Abstract:
A composite protective layer for a photoelectrode, the composite protective layer including a chemical protective layer; and a physical protective layer, wherein the chemical protective layer has corrosion rate of 0.1 Coulombs per square centimeter per 10 hours or less when evaluated at a water decomposition potential, and the physical protective layer has a moisture transmittance rate of 0.001 grams per square meter per day or less and has an electrical conductivity.