Electrooxidation of Alcohols with Electrode-Supported Transfer Hydrogenation Catalysts

A titanium electrode, modified with Ru(OH)x/TiO2, was prepared and observed to mediate both chemical transfer hydrogenation and electrochemical alcohol oxidation. Electro-oxidation of 2-propanol (1.3 M) at room temperature and pH 7.2 exhibits an onset of electrocatalytic current at 1000 mV vs RHE for the two-electron oxidation of 2-propanol to acetone. XPS characterization, cyclic voltammetry, and electrolysis experiments confirm that electrochemically active ruthenium species catalyzed the electro-oxidation of 2-propanol to acetone. These modified electrode surfaces maintain >60% original activity upon reuse, despite low loadings of ruthenium. The applied potentials are consistent with an electrocatalytic mechanism mediated by surface-immobilized Ru–oxo species (1380 mV vs RHE). These results indicate that heterogeneous transfer hydrogenation catalysts can function as alcohol electro-oxidation catalysts.