Application of multi-walled carbon nanotubes to enhance anodic performance of an Enterobacter cloacae-based fuel cell

Abstract

The effect of multi-walled carbon nanotube (MWCNT) modification of anodes and the optimisation of relevant parameters thereof for application in an Enterobacter cloacae microbial fuel cell were examined. The H – type microbial fuel cells were used for the fundamental studies, with a carbon sheet as a control anode and platinum coated carbon sheets as the cathode. Anodes were correspondingly modified with MWCNTs dispersed in either 0.1% chitosan or 1% Nafion®. Maximum power output was observed four hours after inoculation of the anode chamber with the microorganism. A 252.6% increase in power output of the fuel cell was observed at an anode modified with 10 mg MWCNTs/ml dispersed in 0.1% chitosan compared to unmodified anodes (13.8 μW). MWCNTs dispersed in chitosan yielded nearly 50% greater power outputs than when dispersed in Nafion®; attributed to increased aggregation in the latter as evidenced by scanning electron microscopy imaging. When NafionTM 117 membrane was used as a proton exchanger it generally resulted in higher power outputs than the CMI 7000S membrane. These studies also showed that the time-consuming carboxylic acid functionalisation of MWCNT for such applications is not a necessary requirement for enhancing power outputs. The studies thus illustrate the utility of a MWCNT modified anode as a support matrix for E. cloacae in a microbial fuel cell and provide clarity on parameters which can be applied to other such studies in the emerging area of nanostructured material utilisation in alternative energy generation.