Targeted design of alpha-MnO2 based catalysts for oxygen reduction

The paper focuses on theoretical and experimental aspects of an oxide surface optimization for oxygen reduction reaction (ORR). Various doped alpha-MnO2 based electrocatalysts were prepared by microwave-assisted hydrothermal synthesis and electrochemically characterized to validate density functional theory (DFT) based predictions of the oxidation state and local structure effects on the catalytic activity of alpha-MnO2 catalysts in ORR. Both theory and experiments conclude that the highest activity in ORR is to be expected in the case of clustered Mn3+ sites which yield activity comparable with that of the polycrystalline Pt. These active sites have to be formed under in-operando conditions and their formation is hindered in doped alpha-MnO2 catalysts. The activity of the other conceivable active sites based on non-clustered Mn3+ or Mn4+ is inferior to that of clustered Mn3+. The activation of Mn3+ or Mn4+ based active sites leads to a shift in selectivity of the ORR process towards 2 electron formation of hydrogen peroxide. (C) 2016 Elsevier Ltd. All rights reserved.

Published in:
Electrochimica Acta, 191, 452-461
Oxford, Pergamon-Elsevier Science Ltd

 Record created 2016-04-01, last modified 2018-12-03

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