Powdered MnySb1- yOxCatalysts for Cerium-Mediated Oxygen Evolution in Acidic Environments

Abstract

MnySb1-yOxpowders with a series of compositions were evaluated as catalysts for chemical water oxidation in aqueous perchloric, sulfuric, or methanesulfonic acid. O2(g) evolved spontaneously over MnySb1-yOxcatalyst powders that had been suspended in solutions that were pre-loaded with Ce4+ions. The rate of O2evolution depended on the amount, as well as the oxidation state, of the Mn in the powder. The highest O2evolution rate was observed from the most Mn-rich catalyst, which had an effective surface oxidation state of Mn2.9+in its rest state. The facile synthetic accessibility of such catalysts in powder form constitutes a step toward replacing Ir or Ru in Ce-mediated oxygen evolution in decoupled water splitting systems, as well as toward developing inks of earth-abundant catalysts for preparation of catalyst-coated membranes used in conventional proton-exchange membrane electrolyzers.