Porous ionomer free layered metal alloy electrocatalyst electrode

A layered electrocatalyst electrode comprising:

• a macroporous gas diffusion layer and current collector material substrate in the thickness range 0.05 to 1.0 mm;
• and
• an electrocatalyst with an equivalent thickness between 0.05 μm and 5 μm, wherein said electrocatalyst layer comprising a first and a second surface, wherein the first surface is in contact with the surface of the substrate, and wherein the second surface is opposite to the first surface in the direction defined by the thickness of the electrocatalytic layer;
• wherein the substrate is selected from carbon paper, stainless-steel or nickel, wherein carbon paper, stainless-steel and nickel are in the form of microfibers, sponge or mesh like structure;
• wherein the electrocatalyst layer comprises a NiFe alloy with an average value between 0.5% and 30% in weight of Fe in the alloy, wherein the NiFe alloy composition of the first surface of the electrocatalyst layer is between 0.5% and 2% in weight of Fe in the alloy, and the NiFe alloy composition of the electrocatalyst layer at the second surface is between 12% and 30% in weight of Fe in the alloy;
• wherein the electrocatalyst layer has a specific electrochemical active surface area between 1 and 100 cm2/mg with respect to the oxygen evolution reaction expressed in area per catalyst load units determined from the Nyquist plots of the electrode systems by means of electrical impedance spectroscopy measurement;
• and
• wherein the electrocatalyst layer is a mesoporous layer with a total porosity between 20% and 50% measured by Kr gas adsorption isotherm and with a pore size varying between 2 and 100 nm determined by direct quantification on Scanning Electron Microscopy pictures of the films.