Manganese oxide supported on gold/iron as a water-oxidizing catalyst in artificial photosynthetic systems

Abstract

Herein, we reported that KMnO₄ with iron nanoparticles coated with gold layers was a promising catalyst for water oxidation. The compound was characterized by scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic absorption spectroscopy and electrochemistry. The new compound was a conductive, recyclable, highly dispersible, magnetically separable, environmentally friendly, and nano-sized catalyst for water oxidation via cerium(IV) ammonium nitrate or Ru(bpy)₃³⁺ and electrochemical water oxidation. The turnover frequency of Mn oxide/gold/iron for water oxidation via cerium(IV) ammonium nitrate is 0.4 mmol O₂ per mol Mn per second, which shows that this catalyst is among the best Mn-based catalysts for water oxidation. We also showed a strategy for placing this catalyst on the surface of an electrode without adding any other compounds.