Magnetic control of mass transfer and convection in electrochemical processes

Magnetic fields are able to modify mass transfer conditions in electrochemical processes. This can be used, e.g., to increase the efficiency, to improve the space-time yield or to structure galvanic deposits.

Motivation

• the Lorentz force can utilize the existing Faraday current for flow control.
• the magnetic gradient force acts on a para- or diamagnetic electrolyte.
• the control by magnetic fields is contactless.

Fields of research

• detailed understanding of the interplay of magnetic forcing, convection and mass transfer
• increasing the limiting current (space-time yield) in copper electrolysis
• improving the uniformity of deposits, thus saving energy and material
• structured deposition of para- and diamagnetic ions by utilizing the magnetic gradient force
• gas evolution under the influence of magnetic fields for improving the process efficiency and/or the quality of deposits (more details)
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Methods

• lab-scale experiments; visualization of electrolyte convection and species concentration
• numerical modelling and simulation

Selected References

• G. Mutschke: Magnetic Control of Flow and Mass Transfer in Weakly Conducting Fluids; In: B. Doudin et al. (eds.) Magnetic Microhydrodynamics, Topics in Applied Physics 120 (2024) 23-31. 10.1007/978-3-031-58376-6_3 
• J. Massing, G. Mutschke, D. Baczyzmalski, S.S. Hossain, X. Yang, K. Eckert, C. Cierpka: Thermocapillary convection during hydrogen evolution at microelectrodes; Electrochimica Acta 297 (2019) 929-940. 10.1016/j.electacta.2018.11.187
• X. Yang, D. Baczyzmalski, C. Cierpka , G. Mutschke, K. Eckert; Marangoni convection at electrogenerated hydrogen bubbles; Phys. Chem. Chem. Phys. 20 (2018) 11542-11548. 10.1039/C8CP01050A
• D. Baczyzmalski, F. Karnbach, G. Mutschke, X. Yang, K. Eckert, M. Uhlemann, C. Cierpka, Growth and detachment of single hydrogen bubbles in a magnetohydrodynamic shear flow, Physical Review Fluids, 2, 093701 (2017). 10.1103/PhysRevFluids.2.093701
• G. Mutschke, D. Baczyzmalski, C. Cierpka, F. Karnbach, M. Uhlemann, X. Yang, K. Eckert, J. Fröhlich, Numerical simulation of mass transfer and convection near a hydrogen bubble during water electrolysis in a magnetic field, Magnetohydrodynamics, 53, 193-200 (2017). 2017/1/MG.53.1.20.R
• T. Weier, D. Baczyzmalski, J. Massing, S. Landgraf, C. Cierpka, The effect of a Lorentz-force-driven rotating flow on the detachment of gas bubbles from the electrode surface, International Journal of Hydrogen Energy 42(2017)33, 20923-20933. 10.1016/j.ijhydene.2017.07.034
• F. Karnbach, X. Yang, G. Mutschke, J. Fröhlich, J. Eckert, A. Gebert, K. Tschulik, K. Eckert, M. Uhlemann, Interplay of the Open Circuit Potential-Relaxation and the Dissolution Behavior of a Single H2 Bubble Generated at a Pt Microelectrode, The Journal of Physical Chemistry C, 120, 15137-15146 (2016). 10.1021/acs.jpcc.6b02305
• D. Baczyzmalski, F. Karnbach, X. Yang, G. Mutschke, M. Uhlemann, K. Eckert, C. Cierpka,  On the electrolyte convection around a hydrogen bubble evolving at a microelectrode under the influence of a magnetic field, J. Electrochem. Soc. 163 (2016) 9, E248-E257. 10.1149/2.0381609jes
• D. Baczyzmalski, T. Weier, C. Cierpka, C.J. Kähler,  Near-wall measurements of the bubble- and Lorentz-force-driven convection at gas-evolving electrodes, Exp. Fluids 56 (2015), 162. 10.1007/s00348-015-2029-0
• G. Mutschke, K. Tschulik, M. Uhlemann, J. Fröhlich,  Numerical simulation of the mass transfer of magnetic species at electrodes exposed to small-scale gradients of the magnetic field, Magnetohydrodynamics 51(2015)2, 369-374. 2015/2/MG.51.2.22.R
• S. Mühlenhoff, G. Mutschke, M. Uhlemann, X. Yang, S. Odenbach, J. Fröhlich, K. Eckert, On the homogenization of the thickness of Cu deposits by means of MHD convection within small dimension cells, Electrochem. Comm. 36 (2013) 80-83. 10.1016/j.elecom.2013.09.025
• T. Weier, S. Landgraf,  The two-phase flow at gas-evolving electrodes: bubble-driven and Lorentz-force-driven convection, Eur. Phys. J. Spec. Top. 220 (2013), 313-322. 10.1140/epjst/e2013-01816-1
• G. Mutschke, K. Tschulik, M. Uhlemann, A. Bund, J. Fröhlich, Comment on “Magnetic structuring of electrodeposits”, Phys. Rev. Lett. 109 (2012) 229401. 10.1103/PhysRevLett.109.229401
• G. Mutschke, K. Tschulik, T. Weier, M. Uhlemann, A. Bund, J. Fröhlich, On the action of magnetic gradient forces in micro-structured copper deposition. Electrochim. Acta 55 (2010) 9060-9066. 10.1016/j.electacta.2010.08.046
• G. Mutschke, A. Hess, A. Bund, J. Fröhlich, On the origin of horizontal counter-rotating electrolyte flow during copper magnetoelectrolysis. Electrochim. Acta 55 (2010) 1543-1547. 10.1016/j.electacta.2009.10.015
• C. Cierpka, T. Weier, G. Gerbeth, M. Uhlemann, K. Eckert, Copper deposition and dissolution in seemingly parallel electric and magnetic fields: Lorentz force distributions and flow configurations. Journal of Solid State Electrochemistry 11(6) (2007) 687-701. 10.1007/s10008-006-0215-y
• T. Weier, K. Eckert, S. Mühlenhoff, C. Cierpka, A. Bund, M. Uhlemann, Confinement of paramagnetic ions under magnetic field influence: Lorentz versus concentration gradient force based explanations, Electrochem. Comm. 9 (2007) 2479–2483. 10.1016/j.elecom.2007.07.026
• T. Weier, C. Cierpka, J. Hüller, G. Gerbeth, Velocity Measurements and Concentration Field Visualizations in Copper Electrolysis Under the Influence of Lorentz Forces and Buoyancy, Magnetohydrodynamics, 42(4) (2006) 379-387 2006/4/MG.42.4.4
• T. Weier, J. Hüller, G. Gerbeth, F.-P. Weiss, Lorentz force influence on momentum and mass transfer in natural convection copper electrolysis, Chem. Eng. Sci. 60(1) (2005) 293-298. 10.1016/j.ces.2004.07.060 
• T. Weier, J. Hüller, G. Gerbeth, Magnetic Field Influence on Electrochemical Processes, Ann. Rep. 2001 Inst. Safety Research (2002) 81-85 WTB FZR-342