N/NiO-ornated graphitic fiber-engrained micro-carbon beads: Innovative packed bed type capacitive electrodes for microbial fuel cells

Abstract

Nitrogen-doped nickel oxide-catalyzed carbon nanofiber-decorated micro-activated carbon beads (NiO-N-CNF/ACB) were synthesized through suspension polymerization and employed as capacitive fixed-packed bed electrodes in microbial fuel cell (MFC-) for wastewater treatment and byproduct electricity generation. The capacitive electrode was meticulously designed to manifest enhanced characteristics crucial for MFC applications. The large specific surface area of NiO-N-CNF/ACB offers advantages in terms of catalytic sites and stored charge produced by electrogenic bacteria to form an electrochemical double-layer on the electrode, thereby enhancing power generation. The incorporation of NiO, coupled with graphitic contents, biocompatibility, and the formation of three-dimensional structures, contributes to the excellent performance of the NiO-N-CNF/ACB electrodes. The NiO-N-CNF/ACB electrodes-based MFC operated in batch mode demonstrated an open-circuit potential of 0.8 V, an impressive maximum power density of 2900 mW/m3, and a noteworthy 74 % reduction in chemical oxygen demand. Additionally, the synthesized NiO-N-CNF/ACB exhibited a remarkable specific capacitance 754 F/g and a cumulative total charge of 255 C/g, surpassing the corresponding values for plain NiO-ACB and ACB. This study positions NiO-N-CNF/ACB as a promising capacitive packed bed electrode material, offering enhanced power generation, efficient wastewater treatment, and superior biofilm formation, thereby advancing the potential for sustainable and efficient MFC systems.