One-step annealing in situ synthesis of low tortuosity corn straw cellulose biochar/Fe₃C: Application for cathode catalyst in microbial fuel cell

Synthesis of microbial fuel cell (MFC) cathode catalysts using corn straw with natural multi-channel structure is an useful measure for developing sustainable energy sources and making creative use of agricultural waste. The catalytic performance of nanomaterial catalysts in the oxygen reduction reaction (ORR) is clearly influenced by porosity and channel structure. Mesopores usually contribute to the enhancement of reaction kinetics and mass transfer. Therefore, in this paper, we have devised a method for the in situ synthesis of Fe₃C/B (CIP) using cold isostatic pressure (CIP), which is inspired by the natural channel structures in plants that conduct water, salt and organic matter. The low tortuosity in materials due to this special structure can make it easier to create continuous electron channels and direct ion transfer channels. In addition, Fe₃C/B (CIP) has amorphous characteristic defects (I_D/I_G = 0.82), high specific surface area (817.04 m²g^-1), and mesoporous structure (3.240 nm). When Fe₃C/B (CIP) was used as the cathode catalyst, the maximum power density of the MFC (1370.31 mW/m²) was 44.79 % higher than that of the commercial Pt/C catalyst (946.40 mW/m²). The present study offers an MFC cathode catalyst with a long cycling stability and high power density.