Enhanced performance of microbial fuel cells by electrospinning carbon nanofibers hybrid carbon nanotubes composite anode

Abstract

A novel carboxylated multiwalled carbon nanotubes/carbon nanofibers (CNTs/CNFs) composite electrode was fabricated by electrospinning. Heat pressing process was applied to improve the interconnection of fiber aggregates, mechanical stability and reduce the contact resistance. Optimal dose of carbon nanotubes was selected to fabricate the anode in microbial fuel cells after comparing with plain electrospinning CNFs anode and commercial carbon felt (CF) anode. As a result, the optimal anode delivered a maximum power density of 362 ± 20 mW m−2, which is 110%, 122% higher than that of carbon nanofibers and carbon felt anodes. Cyclic voltammograms, Tafel and electrochemical impedance spectroscopy tests also verified that the prepared electrode has largest catalytic current (148 μA cm−2) and exchange current density i0 (6.3 × 10−5 A cm−2), as well as smallest internal resistance (∼40 Ω). The as-prepared anode exhibited a better conductivity, excellent biocompatibility, good hydrophilicity and superior electrocatalytic activity, which was not only beneficial to the attachment and reproduction of microorganisms, but also promoted extracellular electron transfer between bacteria cells and the anode. This result shows that electrospinning has a promising perspective in fabricating high performance electrodes for microbial fuel cells.