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For successful field-scale application of microbial fuel cell (MFC), the power recovery from field-scale MFC needs to be improved considerably with simultaneous reduction in its fabrication cost. These problems can be addressed by applying low-cost and efficient cathode catalyst in MFCs. In this regard, Cu0.5Mn0.5Fe2O4 (CuMnFe) was synthesized and applied as cathode catalyst in lab and field-scale MFCs with capacity of 150 ml and 25 l, respectively. Lab-scale MFC having CuMnFe as cathode catalyst demonstrated power density of 176.0 ± 8.2 mW m-2, which was competitive with MFC having Pt as cathode catalyst (183.0 ± 12.6 mW m-2) and it was about seven times higher than control MFC (25.5 ± 4.5 mW m-2) having no catalyst. Application of CuMnFe as cathode catalyst in field-scale MFC produced power density of 7.74 mW m-2, which was three-times higher than the power produced by the field-scale MFC operated without any cathode catalyst (2.58 mW m-2). The cathode catalyst CuMnFe also demonstrated excellent anti-biofouling properties, which in turn improved the power production of field-scale MFC. Therefore, low-cost CuMnFe can be anticipated as an efficacious cathode catalyst for application in MFCs that would produce long term stable higher power, while offering simultaneous treatment to wastewater. [ABSTRACT FROM AUTHOR]

There has been a considerable increment in the atmospheric CO2 concentration, which has majorly contributed to the problem of global warming. This issue can be extenuated by effectively developing microbial electrosynthesis (MES) for the sequestration of CO2 with the concurrent production of biochemical and biofuels. Though the MES technology is in its infancy, it has exhibited enormous potential for sustainable mitigation of CO2 and bioelectrosynthesis of multi-carbon organic compounds. The problem of storage of excess renewable electrical energy by conventional means can also be alleviated by employing MES, which stores it in the form of C–C bonds of chemicals. This review focuses on the various aspects of MES and recent developments made in this field to overcome its bottlenecks, such as the lower yield of organic compounds, separation of products of higher chain organic compounds, etc. In particular, the microbial catalysts and cathode materials employed in MES have also been emphasized. Keeping in mind the potential of this innovative technology, researchers should focus on improving the yield of MES by developing novel low-cost cathode materials and discovering efficient and robust micro-organisms, which would be a significant step forward towards the further advancement of this technology. [ABSTRACT FROM AUTHOR]

Low cost tungsten oxide/bismuth tungstate (WO3/Bi2WO6) composite was synthesized and used as cathode catalyst in microbial fuel cell (MFC). Almost 1.5 times increment in specific surface area of WO3/Bi2WO6 composite was observed as compared with WO3 and WO3/Bi2WO6 exhibited efficient oxygen reduction reaction (ORR) having a current peak of 8.1 mA at - 12.6 mV during cyclic voltammetry analysis, demonstrating less ORR overpotential. The MFC using WO3/Bi2WO6 catalysed cathode could recover a power density (PD) of 145 ± 4.5 mW/m2 and coulombic efficiency (CE) of 28.3 ± 1.5%, followed by 35 ± 5.8 mW/m2 and 17.5 ± 2.4%, respectively, for MFC with WO3 catalyzed cathode and 10.4 ± 3.2 mW/m2 and 10.3 ± 0.9%, respectively, for MFC without any cathode catalyst. Moreover, the PD and CE of 138 ± 6.8 mW/m2 and 27.5 ± 2.0%, respectively, obtained from MFC using Pt/C cathode catalyst, was slightly lower than the MFC with WO3/Bi2WO6 catalyst on cathode. The specific power recovery per unit cost of cathode fabrication of 23.8 mW/$ obtained from MFC with WO3/Bi2WO6 catalyzed cathode is higher than the MFC with Pt/C (12.2 mW/$), making it low cost alternative for scaling-up of MFCs. [ABSTRACT FROM AUTHOR]

Cu-Sn bimetallic alloy supported on acetylene black was prepared and tested under different loadings per unit cathode surface area viz. 1 mg.cm-2, 2 mg.cm-2 and 5 mg.cm-2 as a catalyst to improve the oxygen reduction reaction (ORR) and to enhance performance of the microbial fuel cell (MFC). Electrochemical analyses were performed to evaluate the ORR kinetics. Results of cyclic voltammetry showed multiple redox current peaks for all the loadings of Cu-Sn with positive onset potential of ~0.25 V. Among different loadings, cathode with Cu-Sn loading of 2 mg.cm-2 proved to be the best choice for application in MFC, due to less charge transfer resistance and high redox current. Power density and coulombic efficiency of 470 mW.m-2 and 36%, respectively, were obtained from MFC using Cu-Sn catalyzed cathode with a loading of 2 mg.cm-2, which was higher than the MFCs using cathodes with 1 and 5 mg.cm-2 of Cu-Sn loadings and it was even found slightly higher than the MFC using Pt-C catalyst on cathode. Power generation per unit cost of catalyst for MFC using Cu-Sn catalyst was found to be 11-fold higher than the MFC using Pt-C cathode, ascertaining former as low-cost cathode catalyst for harvesting more power from MFCs. [ABSTRACT FROM AUTHOR]