Porous oxide electrocatalysts for oxygen evolution reaction prepared through a combination of hydrogen bubble templated deposition, oxidation and galvanic displacement steps

Highlights: • Porous Pb was produced by hydrogen bubble templated cathodic electrodeposition. • Upon oxidation of Pb to PbO₂ and their reaction, Pb₃O₄ formed on Pb nanowires. • Co₃O₄ formed on the surface of Pb/Pb₃O₄ nanowires by galvanic displacement. • Large-area Co₃O₄-modified oxidized Pb deposits were active anodes for OER. Porous oxide layers active in the oxygen evolution reaction (OER) were prepared with the following sequence of steps: (i) porous Pb was produced by cathodic hydrogen bubble templated electrodeposition; (ii) Pb was partially converted to its oxides; (iii) Co₃O₄ shells were formed on the surface of lead/lead oxides nanowires by spontaneous galvanic displacement reactions. The effect of deposition current density and charge on the porous Pb morphology was studied. Deposits with extended surface areas were obtained and then oxidized in neutral Na₂SO₄ solutions. Pb and PbO₂, initially coexisting in oxidized samples, underwent a spontaneous reaction leading to the formation of Pb₃O₄. Both PbO₂ and Pb₃O₄ spontaneously reacted with Co²⁺ to yield Co₃O₄ layers. Co-modified electrodes described in this work had higher activity in oxygen evolution reaction (OER) than those obtained by submitting to galvanic displacement porous PbO₂ layers prepared by oxygen bubble templated anodic deposition.