Wu Ranran, Ma Chunling, Yong Yang-Chun, Job Zhang Yi-Heng P, Zhu Zhiguang
Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences 32 West 7th Avenue, Tianjin Airport Economic Area Tianjin 300308 China
Biofuels Institute, School of the Environment, Jiangsu University 301 Xuefu Road Zhenjiang 212013 Jiangsu Province China.
RSC Adv. 2019 Mar 5;9(13):7292-7300. doi: 10.1039/c8ra09147a. eCollection 2019 Mar 1.
A variety of sugar-based enzymatic fuel cells (EFCs) are able to completely oxidize fuels catalyzed by enzyme cascades, achieving high energy densities. However, the poor power output of EFCs limits their potential applications. In the present study, the composition of internal resistance throughout the EFCs affected by various factors, including the separator, enzyme loading, electron acceptor, applied voltage and operation time, was characterized by electrochemical impedance spectroscopy (EIS). Total resistance is divided into solution-separator resistance, charge transfer resistance, and diffusion resistance, respectively. The Nafion 212 membrane was found to yield a small solution-separator resistance and a high power density. Increased enzyme loading led to reduced internal resistance and improved cell performance, generating a maximum power density of 0.17 mW cm. Using potassium ferricyanide to replace oxygen as the electron acceptor could improve cathode performance significantly and resulted in a 4-fold increase in the power density. EIS was also performed for EFCs operated continuously for 16 h. Power output decreased distinctly over time, while the internal resistance, primarily the diffusion resistance, increased. Additionally, altering operation voltages had an impact on diffusion resistances. These results can be summarized that diffusion plays a rather important role in deciding the power and future efforts should be made towards increasing the mass transfer in EFCs.
多种基于糖的酶燃料电池（EFC）能够在酶级联反应的催化下完全氧化燃料，实现高能量密度。然而，EFC的低功率输出限制了其潜在应用。在本研究中，通过电化学阻抗谱（EIS）对受各种因素（包括隔膜、酶负载量、电子受体、施加电压和运行时间）影响的整个EFC内部电阻的组成进行了表征。总电阻分别分为溶液-隔膜电阻、电荷转移电阻和扩散电阻。发现Nafion 212膜产生的溶液-隔膜电阻较小且功率密度较高。增加酶负载量会导致内阻降低和电池性能改善，产生的最大功率密度为0.17 mW/cm²。使用铁氰化钾代替氧气作为电子受体可显著改善阴极性能，并使功率密度提高4倍。还对连续运行16小时的EFC进行了EIS测试。功率输出随时间明显下降，而内阻（主要是扩散电阻）增加。此外，改变运行电压会对扩散电阻产生影响。这些结果可以总结为，扩散在决定功率方面起着相当重要的作用，未来应努力提高EFC中的传质。
