Kinetics of iron electrochemical reduction into liquid metal at 1823 K in a molten oxide electrolyte

The goal of this study was the measurement of the kinetic parameters of the electrochemical reduction of iron oxide into liquid iron metal in a molten oxide electrolyte, Al2O3-FeOx-MgO-SiO2, at 1823 K. A large surface anode was used to circumvent the need of a reference electrode and a stepped linear scan voltammetry was applied to an iron-bearing silicate electrolyte over a cell-voltage range of 0.8 V to 1.9 V. In order to extract the kinetic parameters the current response is treated concerning the electronic charge transfer and the ohmic drop due to the electrolyte in the electrochemical cell. The cathode half-reaction identified by this method is the reduction of ferrous iron into its metal state. Derived parameters imply that electrode kinetics follow Tafel behavior. An order of reaction close to unity with transfer coefficients between 0.54 and 0.66 is identified.