Analytical Chemistry-Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780, Bochum, Germany.
Angew Chem Int Ed Engl. 2018 Oct 8;57(41):13681-13685. doi: 10.1002/anie.201808450. Epub 2018 Sep 13.
In the development of biofuel cells great effort is dedicated to achieving outstanding figures of merit, such as high stability, maximum power output, and a large open circuit voltage. Biofuel cells with immobilized redox mediators, such as redox polymers with integrated enzymes, show experimentally a substantially higher open circuit voltage than the thermodynamically expected value. Although this phenomenon is widely reported in the literature, there is no comprehensive understanding of the potential shift, the high open circuit voltages have not been discussed in detail, and hence they are only accepted as an inherent property of the investigated systems. We demonstrate that this effect is the result of a Nernstian shift of the electrode potential when catalytic conversion takes place in the absence or at very low current flow. Experimental evidence confirms that the immobilization of redox centers on the electrode surface results in the assembled biofuel cell delivering a higher power output because of charge storage upon catalytic conversion. Our findings have direct implications for the design and evaluation of (bio)fuel cells with pseudocapacitive elements.
在生物燃料电池的发展过程中，人们致力于实现卓越的性能指标，如高稳定性、最大功率输出和大开路电压。与固定化氧化还原介体（如集成酶的氧化还原聚合物）的生物燃料电池在实验中表现出比热力学预期值高得多的开路电压。尽管这种现象在文献中被广泛报道，但人们对潜在的电位偏移没有全面的理解，对高开路电压也没有进行详细的讨论，因此它们仅被视为所研究系统的固有特性。我们证明，当催化转化在不存在或电流非常低的情况下发生时，这种效应是电极电位的能斯特偏移的结果。实验证据证实，由于催化转化时的电荷存储，氧化还原中心在电极表面的固定化导致组装的生物燃料电池产生更高的功率输出。我们的发现对具有赝电容元件的（生物）燃料电池的设计和评估具有直接影响。
