Preparation And Characterization Of Silver Bismuthate/manganese Dioxide Composites And Their Catalytic Properties For Oxygen Reduction

As an efficient clean energy source,fuel cells have broad commercial development and application prospects.The cathodic reduction reaction of cathodic of the fuel cell oxygen has slow rate and large polarization,which makes the improvement of the performance of the fuel cell encounter a big obstacle.The platinum-based catalyst is considered to be a cathode oxygen reduction catalyst with excellent performance,but the scarcity of platinum resources and the high cost limits the large-scale use of the platinum catalyst.At present,people have begun to develop alternative catalysts with low cost,high stability,and high catalytic oxygen reduction performance to replace platinum catalysts.Based on previous research,we synthesized nano-Ag4Bi2O5/MnO2,Ag4Bi2O5/MnO2/CNTs and Ag4Bi2O5/MnO2/rGO by co-precipitation method,respectively.And we have studied its structure,composition and morphology,as well as its catalytic activity for oxygen reduction.The main contents of this article are as follows:(1)Firstly,nano-Ag4Bi2O5/MnO2 catalysts were prepared by co-precipitation method on nano-Ag4Bi2O5 and MnO2 material.The structures and morphologies of the composites were characterized by XRD,SEM,TEM,HRTEM and XPS.The electrochemical properties of the composites were studied by LSV,CV and Tafel tests.The results showed that the oxygen reduction catalytic performance of nano-Ag4Bi2O5/MnO2 is comparable to commercial Pt/C.(2)Secondly,in this thesis,Ag4Bi2O5/MnO2/CNTs composites were prepared by co-precipitation and in-situ growth method,using carbon nanotubes as catalyst carriers.XRD,SEM,XPS and other tests were used to characterize the structure and morphology of the materials.At the same time,the oxygen reduction catalytic performance of the catalyst was analyzed by electrochemical tests such as CV and LSV.The results showed that the catalytic oxygen reduction performance of Ag4Bi2O5/Mn02/CNTs was improved compared with Ag4Bi2O5/MnO2 after adding the carbon nanotubes.And the catalytic oxygen reduction performance was comparable to commercial Pt/C.The introduction of carbon nanotubes,a synergistic effect between Ag,Bi,Mn,and C increase.And the carbon is conducive to the material oxygen reduction catalytic performance.(3)The Ag4Bi2O5/MnO2/rGO composite catalysts were prepared on the basis of nano-Ag4Bi2O5/MnO2 by reduced graphene oxide as catalyst carrier.The structure and morphology of the material were characterized by XRD,SEM,and XPS.The catalytic oxygen reduction performance of the material was investigated by CV,LSV and Tafel.The results show that the catalytic oxygen reduction performance of this catalyst material is comparable to commercial Pt/C,and the stability and resistance to methanol performance are better than commercial Pt/C.The excellent electrochemical properties of this material not only benefit from the synergistic action of several metals such as Ag,Bi,and Mn,but also benefit from the addition of reduced graphene oxide,which can increase the conductivity of the material,and the wrinkle structure of graphene of the material can increase the specific surface area so that more active sites are exposed.In this thesis,Ag4Bi2O5/MnO2,Ag4Bi2O5/MnO2/CNTs and Ag4Bi2O5/MnO2/rGO catalysts were successfully prepared.The experimental results show that the catalysts exhibit high catalytic activity,stability and methanol resistance in the oxygen reduction reaction,which lays significant research foundation for further development and promising application of low cost catalytic materials for oxygen reduction in the field of fuel cells,and it also has the potential application value.