Electrochemical stability of embeddable Mno₂/Mn reference electrode and its AC impedance behavior

A novel embeddable MnO₂/Mn reference electrode for corrosion monitoring is mainly prepared from a mixture of β type manganese dioxide and manganese by high-pressure molding in laboratory. The long-term electrochemical stability of electrodes was studied in cement mortar. AC impedance behavior of the MnO₂/Mn reference electrode was examined in synthetic concrete pore solutions after that. The long-term potentiometric measurements showed good stability and no apparent potential drift within 90 days continuous measurement. The electrochemical stability of MnO₂/Mn reference electrode is related to equilibrium established by double-phase oxides MnO₂ and MnO_x (1≤x<1.5). AC impedance behavior verified that the fabricated reference electrodes were sufficient to meet the requirement for corrosion monitoring in concrete environment.