The Research Of Preparing Fuel Cell Catalysts By Microwave-microemulsion Method

Right now, the research of new preparation method is very important for improvement ofthe fuel cell catalysts'performance. In this paper, microwave polyol process has been used toprepare highly dispersed Pt/C catalysts and the different preparing conditions which influencethe catalysts'performance have been investigated. In the next step, we synthesize Pt and Pt-Rubimetallic catalysts using the CNTs as supporters. Microwave combined with microemulsionmethod has been used to prepare Pt-Ru binary alloy catalysts. We make a preliminary researchto the preparing process. The conclusions are following:1,In this paper, we change the conditions such as adding to sodium acetate solution,adjusting pH of solution, changing the weight ratio of Pt:C and pretreating the carbon supporterin the preparing of Pt/C. The catalysts'size, surface morphology, element ratio andelectrochemical performance have been characterized by XRD, TEM, SEM-EDS and CV. Thecatalysts are well-distributed and have best catalytical performance when add to 0.6ml acetatesolution, adjust pH to10, use HNO3 to pretreate carbon powder or control the weight ratio of Ptto 40%.2,We prepare catalysts using modified CNTs as supporter and characterize the catalysts byXRD,FTIR and CV in this thesis. The conclusion can be drawed as follow:the CNTs is moresuperior than carbon powder. The CNTs has grafted many hydroxyl and carboxyl groups whenacid treated. The amide groups have been grafted to CNTs in amidation process. The methanoloxidation peak current density is 580A g-1Pt and 600A g-1Pt respectively when Pt catalystssupported on the modified CNTs. The average size of Pt-Ru alloy nanoparticles is 5.2nm byXRD measurement and the realistic mole ratio of Pt:Ru is conform to theorical ratio accordingto SEM-EDS measurement. The methanol oxidation peak current is 6.15mA and the onsetpotential is lower than Pt catalyst.3,Pt-Ru binarycatalysts are prepared bymicrowave combined with microemulsion method.The size of catalysts is about 5.2nm, 5.5nm and 7.1nm respectively when heating-treated at 170 ℃,250℃and 600℃.The catalysts is well-dispersed byTEM measurement and the size is about5nm when treated at 250℃.The composition of nanoparticles is well consistent with thetheorical ratio in SEM-EDS measurement by controlling the feeding sequence of raw material.The catalysts which are prepared in heating-treated at 250℃show the best performance incyclic voltammograms measurement. Pt-Ru catalysts prepared in the microaemulsion systermcomposed of triton X-100/ n-butanol/ cyclohexane/ ethylene glycol show the best catalyticalperformance.