Synthesis of Novel Polymer Nanocomposites for Electrochemical Energy Storage

Thesis

Submitted to the

G. B. Pant University of Agriculture and Technology Pantnagar -263145, Uttarakhand, India

By

Ila Joshi (M.Sc. Organic Chemistry)

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS

FOR THE DEGREE OF

Doctor of Philosophy (Chemistry)

August, 2017

ACKNOWLEDGEMENT

A teacher is the representative of god and from the innermost core of my heart I hereby, express my

profound sense of reverence and gratitude to Dr. M.G.H Zaidi, Professor and Head, Department of Chemistry

& Chairman of my Advisory Committee for his inspiration, benign cooperation, industrious guidance,

impeccable supervision, timely criticism and benevolent help during investigation and preparation of this

manuscript. It seems when god make mentor he gave the best to me and I take this opportunity to thank god

for blessing me a wonderful advisor. Without his meticulous counsel and tremendous encouragement, this study

would not have been possible.

I wish to express my gratitude and thanks to Dr. N. K. Sand Professor, Department of Chemistry, Dr.

Reta Goel Professor and Head, Department of Microbiology and Dr. Uma Melkania Professor, Department of

Environmental Science, member of my advisory committee for their valuable and sincere advice during the

course of present investigation.

I acknowledge Special thanks to Dr. (Mrs) Sameena Mehtab, Assistant Professor, Department of

Chemistry for her pleasant company, friendly counseling and continuous support and cooperation.

I acknowledge special thanks to Dr. A.K. Pant, Professor, Dr. Virendra Kumar, Professor, Dr.

Vivekanand, Professor, Dr. Om Prakash, Professor and Dr. (Mrs) Anjana Srivastava, Professor, Dr. Shishir

Tandon, Junior Research Officer (Residue Chemist), Dr. Ravindra, Assistant Professor, Department of

Chemistry for constant help during the investigation.

I also feel great pleasure to acknowledge Dean, College of Post Graduate Studies, Dean, College of

Basic Sciences and Humanities, and staff members of university library, and CCF Pantnagar for providing

necessary facilities during the studies and research work.

I am deeply indebted to all the staff members specially Mr. Anil, Mr. Fullara, Mr. Manish, Mr.

Wazir, Mr. Shakil and Ms. Vimla for their day to day help in research work by providing all essential help

during the studies.

I would like to extend my heartfelt gratitude to my labmates Komal Mam, Bhawana, Anjali, Rekha

and Meenakshi for the supportive attitude mingled with care that I received from them. I am elated with

delight to avail the opportunity to express my thanks to all my seniors, batch mates and juniors for their kind

help, love and care.

“Friends are angels who lift us to our feet when our wings have trouble remembering how to fly”.

Time can never erase the immortal memories of golden times and blue moods shared with Komal Mam,

Archana Mam, Seema Mam, Preti Mam, Archana, Pinky and Megha whose love and care, mischief and kind

support did not ever let me feel out of my family and all the memorable moments shared with them made my

stay at pantnagar a memorable one.

“Parents are God on earth”.

Lastly My deepest gratitude goes to my family for their unflagging love, affection, care ,blessings and

support throughout my life; this dissertation is simply impossible without them They are my greatest assets and

their affection and encouragement made me work efficiently. I am indebted to my father and mother for their

care, erver-growing faith and love. Mumma and Papa, I know that I have never really showed you how

thankful I am to have you, but deep inside me, I am thankful to god that you are my parent. Indeed, words fail

to express my indebtedness to my mumma, papa, chacha, chachi, Bua, brother (Rohan), and Sister (Riya),

Lovey, Diksha, Mannu, Parth, Vrati, Nayan, Vijay ,Pooja, Neha, Shanti, Vibha and Meenu for their

boundless generosity, everlasting inspiration and abundant love without which, I might not have been able to

pursue my consistence. Thanks to all beloved and respected people around me who directly and indirectly helped

me during my degree programme whose names not mentioned here counselors.

Pantnagar Ila Joshi

Date Author ess

CERTIFICATE

This is to certify the thesis entitled “Synthesis of Novel Polymer

Nanocomposites for Electrochemical Energy Storage” submitted in partial

fulfillment of the requirements for the degree of Doctor of Philosophy with

major in Chemistry in the college of Post Graduate Studies, G.B. Pant

University of Agriculture and Technology, Pantnagar, is a record of bona fide

research carried out by Ms. Ila Joshi, Id No. 45720 under my supervision and

no part of the thesis submitted for any other degree or diploma.

The assistance and help received during the course of this investigation

have been dully acknowledged.

Pantnagar (M.G.H. Zaidi) August, 2017 Chairman Advisory Committee

CERTIFICATE

We, the undersigned, member of the Advisory Committee of

Ms. Ila Joshi Id No. 45720, a candidate for the degree of Doctor of Philosophy

with Major in Chemistry agree that the thesis entitled “Synthesis of Novel

Polymer Nanocomposites for Electrochemical Enertorage” may be

submitted in partial fulfillment of the requirements for the degree.

(M.G.H Zaidi) Chairman

Advisory committee

(N.K. Sand) (Uma Melkania) (Reeta Goel) Member Member Member

(M.G.H Ziadi) Ex-Officio Member

CC OO NN TT EE NN TT SS

S. NO. CHAPTERS PAGE

1. INTRODUCTION

2. REVIEW OF LITERATURE

3. MATERIALS AND METHODS

4. RESULTS AND DISCUSSION

5. SUMMARY AND CONCLUSION

LITERATURE CITED

APPENDICES

VITA

ABSTRACT

LIST OF TABLES

Table No. TITLE Page No.

1 Thermal Characteristics of matrix polymers , fillers and respective PNCs.

2 Effect of voltage on DC Conductivity of matrix polymers , fillers and

respective PNCs.

3 I/V Characteristic of PIN, C60, WC and their respective composites

4 Effect of Scan Rate on the Cs of C60 in the Potential Range of PIN

5 Effect of Scan Rate on the Cs of WC in the Potential Range of PIN

6(a-f) Effect of Scan Rate on the Cs of PIN and respective PNCs

7 (a-b) Effect of Scan Rate on the CS of MOF and [VII]

8a EIS data of PIN, [III] and [VI]

8b EIS data of MOF and [VII]

9a Corrosion parameters (Ecorr, Icorr, Rp, CR) obtained from Tafel plots of

bare electrode, PIN, C60, WC, [III] and [VI]

9b Corrosion parameters (Ecorr, Icorr, Rp, CR) obtained from Tafel plots of

bare electrode, MOF and [VII]

LIST OF FIGURES

Figure No.

TITLE Page No

1(a-k)

2(a-g)

3(a-o)

4(a-h)

5(a-k)

6(a-c)

7a

7b

7c

7d

7e

8a

8b

8c

8d

8e

8f

8g

8h

8i

8j

8k

FT-IR Spectra of PIN, C60, WC , MOF and respective PNCs

XRD spectra of PIN,C60,WC ,[III],[VI],MOF and [VII]

SEM of PIN, C60,WC, [III] and [VI]

FESEM of MOF and [VII]

TG-DTA-DTG of PIN,C60,WC , MOF and respective PNCs

Electrical Conductivity of PIN, C60, WC, MOF and respective PNCs

CV of PIN vs. Ag/Ag+ Electrode at various Scan Rate

CV of C60 vs. Ag/Ag+ Electrode at various Scan Rate

CV of WC vs. Ag/Ag+ Electrode at various Scan Rate

CV of [III] vs. Ag/Ag+ Electrode at various Scan Rate

CV of [VI] vs. Ag/Ag+ Electrode at various Scan Rate

Effect of Scan Rate on CV of C60 vs. Ag/Ag+ in Potential Range of PIN

CV of C60 vs. Ag/Ag+ at 0.05 V/s in Potential Range of PIN upto 100 CY

Effect of Scan Rate on CV of WC vs Ag/Ag+ in Potential Range of PIN

CV of WC vs. Ag/Ag+ at 0.05 V/s in Potential Range of PIN upto 100 CY

Effect of Scan Rate on CV of PIN vs. Ag/Ag+

CV of PIN vs. Ag/Ag+ at 0.05 V/s Upto 100 Cycles

CV of [I] vs. Ag/Ag+ at Various Scan Rate

CV of [II] vs. Ag/Ag+ at Various Scan Rate

CV of [III] vs. Ag/Ag+ at Various Scan Rate

CV of [III] vs Ag/Ag+ at 0.05V/s Upto 100 cycles

Comparative CV of [I],[II] and [III] at 0.05 V/s

8l

9a

9b

9c

9d

9e

9f

10a

10b

10c

10d

10e

11(a-n)

12(a-c)

Effect of Scan Rate on Cs of [I],[II] and [III]

CV of [IV] vs. Ag/Ag+ at Various Scan Rate

CV of [V] vs. Ag/Ag+ at Various Scan Rate

CV of [VI] vs. Ag/Ag+ at Various Scan Rate

CV of [VI] vs. Ag/Ag+at 0.05 V/s Upto 100 Cycles

Comparative CV of [IV],[V]and [VI] at 005V/s

Effect of Scan rate on Cs of [IV],[V] and [VI]

CV of ZIF-8 vs. Ag/Ag+ at various Scan Rate

CV of ZIF-8 vs. Ag/Ag+ at 0.1 V/s Upto 100 CY

CV of [VII] vs. Ag/Ag+ at Various Scan Rate

CV of ZIF-8 vs. Ag/Ag+ at 0.1 V/s Upto 100 CY

Effect of Scan Rate on Cs of ZIF-8 and [VII]

Nyquist and Bode plot of PIN ,C60,WC, [III], [VI], ZIF-8 and [VII]

Tafel plot of PNCs

LIST OF ABBREVIATION

APS - Ammonium persulfate

APTES - 3- triethoxysilylpropylamine

ASC - Asymmetric supercapacitor

AuNPS - Gold nanoparticle

BET - Brubauer- Emmett-Teller

C60 - Fullerene

CNOs - Carbon nanoonions

CV - Cyclic Voltammetry

Cs - Specific Capacitance

CY - Cycles

DC - Direct current

DTA - Differential thermal analysis

DTG - Differential thermogravimetry

ECPs

Ecorr

- Electrically conducting polymers

- Corrosion potential

EDLCs - Electric double layer capacitors

EIS - Electrochemical impedance spectroscopy

FESEM - Field- emission scanning electron microscopy

FRA - Frequancy response analyzer

FTIR - Fourier Transform Infrared

G - Graphite

GR - Graphene

Ia - Anodic Current

ia - Anodic Peak Current

Ic - Cathodic Current

ic - Cathodic Peak Current

IND - Indole

MWCNT - Multi walled carbon nanotube

MOF - Metal organic framework

Nhs - Nanohydrates

NMP - N-methyl-2- pyrrolidone

OLC - Onion like carbon

PANI - Polyaniline

PDDA - Poly(diallyldimethylammonium chloride)

PICA - Poly(indole-5-carboxylic acid)

PIN - Polyindole

PNCs - Polymer nanocomposites

PPY - Polypyrrole

PTH - Polythiophene

PVA

PSO

- Polyvinyl alcohol

- Polysulphon

PY - Pyrrole

SCs - Supercapacitors

SEM - Scanning electron microscopy

SWCNT

SCC

SPS

- Single walled carbon nanotube

- Supercritical carbon dioxide

- Sulphonated polysulphone

TEM - Transmission electron microscopy

TGA - Thermogravimetric Analysis

TH - Thiophene

WC - Tungsten Carbide

XRD

ZIF-8

- X-Ray Diffraction

- Zeolitic imidazolate framework-8

Chapter 1 INTRODUCTION

The present century has witnesses accelerated demand of novel electrode materials for

efficient, clean and sustainable ways of energy conversion and storage. This is being executed

through implication of certain electrochemical energy storage devices called SCs. The

performance of SCs may be improved through designing and development of electrodes with

novel class of electroactive materials.

The most frequent applications of SCs are in hybrid electric vehicles, load bearing

appliances, vehicles, electronic devices, emergency doors in airbuses and power backup

(Srimuk et al., 2015). While SCs have energy densities which is approximately 10% of the

rechargeable batteries but their power density is generally 10 to 100 times greater (Wang et al.,

2013, Chen et al., 2014). The inferior power density, low life cycle and charging discharging

rates has raised the demand of stimulus search of novel class of materials that may enhance the

electrochemical performance of SCs. (Halper et al., 2006 ; Zhong et al., 2015 ; Ke et al., 2016,

Iro et al., 2016).

SCs are of two types: (1) electric double layer capacitors (EDLCs) and (2)

pseudocapacitors. EDLCs, stores the charge at the interface of electrode and electrolyte

therefore, Cs can be improved by controlling the pore size, surface area of the electrode material

and by enhancing electrical conductivity of electrolyte. While in pseudocapacitors, faradic

current flows between electrode and electrolyte due to redox reactions and consequently shows

higher Cs over EDLCs (Ke et al., 2016). A material may show enhanced Cs under the judicious

combination of the electrolyte medium , composition of electrode, potential window scan rate.

Electrolytes used in the SCs are of three types : (1) aqueous electrolyte, (2) ionic liquids, and (3)

organic electrolyte. Aqueous solutions of alkalis, mineral acids and salts provides higher Cs due

to high ionic concentration and less resistance in the solution. Most of the organic electrolytes :

acetonitrile, propylene carbonate and tetraethylammonium tetrafluoroborate functions under

wide span of voltage that imparts enhanced energy and power density. Ionic liquids are used

due to high stability, voltage range, conductivity, low flammability and vapour pressure

(Sharma et al., 2010; Wang et al., 2012).

Major technical challenge in achieving the electroactive materials that may display

enhanced Cs over wide span of time. The energy density of SCs depends on the surface area and

conductivity of the electrode material. The electrodes derived from activated carbon do not

perform well under laboratory conditions. For such reasons, the electrochemical performance of

electrodes are improved through blending carbonaceous material with an electroactive material

in presence of a polymeric binder. Common electroactive materials employed are electrically

conducting polymers (ECPs), metal organic frameworks (MOFs) and electrically conducting

fillers (Pande et al., 2012, Xu et al., 2013, Lin et al., 2014, Gonzalez et al., 2015) . ECPs show

higher Cs but are swelled under charging discharging process (Jeong, et. al., 2009). SCs based

on metal oxides (Gonzalez et al., 2015), fillers such as transition metal carbides (Zhu et al.,

2012) and nitrides (Pande et al., 2012) although display enhanced Cs, but display weak

electrochemical stability under prolonged applications.

Literature survey reveals that although PNCs from a wide range of ECPs with various

fillers has been well explored (Snook et al., 2012, Ramya et al., 2013) a few efforts has been

made on exploration of the Cs of the PNCs derived from PIN (Long et al., 2015, Cai et al., 2016,

Oraon et al., 2016, Wang et al., 2017) and MOFs (Zhang et al 2016a, 2016b). In addition,

electrically conductive fillers renders the synergistic impact on the Cs of electrode materials

(Zhu et al., 2012, Tallo et al., 2012, He et al., 2013, Boota et al., 2015). Furthermore, no reports

are available on implication of C60 and WC as conductive fillers in combination with PIN and

MOF as electrode materials. This has prompt us to conduct the synthesis, characterization and

electrochemical investigation of PNCs: PIN/WC, PIN/C60 and MOF/C60 as potential materials

for SCs. For this purpose, PNCs were synthesized in SCC and characterized through diversified

spectral, microanalytical, thermal methods and electrical conductivity. The electrochemical

behavior of PNCs has been investigated through CV in KOH (1.0M), EIS and DC polarization to

ascertain their Cs and electrochemical stability. The current investigation reveals that the

synthesized PNCs may serve as potential electrode materials for SCs with enhanced

electrochemical energy conversion and storage. The current research also reflects its usefulness

towards economically viable development of working electrodes for electrochemical SCs.

Reproducible results of electrochemical characteristics of the proposed composites would be

utilized to work further in the field of SCs.

Chapter 2 REVIEW OF LITERATURE

2.0.Introduction

In recent years, a rapid growing demand of efficient, clean, and sustainable energy

sources for energy conversion and storage has been observed. Considerable efforts are underway

to explore the novel electrode materials that may provide enhanced electrochemical performance

and stability with reduced over potential at high discharge rates. One significant drawback of

existing materials is their lower rate of charge–discharge due to the slow diffusion of ions within

the bulk of the electrode.

2.1. Carbonaceous Materials

This supercapacitive performance of a wide range of allotropic states of carbon has been

investigated since past decades. The electrodes derived from graphite do not perform well under

laboratory conditions. For such reasons, the electrochemical performance of graphite is improved

through blending with other allotropic states of carbon in presence of a polymeric binders

(Frackowiaka and Be´guin, 2001; Chen and Die 2013; Xiong et al., 2014, Wu and Zhu

2016).

C60 is the most investigated allotropic states of carbon for modification of the

electrochemical performance of graphite. This may be due to high electron affinity and electron

transfer ability of C60 from LUMO. (Wang et al., 2017).

Okazima et al., 2005 modified the activated carbon with C60 ratio 1 to 30%.The SEM

micrographs revealed the formation of agglomerated particles of C60 having approximately

200µm diameter. The capacitance of 172 F/g was found at 50mA/cm2 on 1wt% C60 loaded

which is greater than the unloaded C60 electrode The higher specific capacitance was observed

at lowest wt% of C60 due to high rate of dispersion and give best cyclic stability at H2SO4 (0.5

M).

Sridhar et al., 2015 have improved the electrochemical performance of activated carbon

by adding self assembled (FSA) C60 grown on copper surface. SEM reveals morphology with 30

µm rod length. A 35% increment in Cs, maximum power density (20.3KW/kg) and 93% cyclic

stability was observed by in corparatinng FSA with AC.

Zheng et al., 2015 converted the C70 microtubes into 3D porous carbon by KOH

activation. The activation process at 600oC resulted microporous carbon with Cs of 362 F/g

gravimetric capacitance at 0.1 A/g. A good CY life shown after 5K CY by maintaing 92.5%

capcitive activity at 1 A/g.

McDonough et al., 2012 investigated the electrochemical performance of a multi shell

fullerene also known as carbon nanoonions (CNOs). An excellent Cs and 80% cyclic stability

was shown by CNOs at 15 mV/s. The CNOs at 1800oC was resulted 9-14 ms time constant

while OLC at 1500oC were more ordered, highly conductive and large surface area therefore,

concluded as best capacitive material for energy storage .

Azhagan et al., 2014 observed Cs of CNOs of 237 F/g at 0.001V/s that was decreased

with scan rate. The in situ addition of MnO2 nanoparticles to the CNOs exceeded Cs almost five

times i.e, 1207 F/g, which is nearly close to theoretical value of MnO2 and excellent cyclic

stability at 10A/g current density

Yong et al., 2013 prepared and investigated the electrochemical performance of GR/C60

capped gold nanoparticle (AuNPs). The AuNPs shows Cs of 197 F/g, while for GR/C60

electrode was 118 F/g. The Cs of the composite was enhanced by optimizing the size of AuNPs

or maintaing the mass ratio between GR and fullerene-capped AuNPs.

Ma et al., 2015 prepared the composite of GR with Li-functionalized C60. The TEM

images showed that C60 particles were held on GR surface which provided strength to GR sheet.

The Cs of composite was 135.36 F/g which is greater than GR (101.88 F/g) at 1A/g. The

composite also show good cyclic and electrochemical stability.

Signorelli et al., 2009 has investigated the electrochemical performance of vertically

CNT electrode and activated carbon. The CNT based electrodes show seven times high energy

density over activated carbon.

Catalán et al., 2011 has synthesized carbon/PPY via oxidative chemical polymerization.

The electrochemical data show 83.80 F/g Cs of carbon/PPY slightly higher than mesoporous

carbon. The ESR results the lower increament in Cs due to high internal resistance.Vellacheri et

al., 2014 has investigated a graphene electrodes showing Cs 91F/g at moderate temperatue. The

EIS results revealed that at low temperature electrode demonstrate low charge transfer resistance

and remarkable electrochemical performance.

Frackowiak et al., 2014 has noticed that the the Cs of carbon material can be inhance

via chemical oxidation. With ECPs and their derivatives the Cs of carbon increases due to fast

faradic effects.

Zhou et al., 2015 has synthesized non-porous carbon by low temperature solvothermal

process. The electrodes demonstrate Cs 521 F/cm3 good cyclic stability upto 10,000 CY@ 5 A/g.

Frackowiak et al., 2015 has evaluated the Cs of activcated porous carbon are quite complicated

due to presence of mesopores, delivering high energy with high rate. For activated carbon ,

pseudocapcitve behavior is shown due to redox reaction of oxygenated group. While, MWCNT

are quite efficient for accumulation of charge. Activation of MWCNT results high Cs due to

formation of micropores.

2.2. ECPs based PNCs

ECPs has recently attracted growing attention towards development of supercapacitive

materials with enhanced power density and cyclic stability .Common ECPS used for

development of supercapacitive materials are PANI ,PPY, PTH and PIN. ECPs undergo a redox

reaction to store charge in the bulk of the material and thereby increase the energy stored and

reduce self-discharge. Nevertheless, it is still proposed that ECPs can bridge the gap between

batteries and double-layer SCs as these electrodes have better kinetics than nearly all inorganic

battery electrode materials (Snook et al., 2012).

2.2.1. PANI Based PNCs

Gupta et al., 2006 synthesized PNCs through electrochemical polymerization of aniline

in presence of SWCNT in H2SO4 (1.0 M) PNCs resulted 485 F/g Cs, 2250W/kg specific energy

and good life CY at 73 wt%.

Mi et al., 2007 synthesized PNCs with Cs of 322 F/g, energy density of 22 W h/kg and

through microwave assisted polymerization of aniline in presence of MWCNT and APS. The

TEM reveals 50 to 70 nm length of layers PANI in PNCs.

Li et al., 2009 have synthesized the same class of PNCs with improved electrical and

electrochemical behavior through ultrasonically assisted in situ polymerization. Zhou et al.,

2010 prepared structured PNCs of the same class through in-situ polymerization in the presence

of HCl .The Cs, of composite at 66 wt% was 560F/g at 1 mV/s and 70.9 % capcitive retention

over 700 CY.

Xiong et al., 2012 synthesized C60–PANI-EB in acidic medium The coral like

morphology and interrelated nanofibers and nanoparticles of C60–PANI-EB easily mediate both

ion and electron movement in charge discharge method. The 37% enhacement in capacitance of

C60–PANI-EB than PANI-EB was due to increased ionic and electrical conductivity between

C60 and PANI. Thus, concluded that C60 with conducting polymer make a good choice for

electrode material for electrochemical devices. Wang et al., 2017 subsequently synthesized

PNCs based of C60 and polyaniline emeraldine base .The interaction between fullerene whisker

and PANI-EB resulted the formation of charge transfer complex which was confirmed by FTIR,

UV-vis and XPS spectra. PNCs has shown Cs of 813 F/g under identical conditions with higher

retention till 1.5K CY.

2.2.2. PPY Based PNCs

Hughes et al., 2002 synthesized PPY/MWCNT based conducting film on graphite

electrode. The 3-D arrangement of coated PPY on MWCNT show good charge storage with 192

F/g Cs.

Wang et al., 2007 examined PPY/SWNTs and PPY/functionalized SWNTs as electrode

material for SCs. The has shown higher Cs of 200F/g over PPY/SWNTs in KCl (1M) @ 0.2 V/s.

Zhang et al., 2011 synthesized the PPY/MWCNT through chemical oxidative

polymerization with different mass ratio of PY to MWCNT. The thickness of the polymerized

films was adjusted by addition of ethanol and regulating the ratio of PY to MWCNT. The

conductivity and the Cs of composite were influenced by the thickness of PPY/MWCNT films.

Shi et al., 2013 synthesized PPY/MWCNT doped with Ponceau S dye and cetrimonium

persulfate nanocrystals as an oxidant. The dispersion of MWCNT was efficiently increased in the

lower concentration of oxidant. The PNCs demonstrate Cs of 4.1 F/cm2 at 35mg/cm2 loading of

material, high charging discharging time and excellent CY life.

Mahore et al., 2015 have synthesized PNCs through chemical oxidative polymerization.

of PY in presence of carboxylate functional MWCNT. Spectral and microanalysis reveals that

PNCs was associated with granular morphology with good interaction based on the shift to

longer wavelength in electronic transition. PPY and corresponding PNCs have shown Cs of

0.825 and 1.062 F/cm2 in Na2SO4 (1.0M) @ 0.5V/s.

Yang et al., 2015 synthesized the electrode materials for power storage through SCC

assisted insitu polymerization of PY in presence of G/ SWCNT/PANI. The Cs of the PNCs was

compared with G/ SWCNT/PANI/PPY composite synthesized in the absence of SCC. The

composite synthesized in SCC showed 1.4 times greater Cs over those synthesized in the absence

of SCC.

Mykhailiv et al., 2015 made PPY/carbon nanoonions composite by chemical oxidative

and electrochemical polymerizations. The electrochemically derived PNCs has shown Cs of

1300F/g due to enhancement in the surface area by carbon nanoonions .

2.2.3.PTH based PNCs

Alvi et al., 2011 PNCs through chemical oxidative polymerization of EDOT and TH in

presence of grapheme. The synthesized PNCs from EDOT and TH rendered Cs ranges from 160

to 400 F/g .

Fu et al., 2012 synthesized PNCs through electrpolymerization of TH in presence of

MWCNT over GC modified with bmimPF6 solution The PNCs show Cs of 110F/g and 90%

with retention over 1K CY.

Plonska et al, 2012 synthesized the composites of carbon nanoonions

(CNO)/PEDOT:PSS with different mass ratio of PEDOT:PSS were synthesized to analyse the

performance of composites in supercapcitors. The composite at 1:1 mass ratio exhibited 96 F/g

and the electrochemical stability of the composites was enhanced by doping with carbon

nanostructures. Therefore, the dispersion of CNOs in polymer lead to increase the capacitance of

CNO/PEDOT:PSS composites .

Schon et al, 2014 formed ASC by combining PEDOT as positive and C60 as an negative

electrode material. After electrochemical polymerization of C60, PC60 was formed and show Cs

110-220 F/cm3 from 100-10 A/cm3. The PEDOT/PC60 ASC resulted four times more power

density than symmetric PEDOT.

Lethimaki et al., 2015 prepared PNCs through electrochemical polymerization of EDOT

in presence of RGO in BMIMBF4. The PNCs showed higher Cs than PEDOT and PNCs exhibit

90% retention after 2000.

Thakur et al., 2016 synthesized PNCs through in-situ polymerization of TH in presence

of CNT.The structure and morphology of the PNCs were examined by XRD and FESEM. The

PTH/CNT based electrode exhibited Cs of 125F/g due to incorporation of CNT into PTH marix.

Schon et al, 2014 developed a novel asymmetric supercapacitor device by using PEDOT

as positive and C60 polymer (PC60) as an negative electrode material. The C60 was

electrochemically polymerized to form PC60. The PC60 showed Cs from 110-220 F/cm3 at

current densities ranges from 100-10 A/cm3. The combination of PC 60 /PEDOT as asymmetric

device resulted four times more power density than symmetric PEDOT. Therefore, it was

concluded that charge accepting material like PC60 was used as negative material in charge

storage devices.

2.2.4. PIN based PNCs

Cai et al, 2016 synthesized electrically conductive PNCs through APS assisted chemical

oxidative polymerization of IN in presence of CNTs. The interaction between PIN and CNT was

confirmed by the Raman and XPS spectra. PNCs shows Cs of 555.60 F/g at 0.5 A/g with good

cyclic stability till 5K CY at 2 A/g.

Oraon et al, 2016 has modified the PNCs based on PIN/CNTs with nanoclay The

binding among components and the surface morphology of PNCs was ascertained by FTIR

Raman spectra FESEM and XRD. Addition of nanoclay has increased the Cs of PNCs by 25.8%

at 10 mV/s. The energy density of 47Wh/Kg at a power density of 1066 W/Kg at 10mV/s

revealed the excellent capacitive property of PNCs.

Wang et al, 2017 have synthesized a ternary PNCs of CNTs with PIN and RGO and

characterized through XPS and Raman spectra. The Cs of PNCs was 383F/g at 1 A/g in a

potential range of -0.2 to 0.8, maintaining 88.79% stability after 3K CY at 10 A/g.

Mudila et al., 2017 synthesized a series of PNCs through chemical oxidative

polymerization of IN in presence of various concentration of grapheme ranging 3-9% w/w, in

SCC. The PNCs synthesized at 9% grapheme exhibit Cs of 389.17 F/g in KOH (1.0 M) and

good cyclic stability over 1K CY.

2.3. Nanohybrids

2.3.1.PANI based NHs

Yu et al., 2011 synthesized NHs inverted emulsion polymerization of PANI in presence

of Co3O4 . The calcined NHs at 400°C have shown the highest Cs of 357 F/g at 5mV/s.

Jaidev et al., 2011 conducted the polymerization of aniline in presence of α-MnO2 in

acidic medium. The NHs shows Cs of 626 F g−1 in H2SO4 (1.0 M) at 2 A/g in the potential span

of 0.7 V. Under identical conditions, Nam et al., 2012 electrochemically synthesized the PANI/

RuO2 that has shown the Cs of 708 and 517 F g−1 at 5 mV/s. Modification of PANI with SnO2 by

Wang et al., 2014 results NHs that display Cs of 335.5F/g at 0.1A/g with stability till 10K CY.

Zou et al., 2014 electrocodeposited WO3 over PANI in presence of SDS. The NHs exhibited the

Cs 201 F/g at 1.28 mA/cm2 with 78% retention under the scan ranging from 10 to 150 mV/s.

Pandiselvi and Thambidurai 2014 conducted the chemical polymerization of aniline in

presence of ZnO stabilized in Chitisan. The mesoporous CS0.12-ZnO2.5/PANI electrode yields

larger Cs 587.15 F/g than the corresponding ZnO/PANI electrode. The Cs retention was found to

be 80 % after 1,000 charge/discharge CY at a current density 175 mA/cm2 in the potential

window of 0 to 0.8 V vs. SCE.

Han et al., 2014 prepared ternary composite MnO2 nanorods based PANI/GO by two-

step process. The introduction of MnO2 nanorods into PANI/GO composites electrode exhibited

significantly enhanced Cs than PANI/GO binary composite. A Cs, of ternary composite was 512

F/g at 70% (w/w) of MnO2 with outstanding cyclieability over 5K CY. Deshmukh et al., 2015

synthesized a thin films of RuO2 over PANI through chemical bath deposition.. The NHs showed

highest Cs of 830 F/g in acidic medium. The specific energy and specific power of the composite

electrode were 216 W h kg−1 and 4.16 kW kg−1.

Hosseini et al., 2016 has modified the MnO2/PANI with MWCNT. The Cs of

PANI/MnO2/MWCNT, MnO2/MWCNT and MWCNT in Na2SO4 (0.5M)were 321.47 F/g,

277.77 F/g, and 80 F/g.

2.3.2. PPY based NHs

Idris et al., 2011 have synthesized PNCs through FeCl3 assisted chemical oxidative

polymerization of PY in presence of NiO , sodium p-toluenesulfonate dopant and Triton-X as

surfactant .The NiO and respective PNCs have shown the cyclic stability till 30 CY at power

density of 119 and 436 mAhg1.

Qu et al., 2012 has investigated the polymerization of PY in presence of V2O5

nanoribbons in presence of anionic surfactant. The formation of V2O5 nanoribbons and PNCs

was confirmed by SEM and TEM. PNCs has shown Cs of 308F/g Cs at 100mA/g with good

cyclic stability in K2SO4.

Zhou et al., 2013 has immobilized the PPY on surface of the nanowires of CoO to

achieve PNCs.The PNCs have shown Cs of 2223 F/g and better life after 2K CY in aqueous

medim. Eeu et al., 2013 has modified PPY /RGO with iron oxide through chronoamperometry.

The Cs of PNCs was enhanced over PPY and PPY/RGO with Cs retention up to 0.2K CY.

Bahloul et al., 2013 has investigated the electrochemical polymerization of PY in presence of γ-

MnO2.The resulting PNCs have shown Cs of 141.6 F/g at 2 mA/cm2 .

Sidhu et al., 2014 has synthesized NHs through electrochemical polymerization of PY in

presence of ZnO nanorods. NHs shows Cs of 240 mF/cm2 with cyclic stability till 5K CY for

open pore and 180 mF/cm2 for narrow pore with 30 to 36 nm diameters. Under identical

conditions, Gao et al., 2014 synthesized NHs of PY with TiO2 that shows Cs of 459 F/g at

5A/g with 92.6% retention after 1K CY. Li et al., 2014 has deposited RuO2 on tantalum at 260

°C for 2.5 h followed by drying at 80°C for 12h. The deposition of PPY over 10-30 min leads to

the development of NHs with Cs of 657, 553, 471 and 396 F/g.

Tang et al., 2015 synthesized NHs through in-situ oxidative polymerization of PY on

MoS2 in APS solution.The PNCs has high surface area, strong bonding between PPY and MoS2,

high charge storage capability and stability in KCl (1.0M).

Wang et al., 2016 synthesized CeO2/PPY PNCs via in situ chemical oxidative

polymerization. The polymerization involved two kinds of amine-functionalized CeO2

nanoparticles with APTES or p-aminobenzoic acid. The PABA functionalized CeO2/PPY

nanocomposites exhibited a higher Cs, over APTES-functionalized CeO2 nanoparticles.

2.3.3.PTH based NHs

Lu et al., 2011 synthesized PNCs having uniform submicron-spheres microstructure

through polymerization of TH in presence of MnO2.. The PNCs shows performance till 1K CY

with retention of 97.3% at a charge/discharge rate of 2 A/g. Ambade et al., 2013 infiltred PTH

into TiO2 nanotubes (TNTs) by controlled electropolymerization method. The TNTs/PTH

electrode exhibit 640F/g Cs with stable life. Nejati et al., 2014 synthesized unsubstituted PTH in

a single step through oxidative chemical vapour deposition. The coating of PTH within porous

anodized aluminium oxide, TiO2 and activated carbon show significant enhancement Cs of PTH.

The ultrathin PTH coated within activated carbon depict 50 and 250% in specific and volumetric

Cs than other.

2.3.4.PIN based NHs

Rajasudha et al., 2010 synthesized NHs of PIN with ZnO(30nm) through insitu

polymerization.The impedence spectra in LiClO4 solution reveals that the ionic conductivity of

NHs was increased with concentration of ZnO till 50% w/w.

Zhou et al., 2015 synthesized carboxylate functional PIN nanowires (NWs) over GC

electrode. The nanowires shows Cs of 350 F/g capacitance at 1A/g current density in HClO4. The

symmetric SCs of derived from NHs showed Cs of 69.0 F/g at 0.25A/g and 9.4WH/kg energy

density at 1000W/kg made PICA. In subsequent studies, Zhou et al., 2015 synthesized NWs

from PIN functionalized with –COOH at 5,6 and 7- positions by electrodeposition method. The

diameter of 5, 6 and 7 substituted PICA investigated by the SEM were 100 nm, 50 nm, and 30

nm, respectively.The electrochemical capacitance of NHs in LiClO4 (0.1 M) was found greater

for 7 substituted maintaining PIN with 96% cyclic stability after 1K CY.

Raj et al., 2015 synthesized NHs through one step cathodic polymerization of PIN in

presence of spinel CO3O4. The structure of CO3O4 attached to PIN was confirmed by all the

physicochemical characterization. The composite shows 1805 F/g specific capacitance at 2 A/g

excellent cyclic stability over 1K CY.

Zhou et al., 2016 has synthesized the NHs of PIN with V2O5through insitu

polymerization.The electrodes fabricated from NHs in activated carbon exhibited Cs of 535.5

F/g at 1A/g. The energy density of 38.7 W h/kg, power density of 900 W/kg and high life was

found due to unique arrangement between the NHs and activated carbon. In subsequent studies,

Zhou et al., 2016 has grown the PIN nanospheres (300~600 nm) on carbon cloth (CC) by

polymerization of indole in ethanol/water using APS as oxidant. NHs were synthesized through

immersing nanospheres in PEDOT:PSS/ethanol solution. NHs shows Cs of 623F/g, higher over

PIN-NS/CC i.e, 161F/g at 0.5A/g with stability of 84.8% over 3K CY.

2.4. MOF as Supercapacitive Material

MOFs are the coordination polymers consist of metal containing nodes linked by struts of

polydentate organic linkers (Cook et al., 2013; Kitagwa et al., 2014).Their tunable structure,

pore size (0.6 to 2 nm), redox behavior of metal cation and the charge propogation in the

framework makes them suitable as electrode materials for SCs (Kang et al., 2014, Bradshaw et

al., 2014).Their pseudo capacitve redox metal cation centre combinedly make MOFs and their

derivatives potential candidate for SCs (Zhu et al., 2014, Ke et al., 2014).

Yuan et al., 2009 synthesized the worm like mesoporous carbon (WMC) with high

surface area by carbonizing Zn- based MOF with glycerol. WMC showed 344F/g Cs at 50mA/g

and can be used as senergy storage application.

Lee et al., 2011 investigated the pseudocapacitance of Co-based MOF film. The film

exhibited Cs of 206.76F/g and 1.5% loss in capacitance after 1K CY. Loera et al., 2012

reported the synthesis of [Cu3(BTC)2] MOF, also known as HKUST-1 by three different

methods: room temperature stirring, solvothermal and ultrasonication. The EIS results have

shown that the solvothermal approach of synthesis show lower faradic resistance than the other

two methods.

Liao et al., 2013 successfully synthesized the Ni based MOF via solvothermal method.

The MOF was characterized by XRD and BET. The electrode show Cs of 634F/g at 50 mV/s

and 84% cyclic stability after 2K CY . Lee et al., 2013 has modulated the pore size by changing

the length of the organic moiety of Co-based MOF. Depending upon the pore diameter, surface

area and surface morphology, the Cs, energy density and power density of the three cobalt based

MOF electrodes were found in the range of 131.8 - 179.2 F/ g; - 20.7 -31.4 Wh/ kg; and - 3.88 -

5.64 kW/ kg. The Co based MOF depict Cs ranges 131.8 to 179.2 F/g and power density from

3.88 to 5.64 KW/Kg respectively

Kang et al., 2014 synthesized Ni-based MOF via hydrothermal reaction. MOF

demonstrate 726 F/g Cs and 94.6% with retention after 1K CY.

2.4.1.MOF based NHs

Gao et al., 2014 successfully synthesized ZIF-8/ Ni2CO3(OH)2 by solvothermal method.

Their structure and surface morphology are characterized by XRD, SEM, TEM and BET. The

composite shows Cs of 851 F/g at mV/s and good cyclic stability over 5K CY. Gao et al., 2014

prepared NHs through dispersing SnO2 quantum dots into ZIF-8 by in-situ epoxide precipitation

method. The NHs show Cs of 931F/g and good cyclic stability after 0.5K CY.

Banerjee et al., 2015 tested the Cs of NHs based on MOF/RGO composites doped with

Ni. The NHs shows 2 electron faradic reactions and addition of RGO reduces the charge transfer

resistance. The combination of Ni-MOF with RGO have shown energy density of 37.8 Wh/kg at

a power density of 226.7 W/kg.

Fu et al., 2016 electrochemically synthesized the Zr based MOF (UiO-66) and co-

deposited with PEDOT-GO to give a flexible conductive electrode of PEDOT-GO/U-C. An areal

capacitance of 102 mF/cm2 , energy and power densities of 0.0022 mWh/cm2 and 0.2 mWcm2

was shown by the PEDOT-GO/U-C. Therefore, MOF-based solid-state SC is very promising to

be used for flexible and wearable electronics. Zhang et al., 2016 has carbonized the ZIF-8/CNT

that liberated ZnO QDs/carbon/CNTs and porous N-doped carbon/CNTs. The asymmetric

supercapacitor (ASC) was derived through combining ZnO QDs/carbon/CNTs as positive,

porous N-doped carbon/CNTs working as negative electrode and tested at 1.7V in polyvinyl

alcohol. This ASC, have shown energy density of 23.6 W h kg-1 at a power density of 847 W

kg-1 which is better than the ZnO based SCs. Zhang, et al., 2016 A ZIF/GO composites were

prepared by ultrasonication method at ambient temperature. The BET method reveals that the

surface area of composites are greatly influenced by addition of ZIF-8. The NHs demonstrate Cs,

400F/g at 10mV/s and good stability.

2.5. Carbides

Liu et al., 2007 synthesized WC/C porous NCs at 900oC. The electrochemical activity of

NCs have shown Cs of 477 at 20 mA/g in H2SO4 (1.0 M) and moderate stability over 5K CY.

Morishita et al., 2007 made WC and Mo2C nanoparticles by heating K2WO4 and K2MoO4

mixture. The nanoparticles exhibited Cs, 350 F/cm3 for WC and 550–750 F/cm3 for Mo2C.

Liu et al., 2008 investigated the performance of amorphous carbon through

potentiodynamic polarization curve before and after the addition of WC. The result showed that

pre addition of WC inhibits the corrosion of carbon.

Chmiola et al., 2010 made TiC films (2-300 µm) through chlorine treatment. The film of

2 µm exhibit Cs of 180 F/cm3 in TEABF4 and 160 F/cm3 in H2SO4 respectively.

Liu et al.,2011 fabricated supercapacitive electrodes through a SiC derived carbons. The

electrodes show 0. 062 s time constant at high charge discharge rate.

Tallo et al., 2012 made a series of WC derived carbide in different temperature (800-

11000C). The Cs of carbide at 10000C demonstrates 41Wh/kg and 430 kW/kg in the potential

window of 3V. Perez et al., 2012 synthesized TiC derived carbon nanoparticles by chlorinating

carbide. The nanoparticles show the Cs of 130 F/g at 5mV/s in H2SO4 (1.0 M). Alper et al., 2012

developed SiC nanowires based SCs via chemical vapour deposition. The nanowires rendered Cs

of 240 mFcm2 with 95% retention after 200K CY in KCl (1.0 M).

Xu et al, 2013 investigated VC, TiC and NbC derived carbon at different temperature

ranges from 400- 1000 oC. The VC derived carbons resulted high Cs and low IR drop at 600oC.

Naguib et al., 2013 synthesized Nb2C and V2C by treating Nb2AlC and V2AlC with HF. Nb2C

and V2C based electrodes shows reversible capacities of 170 and 110 mA-h/g for Nb2C and 260

and 125 mA-h/g for V2C at 1 and 10 C respectively. He et al., 2013 made TiC/PEDOT based

NCs for solar cell through electrochemical deposition. At 5000C, TiC/PEDOT showed current

density of 13.36 mA/cm2.

Ling et al., 2014 prepared NCs electrode by intercalating PDDA and PVA in Ti3C2Tx via

polymerization. The Ti3C2Tx/PDDA and Ti3C2Tx/PVA electrode has shown Cs of 296 F/cm3 and

528 F/cm3 respectively at 2mV/s in KOH (1.0M). Charge/discharge studies at current density of

5A/g demonstrates stagnated Cs for 10K CY.

Boota et al., 2015 prepared PPY/Ti3C2Tx through polymerization in a ratio 1:1 and 2:1.

The composite shows remarkable Cs 416 F/g and excellent cyclic stability up to 25K CY.

Zhang et al., 2016 synthesized a T-Nb2O5/carbon/Nb2CTx composite via CO2 oxidation

of Nb2CTx to anlayse the Cs in Li–ion capacitors. The composite exhibited 330 F/g and 660

mF/cm2 Cs at discharge rate of 4 min and excellent CY in LiClO4/EC/DMC (1.0 M). Zhang et

al., 2016 synthesized amorphous carbon grown on the surface of Ta, Nb, Hf and Mo by laser

ablation process. TaC/C showed Cs of 223 F/g at 200 mV/s among all nanostructures, along with

86.1 % retention at 8 A/g.

Chapter 3 MATERIALS AND METHODS

3.0. Starting Materials

Commercially available IND (99%, sd fine Chemicals india), C60 (99.5%, SES

Research), WC Nanopowder (60 nm,SRL India), chlorosulfonic acid (98%, Across Chemicals),

PSO (Mn, 26,000, ρ=1.24 g/cc, Aldrich Chemicals) and graphite (98.0%, 500 µm Loba). MOF

(ZIF-8) were procured from Centre for Fire, Explosives and Environment Safety Lab, Defense

research Development Organization Delhi. Other chemicals and solvents were used without

further purification.

3.1. Preparation of Electrode Materials

The PIN and related PNCs were synthesized through SCC assisted chemical oxidative

polymerization of IND in presence of either be C60 or WC (5-25%, w/w of PIN).The electrode

materials of ZIF-8 MOF were synthesized through dispersing the filler (15.5 %,w/w of MOF)

into polymer during the process of electrode formation.

3.2. Synthesis of SPS

PSO resin (3.60 g) was dissolved in DCM (35ml) in a two neck flask at 20±1 oC under

stirring. To this the solution of chlorosulphonic acid in DCM (6.50 5, v/v) was added drop wise

with stirring over 2 h. The precipitated SPS was filtered and washed with NaOH (1.2M). Finally,

SPS was washed with de-ionized water and dried at 50±1 °C overnight (Mudila et al., 2013).

3.3. Synthesis of PNCs in SCC.

PNCs were synthesized in a PID controlled high pressure reactor (100 mL) procured

from Ms PPI USA. The reactor system used works well up to 350 ᵒC (±1 ᵒC), 6000 psi. The

reactor was charged with IN (0.20g) , FeCl3 (0.13g) and filler. The cell was initially pressurized

with carbon dioxide (99.98 %) at 2200 psi at 80 ᵒC for 7 h with an electrical heating tape

wrapped around the cell to execute. The temperature inside the cell was measured by

thermocouple provided and displayed on PID temperature controller. The products were

recovered through venting the carbon dioxide into dichloromethane at 30ᵒC. PIN was also

synthesized through SCC assisted polymerization of IN under identical conditions. The crude

products in each of the case were purified through successive washing with deionized water

(Zaidi et al., 2007; Yang et al., 2015).

3.4. Preparation of the Working Electrodes

The metallic substrates for electrode (4cm2area) were fabricated through cutting a

commercially available 316-SS sheet. Prior to deposition of electroactive material, surface of

electrode was well polished with emery paper (mesh size 320600), followed by cleaning the

surface with acetone. Working electrodes were prepared through depositing (100µL) an

ultrasonically prepared suspension comprising electroactive material (70 mg), graphite (10 mg)

and SPS in NMP (5g/dL) over SS substrate. The treated electrodes were dried at room

temperature for 8 hrs, followed by 60 ºC/400 mm Hg for 48 hours. This has afforded electrodes

with a mass thickness of electroactive materials by 0.04±0.01 mg (Goel et al., 2011 and Mudila

et al., 2013).

3.5. Characterization

3.5.1.Spectral Characterization.

FT-IR spectra of samples were recorded on Thermo Nicolet in KBr from 4000 to 450 cm-

1 on transmission mode. XRD spectra of powdered samples were recorded at room temperature

over Rigaku-Geigerflex, X-Ray diffractometer using Cu-Kα radiation (λ= 0.154 nm) in the range

of 10º-70º at 30 kV and 15mA with step size 0.05 and step time of 19.2 sec.

3.5.2.Thermal Analysis

Thermo-oxidative stability of samples was investigated through simultaneous TG-DTG-

DTA over EXSTAR TG/DTA 6300 instrument in static air at a heating rate of 10oC/ minute at

flow rate of 200 mL/min in the temperature up to 1000 ºC.

3.5.3. Scanning Electron Microscopy (SEM)

SEM images were recorded on Hitachi S 3700 N using a primary beam voltage of 15 kV.

For .this purpose the electrodes were prepared via above mentioned procedure. The SEM images

were at scales 10-50 µm .The corresponding magnifications were ranged as 5.5 to 1.0 KX.

3.5.4. Electrical Conductivity

Electrical conductivities of the samples at room temperature were performed using

Keithley four-point probe DC conductivity meter equipped with 6221 DC current source and

2182 A Nanovoltmeter.

3.5.5. Electrochemical Characterization

All the electrochemical characterizations were made over the electrodes prepared for

supercapacitor applications (Goel et al., 2011 and Mudila et al., 2013). The electrochemical

performance of electrodes was investigated in KOH (1.0 M) over IVIUM Potentiostat-

Galvanostat using a three electrode cell assembly. Ag/AgCl was used as reference electrode. Pt

foil with 1 cm2 area was used as counter electrode CV was conducted at current compliance 1mA

in the range of -1.5-0.0V, at 0.1-0.2 mV/s at ambient temperature. EIS was performed to

determine the parameters for electron transfer reactions at the interface of the working electrode.

An alternating voltage of amplitude 0.05 V with sweeping frequencies between 1000 Hz to 0.001

Hz was coupled to a frequency response analyzer (FRA) to acquire Nyquist plots, @ 4 points per

decade change in frequency, fitted to an equivalent circuit. The EIS results were confirmed by

measurements per sample at intervals from 0 to 24 hrs of immersion. The potentiodynamic

polarization curves were obtained at scan rate of 0.1V/s. Electrochemical parameters (Icorr,

Ecorr, Rp, Corr Rate (mpy) were obtained from polarization curves.

3.5.6. Evaluation of Cs and related PNCs.

The CV of samples were scanned at scan rate ranging 0.001 to 0.2 V/s, at 1 mA and

various voltage compliances. The CS, is calculated from CV according to Eq. (1):

CS=C/m (1)

Where, C is capacitance of electrode, and m is the mass of the active material (0.04±0.01

mg) in various samples.

The capacitance of electrode (C) is calculated as according to Eq. (2):

C = Q/∆V (2)

Here, ∆V is potential difference, Q is charge, and in turn calculated as:

Q= I×dt (3)

Where, I is current and is the average of anodic current (Ia) and cathodic current (Ic):

I=Ia+│Ic│/2 (4)

dt is the time, and is calculated according to Eq. (5):

dt = E-step/scan rate (5)

The overall equation for calculating value of specific capacitance (CS) of the active

material can be written as, CS=I/m (dV/dt) (Ramya et al., 2013).

Chapter 4 RESULTS AND DISCUSSION

4.0. Results and Discussion

4.1. Work Conducted

A series of PNCs was synthesized for development of electrodes for electrochemical SCs.

For this purpose, PIN and ZIF-8 MOF were selected as polymer and C60 or WC as fillers. PIN

based PNCs were synthesized through SCC assisted chemical oxidative polymerization of IND

in presence of fillers .MOF based PNCs were synthesized through dispersing the filler (15.5

%,w/w of ZIF-8 MOF) into polymers during the process of electrode formation. The formation

of PNCs was ascertained through diversified spectral, thermal and microanalytical methods.

The electrodes from all the selected PNCs were fabricated and their electrochemical

investigations has been made @ 0.001-0.2 V/s at a wide range of potential windows -1.5 to –

0.0V investigated in KOH (1.0M). The supercapacitance and electrochemical stability of the

electrodes has been investigated up to 100 CY.

Under identical electrochemical conditions, graphite based electrodes of WC and C60

reveals Cs (F/g) of 110.00 and 113.25. The graphite electrodes modified with polymers have

shown improved Cs over those modified with fillers. The Cs of the graphite electrode modified

with PIN and MOF were observed at 106.75 and 283.63. A remarkable enhancement in Cs was

observed through modification of the electrodes comprising polymers with fillers. Modification

of PIN based electrodes with C60 (25%, w/w of PIN) display Cs of 296.75. Whereas, the

electrodes of PIN, modified with WC (25%, w/w of PIN) display Cs of 490.00. The highest Cs

was displayed by the MOF based electrode modified with C60 even a low concentration of filler.

Maximum inhibition efficiency (%) of 94.61 was observed in the MOF electrodes

modified with C60.This was followed by the PIN electrode modified by C60 [III] at 79.66. A

marginal loss in efficiency was shown by the PIN electrode modified with WC [VI] at 72.77.The

overall investigation reveals the best electrochemical performance the electrodes of MOF

modified with C60.

4.2. Synthesis of Electrode Materials

The present study deals with synthesis of PIN and respective PNCs through ferric

chloride initiated chemical oxidative polymerization of IND in presence of selected fillers in

SCC. For this purpose, C60 and WC were used as filler due to their inherent electrical

conductivity in view to achieve the electrode materials with enhanced the Cs. The

polymerization was investigated at constant concentration of IND (0.2g/dL), pressure (2.2 Kpsi)

at 80oC over 7h. MOF based PNCs were prepared through physical dispersion of C60 (0.01g )

into polymer (0.065 g).

4.2.1. Synthesis of PIN in SCC

The process of polymerization of IND was investigated at a wide range of concentration

of initiator from 0.05 to 0.13 g/dL. No polymerization of IND was appeared till 0.08 g/dL

Polymerization of IND was accomplished at initiator concentration of 0.1 g/dL, however, the

PIN has shown no remarkable electrochemical behaviour in KOH. This has prompt to conduct

the polymerization at higher concentration of initiator. PIN with remarkable electrochemical

behaviour was isolated in 82.32 wt% yield through conducting the polymerization reaction at

initiator concentration of 0.13 g/dL [Fig. 12a].

4.2.2. Synthesis of PIN based PNCs in SCC

PIN based PNCs were synthesized under identical conditions as applied for the synthesis

of PIN. The concentration of filler was selected as 5, 15 and 25 wt% of IND at initiator

concentration of 0.13 g/dL. The PIN based PNCs containing C60 were abbreviated as [I], [II]

and [III].This has afforded PNCs with yield wt% 74.05, 86.00, 88.00 respectively. PNCs of PIN

derived from WC abbreviated as [IV],[V] and [VI] has shown yield wt% 80.00, 78.00 and 84.00.

In general, the polymerization of IND was better progressed in presence of C60 over WC under

identical conditions.

4.3. Spectra

4.3.1. FT-IR Spectra

Fig.1 represents the FT-IR spectra of polymers, fillers and respective PNCs. FT-IR

spectra of PIN shows characteristic absorptions corresponding to vN–H (3411.74), vC –H

(3018.97), v C=C, Ar (1618.85), vC–C (1456.46) and 755.53 out of plane deformation for C–H

(Gupta et al., 2010) [Fig.1a]. C60 show characteristic absorptions at v C=C (3020.71), 1215.70,

ρCH2 (756.93) and skeletal vibrations of C60 (667.42) cm-1. (Huang et al., 2003; Bai et al.,

2014) [Fig.1b]. WC shows symmetric stretches near the low frequency fingerprint region at

665.82 cm-1 (Cheong et al., 2017).The peak at 3583.31 cm-1 correspond to symmetrical stretch

of W...OH , probably due to moisture (Fig.1c) (Delichere et al., 1988 , Pfeifer et al., 1995).

The presence of C60 was clearly reflected in all the PNCs [I-III]. PNCs [I] shows

characteristic absorptions corresponding to vN–H (3403.78), (v C=C) (3019.78), v C=C, Ar

(1617.24), vC–C (1455.13), ρCH2 (1215.11) , deformation for C–H out of plane (756.20) and

skeletal vibrations of C60 (668.31). PNCs [II] shows absorptions corresponding to vN–H

(3409.79), vC–C (1455.47) , deformation for C–H out of plane (741.39) and skeletal vibrations

of C60 (668.31). [III] shows characteristic absorptions corresponding to vN–H (3403.34), (v

C=C) (3020.61), v C=C, Ar (1619.09), ρCH2 (1215.52) , deformation for C–H out of plane

(756.72) and skeletal vibrations of C60 (668.38) [Fig.1d-1f].

All PNCs [IV-VI] indicate the presence of WC into PIN. PNCs [IV] shows characteristic

absorptions corresponding to vN–H (3582.28), v C=C (1215.96), symmetric stretches of W-C

near the low frequency fingerprint region ( 665.84), out of plane deformation for C–H (754.95)

and δ W-O (460.50) (Delichere et al., 1988; Pfeifer et al., 1995). PNCs [V] shows characteristic

absorptions corresponding to vN–H (3407.47), v C=C, (1617.65) , δ N-H (1453.87),out of plane

deformation for C–H (740.37).The peak corresponding to W...OH around 3454 to 3400 seems to

be merged with vN–H. PNCs [VI] shows characteristic absorptions corresponding to vN–H

(3583.19), vC –H (3018.71), v C=C, (1617.65) , δ N-H (1455.98),out of plane deformation for

C–H (755.68), symmetric stretches near the low frequency fingerprint region at 666.47 cm-1

(Cheong et al., 2017), 502 .84 (O-lattice) (Wright et al., 1977; Danial et al., 1987) [Fig.1g-1i].

FT-IR spectra of MOF reveals characteristic peaks at 3134.86 cm-1 and 2929.27 cm-1

due to aliphatic and aromatic C-H stretching of methyl group and imidazole (Tran et al., 2011),

δ C=N (1589.08), v C-N (1143.20) and δ C-N (995.02). The out of plane bending vibration for

alkene C-H of imidazole ring (-C=C-H) occurs at 755 cm-1 while absorption at 420 cm-1

correspond to Zn-N stretching mode (Alifah et al., 2015). PNCs [VII] show characteristic

absorption corresponding to v C=C (3021.17), (1215.52), v C-N (1146.88), ρCH2 (758.21)

,skeletal vibrations of C60 (667.33) and v Zn-N (463.30) cm-1 [Fig.1j-1k].

4.3.2. XRD Spectra

The XRD spectra of the PIN, C60, WC, [III] and [VI] are shown in [Fig. 2]. The PIN

show peaks at 19.53° and 26.01° corresponding to amorphous nature (Gupta et al., 2010) [Fig.

2a]. The diffraction peaks of C60 appear at 10.31°(8.56), 17.26°(5.13), 20.41°(4.34),

21.15°(4.19) and 32.33°(2.76) correspond to [111], [220], [311], [222] and [333] planes (JCPDS

82-0505) (Ma et al., 2015)[Fig. 2b]. For WC the diffraction peaks at 31.49° (2.83), 35.70°

(2.51), 48.35°(1.88), 64.16° (1.45), 65.70°(1.41), 73.22°(1.29), 75.67°(1.25), 77.12°(1.23) and

84.20°(1.14) are correspond to [001],[100], [101], [110], [002], [111], [200], [102] and [201]

planes of hexagonal WC and well matched with JCPDS 73-0471 (Liu et al., 2016) [Fig. 2c]. The

XRD of [III], show diffraction peaks at 10.40°(8.49), 17.22°(5.14), 20.28°(4.37) and 21.00

(4.22) [Fig. 2d]. For [VI], XRD peaks are appeard at 31.28° (2.85), 35.50° (2.52), 48.14°(1.88),

63.97° (1.45) and 73.02°(1.29) are correspond to [001],[100], [101], [110]and [002] [Fig. 2e].

However, when C60 and WC interact with PIN, the diffraction peaks are shifted towards lower

angle and as a result gallery spacing increases. This variation in the spacing confirmed that the

C60 and WC are well dispersed onto the PIN. The most of the peaks in the composites are

slightly different as present in the C60 and WC, thus illustrate the formation of the [III] and [VI].

The XRD pattern of MOF [ZIF-8: Zn5(OH)8(NO3)2(H2O)2] reveals a sharp peak of at 9.3°

correspond to [200] plane (JCPDS 01-072-0627), indicating the crystallinity of MOF (Pan et

al., 2011; Kida et al., 2013) [Fig. 2f-2g]. The diffraction spectra of [VII] shows peaks related to

C60 and ZIF-8 with shifting of diffraction peaks towards higher angle and increased gallery

spacing, indicating the interaction between C60 and MOF.

4.4. Morphology

Effect of filler and DC polarization (−1.5V to 1.5V) on morphology of the electrodes

derived from C60,WC, PIN and respective PNCs was investigated through SEM .The SEM

images were recorded at 2.7KX (5 µm ) and further verified at 5.5KX ( 2µm) [Fig.3]. Whereas

the electrodes derived from MOF were imaged through FESEM [Fig.4]. At all the

magnifications, SEM of the electrodes derived from PIN [Fig.3a-3b], PIN modified with WC

[Fig.3h-3i] display uniform coating. The electrodes modified with C60 [Fig.3c-3d] and WC

[Fig.3e], display phase separated morphology probably due to immiscibility into graphite and

polymeric binder in presence of NMP. The PIN electrode modified with C60 shows porous

morphology [Fig.3f-3g].

SEM images of the electrode modified with C60 after potentiodynamic polarization

display delamination of coating at 2.7KX. The high Warburg resistance attributes to porous

nature of the coating revealed through SEM at 5.5KX [Fig.3j]. At 2.7KX, an intense

delamination of the coating of PIN was appeared on event of potentiodynamic polarization

[Fig.3k]. Presence of PIN into C60 modified electrode has afforded [III] with stable corrosion

resistant coating even after potentiodynamic polarization [Fig.3l]. A clear delamination of the

coating of the electrodes modified with WC was appeared at all the magnifications. This was

associated with separation of the WC phase from coating [Fig.3m-3n]. After potentiodynamic

polarization the surface of the PIN electrode modified with WC [VI] display enhanced roughness

without remarkable delamination. This indicates the modification in the stability of PIN based

electrodes with WC under potentiodynamic conditions [Fig.3o].

FESEM images of MOF based electrodes and their C60 modified analogue [VII] are

shown [Fig.4]. Prior to potentiodynamic polarization, the electrode modified with MOF display

characteristic porous morphology at 1KX [Fig.4a]. Increase in magnification to 5KX,

distribution of crystalline grains was observed in MOF modified electrode [Fig.4b]. A qualitative

reduction in the porosity of the MOF based electrodes was observed on dispersion of

C60[Fig.4c] with reduction in crystalline grains [Fig.4d].Remarkable delamination was observed

in the electrodes modified with MOF at 1.0KX on event of DC polarization [Fig.4e].At 5KX,

delamination of coating of MOF with clear phase separated morphology was appeared .This has

enhanced the Warburg resistance of the electrode due to the migration of water across the porous

channels of the delaminated coating [Fig.4f]. Addition of C60 to MOF however has reduced the

tendency of delamination of the electrode [Fig.4g].Increase in magnification to 5KX clearly

indicates the absence of porous morphology of the MOF coating even after potentiodynamic

polarization [Fig.4h]. The FESEM reveals that C60 serves as a modifier for the MOF to protect

from corrosion, which is also supported with EIS data [Fig.11c].

4.5.Thermal Stability

The thermograms of fillers, polymers and their selected PNCs are shown in [Fig.5] and

the data have been summarized in [Table1] . The TG data has been expressed in terms of onset

and endset (oC), DTA and DTG peak temperatures (oC). Prior to first step decomposition, the

weight losses in the samples attributes to expulsion of moisture and residual solvents. The

weight residue (Wr) corresponding to TG are expressed as %w/w. DTA signals and rate of

degradation of samples in DTG are expressed as mV and mg/Cel respectively. The heat of fusion

data revealed through DTA has been expressed in mJ/mg.

PIN show one step decomposition with TG onset at 365 oC leaving %Wr 78.30 with a

DTA signal (0.903 mV) at 517 oC. Maximum decomposition of PIN was observed @ 1.33 mg/ oC at 510 oC with ∆Hf of -15.10 X103 mJ/mg. TG endset of PIN was appeared at 510 oC leaving

4.1 wt% char residue[Fig.5a].

C60, shows single step decomposition with TG onset at 462 oC leaving %Wr 99.92 with

a DTA signal (1.17 mV) at 634 oC. Maximum decomposition of C60 was observed @ 1.40 mg/

oC at 607 oC with ∆Hf of -29.00 X103 mJ/mg. The TG endset of C60 was appeared at 627 oC

leaving char residue of 1.20 wt % [Fig.5b].

WC was thermally stable up to 384 oC. WC was decomposed with TG onset at 528 oC.

This was accompanied with weight gain of 4.90 % due to oxidation (Liu et al., 2016) .

Decomposition of WC was supported with a DTA signal ( 0.22 mV) at 548 oC. Maximum

decomposition of WC was @ -21.97X103 mg/ oC at 552 oC. The TG endset of WC was

appeared at 597 oC leaving char residue of 114.70 wt % [Fig.5c].

The PNCs [I] was decomposed in a single step with TG onset at 345 oC leaving %Wr

80.80 with a weak DTA signal (1.12 mV) at 490 oC. Such decomposition of [I] was @ 1.67 mg/

oC at 466 oC with ∆Hf of -15.70 X103 mJ/mg [Fig.5d]. The PNCs [II] show single step

decomposition at TG onset 323 oC leaving %Wr 89.0 with a DTA signal (1.31 mV) at 416 oC.

The decomposition of [II] was @1.93 mg/ oC at 369 oC [Fig.5e]. The PNCs [III] was

decomposed in a single step with TG onset at 366 oC leaving %Wr 82.10 with a weak DTA

signal (1.13 mV) at 495 oC. Such decomposition of [III] was @ 1.70 mg/ oC at 475 oC with ∆Hf

of -18.10 X103 mJ/mg [Fig. 5f].

PNCs [IV] shows single step decomposition with TG onset at 300 oC leaving %Wr 78.10

%wt without fusion. The collective weight loss of 21.90 % wt indicates that the thermal stability

of PIN was compromised due to filling of WC. Maximum decomposition of [IV] was appeared

at 467oC leaving Wr of 59.70 wt% with maximum decomposition @ 1.65 mg/oC at 511 oC with

∆Hf of -18.80 X103 mJ/mg at 527 oC.PNCs [IV] has shown TG endset at 512 oC leaving char

residue of 9.50 wt % [Fig. 5g]. PNCs [V] was decomposed in a single step with TG onset at 340

oC leaving %Wr 86.50 with a DTA signals (1.06 mV) at 415 oC. The decomposition was

progressed @1.54mg/ oC at 400 oC with ∆Hf of -13.10 X103 mJ/mg at 415 oC. Decomposition

of [V] was concluded with TG endset at 459 oC leaving char residue 20.10 %wt[Fig. 5h]. PNCs

[VI] was decomposed with TG onset at 338 oC leaving %Wr 84.90 with DTA ( 0.92 mV) at 498

oC. The maximum decomposition of [VI] was observed @.86mg/ oC at 488 oC with ∆Hf of -

12.70X103 mJ/mg at 527 oC. Decomposition of [VI] was concluded at 488 oC leaving char

residue 26.40 %wt [Fig. 5i].

MOF was decomposed in a single step with TG onset at 552 oC leaving %Wr 70.00.

Steep decomposition of MOF was appeared @ 5.61 mg/min in the range of 552 to 591oC with

∆Hf of -2.28 X103 mJ/mg at 601oC. Decomposition of MOF was concluded at TG endset at 591

oC leaving char residue 24.50 %wt (Zhou et al., 2013) [Fig. 5j]. Addition of C60 has raised the

TG onset of MOF to 368 oC leaving %Wr 80.20.This has afforded the PNCs with ∆Hf of -12.70

X103 mJ/mg at 451oC [Fig. 5k]. From thermal data, this has been concluded that addition of WC

has reduced the thermal stability of polymer. However, addition of, C60 provides PNCs with

improved thermal stability.

4.6. Electrical Conductivity

DC conductivity of PNCs was investigated through four probe conductivity method. The

effect of voltage on σ (S/cm) at room temperature with increasing wt % of fillers shown in

[Fig.6a-6c] and respective electrical conductivity data has been summarized in [Table2]. The

conductivity is measured at varying voltages i.e. 1V, 10 V and 100 V. The conductivity data

depict that with increasing concentration of C60 and WC (5-25%, w/w) the σ of PNCs increases

maximum at 100V while the MOF and [VII] demonstrate high conductivity at 10V.

4.7. Electrochemical Behaviour

The CV of PIN, C60 and WC were recorded in a three electrode cell using KOH (1.0M)

as an electrolyte at the common scan rate of 0.05 to 0.2 V/s in the range of 0.0 V and -1.5 V vs.

Ag/AgCl. All the redox peak current and potential data are expressed in mA and V respectively.

With scan rate, the ia of PIN, C60 and WC were ranging from 0.11 to 0.30, 0.30 to 0.49

and 0.19 to 0.57 respectively. The corresponding Ea were -0.75 to -0.72, -0.76 to -0.74 and -0.72

to -0.71 respectively. This was accompanied with the simultaneous reduction in the value of ic

ranging from -0.14 to -0.36, -0.22 to -0.57 and -0.22 to -0.54, having corresponding Ec -0.99 to -

1.02, -1.02 to -1.04 and -0.98 to -1.00 respectively. For [III], with scan rate, the ia was increased

in the range of 0.30 to 0.81 at Ea ranging from -0.75 to -0.73. The corresponding ic and Ec were

in the range of -0.35 to -0.94 and -0.97 to -1.00 respectively. For [VI], with scan rate, ia was

increased in the range of 0.30 to 0.81 at Ea ranging -0.75 to -0.73.The corresponding ic and Ec

were in the range of -0.65 to -1.55 and -1.00 to -1.01 respectively[Fig.7a-7e].

Such increase in the ia may attributes to the oxidation of PIN, C60 and WC in aqueous

KOH. All the polymers show I/V compliance in single anodic and cathodic step. With scan rate,

all such I/V compliances were consist of increasing peak current and a shift in the voltage to

higher values. The peak potential shift in CV is probably due to slow ion diffusion or interfacial

charge transfer processes. The main reasons accounting for this phenomenon seems to slow

heterogeneous electron transfer, effects of local rearrangements of polymer chains, slow mutual

transformations of various electronic species. In a CV the higher the redox peaks, the greater is

the electrochemical activity (Li et al., 2005). The various values of peak current along with their

respective potential values are summarized in [Table 3].

4.7.1. Supercapacitance

The CS (F/g) of the electrodes derived from PIN, C60 and WC and their respective

composites was investigated in the potential window of -0.6 to 0.0 vs. Ag/AgCl, ranging 0.001–

0.2 V/s KOH(1.0 M). Based on the peak current corresponding to cathodic and anodic potentials

of all the samples , their evaluated Cs (F/g) has been summarized in [Table (4-8)].

4.7.1.1 Cs of C60 and WC

The electrochemical data of C60 and WC has been summarized in Table 4. The peak

current of C60 corresponding to Ic and Ia was in range of -0.64 to -5.42 and 0.03 to

1.71[Fig.8a].Under identical electrochemical conditions, WC shows peak current corresponding

to Ic and Ia was in range of -0.41 to -3.31 and 0.26 to 3.07[Fig.8c]. Calculations based on

cathodic and anodic peak current reveals that C60 and WC display stable Cs (F/g) in the range

of 113.25 to 5.75 and 110.00 to 5.00 @ 0.05 V/s up to 100 CY [Fig. 8b and 8d].

4.7.1.2. Cs of PIN and Respective PNCs

The electrochemical behaviour of PIN [Table 6] and respective PNCs [Table 6a-6f] has

been summarized. PIN shows electrochemical behaviour in the potential ranging from -0.6 to 0.0

V with Ic and Ia -0.61 to -2.65 and 0.03 to 0.45[Fig.8e]. The calculations based on I/V

characteristics reveals CS (F/g) of PIN in the range of 106.75 to 4.25 with stability up to 100CY

[Fig.8f]. Ic and Ia ranging -0.64 to -3.35 and 0.09 to 2.57 corresponds to CS (F/g) of [I] in the

range of 123.33 to 5.00 [Fig.8g]. Under identical conditions, Ic and Ia ranging -0.50 to -4.48 and

0.27 to 4.47 corresponds to CS of [II] in the range of 130.00 to 7.50 [Fig.8h]. The Ic and Ia

values ranging -1.47 to -8.38 and 0.31 to 7.31 corresponds to the CS of[III] in the range of

296.75 to 13.00 [Fig.8i]. All such composites display stable Cs till 100 CY @ 0.05 V/s. [Fig.8j].

PNCs [IV] shows Ic and Ia ranging -0.60 to -3.97 and 0.45 to 2.63.This has afforded the

CS in the range of 176.75 to 5.50 [Fig.9a]. Under identical conditions , [V] shows Ic and Ia

ranging -1.63 to -6.38 and 0.81 to 4.97 that corresponds to CS in the range of 406.75 to 9.50

[Fig.9b].The Ic and Ia ranging -1.90 to -9.37 and 1.03 to 8.62 corresponds to Cs of [VI] in the

range of 490.00 to 15.00[Fig.9c]. All such composites display stable Cs till 100 CY @ 0.05 V/s.

[Fig.9d].

The trend in variation of PIN and PNCs have further been investigated through in

recording their I/V characteristics with scan rate at 0.05 V/s. Voltammograms of [I], [II] and [III]

reveals a regular increase in the compliance corresponding to Ic and Ia currents (mA) ranging -

1.33 to -4.37 and 0.88 to 3.77 respectively. This has provided the CS (F/g) of the respective PNCs

ranging 7.50 to 27.00 showing increment in CS indicating novel materials for SCs [Fig.8 k].

Similarly, CV of [IV-VI] show a continuous increase in the compliance corresponding to Ic and

Ia currents (mA) ranging -1.66 to -5.59 and 1.32 to 5.09 respectively. Therefore, Cs (F/g) ranges

from 10.00 to 35.50 [Fig.9e]. A comparative account of effect of concentration of C60 and WC

indicates a regular increase in CS with concentration while a regular decrease in the CS of PNCs

occurs with increase in scan rates [Fig.8l and 9f].

4.7.1.3. Supercapacitive Behaviour of MOF and Respective PNCs

The electrochemical behaviour of ZIF-8 and [VII] was investigated through CV in the

potential ranging from -1.4 to 0.3V [Fig.10a]. In this range, with scan rate, ZIF-8 display range

for Ic and Ia -5.94 to -26.31 and 0.29 to 24.22 respectively. The calculations based on I/V

characteristics reveals ZIF-8 shows CS (F/g) in the range of 283.63 to 11.50. Similarly, [VII]

display range for Ic and Ia -10.43 to -30.76 and 0.44 to 25.33 respectively [Fig.10b]. The

calculations based on I/V characteristics shows CS (F/g) in the range of 494.50 to 15.88

[Table7a-7b]. The ZIF-8 and [VII] display stable I/V compliance till 100 cycles at a scan rate of

0.05 V/s. [Fig. 10c-10d]. The shape of each CV curves shows redox behaviour due to quasi-

reversible electron transfer process, which depicts pseudo-capacitive behaviour of both ZIF-8-

MOF and [VII] (Gao et al., 2014).

4.8. Electrochemical Stability of Electrodes

4.8.1. EIS of PIN and respective PNCs

The EIS spectra were represented through Bode and Nyquist plots to study the stability or

any loss in the protective properties of the ECPs and PNCs coating over the SS surface in KOH

(1.0M). All the impedance data and FRA responses has been expressed in ohm and Hz

respectively. The PNCs electrodes display equivalent circuit model with electrochemical system

that comprise solution resistance (R1), (W) Warburg impedence, polarization resistance (R2) and

Constant phase element (Q1). The impedance moduli (|Z|, Ω) of all the electrodes were fairly

sensitive with immersion time due to their heterogeneous nature. In general, the impedance

moduli of all the electrodes were increased due to swelling of the coating. The decrease in

polarization resistance (Rp, Ω) with time indicates the resistance of coating against oxidation,

whereas opening of loop represents destruction of coating (Mansfeld et al., 1995) [Table 8]. The

Nyquist [Fig. 11a] and Bode plots [Fig.11b] of the electrodes modified with PIN are shown. EIS

data reveals that PIN derived electrodes were found stable thereby maintaining semicircular

loop comprising Rp 9.62X103 and |Z| 9.67X103 up to 6h .The loop were gradually opened

within 24h leaving the electrode Rp1.40X104 and |Z| 1.94X104 .The Nyquist [Fig. 11c]and Bode

plots [Fig.11d] of the electrodes modified with C60 are shown. EIS data reveals that C60 imparts

stability to electrodes due to appearance semicircular loop comprising Rp 4.23X104 and |Z|

4.27X104 up to 6h .The loop were gradually opened within 24h leaving the electrode Rp

6.38X104 and |Z| 7.61X104 .The EIS data reveals that C60 imparts better stability of electrodes

over those derived from PIN. The Nyquist [Fig. 11e] and Bode plots [Fig.11f] of the electrodes

modified with WC are shown.EIS data reveals that WC imparts stability to electrodes due to

appearance semicircular loop comprising Rp 7.55X103 and |Z| 7.61X103 up to 6h .The loop were

gradually opened within 24h leaving the electrode Rp 8.37X103 and |Z| 8.54X103.The EIS data

reveals that WC imparts better stability of electrodes over those derived from PIN. The Nyquist

[Fig. 11g] and Bode plots [Fig.11h] of the electrodes modified with [III] are shown. EIS data

reveals that [III] imparts stability to electrodes due to appearance semicircular loop comprising

Rp 1.50X104 and |Z| 1.52X104 up to 6h .The loop were gradually opened within 24h leaving the

electrode Rp 3.35X104 and |Z| 4.76X104 .The EIS data reveals that [III] imparts better stability of

electrodes over those derived from PIN and C60. The Nyquist [Fig. 11i] and Bode plots

[Fig.11j] of the electrodes modified with [VI] are shown. EIS data reveals that [VI] imparts

stability to electrodes due to appearance semicircular loop comprising Rp 1.59X104 and |Z|

1.62X104 up to 6h .The loop were gradually opened within 24h leaving the electrode Rp

1.14X105 and |Z| 1.25X105. The EIS data reveals that [VI] imparts better stability of electrodes

over those derived from PIN and WC.

4.8.2. EIS of MOF and respective PNCs

The PNCs electrodes derived from MOF display equivalent circuit model with

electrochemical system that comprise solution resistance (R1), (W) warburg impedence,

polarization resistance (R2) and double layer capacitance (C1). The Nyquist [Fig. 11k] and Bode

plots [Fig.11l] of the electrodes modified with MOF are shown. EIS data reveals that MOF

imparts stability to electrodes due to appearance semicircular loop comprising Rp 1.73X104 and

|Z| 2.20X 104 up to 8h .The loop were gradually opened within 24h leaving the electrode Rp

9.79 X103 and |Z| 2.27X 104. The Nyquist [Fig. 11m] and Bode plots [Fig.11n] of the electrodes

modified with [VII] are shown. EIS data reveals that [VII] imparts stability to electrodes due to

appearance semicircular loop comprising Rp 1.164X105 and |Z| 1.26 X 105 up to 8h .The loop

were gradually opened within 24h leaving the electrode Rp 9.16 X104 and |Z| 1.40 X 105. The

EIS data reveals that [VII] imparts better stability of electrodes over those derived from MOF

4.8.3. Potentiodynamic Polarization Measurements

Fig.12, shows Tafel plots representing the extent of corrosion inhibition ability of the

electrode developed by fillers, polymers and selected PNCs in KOH (1.0M). Corrosion inhibition

efficiencies of electrode based on Ecorr (V), Icorr (A/cm2) and CR (mm/year) @ 0.1V/s are

summarized in [Table 9a-9b]. PIN and respected PNCs display potentiodynamic behaviour in the

range of −1.5V to 1.5V. The more negative Ecorr and the larger Icorr usually correspond to

faster corrosion rates and vice-versa. Electrodes developed from PIN display better corrosion

protection over uncoated electrodes. This has been revealed through greater negative value of

Ecorr (-0.93) with larger Icorr (6.06 X10-5). Electrodes derived from C60 depicts Ecorr -0.42 V

and Icorr 5.89 X 10-5 that indicate their stability against corrosion. Modification of PIN based

electrodes with C60 has further improved the resistance of electrodes against corrosion. This has

been revealed through greater negative value of Ecorr (-0.30) with larger Icorr (2.01 X10-5) of

[III]. The graphite electrodes modified with WC display Ecorr -0.85 and Icorr 4.26 X10-5 that

indicate their stability against corrosion. The higher negative values of Ecorr and positive values

of Icorr of WC based electrodes indicate their greater stability against corrosion over C60 based

electrodes. Higher negative value of Ecorr ( -0.44) and decreased Icorr 2.69 X 10-5 of [VI]

reveals that PIN, fillers and their respective PNCs imparts improved corrosion resistance to

graphite based electrodes with I.E (%) 79.66 and 72.77 [Fig.12a-12b].

The polarisation curve of ZIF-8 and [VII] electrodes are shown in [Fig.12c]. The steel

shows Ecorr -0.95and Icorr 20.02X 10-5 (A/cm2) which corresponds to faster corrosion rate.

Under identical conditions, the ZIF-8 coating shows the Ecorr -0.84 V and Icorr 9.68 X10-5

(A/cm2), and [VII] shows more positive Ecorr (-0.76) and lower Icorr (1.08 X 10-5 ). Thus, the

Tafel data revealed the good corrosion activity of [VII] with I.E (%) of 94.61.

Fig.1a: FT-IR spectra of PIN

Fig.1b: FT-IR spectra of C60

Fig .1d: FT-IR spectra of [I]

Fig.1c: FT-IR spectra of WC

Fig.1f: FT-IR spectra of [III]

Fig .1e: FT-IR spectra of [II]

Fig .1g: FT-IR spectra of [IV]

Fig .1h: FT-IR spectra of [V]

Fig

Fig .

Fig. 1i : FT-IR spectra of [VI]

Fig .1j : FT-IR spectra of MOF

Fig . k : FT-IR spectra of [VII]

.

Chapter 5 SUMMARY AND CONCLUSION

· In the present investigation, a series of polymer nanocomposites (PNCs) from Polyindole

(PIN) and metal organic framework (MOF containing) C60 and tungsten carbide (WC)

as was synthesized and investigated for their supercapacitance in KOH (1.0 M).

· PIN based PNCs were synthesized through ferric chloride initiated chemical oxidative

polymerization of IND in presence of fillers (5-25 wt%) in SCC.

· MOF based PNCs were synthesized through dispersing the filler (15.5 %,w/w).

· In general, the polymerization of indole was better progressed in presence of C60 over

WC .

· Diversified spectral, thermal and microanalytical data reveals the formation of polymers

and respective PNCs.

· The electrodes derived from C60 have shown higher thermal stability whereas low

electrical conductivity over those derived from WC.

· Modification of MOF based electrodes with C60 display higher Cs and inhibition

efficiency over those modified with PIN.

· CV@ 0.001 to 0.2 V/s in the potential range -0.6V to 0.0V, reveals ranges of Cs for PIN,

C60 , WC as 106.75 to 6.75 ,110.00-5.00 and 113.25-5.75 respectively. Under identical

conditions, PNCs of PIN containing C60 and WC has shown Cs in the range of 296.75 to

5.00 and 490.00 to 5.50.

· MOF shows Cs ranging 283.63 -11.50. Modification of MOF with C60 results PNCs

with highest Cs in the range of 494.50-32.63.

· A marginal loss in inhibition efficiency was shown by the PIN electrode modified with

WC.

· Presence of PIN into C60 modified electrode has afforded PNCs with stable corrosion

resistant even after potentiodynamic polarization .

· The FESEM in combination of EIS data reveals that C60 serves as a modifier for the

MOF to protect from corrosion.

· The overall investigation reveals the best electrochemical performance and stability of

the electrodes of MOF modified with C60.

The present study provides a pioneer attempt towards synthesis and characterization of the

C60 and WC based electrically conducting polymers for electrochemical energy storage.

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Table 1: Thermal Characteristics of matrix polymers , fillers and respective PNCs.

Sample

code

TG(Onset,oC)

[Wr %]

TG(Endset,oC)

[Wr %]

DTA(oC)

[mV],

-DH

×103(mJ/mg)

DTG(oC)

[Rate:mg/Cel]

PIN 365 [78.30] 510 [4.10] 517 [0.90] 15.10 510 [1.33]

C60 462 [99.20] 627 [1.20] 634 [1.17] 29.00 607 [1.39]

WC 528 [104.90] 656 [115.30] 548 [0.22] 6.78 552 [-0.02]

[I] 345 [80.80] 466 [8.70] 490 [1.12] 15.70 466 [1.67]

[II] 323 [89.00] 442 [20.70] 416 [1.30] 16.20 369 [1.93]

[III] 366 [82.10] 564 [2.40] 390 [0.34]

495 [1.13]

553 [0.15]

0.96

18.10

1.86

388 [0.10]

475 [1.70]

[IV] 300 [78.10] 512 [9.50] 527 [1.01] 18.8 511 [1.65]

[V] 340 [86.50] 459 [20.10] 415 [1.06] 13.10 400 [1.54]

[VI] 338 [84.90] 488 [26.40] 498 [0.92] 12.70 488 [0.86]

MOF 552 [70.70] 591 [24.50] 601 [0.37] 0.02 575 [5.60]

[VII] 368 [80.20] 444 [29.00] 451 [1.11] 12.70 404 [1.79]

Table 2: Effect of voltage on DC Conductivity of matrix polymers ,fillers and respective

PNCs.

Sample

σ × 10-2(S/cm)

1 V 10 V 100 V

PIN 0.13 0.14 0.81

C60 0.32 0.36 0.75

WC 0.32 1.04 1.05

[I] 0.39 0.57 0.90

[II] 0.43 0.94 0.98

[III] 0.54 1.08 1.24

[IV] 0.35 1.09 1.15

[V] 0.35 1.15 1.45

[VI] 0.38 1.17 1.59

MOF 5.84 6.55 2.73

[VII] 9.80 10.90 3.90

Table 3: I/V Characteristic of PIN, C60, WC and their Respective composites

PIN

Scan Rate (V/s) ia (mA) Ea (V) ic (mA) Ec (V)

0.05 0.11 -0.75 -0.14 -0.99

0.10 0.18 -0.74 -0.22 -1.01

0.2 0.30 -0.72 -0.36 -1.02

C60

Scan Rate (V/s) ia (mA) Ea (V) ic (mA) Ec (V)

0.05 0.30 -0.76 -0.22 -1.02

0.10 0.31 -0.75 -0.34 -1.03

0.20 0.49 -0.74 -0.57 -1.04

WC

Scan Rate (V/s) ia (mA) Ea (V) ic (mA) Ec (V)

0.05 0.19 -0.72 -0.22 -0.98

0.10 0.32 -0.72 -0.37 -0.99

0.20 0.568 -0.71 -0.54 -1.00

[III]

Scan Rate (V/s) ia (mA) Ea (V) ic (mA) Ec (V)

0.05 0.30 -0.75 -0.35 -0.97

0.10 0.50 -0.74 -0.57 -0.98

0.20 0.81 -0.73 -0.94 -1.00

[VI]

Scan Rate (V/s) ia (mA) Ea (V) ic (mA) Ec (V)

0.05 0.45 -0.74 -0.65 -1.00

0.10 0.78 -0.74 -0.98 -1.00

0.20 1.33 -0.72 -1.55 -1.01

Table 4. Effect of Scan Rate on the CS of C60

Sc. Rt.

(V/s)

Ic

(mA)

Ia

(mA)

I=Ia+|Ic|/2

(mA)

dt=Estep

/ Sc.Rt

Q=I×dt

(C)

C=Q/∆V

(F)

CS=C/m

(F/g)

0.001 -0.64 0.03 0.34 8 2.72 4.53 113.25

0.005 -0.65 0.07 0.36 1.6 0.58 0.97 24.25

0.01 -0.68 0.10 0.39 0.8 0.31 0.65 16.25

0.05 -1.37 0.75 1.06 0.16 0.17 0.28 7.00

0.1 -2.20 1.57 1.89 0.08 0.15 0.25 6.25

0.2 -5.42 1.71 3.57 0.04 0.14 0.23 5.75

Table 5. Effect of Scan Rate on the CS of WC

Sc. Rt.

(V/s)

Ic

(mA)

Ia

(mA)

I=Ia+|Ic|/2

(mA)

dt=Estep

/ Sc.Rt

Q=I×dt

(C)

C=Q/∆V

(F)

CS=C/m

(F/g)

0.001 -0.41 0.26 0.33 8 2.64 4.40 110.00

0.005 -0.47 0.44 0.45 1.6 0.72 1.20 30.00

0.01 -0.49 0.54 0.52 0.8 0.41 0.68 17.00

0.05 -1.04 1.48 1.26 0.16 0.20 0.33 8.25

0.1 -1.59 2.12 1.86 0.08 0.15 0.25 6.25

0.2 -3.31 3.07 3.19 0.04 0.12 0.20 5.00

Table 6. Effect of Scan Rate on the CS of PIN

Sc. Rt.

(V/s)

Ic

(mA)

Ia

(mA)

I=Ia+|Ic|/2

(mA)

dt=Estep

/ Sc.Rt

Q=I×dt

(C)

C=Q/∆V

(F)

CS=C/m

(F/g)

0.001 -0.61 0.03 0.32 8 2.56 4.27 106.75

0.005 -0.65 0.10 0.38 1.6 0.61 1.02 25.50

0.01 -0.68 0.13 0.41 0.8 0.33 0.55 13.75

0.05 -1.24 0.73 0.99 0.16 0.16 0.27 6.75

0.1 -1.81 1.31 1.56 0.08 0.12 0.20 5.00

0.2 -2.65 2.45 2.55 0.04 0.10 0.17 4.25

Table 6a. Effect of Scan Rate on the CS of [I]

Sc. Rt.

(V/s)

Ic

(mA)

Ia

(mA)

I=Ia+|Ic|/2

(mA)

dt=Estep

/ Sc.Rt

Q=I×dt

(C)

C=Q/∆V

(F)

CS=C/m

(F/g)

0.001 -0.64 0.09 0.37 8 2.96 4.93 123.33

0.005 -0.71 0.20 0.46 1.6 0.74 1.23 30.75

0.01 -0.74 0.24 0.49 0.8 0.39 0.65 16.25

0.05 -1.33 0.88 1.11 0.16 0.18 0.30 7.50

0.1 1.97 1.52 1.75 0.08 0.14 0.23 5.75

0.2 -3.35 2.57 2.96 0.04 0.12 0.20 5.00

Table 6b. Effect of Scan Rate on the CS of [II]

Sc. Rt.

(V/s)

Ic

(mA)

Ia

(mA)

I=Ia+|Ic|/2

(mA)

dt=Estep

/ Sc.Rt

Q=I×dt

(C)

C=Q/∆V

(F)

CS=C/m

(F/g)

0.001 -0.50 0.27 0.39 8 3.12 5.20 130.00

0.005 -0.61 0.43 0.52 1.6 0.83 1.38 34.50

0.01 -0.68 0.61 0.65 0.8 0.52 0.87 21.75

0.05(n) -2.09 1.54 1.82 0.16 0.29 0.48 12.00

0.1 (n) -3.18 2.63 2.91 0.08 0.23 0.38 9.50

0.2 (n) -4.48 4.47 4.48 0.04 0.18 0.30 7.50

Table 6c. Effect of Scan Rate on the CS of [III]

Sc. Rt.

(V/s)

Ic

(mA)

Ia

(mA)

I=Ia+|Ic|/2

(mA)

dt=Estep

/ Sc.Rt

Q=I×dt

(C)

C=Q/∆V

(F)

CS=C/m

(F/g)

0.001 -1.47 0.31 0.89 8 7.12 11.87 296.75

0.005 -1.72 0.70 1.21 1.6 1.94 3.23 80.75

0.01 -1.72 0.90 1.31 0.8 1.05 1.75 43.75

0.05 -4.37 3.77 4.07 0.16 0.65 1.08 27.00

0.1 -6.34 5.83 6.09 0.08 0.49 0.82 20.50

0.2 -8.38 7.31 7.85 0.04 0.31 0.52 13.00

Table 6d. Effect of Scan Rate on the CS of [IV]

Sc. Rt.

(V/s)

Ic

(mA)

Ia

(mA)

I=Ia+|Ic|/2

(mA)

dt=Estep

/ Sc.Rt

Q=I×dt

(C)

C=Q/∆V

(F)

CS=C/m

(F/g)

0.001 -0.60 0.45 0.53 8 4.24 7.07 176.75

0.005 -0.81 0.38 0.60 1.6 0.96 1.60 40.00

0.01 -0.89 0.45 0.67 0.8 0.54 0.90 22.50

0.05 -1.66 1.32 1.49 0.16 0.24 0.40 10.00

0.1 -2.57 2.38 2.48 0.08 0.20 0.33 8.25

0.2 -3.97 2.63 3.30 0.04 0.13 0.22 5.50

Table 6e. Effect of Scan Rate on the CS of [V]

Sc. Rt.

(V/s)

Ic

(mA)

Ia

(mA)

I=Ia+|Ic|/2

(mA)

dt=Estep

/ Sc.Rt

Q=I×dt

(C)

C=Q/∆V

(F)

CS=C/m

(F/g)

0.001 -1.63 0.81 1.22 8 9.76 16.27 406.75

0.005 -1.51 0.87 1.19 1.6 1.90 3.17 79.25

0.01 1.47 0.85 1.16 0.8 0.93 1.55 38.75

0.05 -2.73 2.00 2.37 0.16 0.38 0.63 15.75

0.1 -4.27 3.25 3.76 0.08 0.30 0.50 12.50

0.2 -6.38 4.97 5.68 0.04 0.23 0.38 9.50

Table 6f. Effect of Scan Rate on the CS of [VI]

Sc. Rt.

(V/s)

Ic

(mA)

Ia

(mA)

I=Ia+|Ic|/2

(mA)

dt=Estep

/ Sc.Rt

Q=I×dt

(C)

C=Q/∆V

(F)

CS=C/m

(F/g)

0.001 -1.90 1.03 1.47 8 11.76 19.60 490.00

0.005 -2.63 1.74 2.19 1.6 3.50 5.83 145.75

0.01 -2.83 2.05 2.44 0.8 1.95 3.25 81.25

0.05 -5.59 5.09 5.34 0.16 0.85 1.42 35.50

0.1 -7.12 6.82 6.97 0.08 0.56 0.93 23.25

0.2 -9.37 8.62 9.0 0.04 0.36 0.60 15.00

Table 7a. Effect of Scan Rate on the CS of MOF

Table 7b. Effect of Scan Rate on the CS of [VII]

Sc. Rt.

(V/s)

Ic

(mA)

Ia

(mA)

I=Ia+|Ic|/2

(mA)

dt=Estep/

Sc.Rt

Q=I×dt

(C)

C=Q/∆V

(F)

CS=C/m

(F/g)

0.001 -5.933 0.299 3.12 8 24.96 22.69 283.63

0.005 -5.899 0.928 3.42 1.6 5.47 4.97 62.13

0.01 -6.325 1.846 4.09 0.8 3.27 2.97 37.13

0.05 -10.726 6.955 8.85 0.16 1.42 1.29 16.13

0.1 -16.557 12.93 14.75 0.08 1.18 1.07 13.38

0.2 -26.313 24.226 25.27 0.04 1.01 0.92 11.50

Sc. Rt.

(V/s)

Ic

(mA)

Ia

(mA)

I=Ia+|Ic|/2

(mA)

dt=Estep/

Sc.Rt

Q=I×dt

(C)

C=Q/∆V

(F)

CS=C/m

(F/g)

0.001 -10.433 0.446 5.44 8 43.52 39.56 494.50

0.005 -12.988 1.96 7.50 1.6 12.00 10.91 136.38

0.01 -14.953 3.609 9.28 0.8 7.42 6.75 84.38

0.05 -23.109 12.12 17.62 0.16 2.82 2.56 32.00

0.1 -30.257 20.97 25.62 0.08 2.05 1.86 23.25

0.2 -37.552 34.205 71.76 0.04 2.87 2.61 32.63

Table 8a: EIS data of PIN, [III] and [VI]

Parameters initial 2 hr immersion 6 hr immersion 24 hr immersion

Experimental PIN [III] [VI] PIN [III] [VI] PIN [III] [VI] PIN [III] [VI]

Rp Ω 9.62 X103 1.50X104 1.59X104 1.00X104 2.24X104 4.65X104 1.50X104 3.05X104 5.46X104 1.40X104 3.35X104 1.14X105

|Z| Ω 9.67X 103 1.52X104 1.62X104 1.02X104 2.41X104 4.68X104 1.85X104 4.05X104 5.56X104 1.94X104 4.76X104 1.25X105

Simulated

R1 3.66X101 1.34X101 8.44X101 5.72X101 1.07X102 4.42X102 7.11X101 1.42X101 4.63X102 2.7X102 1.55X102 5.75X102

R2 1.17X104 1.70X104 2.39X104 1.09X104 7.39X104 4.57X104 4.00X101 8.30X104 5.65X104 7.94X103 1.00X105 1.46X105

Q1 5.15X10-4 1.49X10-3 2.65X10-3 8.85X10-4 5.50X103 1.66X103 2.14X10-4 4.08X10-2 1.16X103 1.00X10-

3 1.63X102 1.83X102

W1 1.00X10-6 2.92X10-4 2.16X10-4 6.27X10-4 7.05X10-4 2.77X10-4 5.66X10-4 7.76X10-4 2.86X10-4 1.36X103 7.40X10-4 2.75X10-4

Table 8b: EIS data of MOF and[VII] Parameters initial 2 hr immersion 8 hr immersion 24 hr immersion

Experimental MOF [VII] MOF [VII] MOF [VII] MOF [VII]

Rp Ω 1.73X104 1.16X105 2.72X104 1.03X105 3.97X104 7.06X104 9.79X103 9.16X104

|Z| Ω 2.20X104 1.26X105 4.13X104 2.44X10-4 6.85X104 8.95X104 2.27X104 1.40X105

Simulated

R1 4.98X101 4.36X103 6.98X101 3.92X103 8.85X101 3.62X103 6.28X101 9.20X103

R2 1.47X102 5.68X103 2.01X102 3.14X103 7.35X102 5.21X104 3.59X102 7.87X104

C1 1.18X10-4 8.19X10-7 8.50X10-5 6.69X10-7 2.09X10-4 5.31X10-5 2.37X10-4 1.10X10-6

W1 1.31X10-2 4.61X10-5 2.67X10-3 4.81X10-5 2.67X10-3 4.75X10-5 5.12X10-3 3.98X10-5

Table 9a : Corrosion parameters (Ecorr, Icorr, Rp, CR) obtained from Tafel plots of bare electrode, PIN, C60, WC,[III] and [VI] S.No.

Substrate Ecorr (V) Icorr (A/cm2)X10-5

Rp (Ohm) CR (mm/yr)

IE (%)

1. Bare Steel -1.06 9.88 1489 0.32 - 2. PIN -0.93 6.06 2023 0.20 38.66 3. C60 -0.42 5.89 2308 0.19 40.38 4. WC -0.85 4.26 2775 0.14 56.88 5. [III] -0.30 2.01 4433 0.06 79.66 6. [VI] -0.44 2.69 4311 0.09 72.77 Table 9b : Corrosion parameters (Ecorr, Icorr, Rp, CR) obtained from Tafel plots of bare electrode, MOF, [VII] S.No.

Substrate Ecorr (V) Icorr (A/cm2)X10-5

Rp (Ohm) CR (mm/yr)

IE (%)

1. Bare Steel -0.95 20.02 637.60 0.66 - 2. MOF -0.84 9.68 2129.00 0.32 51.65 3. [VII] -0.76 1.08 4493.00 0.04 94.61

VITA

The authoress of this manuscript was born on 16 June 1991, in Ramnagar

(Uttarakhand). She successfully completed her High School Examination in 2005 and

Intermediate Examination in 2007 from Govt. Girls Inter College. She earned her B.Sc.

degree (PCM) in 2010 from Kumaon University Nainital with first division and

thereafter completed M.Sc. Degree (Organic Chemistry) from the same in 2012. After

that she joined the department of Chemistry at Govind Ballabh Pant University of

Agriculture and Technology, Pantnagar, for Ph.D. in Chemistry in August 2013. The

authoress is the recipient of University Fellowship during her Ph.D. Degree Programme.

Permanent Address:

Ila Joshi D/O Dinesh Chandra Joshi Tera Road, Lakhanpur Ramnagar District Nainital, Uttarakhand Pin code- 244715 Email- ilajoshi15@gmail.com

ABSTRACT

Name : Ila Joshi Id. No : 45720 Sem &Yearof admission : 1st Sem, 2013-14 Degree : Ph.D. Major : Chemistry Department : Chemistry Advisor : Dr. M.G.H. Zaidi Minor : Environmental Science Thesis Title : “Synthesis of Novel Polymer Nanocomposites for Electrochemical Energy Storage”

A series of polymer nanocomposites (PNCs) was synthesized from Polyindole (PIN)

and metal organic framework (MOF). For this purpose, C60 and WC were used as

fillers. PIN based PNCs were synthesized through ferric chloride initiated chemical

oxidative polymerization of Indole in presence of fillers (5-25, wt %) in supercritical

carbon dioxide. MOF based PNCs were synthesized through dispersing the filler (15.5

%, w/w) into polymer matrix. The polymers and respective PNCs were characterized

through various analytical methods. The graphite based electrodes were fabricated from

polymers and respective PNCs in presence of sulphonated polyulphone binder.

Supercapacitance and electrochemical stability of the electrodes were investigated

through cyclic voltammetry (CV), electrochemical impedance spectra (EIS) and

potentiodynamic polarization in KOH (1.0M). CV@ 0.001 to 0.2 V/s in the potential

range -0.6V to 0.0V, reveals ranges of Cs for PIN, C60 , WC as 106.75 to 6.75 ,110.00-

5.00 and 113.25-5.75 respectively. Under identical conditions, PNCs of PIN containing

C60 and WC has shown Cs in the range of 296.75 to 5.00 and 490.00 to 5.50.MOF

shows Cs ranging 283.63 -11.50. Modification of MOF with C60 results PNCs with

highest Cs in the range of 494.50-32.63.All Cs data were found stable to 100 cycles.

DC Polarization data in combination with microscopy reveals delamination of the

coating of PIN based electrodes containing C60 and WC. Whereas, the electrodes

derived from MOF containing C60 were highly resistant towards delamination under

potentiodynamic condition. Modification of MOF based electrodes with C60 display

higher Cs and inhibition efficiency over those modified with PIN. The present study

provides a pioneer attempt towards synthesis and characterization of the C60 and WC

based electrically conducting polymers for electrochemical energy storage.

(M.G.H. Zaidi) (Ila Joshi) Advisor Authoress

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