Gallaway Joshua W, Calabrese Barton Scott A
Department of Chemical Engineering, Columbia University, New York, New York 10027, USA.
J Am Chem Soc. 2008 Jul 2;130(26):8527-36. doi: 10.1021/ja0781543. Epub 2008 Jun 7.
Oxygen-reducing enzyme electrodes are prepared from laccase of Trametes versicolor and a series of osmium-based redox polymer mediators covering a range of redox potentials from 0.11 to 0.85 V. Experimentally obtained current density generated by the film electrodes is analyzed using a one-dimensional numerical model to obtain kinetic parameters. The bimolecular rate constant for mediation is found to vary with mediator redox potential from 250 s(-1) M(-1) when mediator and enzyme are close in redox potential to 9.4 x 10(4) s(-1) M(-1) when the redox potential difference is large. The value of the bimolecular rate constant for the simultaneously occurring laccase-oxygen reaction is found to be 2.4 x 10(5) s(-1) M(-1). The relationship between mediator-enzyme overpotential and bimolecular rate constant is used to determine the optimum mediator redox potential for maximum power output of a hypothetical biofuel cell with a planar cathode and a reversible hydrogen anode. For laccase of T. versicolor (E(e)(0) = 0.82), the optimum mediator potential is 0.66 V (SHE), and a molecular structure is presented to achieve this result.
氧还原酶电极由云芝漆酶和一系列基于锇的氧化还原聚合物介体制备而成，这些介体的氧化还原电位范围为0.11至0.85 V。使用一维数值模型分析膜电极实验获得的电流密度，以获得动力学参数。发现介导的双分子速率常数随介体氧化还原电位而变化，当介体和酶的氧化还原电位接近时为250 s(-1) M(-1)，当氧化还原电位差很大时为9.4 x 10(4) s(-1) M(-1)。发现同时发生的漆酶-氧反应的双分子速率常数的值为2.4 x 10(5) s(-1) M(-1)。介体-酶过电位与双分子速率常数之间的关系用于确定具有平面阴极和可逆氢阳极的假设生物燃料电池最大功率输出的最佳介体氧化还原电位。对于云芝漆酶（E(e)(0) = 0.82），最佳介体电位为0.66 V（标准氢电极），并给出了实现该结果的分子结构。
