iScience (Jun 2018)

Identifying MnVII-oxo Species during Electrochemical Water Oxidation by Manganese Oxide

  • Biaobiao Zhang,
  • Quentin Daniel,
  • Lizhou Fan,
  • Tianqi Liu,
  • Qijun Meng,
  • Licheng Sun

Journal volume & issue
Vol. 4
pp. 144 – 152

Abstract

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Summary: Identifying surface active intermediate species is essential to reveal the catalytic mechanism of water oxidation by metal-oxides-based catalysts and to develop more efficient catalysts for oxygen-oxygen bond formation. Here we report, through electrochemical methods and ex situ infrared spectroscopy, the identification of a MnVII = O intermediate during catalytic water oxidation by a c-disordered δ-MnOx with an onset-potential-dependent reduction peak at 0.93 V and an infrared peak at 912 cm−1. This intermediate is proved to be highly reactive and much more oxidative than permanganate ion. Therefore, we propose a new catalytic mechanism for water oxidation catalyzed by Mn oxides, with involvement of the MnVII = O intermediate in a resting state and the MnIV−O−MnVII = O as a real active species for oxygen-oxygen bond formation. : Inorganic Chemistry; Surface Science; Energy Materials; Electrocatalysis Subject Areas: Inorganic Chemistry, Surface Science, Energy Materials, Electrocatalysis