Preparation and microbial fuel cell application of sponge-structured hierarchical polyaniline-texture bioanode with an integration of electricity generation and energy storage

Abstract

The choice of anode materials and structure has an important influence on the performance of microbial fuel cells (MFCs). In this paper, a flexible and compressible bioanode with the features of integration of electricity generation and energy storage in MFCs was reported. With sponge skeleton as the substrate, this bioanode has been coated with carbon nanotubes and graphene, and then aniline has been polymerized on it. Compared with a carbon nanotube-sponge electrode, the charge transfer impedance of the polyaniline composite bioanode decreases from 26.6 to 4.67 ohm, and the maximum power density increases from 259.7 to 571.5 mW m−2; meanwhile, with the charge–discharge time of 60–60 min, the stored charge increases by 4.7 times, and the steady current density increases by 6.2 times. These results can be ascribed to a synergistic effect of some factors including the great specific surface area and distinct macroporous architecture of the sponge substrate, the effect of two carbon nanomaterials on decreasing the bioanode resistance, the energy storage characteristic of polyaniline, and the good biocompatibility of coating materials. The MFC with the PANI/rGO/CNTs/S capacitive bioanode has a very good ability to synchronously produce electricity and store energy and can release the stored charge in short bursts, which is expected to meet the demand of electric equipment. Schematic illustrations of the fabrication process of PANI/rGO/CNTs/S electrode.