide with the rhombohedral structure and match well with the standard value of JCPDS (No 22e1189), with lattice parameters (a¼ 2.954, c ¼ 7.236) and Space group R-3m

166 From the XRD pattern, it was conﬁrmed that NiO NPs exhibited a crystalline nature with no impurity peaks The crystallite size of NiO NPs was estimated using the Debye-Scherer's formula [32]:

D¼b0:9l

cosq (2)

where, ‘D’ is the crystallite size of synthesized NPs, ‘l’ is the wavelength of X-ray radiation (1.54 Å),‘b’ is the full width at half maximum (FWHM) of the diffraction peak and ‘q’ is Bragg's

Fig (a) XRD pattern (b) EDAX spectrum (c, d) SEM images of synthesized NiO NPs

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diffraction angle The average crystallite size of NiO NPs was found to be 31 nm

InfigFig (b)EDAX report confirms the elemental composition of Ni and O The SEM micrographs (Fig 1(c and d) show the agglomeration with irregularly shaped nanoparticles The TEM micrograph (Fig (a)) confirms that sizes of crystallites are in the range of about 10e30 nm which is in good agreement with the estimated value of XRD the analysis.Fig 2(b and c) represent the HR-TEM micrographs that show particles in hexagonal and rhom-bohedral shape with interplanar spacing of 0.21 nm The SAED pattern depicted inFig 2(d) indicates the presence of (111) (200) and (220) planes of the synthesized rhombohedral NiO NPs 3.2 Fourier transform infrared spectroscopy analysis

The FT-IR spectrum of NiO NPs is shown inFig The spectrum is scanned in the range 400e4000 cm1 to analyse the various

functional groups The absorption band that appeared at

3410 cm1corresponds to (OeH) stretching of water and at 1632 cm1 to (HeOeH) bending vibrations The band at 1114 cm1is due to (CeO) bonds of carbon dioxide adsorbed on the NPs surface The bands corresponding to stretching and bending vibrations of (CeH) were observed at 2912 and 1381 cm1, respectively In addition, the signiﬁcant absorption band at 430 cm1is attributed to metaleoxygen (NieO) stretching vibra-tions [37].Thus, the expected structure and functional groups are conﬁrmed by the above results

3.3 Diffuse reﬂectance spectroscopic (DRS) analysis

Fig (a)shows the DRS spectrum of green synthesized NiO NPs A blue shifted strong absorption peak is observed at 305 nm DRS Spectral data can be used to estimate the optical energy bandgap of biosynthesised NiO NPs as shown inFig (b) The optical energy bandgap was determined using the KubelkaeMunk equation [22]:

Fig FT-IR spectrum of synthesized NiO NPs

Fig (a) Diffuse reﬂectance spectrum (DRS) (b) Optical energy band gap (Eg) of synthesized NiO NPs

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FRị ẳ1 Rị2

2R (3)

where, R is the reﬂection coefﬁcient of the sample From eq.(3), plot of F(R)2 vs the photon energy (eV) gives an optical energy bandgap (Eg) of 3.45 eV Thus, nanoscale NiO exhibits directly a wide bandgap semiconductor nature

3.4 Photocatalytic studies

The photocatalytic behavior of green synthesized NiO NPs is assessed through the photo-degradation of the MB dye with the aid of visible annular type photoreactor under UV light irradiation The actual trail starts when the light is irradiated and, the photon of energy is consumed by the semiconducting NiO in which the band gap is higher Electrons and hole pairs are generated in the con-duction and valence bands If the charge carriers are not put together again, then the migration of free electrons on the surface leads to the oxygen reduction and formation of peroxides and su-peroxides The newly generated holes can oxidizes water and forms OH free radicals Such radicals are unstable and highly reactive in nature, which eventually leads to the organic dye degradation The photocatalytic action on dyes is enhanced by factors like particle size, morphology, composition, size distribution, surface area, band gap, etc The steady decrease in the absorption peak intensity at 663 nm by the time exposed to UV light indicates the dye degra-dation as shown in Fig The degradation efﬁciency has been

calculated using eq (1) The calculated efﬁciency is found to be 97.76% at 180 against MB dye [21] The degradation mechanism in dye solution is stated in the following equations(4e11) Com-parable results of the degradation efﬁciency of MB dye with other metal oxide nanoparticles are tabulated inTable

NiOỵ hv / NiO (e

-cbỵ hỵvb) (4)

NiO (e-cb)ỵ O2/ NiO ỵ O2 (5)

H2O/ Hỵỵ OH (6)

O2ỵ H/ HO2 (7)

NiO (e-cb)ỵ HO2ỵ Hỵ/ H2O2 (8)

NiO (hỵvb)ỵ Dye / Degraded product (9)

HO2ỵ Hỵ/ H2O2 (10)

HO2ỵ e/ HO2- (11)

3.5 Antibacterial studies

The antibacterial study of the synthesized NiO NPs was tested against the human pathogenic bacteria's Staphylococcus aureus and Escherichia coli, employing the Agar well diffusion method Generally, the antibacterial activity depends upon the reactive ox-ygen species (ROS), surface area, particle size, etc NiO NPs produce ROS (hydroxyl, superoxide radical, singlet oxygen, and

alpha-Table

Comparison of results with published data: photocatalytic activity (MB dye) with different metal oxide NPs

Sl No

Photocatalyst Synthesis method average crystal size (nm)

% of dye degradation

references

1 ZnO NPs Sol gel 30 81 [32] Co-precipitation 23 90 [33] Solution combustion 20 81 [25] Ag2O NPs Solution combustion 11 84 [34]

5 MgO NPs Microwave assisted 14 88 [35] Hydrothermal 20 92

6 NiO NPs Green Synthesis 20 97 [36] precipitation 2e3 97 [37] Solution combustion 31 98 Present

work Bold signiﬁes the current work details/data compared to published data

Fig Antibacterial activity of NiO NPs against E.coli and S.aureus bacterial strains (S) Standard antibiotic (C) control (a) 500mg/mL (b) 1000mg/mL Table

Antibacterial activity of synthesized NiO NPs Treatment Bacterial strains Sample Concentration Escherichia coli

(mean± SE)

Staphylococcus aureus (mean± SE) Ciproﬂoxacin 10mg/mL 9.26± 0.28 14.13± 0.67 NiO NPs 500mg/mL 2.95± 0.48 4.63± 0.41

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oxygen) through the Fenton reaction, which leads to lipid peroxi-dation, DNA damage and protein oxidation which can eliminate the bacteria The zone of inhibition formed by the NiO NPs of known concentrations (500 and 1000mg/mL) with reference to the positive control (Ciprofloxacin) is shown inFig 6and corresponding data are tabulated inTable The antibacterial activity of NiO NPs shows a significant inhibition to both bacterial strains compared to stan-dard antibiotic Ciprofloxacin [25,26]

3.6 Electrochemical investigation of NiO nanoparticles

The initial electrochemical characterization of the NiO nano-particles modiﬁed glassy carbon electrode surface was carried out by using the most powerful electrochemical techniques such as cyclic voltammetry (CV) The redox activity of the NiO nano-particles modiﬁed electrode was studied in the presence of a

standard redox standard potassium ferricyanide solution From the voltammogram inFig 7, it is observed that theDE value of 136 mV for NiO NPs modiﬁed electrode (peak b) shows a better redox ac-tivity with increased current density than the bare glassy carbon electrode withDE value of 263 mV (peak a) The decrease in peak potentials has increased effect on conductivity This increased ac-tivity might be attributed to the high surface area provided by the nanoparticles in comparison to the bare glassy carbon electrode [27e30]

The NiO NPs modified electrode was utilized to investigate its electrocatalytic property in the electro oxidation of nitrite The voltammograms at modified interface were recorded in the pres-ence of a nitrite in acetate buffer of pH at the scan rate of 50 mV/ s From Fig 8, it is clear that the NiO nanoparticles modified electrode in the absence of nitrite did not show any redox signa-ture (peak c) suggesting that the modified electrode is inactive in absence of nitrite under the potential window studied However, in the presence of nitrite the modified electrode showed an enhanced current response responsible for the electro oxidation of nitrite with potential at 0.93 V (peak a) in comparison to the unmodified electrode at 1.03 V (peak b) The observed results illustrate the electrocatalytic behaviour of the modified electrode towards the electro oxidation process Hence, the NiO NPs modi-fied electrode can be used in the electrochemical quantification of nitrite at trace level

As presentedFig.S1 (a) (in ESI), with increasing scan rate from 10 to 300 mV/s the anodic peaks were shifting towards more positive potentials with increase in peak current response with R2¼ 0.98 showing that the process of nitrite oxidation at NiO NPs modiﬁed electrode is a diffusion controlled process

3.7 Optimization of experimental parameters

Owing to the excellent analytical sensitivity and resolved re-sponses of the differential pulse voltammetry (DPV) technique over cyclic voltammetry, the experimental parameters were optimized The factors which affect the analytical responses such as pH, deposition potential, deposition time and the concentration were varied and their effect on the current responses were studied The optimized parameters are as follows-pH:4, deposition

Fig Overlaid Cyclic voltammograms at (a) bare (b) NiO NPs modiﬁed electrode in presence of a potassium ferricyanide solution and 0.1 M KCl as supporting electrolyte Scan rate: 50 mV/s

Fig Overlaid Cyclic voltammograms at a) bare, b) NiO NPs modiﬁed electrode in presence and c) absence of nitrite in acetate buffer and 0.1 M KCl

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potential:0.4 V and deposition time:15 s All the graphs are depic-ted inFig.S1 (b-d) (in ESI)

3.8 Calibration plot and linearity

The determination of nitrite has been done using differential pulse voltammetry (DPV) due to its high current sensitivity and better resolution compared to cyclic voltammetry Hence, under the optimized experimental conditions, the performance of the NiO NPs modified electrode on increasing nitrite concentration has been studied as shown in Fig The anodic peak currents linearly increase with the successive addition of nitrite in the concentration range 8e1700mM with linear regression co-efficient of 0.998 The detection limit (3s) was found to be 1.2mM These results convey that the NiO nanoparticles modified electrode can act as a novel non-enzymatic sensor in trace level quantification of nitrite

3.9 Stability of the modiﬁed electrode

The stability of the modified electrode was studied by contin-uously recording the responses at the modified electrode up to 10 cycles as depicted inFig.S5 and S6 (ESI) The modified electrode showed significant analytical responses responsible for the electro oxidation of nitrite even after 10 cycles However, the peak current density decreased which might be due to an oxide layer formation on the electrode surface [31] This reveals that the modified elec-trode is very stable and can be used in the continuous monitoring of nitrite The modified electrode showed excellent analytical per-formance in comparison to other reported nitrite sensors and is given inTable

4 Conclusion

In this study, NiO NPs have been synthesised through a so-lution combustion method using C gigantea leaves extract as a fuel NiO NPs and were characterised using X-RD, SEM with EDAX, HR-TEM with SAED and FT-IR spectroscopy The syn-thesised NiO NPs were utilized to study their diversified appli-cations in dye degradation, anti-bacterial activity and in electrochemical sensing The X-RD pattern confirms the rhom-bohedral structure of NiO NPs with a particle size in the range 10e30 nm The EDAX spectrum confirms the presence of Ni and O as major elements in its elemental composition The NiO NPs exhibited very good photocatalytic activity in the degradation of methylene blue dye The anti bacterial activity studies revealed that the nanoparticles have good ability to inhibit the growth of E.coli and S.aureus pathogens The electrochemical investigation of the NiO NPs modified electrode depicts an excellent electro catalytic behaviour in the quantification of nitrite at trace level in comparison to the bare electrode The modified electrode showed wide linearity in the concentration range 8e1700 mM with a

detection limit of 1.2 mM, which allows the exploration of NiO NPs as a novel non-enzymatic nitrite sensor for biological applications

Declaration of competing interest

The authors declare that they have no known competing ﬁnancial interests or personal relationships that could have appeared to inﬂuence the work reported in this paper

Acknowledgments

Dr G Nagaraju thanks the DST-Nano mission (SR/NM/NS-1262/ 2013) Govt of India, New Delhi for providing characterization techniques and also the VGST, Govt of Karnataka (CISEE-VGST/GRD-531/2016e17) for UV-DRS studies Rajith Kumar C R thanks the Department of Biotechnology, GM Institute of Technology, Davan-gere and Siddaganga Institute of Technology, Tumakuru for providing lab facility

Appendix A Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.jsamd.2020.02.002

References

[1] V.K Prashant, Photophysical, photochemical and photocatalytic aspects of metal nanoparticles, J Phys Chem B 106 (2002) 7729e7744

[2] K.C Patil, S.T Aruna, S Ekambaram, Combustion synthesis, Curr Opin Solid State Mater Sci (1997) 158e165

[3] L Brus, Capped nanometer silicon electronic materials, Adv Mater (1993) 286e288

[4] F Zheng, S Xu, Y Zhang, Facile fabrication of hierarchically porous NiO mi-crospheres as anode materials for lithium ion batteries, J Mater Sci Mater Electron 27 (2016) 3576e3582

[5] M Hassanpour, H Safardoust-Hojaghan, M Salavati-Niasari, J Mater Sci Mater Electron (2017),https://doi.org/10.1007/s10854-017-6860-3 [6] X Xu, Z Liu, Z Zuo, M Zhang, Z Zhao, Y Shen, H Zhou, Q Chen, Y Yang,

M Wang, Hole selective NiO contact for efﬁcient perovskite solar cells with carbon electrode, Nano Lett 15 (2015) 2402e2408

[7] D Li, Y Li, F Li, J Zhang, X Zhu, S Wen, S Ruan, Humidity sensing properties of MoO3-NiO nanocomposite materials, Ceram Int 41 (2015) 4348e4353 [8] J Cheng, B Zhao, W Zhang, F Shi, G Zheng, D Zhang, J Yang,

High-perfor-mance super capacitor applications of NiO-Nanoparticle-Decorated milli me-ter-long vertically aligned carbon nanotube Arrays via an effective supercritical CO2-assisted method, Adv Funct Mater 25 (2015) 7381e7391 [9] A.M El Badawy, R.G Silva, B Morris, K.G Scheckel, M.T Suidan, T MTolaymat, Surface charge-dependent toxicity of silver nanoparticles, Environ Sci Tech-nol 45 (2010) 283e287

[10] V Kumar, S Yadav, Plant-mediated synthesis of silver and gold nanoparticles and their applications, J Chem Technol Biotechnol 84 (2009) 151 [11] C Vidya, S Hiremath, M.N Chandraprabha, M.A.L Antonyraj, I.V Gopal,

A Jain, K Bansal, Green synthesis of ZnO nanoparticles by Calotropis gigantea, Int J Curr Eng Technol (2013) 118

[12] B.A van Driel, P.J Kooyman, K.J van den Berg, A Schmidt-Ott, J Dik, A quick assessment of the photocatalytic activity of TiO2 pigments - from lab to conservation studio, Micro J126 (2016) 162e171

Table

Comparison of reported values with other modiﬁed electrodes

Modiﬁer Technique Linearity range (mM) Limit of detection (mM) Reference

Cu/MWCNTs/GC Differential pulse voltammetry 5e1260 1.8 [38]

SPCE/anodized/CuAgNP Hydrodynamic chronoamperometry 20e370 11.1 [39] poly (4-aminobenzoic acid/o-toluidine) (4-AB/OT)/CPE Amperometry 6e600 3.5 [40]

(AuNPs/MoS2/GN) Amperometry 5.0e5000 1.0 [41]

NiO/GCE Differential pulse voltammetry 8e1700 1.2 Present work

(8)

[13] S Min, F Wang, Z Jin, J Xu, Cu2O nanoparticles decorated BiVO4 as an

effective visible-light-driven p-n heterojunction photocatalyst for methylene blue degradation, SuperlatticesMicrostruct 74 (2014) 294e307

[14] X Wan, M Yuan, Shao-long Tie, S Lan, Effects of catalyst characters on the photocatalytic activity and process of NiO nanoparticles in the degradation of methylene blue, Appl Surf Sci 277 (2013) 40e46

[15] A Azam, A.S Ahmed, M Oves, Antimicrobial activity of metal oxide nano-particles against Gram positive Gram negative bacteria: a comparative study, Int J Nanomed (2012) 6003e6009

[16] Q.A Pankhurst, N TThanh, S.K Jones, J Dobson, Progress in applications of magnetic nanoparticles in biomedicine, J Phys Appl Phys 42 (2009) 224001 [17] J Sa, J.A Anderson, FTIR study of aqueous nitrate reduction over Pd/TiO2,

Appl Catal B Environ 77 (2008) 409e417

[18] WHO (World Health Organization), Guide Lines for Drinking-Water Quality vol 1, World Health Organization, Geneva, 2004

[19] M.J Moorcroft, J Davis, R.G Compton, Detection and determination of nitrate and nitrite: a review, Talanta 54 (2001) 785e803

[20] K Kalcher, Chemically modiﬁed carbon paste electrodes in voltammetric analysis, Electroanalysis (1990) 419e433

[21] Udayabhanu G Nagaraju, H Nagabhushana, R.B Basavaraj, G.K Raghu, D Suresh, H.R Naika, S.C Sharma, Green nonchemical route for the synthesis of NiO superstructures, evaluation of its applications toward photocatalysis, photoluminescence, and biosensing, Cryst Growth Des 16 (2016) 6828e6840

[22] M.M Naik, H.S.B Naik, G Nagaraju, M Vinuth, K Vinu, S.K Rashmi, Effect of aluminium doping on structural, optical, photocatalytic and antibacterial ac-tivity on nickel ferrite nanoparticles by solegel auto-combustion method, J Mater Sci Mater Electron 29 (2018) 20395e20414

[23] K Lingaraju, H.R Naika, H Nagabhushana, G Nagaraju, Euphorbia hetero-phylla (L.) mediated fabrication of Zno NPs: characterization and evaluation of antibacterial and anticancer properties, Biocatal Agric Biotechnol 18 (2019) 100894

[24] K Karthik, S Dhanuskodi, C Gobinath, S Prabukumar, S Sivaramakrishnan, Dielectric and antibacterial studies of microwave assisted calcium hydroxide nanoparticles, J Mater Sci Mater Electron 28 (2017) 16509e16518 [25] N.S Pavithra, K Lingaraju, G.K Raghu, G Nagaraju, Citrus maxima (Pomelo)

juice mediated eco-friendly synthesis of NiO nanoparticles: applications to photocatalytic, electrochemical sensor and antibacterial activities, Spec-trochim Acta Mol Biomol Spectrosc 185 (2017) 11e19

[26] S.B Patil, T.N Ravishankar, K Lingaraju, G.K Raghu, G Nagaraju, Multiple applications of combustion derived nickel oxide nanoparticles, J Mater Sci Mater Electron 29 (2018) 277e287

[27] C.M Welch, R.G Compton, The use of nanoparticles in electroanalysis: a re-view, Anal Bioanal Chem 384 (2006) 601e619

[28] F Pergola, G Raspi, R Guidelli, Voltammetric behavior of nitrite ion on platinum in neutral and weakly acidic media, Anal Chem 44 (1972) 745e755

[29] B Piela, P.K Wrona, Oxidation of nitrites on solid electrodes I Determination of the reaction mechanism on the pure electrode surface, J Electrochem Soc 149 (2002) E55eE63

[30] S.A Prashanth, M Pandurangappa, Amino-calixarene-modiﬁed graphitic carbon as a novel electrochemical interface for simultaneous measurement of lead and cadmium ions at picomolar level, J Solid State Electrochem 20 (2016) 3349e3358

[31] B.P Suma, S.A Prashanth, M Pandurangappa, Silver nanoparticles-chitosan composite embedded graphite screen-printed electrodes as a novel electro-chemical platform in the measurement of trace level nitrite: application to milk powder samples, Curr Anal Chem 15 (2019) 56e65

[32] A Balcha, O.P Yadav, T Dey, Photocatalytic degradation of methylene blue dye by zinc oxide nanoparticles obtained from precipitation and sol-gel methods, Environ Sci Pollut Res 23 (2016) 25485e25493

[33] I Kazeminezhad, A Sadollahkhani, Inﬂuence of pH on the photocatalytic activity of ZnO nanoparticles, J Mater Sci Mater Electron 27 (2016) 4206e4215 [34] S.P Vinay, G Nagaraju, C.P Chandrappa, N Chandrasekhar, Novel Gomutra

(cow urine) mediated synthesis of silver oxide nanoparticles and their enhanced photocatalytic, photoluminescence and antibacterial studies, J Sci.: Adv Mater Devices (2019) 392e399

[35] K Karthik, M Shashank, V Revathi, T 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 673 (2018) 70e80

[36] M.I Din, A.G Nabi, A Rani, A Aihetasham, M Mukhtar, Single step green synthesis of stable nickel and nickel oxide nanoparticles from Calotropis gigantea: catalytic and antimicrobial potentials, Environ Nanotechnol Monit Manag (2018) 29e36

[37] K Maniammal, G Madhu, V Biju, Nanostructured mesoporous NiO as an efﬁcient photocatalyst for degradation of methylene blue: structure, proper-ties and performance, Nanostruct NanoObjects 16 (2018) 266e275 [38] D Manoj, R Saravanan, J Santhanalakshmi, S Agarwal, V.K Gupta,

R Boukherroub, Towards green synthesis of monodisperse Cu nanoparticles: an efﬁcient and high sensitive electrochemical nitrite sensor, Sensor Actuator B Chem 266 (2018) 873e882

[39] N.C Lo, I.W Sun, P.Y Chen, CuAg nanoparticles formed in situ on electro-chemically pre-anodized screen-printed carbon electrodes for the detection of nitrate and nitrite anions, J Chin Chem Soc 65 (2018) 982e988

[40] B Norouzi, M Rajabi, Fabrication of poly (4-aminobenzoic acid/o-toluidine) modiﬁed carbon paste electrode and its electrocatalytic property to the oxidation of nitrite, J Anal Chem 72 (2017) 897e903

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