ELECTROCATALYSIS OF PROTON-COUPLED ELECTRON-TRANSFER REACTIONS AT GLASSY-CARBON ELECTRODES

The activation of glassy carbon electrodes toward electron-transfer pathways involving proton-coupled electron transfer has been investigated. Oxidative activation of glassy carbon electrodes leads to the catalysis of heterogeneous charge transfer for couples involving catechol (1,2-dihydroxybenzene), (bpy)//2(H//2O)Ru(OH)**2** plus (bpy is 2,2 prime -bipyridine), and (NH//3)//5Ru(OH)**2** plus where there are changes in proton content upon oxidation. Comparison of the spectral and electrochemical results with earlier studies on related homogeneous proton-coupled electron-transfer reactions suggests that, although a number of effects may be operative, an important basis for electrode activation may be the appearance of phenolic-like groups on the glassy carbon surface and their subsequent involvement in proton-coupled electron transfer.