Non-metallic working electrodes for high temperature systems

The fabrication of Pyrex-sealed non-metallic electrodes (SnO2, RuO2 and glassy carbon) and their electrochemical characterization in LiCl-KCl (450° C), NaHSO4-KHSO4 (250° C) and LiNO3-KNO3 (175° C) eutectics are presented. Semiconducting SnO films prepared on Pyrex substrates were sealed into Pyrex by using a simple glass-blowing technique. SnO2 electrodes with leak-tight seals are versatile in high temperature systems and have been used to prepare RuO2 electrodes usable in fused salts. A convenient method for obtaining a good glassy carbon-to-Pyrex seal is presented for the construction of glassy carbon electrodes. A comparison of these electrodes in blank melts has been made with special interest in the electron tunnelling nature of SnO2 and the electrocatalytic activity of RuO2.