Oxygen Is Electroreduced to Water on a “Wired” Enzyme Electrode at a Lesser Overpotential than on Platinum

• Published in: Journal of the American Chemical Society Vol. 125; no. 50; pp. 15290 - 15291
• Main Authors: Mano, Nicolas, Fernandez, Jose L, Kim, Yousung, Shin, Woonsup, Bard, Allen J, Heller, Adam
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 17.12.2003
• Subjects: Basidiomycota - enzymology; Biological and medical sciences; Chemistry; Electrochemistry; Electrodes; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General and physical chemistry; Kinetics and mechanism of reactions; Molecular biophysics; Oxidation-Reduction; Oxidoreductases Acting on CH-CH Group Donors - chemistry; Oxygen - chemistry; Physical chemistry in biology; Platinum - chemistry; Water - chemistry; Oxygen; Catalytic reaction; Enzyme; Electron transfer; Experimental study; Enzyme electrode; Chemical reduction; Cyclic voltammetry; Electrocatalysis; Bilirubin oxidase; Electrode reaction; Reaction mechanism; Oxidoreductases; Electrochemical reaction; Catalyst activity; Current density; Immobilized enzyme
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja038285d

The first enzyme-based catalyst that is superior to platinum in the four-electron electroreduction of oxygen to water is reported. The smooth Pt cathode reached half and 90% of the mass transport-limited current density at respective overpotentials of −0.4 and −0.58 V in 0.5 M sulfuric acid, and only at even higher overpotentials in pH 7.2 phosphate buffer. In contrast, the smooth “wired” bilirubin oxidase cathode reached half and 90% of the mass transport-limited current density at respective overpotentials as low as −0.2 and −0.25 V. The mass transport-limited current density for the smooth “wired” enzyme cathode in PBS was twice that with smooth Pt in 0.5 M sulfuric acid. Under 1 atm O2 pressure, O2 was electroreduced to water on a polished carbon cathode, coated with the “wired” BOD film, in pH 7.2 saline buffer (PBS) at an overpotential of −0.31 V at a current density of 9.5 mA cm-2. At the same overpotential, the current density of the polished platinum cathode in 0.5 M H2SO4 was 16-fold lower, only 0.6 mA cm-2.