Electrooxidation of Alcohols Catalyzed by Amino Alcohol Ligated Ruthenium Complexes

Ruthenium transfer hydrogenation catalysts physisorbed onto edge-plane graphite electrodes are active electrocatalysts for the oxidation of alcohols. Electrooxidation of CH3OH (1.23 M) in a buffered aqueous solution at pH 11.5 with [(η6-p-cymene)(η2-N,O-(1R,2S)-cis-1-amino-2-indanol)]RuIICl (2) on edge-plane graphite exhibits an onset current at 560 mV vs NHE. Koutecky–Levich analysis at 750 mV reveals a four-electron oxidation of methanol with a rate of 1.35 M–1 s–1. Mechanistic investigations by 1H NMR, cyclic voltammetry, and desorption electrospray ionization mass spectrometry indicate that the electroxidation of methanol to generate formate is mediated by surface-supported Ru–oxo complexes.