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Oxygen Electrocatalysis
C. R. Raj
Functional Materials and Electrochemistry Laboratory Department of Chemistry
Indian Institute of TechnologyKharagpur 721302, West Bengal, India
E‐mail: [email protected]://www.chem.iitkgp.ernet.in/faculty/CRR
iitkgp Workshop JNCSR Banglore, 27th November – 2nd December 2017
Sensors & Biosensors:Clinical and environmental
Energy Conversion & Storage: Fuel cell &
Supercapacitor
Synthesis:Chemical &
Electrochemical
0.0 0.2 0.4
Chem. Asian J. 2015, 10, 1554 ChemNanoMat 2015, 1, 615Biosens. Bioelectron. 2014, 62, 357 J. Mater. Chem. A, 2016, DOI :10.1039/c5ta08426aAnal. Bioanal. Chem. 2013, 405, 3431 J. Mater. Chem. A, 2014, 2,17848ACS Appl. Mater. Interface 2013, 5, 4791 J. Mater. Chem. A, 2014, 2, 2233Chem. Commun., 2011, 47, 11498 ACS Appl. Mater. Interfaces 2014, 6, 2692Chem. Commun., 2012, 48, 1787 Chem. Mater. 2010, 22, 4505Anal. Chem. 2008, 80, 4836 J. Phys. Chem. 2011, 115, 21041
Functional Materials and Electrochemistry Lab@ IITKgp
N
N
N
NS
OH
OH
N
N N
S
OH
OH
AcknowledgementMr. Bhaskar MannaDr. S. Bag (University of Calgary, Canada)Dr. Sourav Ghosh (TUM, Germany)Dr. Ramendra Sunder Dey (NSIT, India)Dr. Raj Kumar Bera (Hebrew University, Israel)Dr. Ashok Kumar Das (South Korea)Dr. Sudip Chakraborty (India)Dr. Bikash Kumar Jean (IMMT, India)Dr. Susmita Behera (UK)
Financial supportDST, CSIR and IIT Kharagpur
Mr. S. Bag Mr. B. Manna
Ms. S. Mondal Mr. A. Samanta
N
N
S
O
OHHO
N
N
N
NS
OH
OH
N
N N
S
OH
OH
N
N
S
OH
OH
Redox Molecular Assemblies: Electrochemically triggered Michael Addition Reaction on Au Surface
Langmuir 2007, 23, 1600J. Phys. Chem. C. 2008, 112, 3734
ACS Appl. Mater. Interfaces, 2010, 2 1355
J. Phys. Chem. C. 2007, 111, 15146
Functional Nanomaterial Library
Chem. Commun. 2005, 2005Anal. Chem. 2008, 80, 4836
Chem. Mater. 2008, 20, 3546
Anal. Chem. 2006, 78, 6332
J. Phys. Chem. C 2008, 112, 3496
nAu‐Enzyme nAu
nAu nAunPt
12/1/20175
Langmuir 2006, 112, 3734
nAu
J. Phys. Chem. C. 2011, 115, 21041
Patent: No. 36/KOL/2010Biosens. Bioelectron. 2010
J. Phys. Chem. C. 2010, 114, 21427
Au(III)
I-
Au(I)45 minSlow
disproportionation
Ag(I)
Nak
ed
Au
seed
s
12 h
No surfactants Room temperature
Fastdisproportionation
Fast
500 750 1000 1250
c
b
a
Disk
Ring
J. Mater. Chem. 2011, 21, 11973
CNT‐nPt
Chem. Mater. 2010, 12, 4505
Functional Nanomaterial Library
nAgrGO‐nPtEnzyme‐ nPt
Nanotechnology 2012, 23, 385602
Cat. Sci. Tech. 2013, 3, 1078
Electrochim. Acta2013, 107, 592
CNT‐nPt‐Pd
nAu nPt
Chem. Commum. 2012, 48, 1787 Chem. Asian. J. 2012, 7, 417
Graphene
Functional Nanomaterial Library
RSC Advance2013, 3, 25858
rGO‐ZnO
nAu
rGO‐Ni(OH)2
J. Mater. Chem. A. 2014, 2, 17848
rGO‐Mn3O4
ACS Appl. Mater. Interface 2014, 6, 2692
Fe
O
Fe
O
Biosens. Bioelectron. 2014, 62, 357
J. Chem. Sci. 2014ACS Appl. Mater. Interface 2013, 5, 4791
GO‐Fc
nPt‐nPd
rGO‐nPd
Functional Nanomaterial Library
J. Mater. Chem. A 2014, 2, 2233
CNT‐nPtPd
Electrochim. Acta, 2015, 163, 16
ChemNanoMat 2015, 1, 615
Functional Nanomaterial Library
J. Chem. Sci. 2016, 128, 339
Poly‐nAu
N‐rGO
SN‐rGO
J. Mater. Chem. A 2016, 4, 587
‐MnO2
‐MnO2
J. Mater. Chem. A 20164, 8384
Functional Nanomaterial Library
Electrochemistry of Oxygen
Fuel Cell
Metal-Air Battery
Alkaline Battery
Industrial Process
Water Electrolysis
Ozone Generation
Zn-Air Battery
1.23 V
OER: 2H2O O2 + 4H+ + 4e
ORR: O2 + 4H+ + 4e 2H2O
E1/2
10 mA/cm2E
ORROER
Oxygen Electrocatalysis
O2 + 4H+ + 4e 2H2O
Oxygen Reduction Reaction
Noble Metal
Noble Metal‐free
Transition Metal Oxides
Metal‐free
Func
tion
al M
ater
ials f
or O
RR &
OER
Brief history of ORR
1823 1975 1980‐90 1993‐97 2000‐
1965 1975 1989‐92 2008‐ 2009‐
J. J. Lingane, J. Electroanal. Chem., 2 (1961) 296
ORR OER
Ideal bifunctional electrocatalyst:
(a) Onset PotentialIntersection of the tangents between the baseline and the rising current in the voltammogram
RDE
RRDE
OER
ORR: O2 + 4H+ + 4e 2H2O
OER: 2H2O O2 + 4H+ + 4e
Ideal bifunctional electrocatalyst:
(b) Current density (j)
Normalization with electrochemically active surface area (ECA) or mass
• Hydrogen adsorption/desorption• CO stripping• Underpotential deposition of Cu
210 C/cm2
Pure & Appl. Chern., Vol. 63, No. 5, pp. 71 1‐734, 1991
Ideal bifunctional electrocatalyst:
(b) Overpotential ()
= E‐Eeq
(c) Current density (j)OER: Benchmark current density: 10 mA/cm2
ORR: ?? ‐3 mA/cm2
OER Ideal: 200–300 mV Excellent: 300–400 mV Good: 400–500 mVSatisfactory: 500 mV
Nano Energy 37 (2017) 136–157
(d) Potential gap (E)
E = EOERj10 mA/cm2 – EORRj‐3mA/cm2
EOERj10 mA/cm2 – EORRj1/2
Caution:Potential gap should be made based on similar catalyst loading
Ideal bifunctional electrocatalyst:
(e) Tafel slope and exchange current density
Tafel slope: Small Exchange current density: High
Current density vs Overpotential at different exchange current density
O + ne ↔ R (n=1)
(f) Electron Transfer Number and % HO2−
Rotating disk electrode and Rotating ring‐disk electrodeKoutecky‐Levich Analysis
(g) Turn Over Frequency (TOF)
TOF = (j × A) (n × F × m)−1
n4
/ % 200
The Levich EquationVeniamin Grigorievich (Benjamin) Levichwas a leading scientist in electrochemicalhydrodynamics, ‐ invented and developedby him. The famous Levich equationdescribing a current at a rotating diskelectrode is named after him.
https://www.ceb.cam.ac.uk/research/groups/rg‐eme/teaching‐notes/hydrodynamic‐voltammetry
Kouteck-Levich AnalysisRDE
Rotating Ring-Disk Electrode Analysis
n4
/ % 200
What is happening at the ring?
Pure and Applied Chemistry 76(2):303‐319
Some Practical Notes
RDE Analysis: Does electrode preparation matters?
Ink Formulation
• Type of solvent, • Water/Solvent/Nafion content• Ultrasonication
Electrode surface
• Surface preparation: cleaning, polishing• Electrode material• Quality of film ‐ uniform
Deposition & drying
• Stationary/rotation• Temperature• Atmosphere – inert, gas flow rate
Ink Formulation: Electrochemically Active Surface Area (ECA) (for Pt only)
https://www1.eere.energy.gov
Film drying method: stationary vs rotational
J. Electroanal. Chem. 662, 2011, 396
Stationary Rotational
SEM: Surface SEM: EdgeSEM: Surface SEM: Edge
Ink Formulation and Drying: Electrocatalytic activity (for Pt only)
III
I s I r I r+iR II Nafion II
Does the quality of catalyst ink and film matters?
Ink Formulation and Film quality: ECA
Anal. Chem. 2010, 82, 6321
Does the catalyst ink and film quality has any impact?
Ink Formulation and Film quality: Electrocatalytic activity
Electrolyte purity and nature of anionOxygen purity
Durability
Pulse voltammetry
Chronoamperometry
Cyclic voltammetry
Loss of ECA: dissolution, re‐deposition‐ larger particle, aggregation
Post‐mortem analysis is critically required to evaluate the durability
Noble Metal
Noble Metal‐free
Transition Metal Oxides
Metal‐free
Func
tion
al M
ater
ials f
or O
RR
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Synthesis of Pt nanostructure in the absence of PDDA
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0.0 0.3 0.6 0.9 1.2 1.5
ba
E/V vs. SHE
ORR activity
10 nm 100 nm
Onset: 1.06 V
Pt loading 20 g/ cm2
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0
50
100
150
200
250
300
J k (A
/cm
2 )
0
10
20
30
40
50
I (A
/g)
Onset: 1.06 V
Pt loading 20 g/ cm2@ 0.9 V @ 0.9 V
Durability??
Kinetic current density: Mass activity:
44
Pt alloys are more active for oxygen reduction - Why?
* Inhibition of –OH species on Pt
* Shortening of Pt-Pt interatomic distance
* Increased d-band vacanciesCatalyst Pt-Pt
distance (Å)
Pt d-band vacancies
PtPt53Ni47
Pt51Fe49
Pt49Co51
Pt50Cr50
2.772.662.692.712.73
0.3700.3780.3900.3900.401
Mukerjee, et al. J. Electrochem. Soc., 1995,142, 1409
Order of oxide formation: Pt > Pt-Ni > Pt-Fe > Pt-Co > Pt-Cr
Order of oxygen reduction activity:Pt < Pt-Ni < Pt-Fe < Pt-Co < Pt-Cr
Shortening of Pt‐Pt interatomic distances ‐ Jalan and TaylorLattice contractions due to alloying – ApplebyFavorable Pt‐Pt distances at supported Pt binary alloys – Mukerjee and Srinivasan
45
Proposed mechanism for oxygen reduction on Pt alloys
* Increase of 5d vacancies led to an increased 2 electron donation from O2 to surface Pt and weaken the O-O bond
* As a result, scission of the bond must occur instantaneously as electrons are back donated from 5d orbitals of Pt to 2* orbitals of the adsorbed O2
Watanabe, et al. J. Electrochem. Soc., 1999, 146, 3750
1:1
1:0.5
0.5:1
Pt46Pd54
Pt64Pd36
Pt28Pd72
Pt/Pd
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Composition of catalyst
Molar ratio of Composition Precursors
Average size 10 nm.
Shape: Truncated octahedra, near spherical.
Uniform particle distribution.
Particles are inside the CNT as well as grafted on the wall.
Pt46Pd54
Elemental mapping
Characterization:
7 8 9 10 11 120
20
40
60
80
Diameter (nm)
Abu
ndan
ce (%
)
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ORR activity:
100
200
300
400
Pt-MCNT
Pt-Blac
k
J k (A
/cm
2 )
Pt 28Pd 72
Pt 64Pd 36
Pt 46Pd 54 0
20
40
60
80
100
120
Pt blac
k
Spherica
l nPt
Pt 46Pd 54
I (A
/g)
Kinetic current density: Mass activity:
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0.4 0.6 0.8 1.0
2.0
1.5
1.0
0.5
0.0
after cyclingbefore cycling
j (m
A/c
m2 )
E/V vs. SHE
Catalytic activity remains same after 1000 potential scan
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Highly cited paper (ISI web of knowledge)
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-0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
j / m
A c
m-2
Potential vs SCE E/V
B
100 rpm40090016002500
N-rGO-Mn3O4
0
10
20
30
40
50
Current density
N-rGO/Mn3O4 Pt/CmixtureN-rGOMn3O4
n=3.96n=3.75
n=3.49
n=3.2
n=3.51
HO
2- yie
ld /%
HO2- yield
0.0
0.5
1.0
1.5
2.0
2.5
3.0
j /mA
cm-2
D
-0.6 -0.5 -0.4 -0.3 -0.20
4
8
12
Potential vs SCE E/ V
% o
f HO
2-
3.70
3.75
3.80
3.85
3.90
3.95
n
-0.8 -0.6 -0.4 -0.2 0.0 0.2
-2.0
-1.5
-1.0
-0.5
0.0
ab0.075 mA/cm-2
10 mV
j / m
A c
m-2
Potential vs SCE E/ V
B Durability
Metal‐free Electrocatalyst
Jahanke et al, Bagotskii et al and Fuhrmann A, Wiesener & Yeager’s group:Electrocatalytic ORR activity of nitrogen‐based catalyst ‐ pyrolysis ofmetallomacrocycles and acrylonitrile polymer and metal salts.
C.R.Raj and S. Bag, J. Chem. Sci. 2016
Electrocatalysts(N‐rGOs)
Onset potential(V)
Current densityAt 0.27
(mA/cm2)
N‐rGO1 0.55 1.64
N‐rGO2 0.58 1.94
N‐rGO3 0.66 2.71
N‐rGO4 0.66 2.76
Pyridinic: Limiting current
Graphitic: Onset potential
N‐doped reduced graphene oxideDoes the chemical nature of N impacts the ORR activity?
Nitrogen and Sulfur Dual‐Doped Reduced Graphene Oxide
C.R.Raj and S. BagElectrochimica Acta 2016
iit kgp
-0.6 -0.3 0.0 0.3Potential (vs Hg/HgO)
SN-rGO
N-rGO
S-rGO
rGO
50mA
S‐rGO & N‐rGO : 2 electron pathway SN‐rGO: mixed pathway
0
10
20
30
40
50
Pt/C
% of HO2-
n
S/N-rGON-rGO
n
% o
f HO
2-
S-rGO2.5
3.0
3.5
4.0
ACS Nano, 2014, 8, 6856
What is the active site? Pyridinic or graphitic??
What is the active site?
J. Am. Chem. Soc., 2014, 136, 10882FeNx/C Catalyst
Adv. Funct. Mater. 2017, 1700795
MO‐Co@N‐Doped Carbon
Emerging new generation electrocatalysts for the oxygen reduction reaction C. R. Raj et al. J. Mater. Chem. A, 2016, 4, 11156
Design of Efficient Bifunctional Oxygen Reduction/Evolution Electrocatalyst: Recent Advances and Perspectives, Adv. Energy Mater. 2017, 1700544
Electrocatalytic Oxygen Evolution Reaction in Acidic Environments – Reaction Mechanisms and Catalysts, Adv. Energy Mater. 2017, 7, 1601275
Oxygen Evolution Reaction Electrocatalysis on Transition Metal Oxides and (Oxy)hydroxides: Activity Trends and Design Principles, Chem. Mater. 2015, 27, 7549
Electrochemical Methods: Fundamentals and ApplicationsAllen J. Bard, Larry R. Faulkner
Modern ElectrochemistryBockris, John O'M., Reddy, AmulyaK.N., Gamboa‐Aldeco, Maria E.
What is the role of supporting electrolyte?
What is overpotential?
What are the different methods available for the measurement of ECA?
What is exchange current density?
What are the different modes of mass transport to electrode surface?
g{tÇ~ lÉâ12/1/2017