Substituent Effects in Carbon-Nanotube-Supported Copper Phenolato Complexes for Oxygen Reduction Reaction

Unprotected mononuclear pyrene-modified (bispyridylaminomethyl)­methylphenol copper complexes were designed to be immobilized at multiwalled carbon nanotube (MWCNT) electrodes and form dinuclear bis­(μ-phenolato) complexes on the surface. These complexes exhibit a high oxygen reduction reaction activity of 12.7 mA cm^–2 and an onset potential of 0.78 V versus reversible hydrogen electrode. The higher activity of these complexes compared to that of mononuclear complexes with bulkier groups is induced by the favorable early formation of a dinuclear catalytic species on MWCNT.