EFFECT OF CATIONIC COMPOSITION ON THE MECHANISM OF THE OXYGEN CATHODIC REDUCTION IN CARBONATE MELTS

The mechanism of the oxygen electroreduction in fused KCl-K2CO3 and Li Cl-Li2CO3 at 650 degrees C is studied using the reversal chronoamperom etric and coulostatic methods with switching from a steady state. It i s shown that the mechanism of oxygen reduction in a potassium melt doe s not differ from the mechanism in a K, LiCO3 eutectic, which was stud ied earlier [1]. A peroxide mechanism takes place in a CO2 atmosphere, and a superoxide mechanism occurs in an O-2 atmosphere. On the basis of found values of charge transfer coefficients and the reaction order with respect to oxygen, in a lithium melt, it was found that, in a CO 2 atmosphere, the process occurs according to the scheme: O-2 + e = O- 2(-) (1), O-2(-) + e = O-2(2-) (2) O-2(2-) + e = O2- (3), O- + e = O2- (4) 2O(2-) + 2CO(2) = 2CO(3)(2-) (5), where (3) is the limiting stage . In an O-2 atmosphere, the reaction steps are: O-2 + 2e = O-2(2-) (1' ), O-2(2-) + e = O2- (3'), 2CO(3)(2-) (4'), and (1') is the limiting s tage. A proposed mechanism which was named the molecular mechanism is substantiated.