Cathode performance as a factor in electricity generation in microbial fuel cells
Cathode performance as a factor in electricity generation in microbial fuel cells
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DOI：
10.1021/es049422p
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发表时间：
2004-09-15
影响因子：
11.4
通讯作者：
Logan, BE
中科院分区：
文献类型：
--
作者：
Oh, S;Min, B;Logan, BE
虽然微生物燃料电池（MFC）产生的功率密度比氢燃料电池低得多，但阴极的特性也会显著影响发电。用于MFC的阴极通常是浸在水中使用溶解氧作为电子受体的Pt涂覆的碳电极，或者它们是铁氰化物溶液中的普通碳电极。使用双室MFC比较这两种阴极的特性和性能。当阴极与阳极尺寸相等（2.5 × 4.5 cm）时，使用Pt-碳阴极和溶解氧（饱和）的发电在接种（废水污泥和20 mM乙酸盐）后120 h内达到最大值0.097 mW。一旦用新鲜培养基（无污泥）替换MFC后产生稳定的功率，库仑效率范围为63至78%。功率与溶解氧浓度成正比，与Monod型动力学一致，霍尔饱和常数K-DO = 1.74 mg O-2/L。当阴极表面积从22.5 cm（2）增加到67.5 cm（2）时，功率增加了24%，而当阴极表面积减少到5.8 cm（2）时，功率降低了56%。如果在阴极上不使用Pt，则功率也显著降低（降低78%至0.02mW）。通过使用铁氰化物代替溶解氧，最大功率比用溶解氧获得的最大功率增加50-80%。这一结果主要是由于增加的传质效率和铁氰化物的阴极电位（332 mV）比溶解氧（268 mV）获得的更大。使用溶解氧理论上可以获得804 mV（NHE基础）的阴极电势，这表明使用氧作为电子受体的阴极性能的进一步改进是可能的，这可以导致这种类型的MFC中的功率密度增加。
Although microbial fuel cells (MFCs) generate much lower power densities than hydrogen fuel cells,the characteristics of the cathode can also substantially affect electricity generation. Cathodes used for MFCs are often either Pt-coated carbon electrodes immersed in water that use dissolved oxygen as the electron acceptor or they are plain carbon electrodes in a ferricyanide solution. The characteristics and performance of these two cathodes were compared using a two-chambered MFC. Power generation using the Pt-carbon cathode and dissolved oxygen (saturated) reached a maximum of 0.097 mW within 120 h after inoculation (wastewater sludge and 20 mM acetate) when the cathode was equal size to the anode (2.5 x 4.5 cm). Once stable power was generated after replacing the MFC with fresh medium (no sludge), the Coulombic efficiency ranged from 63 to 78%. Power was proportional to the dissolved oxygen concentration in a manner consistent with Monod-type kinetics, with a hall: saturation constant of K-DO = 1.74 mg of O-2/L. Power increased by 24% when the cathode surface areas were increased from 22.5 to 67.5 cm(2) and decreased by 56% when the cathode surface area was reduced to 5.8 cm(2). Power was also substantially reduced (by 78% to 0.02 mW) if Pt was not used on the cathode. By using ferricyanide instead of dissolved oxygen, the maximum power increased by 50-80% versus that obtained with dissolved oxygen. This result was primarily due to increased mass transfer efficiencies and the larger cathode potential (332 mV) of ferricyanide than that obtained with dissolved oxygen (268 mV). A cathode potential of 804 mV (NHE basis) is theoretically possible using dissolved oxygen, indicating that further improvements in cathode performance with oxygen as the electron acceptor are possible that could lead to increased power densities in this type of MFC.