Improved symmetry and current distribution in a gastight rotating cylinder electrode cell: Design and characterization

Understanding the interplay between intrinsic kinetics and transport remains a central challenge in electrocatalysis. Rotating disk electrodes (RDE) are widely used because their transport can be described analytically, but radial concentration gradients complicate analysis of multi‐electron processes. Rotating cylinder electrodes (RCE) provide an improved convective transport profile that better separates transport from kinetics. However, multiphysics simulations show that the use of a single flat counter electrode distorts the electric field in low‐conductivity electrolytes. We present a third‐generation gastight RCE cell (RCE‐3) with two flat counter electrodes symmetrically positioned around the cylinder. This configuration doubles the counter electrode area, increases achievable current density, and improves field symmetry while maintaining well‐defined hydrodynamics. Electrochemical CO 2 reduction experiments demonstrate that asymmetric electric fields bias apparent kinetics in non‐aqueous electrolytes, whereas symmetric counter electrode operation minimizes these distortions, enabling reliable extraction of intrinsic kinetic parameters. The RCE‐3 cell contributes to advancing the mechanistic understanding of non‐aqueous electrocatalytic systems.