Oxygen Reduction And Pollutant Detoxification Based On The Microbial Fuel Cell Cathode

Microbial Fuel Cell(MFC),using electricigens as catalysts,could harvest energy from wastewater.which is regarded as a prospective technology for environmental pollution control and energy recovery.In this thesis,a novel manganese oxide nanosheets was developed as the cathodic catalysts for oxygen reduction.The removal of onearomatic azo dye and heavy metal Cr(VI)in the novel Photoelectrical Microbial Fuel Cell(PMFC)was evaluated,and the photo-electricity synergistic mechanism for pollutants removal was discussed.The main results are listed as follows:1.A novel layered manganese oxide(MnO2)nanosheets was prepared by using a facile method with graphene oxide(GO)as the template and its electrocatalytic performance was studied.Results show that the MnO2,nanosheets could catalyze the oxygen reduction efficiently,and the electron transfer number of the nanosheets for the oxygen reduction reaction(ORR)was measured to be 3.4,suggesting that the oxygen reduction reaction(ORR)on nanosheets might proceed through a coexisting pathway involving the two-electron and four-electron transfer2.A silicon nanowires(SiNWs)electrode was prepared using chemical etching method and then Pd nano-particles were chemically deposited onto its surface.The obtained palladium deposited silicon nanowires(Pd-SiNWs)electrode was used as the cathode in a PMFC system for methyl orange(MO)degradation through cathodic reduction reaction under illumination.The results reveal that both MO degradation rate and electricity generation were improved significantly after the Pd-SiNWs electrode was illuminated.The highest removal efficiency for MO in PMFC could reach 85%in 36 hours at pH 1 under illumination.3.The Pd-SiNWs electrode was prepared through the electrichemical deposition method and used for Cr(VI)reduction in PMFC.Experimental results Show that both the rate of Cr(VI)reduction and electricity generation were obviously improved after Pd-SiNWs was illuminated.The mechanism of Cr(VI)removal through MFC strengthened by Pd-SiNWs might be as follows:the Pd-SiNWs can provide external voltage to the MFC under illumination to enhance the sepration of the photho-generated holes and electrons and to overcome the over potential of Cr(VI)reduction on the cathode,which would improve the removal efficiency of Cr(VI).