A layered construction for application to a device or substrate or placement in an enclosed space for use in decontaminating the underlying surface or enclosed space comprises a cathode, an electrolyte layer, an anode and a protective surface layer. A compound that can be electrically decomposed to release on demand and over an extended period of time, an oxidant is included in the layered structure, preferably in the electrolyte layer. Preferred compounds are those which can release halogen ions which react with various different chemical or biological contaminants which may contact the protective layer, destroying, or devitalizing the contaminants.