title: A laccase-wiring redox hydrogel for efficient catalysis of O2 electroreduction.
abstract: Laccase was earlier wired to yield an O2 electroreduction catalyst greatly outperforming platinum and its alloys. Here we describe the design, synthesis optimization of the composition, and characterization of the +0.55 V (AgAgCl) laccase-wiring redox hydrogel, with an apparent electron diffusion coefficient (D(app)) of 7.6 x 10(-7) cm2 s(-1). The high D(app) results in the tethering of redox centers to the polymer backbone through eight-atom-long spacer arms, which facilitate collisional electron transfer between proximal redox centers. The O2 flux-limited, true-area-based current density was increased from the earlier reported 560 to 860 microA cm(-2). When the O2 diffusion to the 7-microm-diameter carbon fiber cathode was cylindrical, half of the O2 flux-limited current was reached already at 0.62 V and 90% at 0.56 V vs Ag/AgCl, merely -0.08 and -0.14 V versus the 0.7 V (Ag/AgCl) reversible O2/H2O half-cell potential at pH 5.
authors.affiliation: Department of Chemical Engineering and Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, USA. mano@mail.utexas.edu
authors.forename: Nicolas
authors.initials: N
authors.lastname: Mano
authors.forename: Valentine
authors.initials: V
authors.lastname: Soukharev
authors.forename: Adam
authors.initials: A
authors.lastname: Heller
mesh_terms: D002384:Catalysis; D004563:Electrochemistry / Q000379:methods*; D020100:Hydrogels / Q000737:chemistry*; D042845:Laccase / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*
chemical_list: D020100:Hydrogels; D042845:Laccase; D010100:Oxygen