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Updated: Apr 6, 2026

Generation and Control of Electrohydrodynamic Flows in Aqueous Electrolyte Solutions
Published on: September 7, 2018
Hydrodynamic Microgap Voltammetry under Couette Flow Conditions: Electrochemistry at a Rotating Drum in Viscous
Christopher E Hotchen1, H Viet Nguyen2, Adrian C Fisher2
1Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (UK).
Abstract:
Electrochemical processes in highly viscous media such as poly(ethylene glycol) (herein PEG200) are interesting for energy-conversion applications, but problematic due to slow diffusion causing low current densities. Here, a hydrodynamic microgap experiment based on Couette flow is introduced for an inlaid disc electrode approaching a rotating drum. Steady-state voltammetric currents are independent of viscosity and readily increased by two orders of magnitude with further potential to go to higher rotation rates and nanogaps. A quantitative theory is derived for the prediction of currents under high-shear Couette flow conditions and generalised for different electrode shapes. The 1,1'-ferrocene dimethanol redox probe in PEG200 (D=1.4×10-11 m2 s-1 ) is employed and data are compared with 1) a Levich-type equation expressing the diffusion-convection-limited current and 2) a COMSOL simulation model providing a potential-dependent current trace.
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