抄録
A boron-doped diamond (BDD) electrode was examined as an oxygen evolution electrode in molten chlorides. It was confirmed that the BDD electrode has a potential to be employed for a stable oxygen evolution electrode in molten LiCl-KCl systems with any compositions below 773 K. However, in the melt containing CaCl2 such as LiCl-CaCl2, apparent degradation of the electrode was observed. In addition, the standard formal potentials of O2/O2− were measured by emf measurement with the BDD electrode and activity coefficients of oxide ion were determined in molten LiCl-KCl systems. The standard formal potential of O2/O2− is more positive and the activity coefficient of oxide ion is lower in the melt which has a larger content of LiCl. Moreover, the Li2O solubility was measured by electrochemical method. The melt with a larger content of LiCl has a higher solubility of Li2O. Thus, this study has given beneficial data for thermodynamic consideration on thermochemical and electrochemical processes involving oxygen gas and/or oxide ion such as reduction processes of metal oxides in molten LiCl-KCl systems.
