Tailoring macro-microporous carbon using porphyrin-based zeolitic imidazole framework as an efficient cathodic component for microbial fuel cell

In this study, a porphyrin-based bimetallic zeolitic imidazole framework (FeTCPP-Zn/Co ZIF) was tailored via the reaction of Fe(III) meso-tetra(4-carboxyphenyl)porphyrin (FeTCPP), Zn(NO₃)₂, and Co(NO₃)₂, in the presence of 2-methylimidazole to prepare a M−N architecture with abundant active sites for electrocatalytic reduction of oxygen. Nano-sized polystyrene spheres were utilized as a precursor to develop three-dimensionally ordered macro-microporous (3DOM) FeTCPP-Zn/Co ZIF. Direct pyrolysis was adopted to obtain 3DOM Fe,Co-NC in order to enhance electrocatalytic performance toward the oxygen reduction reaction (ORR). The FE-SEM images revealed a unique porous morphology for the produced 3DOM Fe,Co-NC, offering a favorable environment for enhancing ORR kinetics due to the substantial availability of active sites. Electrochemical investigation revealed that the 3DOM Fe,Co-NC highlighted a higher level of ORR performance when compared to Fe,Co-NC. This superiority can be attributed to the 3DOM architecture, which enhances the efficiency of charge transportation. Further investigation of the prepared catalysts was performed using a dual-chamber microbial fuel cell (MFC). The MFC-3DOM Fe,Co-NC demonstrated a high power density of 147. 1 mW m⁻² compared with the MFC-Fe,Co-NC (107.1 mW m⁻²). In this study, the importance of engineering design in developing porous structures was well-proven.