Advancing Hydrodynamic Electrochemistry: A Channel Flow Cell for High-Temperature and High-Pressure Applications

This work represents a significant advancement toward developing a channel flow cell for hydrodynamic electrochemical studies at elevated temperatures and pressures. For these initial studies, multilayer Pt thin-film electrodes were deposited on a sapphire wafer and used as the working, pseudoreference, and counter electrodes. The reduction of ferricyanide ([Fe(CN)6]3–) and oxidation of ferrocyanide ([Fe(CN)6]4–) in KCl, as well as the oxidation of iodide (I–) in NaHSO4 were used to validate the proposed setup at temperatures up to 150 °C and pressures up to 65 bar. Linear sweep voltammograms obtained for these systems exhibited well-defined plateaus under hydrodynamic conditions, as expected for reversible reactions under diffusional mass transfer control. The limiting currents also follow the behavior predicted by the Levich equation for a channel cell operating under laminar flow conditions. Diffusion coefficients for [Fe(CN)6]3–, [Fe(CN)6]4–, and I–, retrieved from the Levich plots, showed excellent agreement with reported values and with results obtained from numerical simulations using COMSOL Multiphysics and models developed as part of this study.