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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

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Magnetic field influences on electrochemical processes

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  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 TU Dresden Institut für Physikalische Chemie und Elektrochemie

  2. Motivation and Aim • to find out How does a magnetic field influence the several parts of an electrochemical reaction? • to describe explaining of phenomena and creation of an experimental basis for numerical simulations • to tailor combinations 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

  3. Electrochemical Reactions Influence on electron transfer kinetics? Influence on mass transport MHD effect  Gradient effects  Influence on surface diffusion/crystallization? TU Dresden Institut für Physikalische Chemie und Elektrochemie

  4. Va VIa B B RE RE AE GE GE AE unstirred stirred Copper dissolution in microstructures MHD-effect B  E Lorentz-Force FL + natural convection Fconv Magnetic field on TU Dresden Institut für Physikalische Chemie und Elektrochemie

  5. IIIa IVa B B RE RE GE GE AE AE unstirred stirred Copper dissolution in microstructures MHD-effect B  E Paramagnetic gradient Force Fgrad TU Dresden Institut für Physikalische Chemie und Elektrochemie

  6. Charge transfer reaction Butler- Volmer- Equation: (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

  7. Reference Electrode Hg/ Hg2Cl2 RE CE WE Counter electrode Potentiostat Cell Computer N S Working electrode Quartz Networkanalyser Electrochemical Quartz Crystal Microbalance (EQCM) TU Dresden Institut für Physikalische Chemie und Elektrochemie

  8. Quartz with Unloaded Rigid Layer Quartz 100 film 80 60 gold electrodes Quartz with of Admittance / mS Real Part 40 Damping Layer 20 Damping Mass Layer 2 0 shear motion 9,997 9,998 9,999 10,000 quartz f / MHZ Experimental Technique (EQCM) • in situ measurements of the mass changes at electrode surfaces during electrodeposition • its functionality is based on the converse piezoelectric effect f f R,Layer 1 R,0 w w Layer 1 0 f R,Layer 2 w Sauerbreyequation: Complex frequency shift CSB: Sauerbrey constant TU Dresden Institut für Physikalische Chemie und Elektrochemie

  9. Deposition of Nickel Galvanostatic deposition Ni2+ + 2e- Ni 2 H+ + 2e- H2 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 efficiency not affected by B  B=0    B>0 TU Dresden Institut für Physikalische Chemie und Elektrochemie

  10. Morphology and Roughness Atomic Force Microscopy 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 Ramean roughness Lx, Ly dimension of the surface f(x,y) relative surface to the central plane TU Dresden Institut für Physikalische Chemie und Elektrochemie

  11. Deposition of Polypyrrole (PPy) • delocalized π-bonds • doping with anions (A-) • Electrical conductivity A- = perchlorate ClO4- A- = p-toluenesulfonate TsO- smooth layers rough layers MFD-effect at PPy|ClO4- orientation-effect at PPy|TsO- TU Dresden Institut für Physikalische Chemie und Elektrochemie

  12. Ion Exchange Cyclovoltammetry 10mV/s 5 cycles at B= 0T in monomer free solution • Exchange of anions • No visible differences in Exchange behavior. • Exchange of cations • Exchange suppressed in the case of magnetopolymerized Polypyrrole TU Dresden Institut für Physikalische Chemie und Elektrochemie

  13. 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

  14. 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

  15. Acknowledgements The authors are grateful to SFB 609 (Institution of German Research) for the financial supportand Sino-German Scientific Center for the invitation to the workshop. Thank you for your attention! TU Dresden Institut für Physikalische Chemie und Elektrochemie

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