Model Passivated Carbon Electrodes for Fluorine Generation in Molten KF-2HF Electrolyte

Abstract

Vulcan carbon electrodes of varying PTFE-content (20 w.% and 35 w.%) were synthesized using a sol-gel process. Electrochemical fluorination was carried out over a range of potentials for fluorine generation (4 to 8 V) in molten, KF·2HF electrolyte at ~90 °C. Electrochemical behaviour of PTFE-embedded carbon electrodes was compared to both passivated and non-passivated graphite and amorphous carbon electrodes. An attempt to correlate the amount of embedded PTFE with the degree of passivation on carbon electrodes was made. This was used to compare the non-wetting characteristics of an electrochemically passivated carbon electrode to those of an artificially “passivated” electrode. PTFE contents in the embedded electrodes were confirmed using TGA. The effects of surface and embedded C-F compounds on the electrical properties of the different electrodes were investigated using AC impedance.