Organic Redox Probes for the Key Oxidation States in Mixed Valence Ruthenium Oxide/Cyanometallate (Ruthenium Prussian Blue Analogue) Catalysts

The electrochemical redox behavior of the polynuclear mixed valence ruthenium oxide cyanometallate complexes (mvRuOxMCN, M=Fe, Cr, Ni, Cu, Ru and Pt) have been systematically studied in this report by using three redox sensitive organic probes of glucose, ethanol and formaldehyde. The results were interpreted by the well‐established ruthenium oxide and Prussian blue chemistry. The mvRuOxMCN, under the category of Ru‐based Prussian blue analogue, was found to possess superior electrocatalytic activity than either ruthenium oxide or Prussian blue in acidic mediums. The electrogenerated oxy/hydroxy‐RuVII state (at +1.1 V vs. Ag/AgCl) was unusually stabilized in the mvRuOxMCN matrix without any disproportion reaction in acidic environments. In contrast to those of earlier studies, possible structure in terms of the RuIII/IINCMand RuIII/IIORuVII/VIsites was proposed here. Enzyme‐less analytical detection of glucose in acidic conditions was first time demonstrated with sensitivity comparable to that of ruthenium oxide‐based electrodes in alkaline solutions.