Uniform secondary current distribution at disk electrodes under Tafel kinetics enabled by concentric current-shielding rings

Jeganathan, Vaishnavi Sree [Case Western Reserve Univ., Cleveland, OH (United States)]; Akolkar, Rohan [Case Inst. of Technology, Cleveland, OH (United States)]

doi:10.1016/j.elecom.2025.108087

DOE OSTI · 3025694

Uniform secondary current distribution at disk electrodes under Tafel kinetics enabled by concentric current-shielding rings

Jeganathan, Vaishnavi Sree [Case Western Reserve Univ., Cleveland, OH (United States)]·Akolkar, Rohan [Case Inst. of Technology, Cleveland, OH (United States)]

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Abstract

Non-uniform secondary current distribution at rotating disk electrodes (RDE) is a common problem when using resistive electrolyte media or large applied currents. In a recent publication, we have shown that auxiliary electrodes such as the ring of a rotating ring disk electrode (RRDE) can help suppress current non-uniformities at the disk enabling reliable electroanalytical measurements. However, this previous work considered linear kinetics where current distribution non-uniformities were moderate. In the present contribution, we consider current distribution non-uniformities encountered under Tafel kinetics. We show, for the case of 2,5-dihydroxy-1,4-benzoquinone (DHBQ) reduction, that optimally chosen ring conditions serve to provide effective shielding at the disk edge rendering the overall disk current distribution to be uniform. Numerical modeling and scaling analysis (using the Wagner number) are presented to aid a user in determining the optimal ring current density for achieving uniform disk current distribution under Tafel kinetics. This approach is especially useful when studying soluble-soluble redox transitions for which, unlike deposit distribution in electrodeposition, the current distribution non-uniformity is not visually apparent.

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Jeganathan, Vaishnavi Sree [Case Western Reserve Univ., Cleveland, OH (United States)], Akolkar, Rohan [Case Inst. of Technology, Cleveland, OH (United States)]. 2025-11-24. Uniform secondary current distribution at disk electrodes under Tafel kinetics enabled by concentric current-shielding rings. https://doi.org/10.1016/j.elecom.2025.108087

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