High‐performance Microbial Fuel Cell Using Metal Ion Complexes as Electron Acceptors

Abstract

Metal complex‐microbial fuel cells (MFCs) have been investigated in this work with intent manufacturing highly efficient MFC batteries. The performance of metal complex MFCs was evaluated by polarization and discharge experiments using a battery consisting of three MFC unit cells. The results indicated that the performance of the [Fe(III)(4,4′‐dimethyl‐2,2′‐bipyridyl)3]‐MFC was much better than the other MFC containing Cr(VI) or Fe(III) as an electron acceptor. At a discharging current of 3 mA (17.6 A/m3), the average discharging potential was found to be 0.927 V under a parallel‐connection, sustaining longer than 20 h with an open circuit voltage of 1.210 V. [Fe(III)(4,4′‐dimethyl‐2,2′‐bipyridyl)3]‐MFC showed much higher electrochemical parameters than Cr(VI)‐MFC and Fe(III)‐MFC. Highest maximum power of 34.87 Wm−3 could be obtained from the battery consisting of three MFCs in parallel‐connection, when each cell contains a carbon brush anode and a graphite plate. MFC battery containing a carbon brush anode and a carbon brush cathode showed better polarization and discharging performance. In particular, the maximum power of 45.45 Wm−3 was achieved. By installing the maximum amount of carbon brush anode and adjusting the amount of carbon brush cathode and the electron acceptors, the magnitude of current and the maximum power can be maximized.