Powdered MnySb1-yOx Catalysts for Cerium- Mediated Oxygen Evolution in Acidic Environments

MnySb1-yOx powders 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-yOx catalyst powders that had been suspended in solutions that were pre-loaded with Ce4+ ions. The rate of O2 evolution depended on the amount, as well as the oxidation state, of the Mn in the powder. The highest O2 evolution 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 Cemediated 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.