Study On The Effects And Catalytic Mechanism Of Co/N-C And CoP On The Performance Of Activated Carbon Air Cathode Microbial Fuel Cell

The increasingly serious problem of environmental pollution and energy shortage has become a major threat to the development of human and society,therefore,the exploration of new clean energy has become the only way which must be passed for sustainable development.Microbial fuel cell?MFC?is a new type of bioreactor,which can use the electricigens to convert the chemical organic in the wastewater into electrical energy during the sewage treatment,at the same time generate new sources of energy,therefore,it is regarded as a sustainable wastewater treatment technology.In the MFC,the performance of air-cathode is the key factor affecting the battery power output.So,the development of a cathode catalyst with superior performance,low cost and strong practicability is the main goal of this paper.The hollow-spherical Co/N-C nanoparticle,which is synthesized via a simple hydrothermal reaction followed by heat treatment,is firstly used as electrocatalyst for oxygen reduction reaction?ORR?in aircathode microbial fuel cell?MFC?,N-C was used as the comparison.The maximum power density of MFC with 10%Co/N-C air-cathode is as high as 2514±59 mW m^-2,which is almost 174%higher than the control.The exchange current density?i₀?of cathode equipped with 10%Co/N-C is 238%higher than that of untreated AC.While the total resistance of treated samples decreases from 13.017?to 10.255?.The four-electron pathway of the Co/N-C also plays a crucial role in electrochemical catalytic activity.All these results revealed that Co/N-C has good electrochemical performance.The intensity ratio of Raman D to G band?I_D/I_G?decreases from 0.93?N-C?to 0.73?Co/N-C?,indicating the catalyst forms graphite structure.Both XRD and XPS testify that Co is bonded to N within graphitic sheets and serves as the active sites in ORR.As a result,it can be expected that the as-synthesized Co/N-C,with extraordinary electro-catalytic performance towards ORR,will be a promising alternative to the state-of-the-art non-precious metal ORR electro-catalysts for electrochemical energy applications.Then,the corallite-like CoP catalyst was synthetised by the high temperature phosphating method in nitrogen environment,and was used as a redox reaction catalyst applied to microbial fuel cell for the first time.The electrochemical test results show that the modified microbial fuel cells exhibited a comparable onset potential,inferior resistance and long-term stability.Tafel analysis showed that the exchange current density?i₀?was increased after treatment,which meant a faster reaction rate with a lower activation energy barrier of forward reaction.The maximum power density of MFC embellished with 10%CoP reached 1914.4±59.7mW m^-2,which is 108.5%higher than the control.The four-electron pathway,observed by the RDE,plays a crucial role in electrochemical catalytic activity.In addition,material characterizations indicate that the surface oxide layer?CoOx?around the metallic CoP core is important and beneficial for ORR.