Mustard (Brassica Nigra) Cake Powder Biochar/Nafion Composite as ORR Catalyst in Single Chambered Air Cathode MFC

The electrocatalytic activity of a cathode catalyst is one of the vital factors in the performance of a Single Chambered Air Cathode - Microbial Fuel Cell (SCAC-MFC). Developing a minimal-cost, highly efficient electrocatalyst for Oxygen Reduction Reaction (ORR) is essential for expanding MFC’s utilization, scale-up, and commercialization. In the present study, Mustard Cake Powder Biochar (MCPB) is produced by pyrolysis at 600˚C. Scanning Electron Microscopy (SEM) revealed the presence of a non-homogeneous porous structure. Based on pore size analysis, mesoporous structures are identified. The surface area is 1.732 m2/g by Brunauer-Emmett-Teller (BET) analysis. Fourier Transform InfraRed (FT-IR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS) confirm the presence of more oxygen functional groups and high nitrogen content in the carbon matrix. Energy Dispersive X-ray (EDX) and XPS show transition elements that enhance ORR activity. Electrochemical characters have been identified by adopting Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV). Electrochemical analyses reveal the existence of a two-electron pathway with 2.2 electrons transferred per oxygen molecule. The maximum power density obtained is 11.5±30 mW/m. This study shows that MCPB exhibits ORR electrocatalytic properties and is suitable as an inexpensive cathode catalyst in SCAC-MFC. Further pyrolysis at a higher temperature, chemical activation, and doping of heteroatoms like N, P, and Fe may enhance its electrocatalytic property with a four-electron pathway.