Polyaniline and sulfonated graphene oxide supported bimetallic manganese cobalt oxides as an effective and non-precious cathode catalyst in air-cathode microbial fuel cells

Abstract

This study examines the feasibility of the use of nanocomposite of polyaniline (PAni) grafted sulfonated graphene oxide (SGO) supported manganese cobalt oxide as a novel and effective cathode catalyst for single chamber microbial fuel cell (SC-MFC). The graphene oxide (GO) was sulfonated to SGO for the development of a significant increase in the hydrophilicity of GO to enhance the nano−catalyst dispersion. The structural properties of the prepared nanocomposite were studied by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. Morphological studies of the nanocomposite revealed a wrinkled paper−like structure of SGO and a spherical type structure of Mn−Co. Both cyclic voltammetry and electrochemical impedance spectroscopy showed a reduction current value of −1.04 mA, and charge-transfer resistance of 52.4 ohm, which exhibited a higher oxygen reduction reaction activity and good conductivity compared to Mn−Co/GO−PAni, Mn−Co/rGO−PAni and Pt/C catalyst. Electrochemical tests also suggest that the Mn−Co/SGO−PAni nanocomposite exhibited excellent durability among the other three cathodes. Furthermore, the MFCs equipped with Mn−Co/SGO−PAni nanocomposite modified electrode achieved power density of 1392.68 mW m−2 which is 2.89 times higher than state-of-art Pt/C (481.3 mWm−2). The Electrochemical studies also displayed a similar result. The significant increase in power generation with Mn−Co/SGO−PAni nanocomposite as a cathode catalyst indicates that it can be used as a promising, inexpensive electrocatalyst for the long-term operation for MFC.