Electroreduction of O₂ to Water on the “Wired” Laccase Cathode

Oxygen was electrocatalytically reduced to water at a current density of 5 mA/cm 2 and at +0.7 V (NHE) in pH 5 citrate buffer at 37.5 °C. The electrocatalyst was a composite of laccase cross-linked with a redox polymer on a hydrophilic cloth of 10 μm diameter carbon fibers. The redox polymer, PVI−Os(tpy)(dme-bpy) 2+/3+, [poly-N-vinyl imidazole with 1/5 th of the imidazoles complexed with [Os(tpy)(dme-bpy)] 2+/3+ (tpy=terpyridine; dme-bpy= 4,4‘-dimethyl-2,2‘-bipyridine)], electrically connected (“wired”) the laccase reaction centers to the fibers.