Abstract: The present invention provides an oxygen generation electrode provided with a catalyst layer having a high specific electric conductivity, and having excellent durability such that even when an acidic electrolyte is electrolyzed, the catalyst components are unlikely to be consumed and long-term electrolysis can be performed. The oxygen generation electrode is an oxygen generation electrode 10 provided with a substrate 2 formed with titanium or a titanium alloy, and a catalyst layer 4 disposed on the substrate 2 and formed with a mixed metal oxide, wherein the catalyst layer 4 satisfies at least any one of the following condition (1) and condition (2). Condition (1): containing ruthenium, tin, and trivalent or higher polyvalent metal element excluding a tetravalent metal element. Condition (2): containing ruthenium and tin, and having a content of ruthenium of 40 mol % or more based on the total content of the ruthenium and tin.

Abstract: The present invention aims to provide an activated cathode enabling a long-time stable operation with hydrogen overvoltage maintained at a low value, keeping a high remaining rate of the catalyst element after a cease of operation for a short-circuiting and after an electrolysis operation at a high current density, restricting catalyst loss to a little, and having a strong resistance to contamination caused by electrolyte impurity elements. The present invention relates to a cathode for hydrogen evolution with a catalyst layer formed on the cathode substrate, having, at least, three elements comprising platinum, cerium and palladium, as essential element, in a state of metal, metal oxide, or hydroxide, contained, where the mole fraction of respective element being x, y, and z, within a range of 5 mol %?x?90 mol %, 5 mol %?y?55 mol %, 5 mol %?z?65 mol %.

Abstract: The present invention aims to provide an activated cathode enabling a long-time stable operation with hydrogen overvoltage maintained at a low value, keeping a high remaining rate of the catalyst element after a cease of operation for a short-circuiting and after an electrolysis operation at a high current density, restricting catalyst loss to a little, and having a strong resistance to contamination caused by electrolyte impurity elements. The present invention relates to a cathode for hydrogen evolution with a catalyst layer formed on the cathode substrate, having, at least, three elements comprising platinum, cerium and palladium, as essential element, in a state of metal, metal oxide, or hydroxide, contained, where the mole fraction of respective element being x, y, and z, within a range of 5 mol %?x?90 mol %, 5 mol %?y?55 mol %, 5 mol %?z?65 mol %.