Study of Surface Tension in Alkaline Electrolytes for Water Electrolysis

Institute

Lehrstuhl für Thermodynamik (TUM-ED)

Type

Bachelor's Thesis / Semester Thesis /

Content

 

Description

Background:
During water electrolysis at high current densities, the gaseous products oxygen and hydrogen form bubbles that stick to the electrode starving the electrochemical surface area and creating high resistances in the electrolyzer. Manipulating the forces acting on the gas bubbles during this process promises to decrease the bubble coverage and increase the overall efficiency of the electrolysis. The occurrence of Marangoni Forces in water electrolysis has spurred much research efforts in recent times. Marangoni forces are the result of a surface tension gradient at the bubble-electrolyte interphase. The surface tension is dependent on, among others, the temperature and ion concentration in the electrolyte. Therefore, a gradient in ionic concentration or temperature will cause such a surface tension gradient and subsequently a Marangoni force. 
The solutal Marangoni Force is proportional to the product of surface tension change w.r.t. the ion concentration and the change in ion concentration w.r.t. the distance of the electrode. 

Objectives:

• Literature review of different ∂gamma/∂c of different electrolytes
• Literature review of in situ measurements techniques of temperature and pH gradients during electrolysis 
• Design of an experiment using electrolytes at different electrodes combined with optical measurements 

References:

1. Park, S., Liu, L., Demirkır, Ç. et al. Solutal Marangoni effect determines bubble dynamics during electrocatalytic hydrogen evolution. Nat. Chem. 15, 1532–1540 (2023). https://doi.org/10.1038/s41557-023-01294-y
2. Meulenbroek, A., Deen, N., & Vreman, A. (2024). Marangoni forces on electrolytic bubbles on microelectrodes. Electrochimica Acta, 497, 144510. https://doi.org/10.1016/j.electacta.2024.144510
3. Weissenborn, P. K., & Pugh, R. J. (1996). Surface Tension of Aqueous Solutions of Electrolytes: Relationship with Ion Hydration, Oxygen Solubility, and Bubble Coalescence. Journal of Colloid and Interface Science, 184(2), 550–563. https://doi.org/10.1006/jcis.1996.0651

Requirements

• Enrolled in a B.Sc. program of mechanical/chemical engineering
• Experience with fluid dynamics, thermodynamics or electrochemistry preferred

Possible start

immediately

Contact

M.Sc. Thomas Heipke
Room: 5507.01.728
ge25hepmytum.de