Non-noble Metal Modified Carbon-based Materials As Cathode Catalysts For Microbial Fuel Cells

Microbial Fuel Cells?MFCs?is a new type of energy technology that uses electricity-generating microorganisms to convert biomass energy into electrical energy through bioelectrochemical reactions,while simultaneously degrading organic matter in sewage.Increasing efforts have been devoted to enhancing the cathode activity towards oxygen reduction and improve power generation of air breathing microbial fuel cells.Taking the step towards real industrial applications of microbial fuel cells requires highly active and cost-effective cathode catalyst to alternative existing platinum based noble catalysts.In this study,two transition metals?molybdenum disulfide and copper?doped carbon nanotube materials were selected and used as catalysts for the cathodic oxygen reduction reaction.Our work aims to investigate the electrocatalyst behavior and power output of the single-chamber MFC equipped with Mo S₂/CNT and Cu-CNT cathode.Mo S₂ nanosheets embedded into the CNTs network structure is synthesized by a facile hydrothermal method.From the XPS measurements,one can see that plentifully exposed Mo edges exist in the Mo S₂/CNT sample,which reported favorable for oxygen reduction reaction?ORR?.The CNT/Mo S₂-MFC achieves a maximum power density of 53.0 m W m^-2,which is much higher than those MFCs with pure CNTs(21.4 m W m^-2)or solely Mo S₂(14.4 m W m^-2)cathode.The ORR test also demonstrates a promoted electrocatalytic activity of synthesized material,which may be attributed to the special interlaced structure and abundant oxygen chemisorption sites of CNT/Mo S₂.The cost of CNT/Mo S₂ was 95.4$/W,which was95.4%lower than that of Pt/C.Such CNTs-based noble-metal-free catalyst presents a new approach to the application of MFCs cathode materials.The Cu loaded CNT was prepared by a single chemical process.It can be seen that the amount and size of metal nanoparticles increased as the loading of copper increased.XPS results indicate that Cu⁰ particles and copper compounds coexist on the surface of CNTs.An appropriate loading amount of Cu is crucial to achieve the best electrocatalytic activity,which is 2/10 of CNTs weight?Cu-CNT-2?.Cu-CNT-2 exhibits an electron transfer number of 3.95which suggested that four-electron reduction pathway was the main electron transfer process during the ORR on Cu-CNT-2 modified electrode,with little H₂O₂formed as intermediate.The MFC with Cu-CNT-2 cathode catalyst also generate the highest maximum power density of 106.13 m W m^-2 among all of the MFC with Cu-CNT catalysts prepared and tested.The cost of Cu-CNT was 79.5$/W,which was 97.1%lower than that of Pt/C.