Gastight Hydrodynamic Electrochemistry: Design for a Hermetically Sealed Rotating Disk Electrode Cell

Abstract

Rotating disk electrodes (RDEs) are widely used in electrochemical characterization to analyze the mechanisms of various electrocatalytic reactions. RDE experiments often make use of or require collection and quantification of gaseous products. The combination of rotating parts and gaseous analytes makes the design of RDE cells that allow for headspace analysis challenging due to gas leaks at the interface of the cell body and the rotator. In this manuscript we describe a new, hermetically-sealed electrochemical cell that allows for electrode rotation while simultaneously providing a gastight environment. Electrode rotation in this new cell design is controlled by magnetically coupling the working electrode to a rotating magnetic driver. Calibration of the RDE using a tachometer shows that the rotation speed of the electrode is the same as that of the magnetic driver. To validate the performance of this cell for hydrodynamic measurements, limiting currents from the reduction of a potassium ferrocyanide (K 4 [Fe(CN) 6 ] 3H 2 O) were measured and shown to compare favorably with calculated values from the Levich equation and with data obtained using more typical, non-gastight RDE cells. Faradaic efficiencies of ~95% were measured in the gas phase for oxygen evolution in alkaline media at an Inconel 625 alloy electrocatalyst during rotation at 1600 rpm. These data verify that a gastight environment is maintained even during rotation.

Gastight rotating cylinder electrode: Toward decoupling mass transport and intrinsic kinetics in electrocatalysis

“…The first prototype of the gas-tight RCE cell (Figure 1) is based on the design introduced by Jung et al 6,7 where a follower magnet inside the cell traces, via magnetic coupling, a driver magnet outside the cell.…”

“…The reduction of ferricyanide, nitrite, and protons are facile reactions resulting in the observed partial current to be solely limited by mass transfer at high overpotentials. The measured diffusion-limited current density, j lim is related to the mass transfer coefficient k m by Equation (6).…”

“…The first prototype of the gas‐tight RCE cell (Figure 1) is based on the design introduced by Jung et al 6,7 where a follower magnet inside the cell traces, via magnetic coupling, a driver magnet outside the cell. The driver magnet is mounted on the shaft of a modulated speed rotator (MSR, Pine Research Instrumentation) with a range of rotation speeds that extends over 3000 rpm.…”

Electrochemical CO2 reduction on nanostructured metal electrodes: fact or defect?

“…85 Recently, gastight RDE cells have been developed that either employ a gastight seal between the rotator and the cell, 13,25,86 or use magnetic coupling to transfer the rotation from an external motor to a rotating sha housed within the cell. 87 These designs allow for in-line gas product analysis during experiments under mass transport control, which are essential to derive meaningful structure-property relationships for electrochemical CO 2 reduction.…”

Influence of Geometry and Velocity of Rotating Solids on Hydrodynamics of a Confined Volume

“…Some designs reduced the dimensions of the cells to work with lower rotation speeds. Other designs have isolated the working electrode to minimize the effect of counter electrode and the reference electrode [20].…”