Applying air-cathodes to replace potassium ferricyanide

Another challenge are the low reaction kinetics of oxygen. Performance of air-cathode MFCs is mostly limited by the air-cathode, which degrades the performance of the MFC. Fan et al (2007) changed the size of the air-cathode, and reported that as anode/cathode area ratio reduces from 1 1 to 1 7, the areal power density increased from 1.04 W m to 6.71 W m (normalized to the anode area). Thus, enhancing the reaction kinetics of oxygen is critical. 

A further critical challenge in miniaturized MFCs is that most research utilizes an electrically driven peristaltic or syringe pump to drive the electrolyte into the corresponding chambers, and more often than not, the electricity generated is far less than the electricity consumed by these pumps. 

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Miniaturized MF Cs have demonstrated plenty of promise and indeed much progress has prevailed for such a short period of time yet, miniaturized MFCs face many different challenges to overcome, including further enhancing current and power density, applying air-cathodes to replace potassium ferricyanide, and autonomous operation. 

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