Patent ID: 7815781

Claim:
A method for applying an electrocatalytic coating to a valve metal electrode substrate, the coating comprising an inner layer and an outer layer, said inner and outer layer containing a noble metal and a non-noble metal, the composition of said outer layer being progressively richer in non-noble metal toward the surface, wherein the method comprises the steps of: preparation of a first solution and of a second solution, both containing the precursor of at least one oxide of a non noble transition metal and the precursor of at least one noble metal or oxide thereof application of said first solution in at least one coat to the valve metal substrate, with the execution of an intermediate thermal treatment between one coat and the next subsequent alternate application of said first and second solution in at least two alternate cycles per each solution, each of said cycles consisting of at least one coat, with the execution of an intermediate thermal treatment between one coat and the next wherein said first and second solutions contain said precursor of said at least one oxide of a non noble transition metal and said precursor of at least one noble metal or oxide thereof in a different ratio, said ratio being lower for the first solution directly applied to the valve metal substrate in the first of said application cycles.