Electrochemistry of a new carbon-rich fluorine-doped tin oxide (CFTO) material as a powder electrode in chloride electrolytes

The electrochemical behavior of a conductive carbon-rich fluorine-doped tin oxide (CFTO) powder synthesized via the sol-gel process was investigated by studying the chloride oxidation reaction in aqueous media with the help of a cavity microelectrode (CME) without any binding additive. This new electroactive compound was found to be very efficient with respect to the chloride-chlorine reaction which was reversible in the 2-7 pH range. The CFTO powder electrode was characterized by linear sweep voltamperometry and electrochemical impedance measurements. On the basis of numerical simulations, impedance spectra were interpreted by considering a porous electrode behavior with a coupled concentration and potential axial gradients. The experimental data were quantitatively accounted for by considering the parallel combination of a number of cylindrical pores. On the CFTO powder, the chloride oxidation mechanism was simply described by a single electron exchange, in accordance with a Volmer-Tafel mechanism.