| CPC C25B 11/031 (2021.01) [C25B 1/04 (2013.01); C25B 11/061 (2021.01); C25B 11/089 (2021.01)] | 20 Claims |

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1. A method to produce an oxygen evolution reaction electrode catalyst assembly comprising a dendritic nickel foam; the method is characterized in that it comprises the steps
(a) providing a dendritic nickel foam material being a nickel foam that shows a dendrite morphology evidenced by scanning electron microscopy with nickel dendrites forming a nickel dendrites layer;
(b) etching the dendritic nickel foam material by placing it in a etch solution having a pH ranging from 1.0 to 4.0 and being an aqueous acidic solution or an aqueous solution of metal chloride, and recovering an etched dendritic nickel foam with nickel dendrites showing a chimney-like structure that is porous with three levels of porosity and shows pores of a first type having an average pore size diameter ranging from 20.0 μm to 50.0 μm as determined by scanning electron microscopy, pores of a second type having an average pore size diameter ranging from 1.0 to 5.0 μm as determined by scanning electron microscopy, and pores of a third type having an average pore size diameter ranging from 0.1 μm to 1.0 μm as determined by scanning electron microscopy; and
(c) of addition of one or more transition metals, wherein step (c) comprises a step (c1) of galvanic exchange reaction or a step (c2) of electrodeposition or both steps c1) of galvanic exchange reaction and step (c2) of electrodeposition.
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