Carbon Nanotube Planted on Ni-Based Alloy in Microbial Fuel Cell

The improvement of electrode materials used in microbial fuel cell (MFC) technology for enhancing the power performance of MFCs has attracted more and more attention lately. In this study, an new electrode material with a carbon nanotube planted on an Ni-based alloy substrate is applied to the MFC. Results show that a well-synthesized, straight CNT electrode performs the best, with a high open circuit voltage of 0.82？V and a maximum power density of 2.31？W/m2. It is believed that this new kind of electrode will have a promising future in the technology of power generation from MFCs. 1. Introduction The microbial fuel cell (MFC) is a rising form of power technology, as its use in the wastewater treatment process can become a method of capturing energy in the form of electricity or hydrogen gas, rather than being a drain on electrical energy [1]. However, a high internal resistance still exists in the MFC [2, 3], with a low power density appearing in MFCs that is needed to be overcome. Recent studies have shown that an MFC must be first able to reduce the loss in polarization effectively [4]. Microbial inoculums [5], chemical substrates [6], proton exchange materials [7], internal and external cell resistance [8], ionic solution strength [9], electrode materials [10], and operation conditions and configuration [1] have been continued to be studied. Among all these influencing factors in MFCs, the effect of electrode material on the power performance of MFCs is most significant [11]. This is because an inferior material feature of an electrode, mainly resulting from a difficult electron transfer between the bacteria and the electrode, will cause a low power output from MFCs [11]. Nowadays, carbon nanotubes (CNTs) have exhibited great potential as electrode materials in fuel cell applications due to their high surface-to-volume ratio and unique electrical and mechanical properties [12]. There has been little research done of MFCs in spite of the fact that the CNTs in the composite substrate can also facilitate the formation of biofilm in them, which is necessary for electron transfer via c-type cytochromes and nanowires [13]. In addition, several reports related to the CNT were also utilized to modify the anode electrode materials in MFCs [14–17]. The study by Sun et al., 2010, indicated that a multilayer modification would provide a free-standing three-dimensional network structure of interwoven nanotubes. This would enable a more specific surface area for anodic bacteria to anchor and decrease the interfacial charge transfer resistance from 1163 to 258？Ω.