The exceptional performance of polyhedral porous carbon embedded nitrogen-doped carbon networks as cathode catalyst in microbial fuel cells

The ZIF-8/polypyrrole fabricated polyhedral porous carbon embedded nitrogen-doped carbon networks complex (PPC/NC) is successfully prepared via a carbonization process followed by an acid washing. The PPC/NC with special hybrid structure presents a significant exchange current density (37.113 × 10−4 A cm−2) and a higher open circuit potential (0.310 V) compared with the control. The maximum power density of PPC/NC modified activated carbon air-cathode microbial fuel cells is up to 2401 ± 0.7 mW m−2, 3.3 times as high as that of the control (725 ± 0.5 mW m−2). Besides, the PPC/NC expresses a desired four-electron process towards ORR comparable to commercial Pt/C catalyst. The PPC/NC displays polyhedral porous carbon well embedded in interconnected carbon networks hierarchical structure, in which the carbon networks with the highly conductive hollow tubular structure acts as the central skeleton of the entire conductive system, thereby facilitating electron diffusion between polyhedral carbon particles. This exceptional 3D stacked structure enriches catalytically active sites and contributes significantly to the oxygen reduction reaction as the obtained complex possesses large content of nitrogen and hierarchical carbon structure. PPC/NC is considered to be a prospective catalyst to enhance the capability of the microbial fuel cells.