An oxygen evolution reaction catalyst electrode may include: a glass electrode; a first coating, directly upon the glass electrode, comprising a layer of fluorine-doped tin oxide (FTO); and a second coating, directly upon the first coating, comprising a layer comprising at least 95 wt. % palladium, relative to a total weight of the second coating, wherein the palladium in the second coating is in the form of porous, spongy-textured clusters comprising palladium spheroid nanoparticles in cubic crystalline phase. The second coating may have a thickness in a range of from 0.5 to 10 μm, and the clusters may have an average largest dimension in a range of from 500 to nm.