Anodic behavior of carbon electrodes in CaO-CaCl2 melts at 1123 K

The anodic process on glassy carbon electrodes in molten CaCl2 containing C aO was investigated at 1123 K by cyclic voltammetry and convolution voltamm etry. It was found that the oxidation sequence occurs through a consecutive two-step electrochemical reaction: O2-(diss) + xC --> CxO(ads) + 2e and O2 -(diss) + CxO(ads) --> CO2(gas) + (x - 1)C + 2e. Both steps were found to b e irreversible. Experimental data indicate that the first electrochemical s tep is preceded by the dissociation of a complex. The diffusion coefficient of the oxygen-containing species, the charge-transfer coefficient, and the charge-transfer rate constant were found equal to 2.0 x 10(-6) cm(2) s(-1) , 0.43, and 1.8 x 10(-5) cm s(-1), respectively. (C) 1999 The Electrochemic al Society. S0013-4651(98)06-045-5. All rights reserved.