Microbial fuel cells (MFCs) exhibit asymmetric overpotentials and redox potentials/rates at the cathode and anode. However, the impact of this asymmetric on power density and anode microbial community remains poorly understood. In this study, asymmetric reactors were designed for H-type MFCs to investigate this configuration. Contrary to the initial expectation of increased MFC power output with larger cathode volumes, it was unexpectedly found that the small-cathode reactor outperformed the large-cathode reactor, achieving a 61 % increase in maximum power density. Electrochemical characterization revealed a slightly lower charge transfer resistance (29.34 Ω) in the small-cathode reactor with carbon-felt anode biofilm in PBS. Moreover, 16S rRNA sequence analysis showed that the small-cathode reactor harbored a higher proportion of anaerobic bacteria (83 %), lower species diversity, and a higher abundance of exoelectrogens. Additionally, higher abundances of key gene modules (top eight), such as quinone oxidoreductase and citrate cycle, were observed in the small-cathode reactor. The anode biofilms in both reactors also synthesized some vitamins, such as menaquinone and thiamine. Furthermore, compared to the large-cathode reactor, each set of the small-cathode reactor saved ¥ 20, 23 g of borosilicate, and 55 mL of cathode electrolytes. This study sheds light on the interplay between reactor conformation and performance, contributing to the development of low-cost, high-performance MFCs for real field conditions.

中文翻译：

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不对称反应器作为优化微生物燃料电池性能的创新方法

微生物燃料电池（MFC）在阴极和阳极表现出不对称的超电势和氧化还原电势/速率。然而，这种不对称对功率密度和阳极微生物群落的影响仍然知之甚少。在本研究中，为 H 型 MFC 设计了不对称反应器来研究这种配置。与最初预期的通过更大的阴极体积增加MFC功率输出的预期相反，意外地发现小阴极反应器优于大阴极反应器，实现了最大功率密度的61%的增加。电化学表征显示，在 PBS 中具有碳毡阳极生物膜的小阴极反应器中，电荷转移电阻略低（29.34 Ω）。此外，16S rRNA序列分析表明，小型阴极反应器中厌氧菌比例较高（83%），物种多样性较低，而外产电丰度较高。此外，在小型阴极反应器中观察到了更高丰度的关键基因模块（前八个），例如醌氧化还原酶和柠檬酸循环。两个反应器中的阳极生物膜还合成了一些维生素，例如甲基萘醌和硫胺素。此外，与大阴极反应器相比，每套小阴极反应器节省20元、硼硅酸盐23克、阴极电解液55毫升。这项研究揭示了反应器构象和性能之间的相互作用，有助于开发适合实际现场条件的低成本、高性能 MFC。