Oxygen is electroreduced to water on a "wired" enzyme electrode at a lesser overpotential than on platinum.
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.
Mano
Nicolas
N
Department of Chemical Engineering, Texas Materials Institute, University of Texas, Austin, TX 78712, USA.
Fernandez
Jose L
JL
Kim
Yousung
Y
Shin
Woonsup
W
Bard
Allen J
AJ
Heller
Adam
A
D001487:Basidiomycota / Q000201:enzymology; D004566:Electrodes; D010084:Oxidation-Reduction; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D014867:Water; D010984:Platinum; D044925:Oxidoreductases Acting on CH-CH Group Donors; C042401:bilirubin oxidase; D010100:Oxygen