Synthesis And Characterization Of Fuel Cell Cathode Catalysts For Improving The Electrocatalytic Performance Of Oxygen Reduction Reaction (ORR)

Fuel cell,as an electrochemical power source with high energy conversion efficiency,high specific energy density,low emission and low noise,is an ideal candidate to replace fuel engine.However,fuel cells are still at a standstill in the process of civilianization because of their high cost and high demand for fuel.The main reasons are the slow rate of oxygen reduction reaction(ORR)in fuel cell cathode and the costly platinum(Pt)catalyst for catalyzing it.In this regard,scientists have put forward some solutions.For example,doping transition metal with Pt to form bimetallic catalysts thus reducing the using amount of Pt,or seeking for non-platinum catalysts,mainly focusing on Pd and other metal elements with similar atomic structure as Pt,as well as transition metal with nitrogen-doped carbon materials(M-N-C).At the same time,it has been found that the the support of catalyst has a great influence on the ORR reaction.Compared with the commercial Vulcan carbon support,the support with certain structure can improve the three-phase interface of ORR reaction and make the reactants and catalyst combine better,which is of great help to improve the catalytic performance of ORR.In this thesis,the cathode catalysts of PEMFC were carefully studied from the aspect of catalyst carbon support.In the third chapter of this thesis,a method of roe-like nitrogen-doped mesoporous carbon material(NMC)with polydopamine(pDA)as precursor and surfactant as morphology regulator has been developed.The material has high specific surface area and pore volume.Unlike polyacrylonitrile(PAN),which requires low temperature polymerization,the precursor of pDA can be synthesized at room temperature.At the same time,the size of pore can be adjusted by changing the diameter of silica template.Then the physical and chemical properties and electrochemical properties of the product were verified and characterized.In the fourth chapter of this thesis,the Pt nanoparticles supported on NMC(Pt/NMC)was synthesized by using the NMC materials obtained in the previous chapter,and a series of physical and electrochemical properties were characterized.The results showed that the catalytic efficiency of Pt nanoparticles for ORR was significantly improved by using nitrogen-doped carbon as catalyst support,and the catalytic activity was more stable in accelerated degradation tests.