Electrochemical synthesis of 3D hierarchical S /Co S ...(E/C) using cobalt coated Pt-electrodes in...

International Journal of Applied Chemistry.

ISSN 0973-1792 Volume 15, Number 2 (2019) pp. 81-97

© Research India Publications

http://www.ripublication.com

Electrochemical synthesis of 3D hierarchical

Co3S4/Co9S8 nanoparticles as photocatalysts for

degradation of Carboxylic acids

Gubran Alnaggar, Sanniaha Ananda*

Department of studies in chemistry, University of Mysore, Manasagangotri, Mysore- 570006, India.

*Corresponding author

Abstract

Three dimensional (3D) hierarchical Co3S4/Co9S8 nanoparticles were

synthesised by a facile electrochemical method. The structural, morphology

and optical properties of prepared Co3S4/Co9S8 nanoparticles are characterized

by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-vis

spectroscopy, FTIR spectroscopy. The XRD pattern shows that the present of

spinel Co3S4 with hexagonal Co9S8 nanoparticles. The SEM images have been

confirmed the XRD results. The band gap of the prepared Co3S4/Co9S8

nanoparticles was found to be (2.88 eV) lesser than pure hexagonal Co9S8

which can be attributed to the present of a spinel Co3S4 with hexagonal Co9S8.

The degradation of carboxylic acids mainly acetic acid, formic acid and oxalic

acid as organic pollutants were used to estimate the catalytic activity of

prepared Co3S4/Co9S8 nanoparticles. The Taft linear free energy relationship

(LFER) was tested, isokinetic temperature β was calculated for oxidation of

carboxylic acids. The biological activity for prepared Co3S4/Co9S8

nanoparticles has been studied. The result indicates that the prepared

Co3S4/Co9S8 nanoparticles displayed high photocatalytic activity under

sunlight and the oxidation /degradation of carboxylic acids was enthalpy

controlled.

Keywords: Cobalt sulphide, electrochemical, photo catalyst, LFER and

biological activity

INTRODUCTION

Chalcogenides nanoparticles are extremely studied due to their significant

applications and size dependent properties. Metal chalcogenides like vanadium

http://www.ripublication.com/

82 Nur A. Limatahu, Nur Jannah Baturante, St. Hayatun Nur Abu, Nurul Aulia Rahman

sulphide, molybdenum sulphide, nickel sulphide and cobalt sulphide have been

studied for several kinds of applications [1-5].

Cobalt sulphide compounds with varied stoichiometric compositions, like Co9S8,

CoS2, CoS and Co1-xS, have attracted significant attention due to their electronic,

chemical, physical, and optical properties and their wide range of potential application

in Li-ion batteries, electrochemical supercapacitor and catalyst, owing to easy

oxidation of sulphide ion and easy reduction of cobalt ion which outcomes in the

hardness in controlling the stoichiometry of cobalt sulphide. Cobalt sulphide has been recorded as the most challenging metal chalcogenides to synthesise [1, 3-10].

Cobalt sulphides usually have many stable phases and intricate structure. However,

Co9S8 nanoparticles have attracted considerable attention. For instant, Co9S8 has

significant catalytic activity such as in hydrodesulphurization catalysts and magnetic

devices [2,7,10-12].

So far, cobalt sulphides have synthesised with different stiochiometry composition

and morphologies by several synthesis methods including hydrothermal, microwave-

assisted techniques, solvothermal method, wet-chemical methods, colloidal syntheses,

electrochemical method and catalytic chemical vapour deposition [3,7-10,12-14].

Colourless organic compounds are one of main class of environmental pollutants. The

organic acids are most widely used in the field of pharmaceutical, food, beverages and

also in chemical industries. Carboxylic Acids such as Oxalic acid, Formic acid and

Acidic acid are common Pollutants in industrial wastewater. Acetic acid is used in the

synthesis of plastics and acetyl cellulose and also in the dyeing and printing industry,

as well as in the food industries. Formic acid is used in the tanning, in rubber

processing, in textile industry and in the manufacture of pharmaceuticals [15-19].

Herein, cobalt sulphide nanoparticles were synthesised by a facile electrochemical

process which display a superior photocatalytic activity, under sunlight irradiation, for

different type of carboxylic acids mainly Acetic acid, Formic acid and Oxalic acid as

colourless pollutant organic compound. The volumetric titration methodology was

used to determine the degradation efficiency and results proved the complete

degradation of those pollutants.

The obtained cobalt sulphides nanoparticles and their structural, optical properties and

photocatalytic activity are studied.

EXPERIMENTAL PROCEDURE:

Materials:

Cobalt (II) Chloride hexahydrate (CoCl2 6H2O, Alfa Aesar, 99%), Sodium

sulphide (Na2S, Alfa Aesar, 99%) and Platinum electrode from Elico Pvt. Ltd were

used in the present work. All chemicals were used without further purification.

Deionised water produced by a PURELAB Ultra water purification system was used

for all the experiments.

Electrochemical synthesis of 3D hierarchical Co3S4/Co9S8 nanoparticles… 83

Synthesis:

Cobalt sulphide nanoparticals was synthesized by electrochemical process (E/C) using

cobalt coated Pt-electrodes in an aqueous system with sodium sulphide as a

conductive salt. Sodium sulphide was used as the sulphur source. The E/C synthesis

of nanoparticals of Cobalt sulphide involves two steps (Scheme 1), first,

electrochemically Cobalt is deposited on the surface of Pt-electrode from an aqueous

solution containing Cobalt ion, second, the Co2+ coated electrode is connected in

electrochemical cell as anode and gets oxidized and uncoated pt-electrode connected

as cathode in sodium sulphide solution (0.2M, 20 ml) to yield semiconducting Cobalt

sulphide nanoparticles. In the electrochemical cell, the electrodes were fixed in a

holder with a side distance of 1.5 cm, so that they were totally surrounded by the

electrolyte. DC source was used to apply 1.7 V as a potential difference between the

electrodes. The synthesis process was conducted galvanostatically at current density,

j, of 30.0 mA cm-2, without stirring, to simplify the formation of the crystal at room

temperature for 2 h (scheme 1).

In such synthesis, the size of the nanoparticle depends upon various parameters such

as current density, applied voltage, distance between 2 electrodes, concentration and

volume of Na2S solution so, synthesis was well optimized. As a result, yield of Cobalt

sulphide nanoparticle obtained is 0.6–1.5 g. obtaining a more amount of the

nanoparticles product, the repetition of the whole reaction is required at the standard

conditions. The obtained nanoparticles were washed several times with distilled

water, centrifuged and calcined for 1 h at 700 C0 to remove impurities which might be

formed due to atmospheric oxidation and electrolysis.

Scheme1. Electrochemical Synthesis of cobalt sulphide nanoparticles

Characterisation:

The structure of obtain cobalt sulphides nanoparticles were investigated by X-ray

diffractometer with a Cu Kα radiation source of λ = 1.5406 Å wavelength. The range


of scanning was 6–80° in steps of 0.02°. Field emission scanning electron microscope

(FE-SEM /EDX) was employed to study the morphology and the composition of the

prepared nanoparticles. Also, the optical properties was studied by Diffuse

Reflectance UV-vis spectrophotometer (UV-vis DRS, Shimadzu UV-3600 UV) and

Fourier transform infrared spectroscopy was recorded using (FT-IR, JASCO 460 plus,

using KBr wafers).

Photocatalytic study:

The sunlight photocatalytic performance for prepared cobalt sulphide nanoparticles

was investigated by decomposition of Carboxylic Acids (as colourless compounds)

mainly, Acetic Acid, Oxalic Acid and Formic Acid. In a typical experiment, 20 ml of

each Acid was taken to conduct the experiment. The effect of initial carboxylic acid

concentration, catalyst dosage and the Temperature in the degradation rate were

studied. In each case, to study the effect of photocatalyst weight in the degradation

rate 20, 30, 40 and 60 mg of the as-prepared photocatalyst were add to 20 ml of

carboxylic acid solution separately. In contrast, (0.0005, 0.001 and 0.002 Normality)

of each carboxylic acid were used to investigate the initial concentration effect of the

corresponding carboxylic acids, whereas the effect of Temperature was done at three

different temperature mainly 293, 313 and 333 Kelvin.

The mineralization of carboxylic acids was measured by the drop down value of

Chemical Oxygen Demand COD of the solution. Standard dichromate titration

method was used to determine COD before and after the degradation process. The

COD value and the degradation efficiency were calculated [20][21][22] by the

following equation

COD = 8000 (vol. of FAS in blank – vol. of FAS in acid soln.) normality of FAS ∕

sample volume

Photodegradation kinetics by volumetric method:

Volumetric titration is widely-used in quantitative analytical method. In the present

work, the volumetric titration methodology was used to determine the degradation

efficiency. The concentrations of the different carboxylic acids used in this work were

measured by the titration against standard sodium hydroxide solution in the present of

phenolphthalein indicator. The volume of sodium hydroxide solution required to react

at different interval of time with the acid before and after the degradation was

compared and recorded.

RESULTS AND DISCUSSION:

Morphology and structural properties:

Fig.1. shows the XRD Pattern of prepared cobalt sulphide nanoparticles. The analysis

of the obtained peaks indicated the presence of mixed phases of cobalt sulphide. The


high intensity peaks corresponded to (200), (220), (311), (400), (422), (511), (440),

(531) and (533) crystal planes are coherent with the standard pattern of hexagonal

Co9S8 (JCPDS card No. 75-2023).[10] The other six diffraction peaks, mainly (220),

(311), (400), (511), (440) and (620) crystal planes are well matched with standard

pattern of spinel Co3S4 (JCPDS card no. 19-0367)[23]. The high intensity peaks

indicate the high crystalline product. The average crystalline size of the prepared

particles (D) was calculated by using Scherrer’s formula is 44nm.

Figure1. Powder XRD Pattern of Cobalt sulphide nanoparticles

The morphology and surface properties of the as-prepared nanoparticles were studied

by using Scanning Electron Microscopy (SEM). The SEM Images of the as-prepared

nanoparticles were shown in Fig.2. It is clear that the presence of two phases in the

prepared cobalt sulphide nanoparticles. Two different morphologies are available

which one can notice that easily. The first and major one is hexagonal structure

(surrounded by black circles) which beautifully decorated by the second one with

flower-like nanoparticles (pointed by arrows), it is in good agreement to XRD

Results, as XRD explanation, the hexagonal structure representing Co9S8 nanparticles

and the flower-like structure (spinel structure ) representing Co3S4 nanoparticles.

FTIR spectroscopy study:

The FT-IR spectrum of prepared cobalt sulphide nanoparticles was shown in Fig.3,

bands at 400, 422, 449, 484, 550, 600, 620 and 720 (symmetrical stretch) and 1100


cm-1 (asymmetrical stretch) were assigned to sulphides. The band at 484 cm-1

frequency could be attributed to S-S disulphide group which indicates about

polysulfide formation [3][6], which is in agreement to XRD results.

Figure 2. SEM images of Cobalt sulphide nanoparticles

Figure 3. FTIR spectra of Cobalt sulphide nanoparticles

Optical properties

To understand the optical behaviour of prepared cobalt sulphide nanoparticles, the

optical absorption at room temperature was investigated by using UV-Vis

spectroscopy. Figure (4) shows the absorption spectrum of prepared cobalt sulphide

nanoparticles. It showed that the maximum absorption peak at (415nm) which

indicate the prepared cobalt sulphide nanoparticles visible light active. Based in the

direct transition, the band gap was calculated from a Tauc plot (inset, fig.4) and found


to be (2.88 eV). According to the literature reports, the band gap value of pure Co8S9

is 3.2 eV [2]. The decrease in band gap value could be attributed to the formation of

composite from two different phases of cobalt sulphide where the flower-like

structure (spinel structure) represented Co3S4 nanoparticles acts as doping material

with the hexagonal structure of Co8S9.

Figure4. UV-vis spectra and Tauc’s plot

Photocatalytic activity and COD Measurements:

The kinetic reaction constants have been obtained in the presence of sun light, by

taking the slope of ln (V/V0) versus time as showed in Fig.6a, 6b where V0 is the

volume before solar light irradiation and the V is the volume at different interval of

time. The kinetics indicates that the photocatalysis obey first order reaction

mechanism. The COD measurement of the carboxylic acids solution was carried out

before and after degradation by Potassium dichromate methods as shown in Fig. 6b,

6d and Table-1. The results showed the disappearance of carboxylic which indicates

that it has undergone decomposition [24]. The rate of degradation of carboxylic acids

follows the trend.

Oxalic acid > Formic acid > Acetic acid

This could be attributed to the fact that the electron donating capacity decreases the

rate of degradation reaction, which is supported by Taft LEFR.


Effect of initial acid concentration:

The effect of initial acids concentration on the degradation efficiency was tested by

using three different concentrations mainly (0.0005, 0.001 and 0.002 N), as shown in

Fig.5a. The photodegradation efficiency was decreased with increased the initial

carboxylic acids concentration. Noticeably, with the increase of carboxylic acids

concentration the kinetics rate constant decrease. This can be ascribed to that, higher

carboxylic acids concentration leads to higher acid molecules around the catalyst

which prevents the absorbance of sunlight by the surface of the catalyst. As a result,

the formation of •O2-and •OH decreases and hence the rate of the reaction decrease, as

a result, the photocatalytic efficiency decreases [21, 25, 26] Table-1.

Effect of catalyst dosage:

The effect of catalyst dosage on the degradation efficiency for acids (0.001 N)

different amount of catalyst has used 0.02, 0.03, 0.04 and 0.06 gm. As shown in

Fig.5c as the catalyst dosage increase from 0.02g to 0.04 the photodegradation

efficiency increase, further increasing in catalyst dosage above 0.04g, the

photodegradation efficiency decreases. Initially, the numbers of the active sites in the

surface of the catalyst increase so the efficiency of the degradation increase, but the

present of more particles of catalyst causes light scattering which effect on the light

absorption by the catalyst and thus the number of active sites species [20, 25, 26]. The

kinetics rate constant for the degradation reaction and degradation efficiency of

carboxylic acids were the highest at 0.03g catalyst dosage Table-1.

Effect of Temperature:

The decomposition of the carboxylic acids solution carried out at three different

temperatures Fig.6a. It has been found that with increase of the temperature the

degradation rate also increase [21, 26] Table-1. The thermodynamic parameters are

calculated Table-3.

Reusability of the photocatalyst:

The possibility of using the photocatalyst again for degradation reaction was

examined Fig.6b. The used photocatalyst was filtered from the first solution and used

for fresh acid solution. The result shows that the photocatalyst still active but with

lesser degradation efficiency Table-1.

Linear free energy relation (LFER):

Attempts were made to arrive at a linear free energy relation for the

oxidation/degradation of carboxylic acids by using cobalt sulphide nanoparticles [27].

Test of Taft equation was obtained for plot of logk v/s σ* (σ* = Polar substituent


constant) Fig.7b. The following Regression was obtained [28]

log k = 0.27 σ* ─ 3.13 (r = 0.993)

The positive slope value of polar constant ρ* although small it indicates that electron

donating capacity decreases the rate of degradation [27-28] as it is seen from Table-2.

The rate of oxidation/ degradation of carboxylic acids by using cobalt sulphide

nanoparticles decrease in the order

Oxalic acid > Formic acid >Acetic acid

The activation energy value is highest for the slowest reaction and vice-versa,

indicating that the reaction is enthalpy controlled Table-3. The activation enthalpies

(∆H#) and entropy (∆S#) for the degradation of carboxylic acids through oxidation are

linearly related Table-4. From the slope of ∆H# v/s ∆S# Fig.7c the isokinetic

temperature β was calculated and found to be 381 K0. [29] This is further verified by

employing the Exner criterion with a plot of logk1 293 K0 v/s log K2 333K0 which is

linear Fig.7d. From the Exner’s slope β was calculated by using following expression

[30] and found to be 388.5 K0.

β = T2T1 (b-1) / (b T2 – T1)

Where, k1 and k2 are the rate constants at the temperature T2 and T1 respectively and

T2>T1, b is the slope of logk2 against logk1.

The value of β is higher than the temperature range employed in the present work,

supporting the fact that the oxidation of carboxylic acids is enthalpy controlled. In this

region, the reaction with the lowest activation energy will react the fastest.

The fairly high negative values of entropy of activation point towards the formation of

fairly rigid activated state [29] Table-3. The constancy of ∆G# values indicates that the

carboxylic acids undergo oxidation/degradation via an identical mechanism [29-31].

Antibacterial assay:

The antibacterial susceptibility of synthesized Cobalt sulphide nanoparticles was

evaluated by using the disc diffusion Kirby-Bauer method in Mueller Hinton Agar

Plate [32]. All reference bacterial strains were obtained from Microbial Typing

Culture Collection (MTCC), Chandigarh, India. Gram-positive Bacillus subtilis (MTCC 2763) and gram-negative Escherichia coli (MTCC 40) were cultured as per

the protocol prescribed by MTCC.

Antimicrobial activity

To test disc diffusion assay, 20 mL of sterilized and molten Mueller Hinton Agar


media was poured in to the sterilized petri plates. The reference bacterial strains were

cultured overnight at 37 °C in Mueller Hinton broth and adjusted to a final density of

107 CFU/mL by 0.5 McFarland standards. 100 μL of the pathogenic bacteria cultures

were transferred onto plate and made culture lawn. The comparative stability of discs

containing Gentamycin was made. Test synthesized Cobalt sulphide nanoparticles

were loaded into 6 mm sterile discs and placed on the culture plates and incubated at

370C for 24 hours. By measuring the diameter of the ZOI formed around the disc, the

antibacterial efficacy of synthesized Cobalt sulphide nanoparticles was determined

[33]. All assays were performed in triplicates.

Figure8. Shows the growth inhibition Compound inhibited bacterial growth by the

clear inhibition zone (a concentration of30 μg/ml). The diameter of inhibition zones

(in millimetres) around the Compound against test strain are shown in Table 4.

Table 4 Antibacterial effect of synthesized Cobalt sulphide nanoparticles by Zone of

Inhibition (mm) against test strains

Test Bacteria Co3S4/Co9S8 Positive control Gentamycin (30

μg/ml)

Bacillus subtilis MTCC 2763

12.07 ± 0.12 30.05 ± 0.07

Escherichia coli MTCC 40 11.91 ± 0.04 26.14 ± 0.12

Note: Values are the mean ± SE of triplicate experiments

Figurer8. Zone of inhibition against (A) Bacillus subtilis and

(B) Escherichia coli bacteria


Table (1) Effect of different variation on the rate of photo degradation of carboxylic

acids (Oxalic acid, Formic acid and Acetic acid)

Carboxylic

Acid

Concentration

Of the acids

(N, 20 ml)

Dosage

in g

Rate

constant

*104 S-1

Time (min)

For complete

degradation

COD (mg/L) Deg.

Efficiency

(%) Before

degradation

After

degradation

Oxalic

acid

0.001

0.02 13.2 60

816

60 92.6

0.03 23 40 15 98.2

0.04 4.6 20 15 98.2

0.06 1.1 60 100 87.7

0.0005

0.03

32 20 610 8 98.7

0.001 23 40 816 15 98.2

0.002 9.3 60 991 85 91.4

Reuse(0.001) 17 40 816 30 96.3

Effect of Temp.

(K0)

293

0.03

11.5 60

816

15 98.2

313 23 40 15 98.2

333 60 10 15 98.2

Formic

acid

0.001

0.02 4.9 50

672

55 91.8

0.03 12 40 13 98

0.04 18 30 13 98

0.06 1.88 60 80 88.1

0.0005

0.03

17 30 499 7 98.6

0.001 12 40 672 13 98

0.002 3.8 60 792 77 88.5

Reuse(0.001) 9.5 40 672 20 97

Effect of Temp.

(K0)

293

0.03

3.8 60

672

13 98

313 12 40 13 98

333 39 30 13 98

Acetic acid

0.001

0.02 3.35 60

544

60 88.9

0.03 6.6 50 9 98.3

0.04 7.22 30 9 98.3

0.06 1.78 60 100 81.6

0.0005

0.03

13.7 20 443 5 98.9

0.001 6.6 50 544 9 98.3

0.002 4.6 60 692 85 87.7

Reuse(0.001) 4.5 50 544 15 97.2

Effect of Temp.

(K0)

293

0.03

2.25 60

544

12 97.8

313 6.6 50 9 98.3

333 25 40 8 98.5


Table (2) Rate constants of Carboxylic acid

(T=313 K0, [Acid] = 0.001 N, Catalyst dosage = 0.03g)

Carboxylic Acid Rate constant

(k, S-1) 4+log k σ*

Oxalic Acid 23 x 10-4 1.4 2.08

Formic Acid 12 x 10-4 1.08 0.49

Acetic Acid 6.6 x 10-4 0.81 0

Table (3) Thermodynamics parameters

Substrates Temperature

(Kelvin)

∆H#

(KJ/mol)

∆ S#

(J/mol.K)

∆ G#

(KJ/mol)

Ea

(kcal/mol)

Oxalic acid

293 35.82 -178.57 88.15

9.15 313 35.69 -181.71 92.59

333 35.48 -181.58 95.98

Formic acid

293 45.44 -155.06 90.92

11.44 313 45.27 -156.52 94.43

333 45.10 -156.44 97.24

Acetic acid

293 58.58 -113.76 92.17

14.64 313 58.65 -118.74 95.85

333 58.49 -119.95 98.45


Figure5. (a) Effect of initial acid concentration in the Photodegradation Kinetic of

Acids (b) COD value before and after the degradation at different concentration of

carboxylic acid(c) Effect of dosage in the Photodegradation Kinetic of carboxylic

acids, (d) COD value before and after the degradation at different catalyst dosage

Figure6. (a) Effect of Temperature in the Photodegradation Kinetic of carboxylic

acids (b) Degradation efficiency of the Reusability of the catalyst


Fig.7. (a) Arrhenius plot for carboxylic acids (b) Taft plot LFER for carboxylic acids

(c) Isokinetic Temperature relationship for carboxylic acids (d) Exner criterion for

carboxylic acids

CONCLUSION:

In the current work, 3D hierarchical Co3S4/Co9S8 nanoparticles are synthesized by a

facile electrochemical method. The prepared Co3S4/Co9S8 nanoparticles exhibit lesser

band gap value than pure Co9S8 which can be attributed to the present of Co3S4 as

doped material. The obtained Co3S4/Co9S8 nanoparticles exhibit high activity in the

photodegradation of carboxylic acid mainly acetic acid, formic acid and oxalic acid

and exhibit moderate biological activity. LFER indicate similar mechanism involves

in the degradation of carboxylic acids.

Acknowledgements:

The authors Acknowledge UGC (BSR) DST-PURSE Programme, IOE, UPE CPEPA

and University of Mysore, Mysuru, India

Conflict of interest

The authors declare that there is no conflict of interests regarding the publication of

this article.


REFERENCE

[1] J. Joshi, D. Kanchan, M.J. Joshi, H.O. Jethva, Dielectric Relaxation , Complex

Impedance and Modulus Spectroscopic Studies Dielectric relaxation , complex

impedance and modulus spectroscopic studies of mix phase rod like cobalt

sulfide ..., (2017). doi:10.1016/j.materresbull.2017.04.013.

[2] V.A. Online, RSC Advances, (2014) 21151–21162. doi:10.1039/c4ra01515k.

[3] B. Dojer, J. Kristl, Synthesis of nickel and cobalt sulfide nanoparticles using a

low cost sonochemical method, (2017) 1–19.

[4] B.F. Srouji, M. Afzaal, J. Waters, P.O. Brien, Single-Source Routes to Cobalt

Sulfide and Manganese Sulfide Thin Films**, 035 (2005) 91–94.

doi:10.1002/cvde.200404185.

[5] S.B. Sibokoza, The effect of temperature and precursor concentration on the

synthesis of cobalt sulphide nanoparticles using cobalt diethyldithiocarbamate

complex, (2017).

[6] M.B. Muradov, O.O. Balayeva, G. Eyvazova, Z.A. Aghamaliyev, CO, (2018).

doi:10.1016/j.infrared.2018.01.014.

[7] R.D. Apostolova, I. Talyosef, J. Grinblat, B. Markovsky, D. Aurbach, Study of

Electrolytic Cobalt Sulfide Co 9 S 8 as an Electrode, 45 (2009) 311–319.

doi:10.1134/S1023193509030112.

[8] I. Bibi, N. Nazar, M. Iqbal, S. Kamal, H. Nawaz, S. Nouren, Green synthesis of

cobalt-oxide nanoparticle : Characterization and photocatalytic activity

Green and eco-friendly synthesis of cobalt-oxide nanoparticle :

Characterization and photo-catalytic activity, Adv. Powder Technol. 28 (2017)

2035–2043. doi:10.1016/j.apt.2017.05.008.

[9] as photocatalyst and adsorbent for removal of dye pollutants Phase tuned

originated dual properties of cobalt sulphide nanostructures as photocatalyst

and adsorbent for removal of dye pollutants †, (2018).

doi:10.1021/acsanm.8b00656.

[10] P. Yin, L. Sun, Y. Gao, S. Wang, Preparation and characterization of Co 9 S 8

nanocrystalline and nanorods, 31 (2008) 593–596.

[11] J. He, J. He, Y. Chen, A. Manthiram, MOF-derived Cobalt Sulfide Grown on

3D Graphene Foam as an Efficient Sulfur Host for Long-Life Lithium-Sulfur

Batteries MOF-derived Cobalt Sulfide Grown on 3D Graphene Foam as an

Efficient Sulfur Host for Long-Life Lithium-Sulfur Batteries, ISCIENCE. 4

(n.d.) 36–43. doi:10.1016/j.isci.2018.05.005.

[12] B. Li, Y. Hu, J. Li, M. Liu, L. Kong, Y. Hu, L. Kang, Mechanical Alloying

Synthesis of Co 9 S 8 Particles as Materials for Supercapacitors, (2016) 6–11.

doi:10.3390/met6060142.

[13] Z. Jiang, W. Lu, Z. Li, K.H. Ho, X. Li, X. Jiao, D. Chen, Synthesis of


amorphous cobalt sulfide polyhedral nanocages for high performance

supercapacitors, J. Mater. Chem. A. 2 (2014) 8603–8606.

doi:10.1039/c3ta14430e.

[14] S. Felix, A. Grace, C. Santhosh, S. Jeong, B. Ragupathy, M. Saranya, R.

Ramachandran, Synthesis of Cobalt sulfide-Graphene (CoS/G) nanocomposites

for supercapacitor applications, IEEE Trans. Nanotechnol. 12 (2013) 1–1.

doi:10.1109/tnano.2013.2274461.

[15] S. Kumar, B. V Babu, Separation of Carboxylic Acids from Waste Water via

Reactive Extraction, (n.d.) 1–9.

[16] S.L. Gayatri, B.V. M, R.V. V, INDUSTRIAL WASTEWATER TREATMENT

- REMOVAL OF ACID FROM WASTEWATER, 8 (2014) 697–704.

[17] J.M. Wardell, C.J. King, Solvent Equilibria for Extraction of Carboxylic Acids

from Water, J. Chem. Eng. Data. 23 (1978) 144–148.

doi:10.1021/je60077a009.

[18] K.D. Patil, B.D. Kulkarni, Review of Recovery Methods for Acetic Acid from

Industrial Waste Streams by Reactive Distillation, J. Water Pollut. Purif. Res. 1

(2014) 13–18.

[19] M.. Paridah, A. Moradbak, A.. Mohamed, F. abdulwahab taiwo Owolabi, M.

Asniza, S.H.. Abdul Khalid, We are IntechOpen , the world ’ s leading

publisher of Open Access books Built by scientists , for scientists TOP 1 %,

Intech. i (2016) 13. doi:http://dx.doi.org/10.5772/57353.

[20] Z.I.Takai, Ournal of, Asian J. Chem. 30 (2018) 2424–2430.

[21] K.R. Raksha, S. Ananda, N.M. Madegowda, Journal of Molecular Catalysis

A : Chemical Study of kinetics of photocatalysis , bacterial inactivation and •

OH scavenging activity of electrochemically synthesized Se 4 + doped ZnS

nanoparticles, "Journal Mol. Catal. A, Chem. 396 (2015) 319–327.

doi:10.1016/j.molcata.2014.10.005.

[22] K.R. Raksha, S. Ananda, R. Narayanaswamy, High-efficient photocatalytic

treatment of dye and anti-bacterial activity via electrochemically synthesized

SeS<inf>2</inf> nanoparticles, J. Sulfur Chem. 36 (2015) 471–481.

doi:10.1080/17415993.2015.1057511.

[23] V.A. Online, Materials Chemistry A, (2016) 3287–3296.

doi:10.1039/c5ta09344a.

[24] B. Kraeutler, A.J. Bard, Heterogeneous Photocatalytic Decomposition of

Saturated Carboxylic Acids on TiO2 Powder. Decarboxylative Route to

Alkanes, J. Am. Chem. Soc. 100 (1978) 5985–5992. doi:10.1021/ja00487a001.

[25] A. Hezam, K. Namratha, Q.A. Drmosh, B.N. Chandrashekar, G.K.

Jayaprakash, C. Cheng, S.S. Swamy, K. Byrappa, CO CO, (2018).

[26] A. Ajmal, I. Majeed, R.N. Malik, H. Idriss, M.A. Nadeem, Principles and


mechanisms of photocatalytic dye degradation on TiO 2 based photocatalysts: a

comparative overview, RSC Adv. 4 (2014) 37003–37026.

doi:10.1039/C4RA06658H.

[27] Gilliom, Richard D. Introduction to physical organic chemistry. Vol. 2375.

Addison-Wesley, 1970.

[28] Streitwieser Jr, Andrew. "The Application of Taft's Equation to Polar Effects in

Solvolyses." Journal of the American Chemical Society 78, no. 19 (1956):

4935-4938.

[29] Exner, Otto. "The enthalpy-entropy relationship." Prog. Phys. Org. Chem 10

(1973): 411-482.

[30] Exner, O. "Correlation analysis in chemistry." by NB Chapman, and J. Shorter,

Plenum Press, London (1978).

[31] Bott, Garry, Leslie D. Field, and Sever Sternhell. "Steric effects. A study of a

rationally designed system." Journal of the American Chemical Society 102,

no. 17 (1980): 5618-5626.

[32] Bauer, A. W., Kirby, W. M. M., Sherris, J. C., & Turck, M. (1966). Antibiotic

susceptibility testing by a standardized single disk method. American journal of

clinical pathology,45(4_ts), 493-496.

[33] Parameswaran, V., and E. R. Nagarajan. "Antibacterial Activity and

Conductivity Studies of CoS Nanoparticles Incorporated in PVA/PVP/NH4Br

Electrolyte." Journal of nanoscience and nanotechnology 19, no. 5 (2019):

2522-2536.

Electrochemical synthesis of 3D hierarchical S /Co S ...(E/C) using cobalt coated Pt-electrodes in...

Documents

Transcript of Electrochemical synthesis of 3D hierarchical S /Co S ...(E/C) using cobalt coated Pt-electrodes in...