Université de Rennes 1, CNRS UMR no. 6226, Sciences Chimiques de Rennes, Equipe MaCSE, France.
Biosens Bioelectron. 2011 Oct 15;28(1):181-8. doi: 10.1016/j.bios.2011.07.017. Epub 2011 Jul 19.
Graphite electrodes were modified with reduction of aryl diazonium salts and implemented as anodes in microbial fuel cells. First, reduction of 4-aminophenyl diazonium is considered using increased coulombic charge density from 16.5 to 200 mC/cm(2). This procedure introduced aryl amine functionalities at the surface which are neutral at neutral pH. These electrodes were implemented as anodes in "H" type microbial fuel cells inoculated with waste water, acetate as the substrate and using ferricyanide reduction at the cathode and a 1000 Ω external resistance. When the microbial anode had developed, the performances of the microbial fuel cells were measured under acetate saturation conditions and compared with those of control microbial fuel cells having an unmodified graphite anode. We found that the maximum power density of microbial fuel cell first increased as a function of the extent of modification, reaching an optimum after which it decreased for higher degree of surface modification, becoming even less performing than the control microbial fuel cell. Then, the effect of the introduction of charged groups at the surface was investigated at a low degree of surface modification. It was found that negatively charged groups at the surface (carboxylate) decreased microbial fuel cell power output while the introduction of positively charged groups doubled the power output. Scanning electron microscopy revealed that the microbial anode modified with positively charged groups was covered by a dense and homogeneous biofilm. Fluorescence in situ hybridization analyses showed that this biofilm consisted to a large extent of bacteria from the known electroactive Geobacter genus. In summary, the extent of modification of the anode was found to be critical for the microbial fuel cell performance. The nature of the chemical group introduced at the electrode surface was also found to significantly affect the performance of the microbial fuel cells. The method used for modification is easy to control and can be optimized and implemented for many carbon materials currently used in microbial fuel cells and other bioelectrochemical systems.
石墨电极通过还原芳基重氮盐进行改性，并作为微生物燃料电池的阳极。首先，通过从 16.5 增加到 200 mC/cm(2) 的库仑电荷密度来考虑 4-氨基苯重氮盐的还原。该过程在中性 pH 下在表面引入了芳基胺官能团，这些官能团呈中性。这些电极作为“H”型微生物燃料电池的阳极，该燃料电池接种废水、乙酸盐作为基质，在阴极还原铁氰化物，并在外阻为 1000 Ω 的情况下运行。当微生物阳极得到发展后，在乙酸盐饱和条件下测量微生物燃料电池的性能，并与具有未改性石墨阳极的对照微生物燃料电池进行比较。我们发现，微生物燃料电池的最大功率密度首先随着改性程度的增加而增加，达到最佳后，随着表面改性程度的增加而降低，甚至比对照微生物燃料电池的性能更差。然后，在低表面改性程度下，研究了表面引入带电基团的影响。发现表面带负电荷的基团（羧酸盐）降低了微生物燃料电池的功率输出，而引入带正电荷的基团则使功率输出增加了一倍。扫描电子显微镜显示，用带正电荷的基团改性的微生物阳极被一层致密且均匀的生物膜覆盖。荧光原位杂交分析表明，该生物膜在很大程度上由已知的电活性 Geobacter 属细菌组成。总之，阳极的改性程度被发现对微生物燃料电池的性能至关重要。电极表面引入的化学基团的性质也被发现显著影响微生物燃料电池的性能。所使用的改性方法易于控制，并且可以针对当前在微生物燃料电池和其他生物电化学系统中使用的许多碳材料进行优化和实施。
