Preparation Of Pt-based Catalysts And Their Application In Methanol Electrooxidation

In recent years, the research of Pt-based catalysts in direct methanol fuel cell anode have been widely concerned. Pt catalyst is considered to be the most effective catalyst for direct methanol fuel cell (DMFC), however, some disadvantages such as high cost, easy to be poisoned, etc. have hindered the development of DMFC. The addition of the second metal such as Ru, Rh, Sn, Ni and Co etc., could not only change the surface electric property of Pt, but also provide oxygen species at lower potential and improve the anti-poisoning ability to CO. This paper presented the preparation, characterization and application of surface-etched silicon carbide (SiCetched) supported PtNi and PtCo bimetallic catalysts using H2PtCl6·2H2O, NiCl2·6H2O and COCl26H2O as the precursors. The influence of different PtNi, PtCo molar ratios on the catalytic performance for methanol electrooxidation were investigated. Besides, using the mixture of SiCetched and antimony doped tin oxide (ATO) as support, the Pt catalysts with different amount of ATO was prepared and studied for methanol electrooxidation.The thesis is divided into six chapters, in which the research and main conclusions are introduced as follows:The first chapter mainly summarized the overview of the anode catalyst of direct methanol fuel cell (DMFC) from two aspects:the platinum-based catalyst system and the research progress of catalyst support in DMFC anode. Then scientific significance, main contents, and the innovation points were also described.In the second chapter, the experimental apparatus, drug information, preparation methods and character methods used in this thesis were listed.In chapter three, a series of surface-etched silicon carbide (SiCetched) supported PtNi bimetallic catalysts with different ratios of Pt/Ni were prepared by chemical reduction and applied in methanol electrooxidation. The catalysts were characterized by means of XRD, TEM, CV and chronoamperometry. The results showed that Ni atoms have been doped into the face-centered cubic lattice of Pt crystal and formed PtNi alloy.The catalytic activity and stability of the catalyst with n (Pt):n (Ni)= 3 for methanol electrooxidation was the best, indicating the addition of Ni significantly improved the catalytic properties of Pt catalyst.In chapter four, using the same method as in chapter 3, a series of PtCo/SiCetched catalysts with different molar ratios of Pt and Co were prepared and characterized by means of XRD, TEM, CV and chronoamperometry. The results showed that the catalytic activity and stability of PtCo/SiCetched catalysts with n (Pt):n (Co)=1 for methanol electrooxidation was the best due to the formation of PtCo alloy weakened the bonding strength of Pt-CO.In chapter five, using the mixture of SiCetched and antimony doped tin oxide (ATO) as support, the catalysts Pt/SiCetChed, Pt/(SiCetched+ATO) and Pt/ATO with different amount of ATO were prepared and studied for methanol electrooxidation. The results showed that the catalytic activity and stability of Pt/(SiCetched+ATO) for methanol oxidation was better in comparison with those of Pt/SiCetched and Pt/ATO catalyst. The addition of ATO effectively enhanced the stability of the catalyst.Chapter 6 summarized the research conclusions of the thesis..