TU Dresden Institut für P hysikalische Chemie und E lektrochemie 1 Magnetic field influences on electrochemical processes Silvio Köhler , Andreas Bund, Holger H. Kühnlein, Adriana Ispas, Waldfried Plieth SFB 609, C5 Magnetic Field Control of Metal Deposition
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Magnetic field influences on electrochemical processes
Magnetic field influences on electrochemical processes. Silvio Köhler , Andreas Bund, Holger H. Kühnlein, Adriana Ispas, Waldfried Plieth. SFB 609, C5 Magnetic Field Control of Metal Deposition. Motivation and Aim. to find out - PowerPoint PPT Presentation
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TU Dresden Institut für Physikalische Chemie und Elektrochemie
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Magnetic field influences on electrochemical processes
Silvio Köhler, Andreas Bund, Holger H. Kühnlein, Adriana Ispas, Waldfried Plieth
SFB 609, C5 Magnetic Field Control of Metal Deposition
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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Motivation and Aimto find out
How does a magnetic field influence the several parts of an electrochemical reaction?
to describeexplaining of phenomena and creation of an
experimental basis for numerical simulations
to tailorcombinations of electric and magnetic fields for deposition of functionalized layers with defined properties and improving the mass transport in micro and nano structures, respectively
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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Electrochemical Reactions
Influence on electron transfer kinetics ?
Influence on mass transportMHD effect
Gradient effects
Influence on surface diffusion/crystallization ?
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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unstirred
Copper dissolution in microstructures
RE
AE
Va
GE
BRE
AE
VIa
GE
B
stirred
MHD-effectB E
Lorentz-Force FL +natural convection Fconv
))((
)(
.., ByvqF
BvqF
convLconv
L
Magnetic field on
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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Copper dissolution in microstructures
RE
AE
IIIa
GE
BRE
AE
IVa
GE
B
unstirred stirred
02 2/ cBF mgrad
MHD-effectB E
Paramagneticgradient Force Fgrad
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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Charge transfer reaction
0,0 0,2 0,4 0,6 0,8 1,00,8
1,0
1,2
1,4
i 0 / (
mA
cm
-2)
B / T
[Fe(H2O)
6]2+/ [Fe(H
2O)
6]3+
[Ir(Cl)6]2-/ [Ir(Cl)
6]3-
0,0
0,4
0,8
1,2 0,01M
0,00,40,81,21,6
0,008M
0,01M[Fe(CN)6]3-/ [Fe(CN)
6]4-
0,0 0,2 0,4 0,6 0,8 1,00,450,500,550,600,65
tran
sfer
coe
ffici
ent
B / T
0,450,500,550,600,65
[Ir(Cl)6]2-/ [Ir(Cl)
6]3-
0,450,500,550,600,65
[Fe(CN)6]3-/ [Fe(CN)
6]4-
[Fe(H2O)
6]2+/ [Fe(H
2O)
6]3+
Butler- Volmer- Equation:
TR
Fz
TR
Fz
ka
DD
eeiiii 1
0
(i: current density; i0: exchange current density; D : overvoltage ; z: number of electrons; :
transfer coefficient; F: Faraday´s constant; R: universal gas constant; T: absolute temperature)
TU Dresden Institut für Physikalische Chemie und Elektrochemie
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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Experimental Technique (EQCM)
w0wLayer 1
w
f R,Layer 2
f R,Layer 1 fR,0
Layer 2
9,997 9,998 9,999 10,000
0
20
40
60
80
100
Quartz withRigid Layer
UnloadedQuartz
Quartz withDamping Layer
Re
al P
art
of
Ad
mitt
an
ce /
mS
f / MHZ
2* w
iΔff
Mass Damping
Complex frequency shift
in situ measurements of the mass changes at electrode surfaces during electrodepositionits functionality is based on the converse piezoelectric effect
quartz
gold electrodes
film
shear motion
mCf SB
Sauerbrey equation:
CSB: Sauerbrey constant
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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curr
en
t d
en
sity
polarization
E2 E
1
02 H+ + 2e- H2
Ni2+ + 2e- Ni
B>0 B=0
Small Current Density (E1)iNi(B)iNi(B=0)iH2(B)>iH2(B=0) Current efficiency decreases
High Current Density (E2)iNi(B)>iNi(B=0)iH2(B)>iH2(B=0) Current efficiencynot affected by B
Deposition of NickelGalvanostatic deposition
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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B= 0 mT, i=-50 mA cm2
i(H2)=-12.9 mA cm-2
Small damping change
B= 740 mT, i=-50 mA cm2
i(H2)=-7.8 mA cm-2
Large damping change
y x
L
0
L
0yxa dxdyyx,f
LL
1R
0 200 400 600 800
-2
0
2
4
6
8
Ra
(B)/
Ra
(B=
0mT
)
B / mT
itotal
= -50 mA.cm-2
itotal
= -0.5 mA.cm-2
Ra mean roughness
Lx, Ly dimension of the surface
f(x,y) relative surface to the central plane
Morphology and RoughnessAtomic Force Microscopy
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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Deposition of Polypyrrole (PPy)
0 50 100 150 200 250
0.00
-0.00
-0.00
-0.00
curr
ent d
ensi
ty i
in m
A/c
m²
time in s
0T 0,7T
A- =
perchlorate ClO4-
A- =
p-toluenesulfonate TsO-
delocalized π-bondsdoping with anions (A-)Electrical conductivity
0 50 100 150 200 250
0
10000
20000
30000
40000
50000
dam
ping
in H
z
time in s
0T 0,7T
rough layers
0 50 100 150 200 250-400
-200
0
200
400
600
dam
ping
in H
z
time in s
0T0,7T
smooth layers
MFD-effectat PPy|ClO4
-
orientation-effect at
PPy|TsO-
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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Ion ExchangeCyclovoltammetry 10mV/s 5 cycles at B= 0T in
monomer free solution
Exchange of anionsNo visible differences in Exchange behavior.
Exchange of cationsExchange suppressed in the case of magnetopolymerized Polypyrrole
-0,8 -0,6 -0,4 -0,2 0,0 0,2 0,4
-0,400
-0,200
0,000
0,200
curr
ent d
ensi
ty in
mA
/cm
²potential vs SCE in V
0T 0,7T
last cycle
-1,0 -0,8 -0,6 -0,4 -0,2 0,0 0,2 0,4-0,136
-0,090
-0,045
0,000
0,045
0,090
0,136
last cycle
curr
ent d
ensi
ty in
mA
/cm
²
potential vs SCE in V
0T 0,5T
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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Conclusions
Influence on mass transport by Lorentz-Force (MHD-effect) and paramagnetic-gradient- Force
No influence on charge transfer kinetic
Magnetic field induces changes in surface roughness (nickel deposition)
MHD- (Polypyrrole|Perchlorate-Anions) and orientation effect (Polypyrrole|p-toluenesulfonate-Anions) at conducting polymers
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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Outlook
Investigation of mass transport in microstructures including diamagnetic ions (Zn2+, Ag+)model system for numerical simulations
Deposition of alloys with different magnetic properties (NiFe)
Investigation of the magnetic field influences on the conductivity and dopand exchange kinetic of conducting polymers (Polypyrrole in combination with several anions)
TU Dresden Institut für Physikalische Chemie und Elektrochemie
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Acknowledgements
The authors are grateful to SFB 609 (Institution of German Research) for the financial support and Sino-German Scientific Center for the invitation