The Research Of Co-based Metal-organic Framework-derived Nanomaterials Modified Activated Carbon Air-cathode Performance In Microbial Fuel Cell

Microbial fuel cell（MFC）is a novel and green energy recovery technology that directly utilizes bacteria to oxidize organic substances and generates electricity.However,the performance of air cathode directly affects the power output of MFC.Therefore,the develop of cathode electrocatalysts with high electrocatalytic activity and low cost to improve the performance of activated carbon air cathode MFC is the main major of this reaearch.Co₃O₄/Ni Co₂O₄ double-shelled nanocage was successfully synthesized using metal-organic framework ZIF-67 as precursor,and used to modify activated carbon cathode MFC.It was found that the electrochemcial performance of MFCs modified by Co₃O₄/Ni Co₂O₄ were improved significantly,which was mainly ascribed to existence of redox electron pairs of Co²⁺/Co³⁺,Ni²⁺/Ni³⁺in catalyst and the unique nanocage structure.Moreover,the maximum power density（MPD）of the optimized MFC reached 1810 m W﹒m^-2,104%higher than that of bare activated carbon cathode MFC.Co-NCNT,a nitrogen-doped carbon nanotube nanopolyhedral embedded in cobalt nanoparticles catalyst,was synthesized via calcinaton of bimetallic organic framework Zn Co-ZIFs in reducing atmosphere.It was used as oxygen reduction electrocatalyst in activated carbon air-cathode MFC for the first time.The results indicated that the synergistic effect between cobalt nanoparticles and nitrogen-doped carbon nanotube greatly improved the oxygen reduction activity of catalyst,showing a four-electron transfer pathway like the Pt/C.Moreover,the total resistance and electron transfer resistance of modified cathodes were significantly reduced,the open circuit potential and exchange current density were greatly increased,which finally obtained 2252 m W﹒m^-2 ultra-high power output,154%higher than that of bare activated carbon cathode MFC.Therefore,the as-synthesized Co-NCNT exhibited better electricity generation performance,and expected to be a cathode electrocatalyst for replacing noble Pt and applying in MFC.Co₂PNC,a Co₂P embedded in nitrogen-doped carbon nanoframework electrocatalyst,was successfully prepared by carbonization at high temperature and phosphatization with Na H₂PO₂ using metal-organic framework ZIF-67 as precursor.When used as oxygen reduction electrocatalyst to modify activated carbon cathode,it significantly enahnced the electrochemical performance of cathodes.The MPD of modified MFC reached 1994 m W﹒m^-2,125%higher than that of bare activated carbon cathode MFC.Moreover,the results showed that the electron interaction between Co₂P and nitrogen-doped carbon strongly improved the ORR activity of catalyst,and exhibited a similar electron transfer mechanism like commercial Pt/C electrode during the process of oxygen reduction.