Fabrication of a Carbon Paper/Polyaniline-Copper Hybrid and Its Utilization as an Air Cathode for Microbial Fuel Cells

The use of platinum (Pt) catalysts in air cathode for microbial fuel cells (MFCs) is expensive and is limiting the adoption of MFCs for power generation from wastewaters. In this study, we propose an innovative approach for the fabrication of a carbon paper/copper-polyaniline (CP/PANi-Cu) hybrid which can be employed as a relatively inexpensive and effective air cathode for MFCs. The CP/PANi-Cu hybrid cathode composed of the uniform layer and relatively strong adhesion of PANi-Cu to CP which enables a significant oxygen reduction reaction (ORR). Consequently, the composite cathode demonstrated superior performance compared to that of a conventional Pt (CP/Pt) cathode by generating a maximum current of 0.50 ± 0.02 mA cm–2 compared with 0.35 ± 0.03 mA cm–2 obtained with the latter. When employed in MFCs, the power densities obtained with these cathodes were 0.244 ± 0.014 mW cm–2 under a current density of 0.85 ± 0.08 mA cm–2 for the Pt cathode, and 0.101 ± 0.01 mW cm–2 at 0.37 ± 0.04 mA cm–2 for the CP/PANi-Cu cathode. Moreover, the Nafion membrane attached to the CP/PANi-Cu cathode experienced much less biofouling than that used with the CP/Pt cathode and, thus, indicates that the new hybrid cathode is superior on the basis of overall performance, usage, and stability. A very detailed characterization of the Nafion membranes by Fourier transform infrared spectroscopy and 3D profilometry revealed more complex and thicker biofouling of the membrane attached to the CP/Pt cathode than that of the CP/PANi-Cu cathode.