Controllably Construct And Oxygen Reduction Performance Of Au-Cu_2-xM/Cnts?M=O,S? Nanocomposite Catalysts

The oxygen reduction reaction?ORR?is a high-efficiency energy conversion process,in which O₂ directly generates electrons to form H₂O on the surface of the cathode catalysts in proton exchange membrane fuel cells?PEMFCs?.At present,the high price and rare content of Pt used in ORR are the bottlenecks for ultimate commercialization of PEMFCs.The combination of transition metal oxides with noble metals Au,Pd to form nanocomposite catalysts can effectively improve electrocatalytic activity and reduce cost.Among them,Cu-based materials have attracted widespread attention in electrocatalysis owing to low cost,abundant content and the ability of providing electrons to O₂.Based on this,a small amount of Au-modified Cu_2-xM/CNTs?M=O,S?nanocomposites were prepared.The thesis focuses on the effects of Au introduction,Cu₂O morphology and Cu vacancy defects on the catalytic performance of ORR.In addition,the structure-activity relationship,synergistic effect and electrocatalytic performance of the catalyst are revealed.The specific research contents of this thesis are as follows:A seirse of Au-Cu₂O/CNTs nanocomposite catalysts with low Au content were prepared to explore the synergistic effects of Au and Cu₂O on the catalytic performance of ORR.It is found that the Au-Cu₂O/CNTs nanocomposite catalysts modificated by Au exhibits higher ORR catalytic performance due to the synergy between Au and Cu₂O.When the Au content is 0.52 wt.%,the catalyst can expose the more active sites and display the better ORR activity.The Au-Cu₂O/CNTs nanocomposite catalysts with different Cu₂O morphologywere prepared to explore the effect of catalystic morphology on the catalytic performance of ORR.The researches show that the coexisting crystal facet?111?and?110?contribute to generate more O₂ adsorption activation sites,and result in the better electrocatalystic performance of ORR.The porous Au@Cu_2-xS/CNTs nanocore-shell catalysts,with Cu vacancy defects,were prepared.Cu vacancy defects are generated by vulcanization etching of Cu₂O and adjustment of the electronic structure around the Cu atom,and finally form a porous Au@Cu_2-xS/CNTs core-shell catalysts.The results show that Au particles have the function of agglomerating and attracting copper species,which plays an important role in the formation of Cu_2-xS shells and further affect the catalystic electrocatalytic activities.