Synthesis of single metal and bimetallic cathode catalyst for microbial fuel cells using M-BTC (M= Cu, Ni, Fe, Co)

Metal-organic frameworks (MOFs) possess large surface area, high stability, and porous structure, making them suitable for oxygen reduction reaction catalysts in the cathode compartments of microbial fuel cells. In this study, 1,3,5-benzene tricarboxylic acid was used as an organic linker in metal-organic frameworks, and the metal centers were changed. For this purpose, Copper, Nickel, Cobalt, and Iron salts were used as metal sources. In addition to monometallic MOFs, bimetallic metal-organic frameworks were synthesized using copper-nickel and cobalt-iron pairs. Comparisons were made among copper, nickel, and copper-nickel BTC and cobalt, iron, and cobalt-iron BTC separately. Also, the solvent of the precursors was changed and a group of MOFs was synthesized using dimethylformamide (DMF) while the second group was synthesized with ammonia (NH3) solvent. The effect of metal and solvent selection was examined. Sonochemically synthesized metal-organic frameworks were analyzed using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and X-ray photoelectron Spectroscopy (XPS) techniques. Synthesized metal-organic frameworks as cathode catalysts in microbial fuel cells were applied by preparing slurries using carbon black as a carbon source and polyvinyl alcohol binder. The slurries were coated on stainless-steel meshes and coated meshes were analyzed before constructing Microbial fuel cells; Chronopotentiometry and Cyclic voltammetry (CV) were applied to meshes to obtain conductivity and oxygen reduction reaction activity information. The electrochemical properties of the MFC were obtained using electrochemical methods such as open-circuit voltage (OCV), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV).