Preparation And Electrocatalytic Performance Of PtRu Catalysts Supported On Novel Carbon Materials

With the development of society,the energy crisis and environmental pollution problems have become more and more serious.Direct methanol fuel cells(DMFC)have attracted wide attention owing to their high energy conversion efficiency,low pollutant emission and easy transportation.However,Pt-based anodic catalysts are not efficient due to the poisoning of the intermediates that formed during the methanol electrooxidation reaction as well as their high costs.Developing carries with unique structure to prepare high performance of supported PtRu catalysts is one of the main ways to solve the problems.The biomass mesoporous carbon material is cheap and it has large surface area and suitable porous structure.Carbon nanotubes(CNTs)have high electrical conductivity and chemical stability.After CNTs functionalization,the incorporation of special functionalities facilitates to improve their loading capacity.In this thesis,the biomass-derived mesoporous carbon material and functionalized CNTs were used as supports to prepare PtRu catalysts and applying to the electrooxidation of methanol.The main research contents are summarized as follows:(1)Preparation of PtRu/LCS-s catalyst and its application in DMFC.Firstly,the lotus seedpods(LS)were hydrothermally treated in a KOH aqueous solution.After filtration and drying,the hydrothermal product was directly subjected to simultaneous pyrolysis and activation,giving LS-derived porous carbon(LSC).For comparson,the hydrothermal fibers was also fixed and fully sealed inside NaCl via recrystallization of NaCl/KOH solution.After pyrolysis and activation followed by the dissolution of NaCl,LS-derived mesoporous carbon(LSC-s)was obtained.The electrocatalysts,PtRu nanoparticles supported on LSC-s(Pt Ru/LSC-s)and LSC(PtRu/LSC),were prepared by the impregnation and reduction method with sodium borohydride as the reducing agent.The experimental results indicated that PtRu nanoparticles in PtRu/LSC-s were smaller and distributed more uniform than that of PtRu/LSC.The average PtRu nanoparticle size in LSC-s support was 1.77 nm.The electrooxidation of methanol on the PtRu/LSC-s and PtRu/LSC catalysts was investigated.The results showed that PtRu/LSC-s had higher catalytic activity than that of PtRu/LSC.The peak current of methanol oxidation for PtRu/LSC-s was 798.4 mA mg-1Pt,which was 1.7 times higher than that of Pt Ru/LSC.(2)Preparation of PtRu/CNTs catalysts and their application in DMFC.Firstly,4-thiolbenzene functionalized carbon nanotubes(CNTs-PhSH)were synthesized by diazonium reaction.And then it reacted with p-benzenedithiol and aminothiophenol in DMSO to give benzenedithiol oligomer functionalized CNTs(CNTs-Ph(SSPh)nNH2).The catalysts,PtRu nanoparticles supported on CNTs-PhSH(PtRu/CNTs-PhSH)and CNTs-Ph(SSPh)n NH2(PtRu/CNTs-Ph(SSPh)n NH2),were prepared by impregnation and reduction method with sodium borohydride as the reducing reagent.The TEM results indicated that PtRu nanoparticles in PtRu/CNTs-Ph(SSPh)nNH2 were uniform with average PtRu nanoparticle size of 2.1 nm.On the other hand,the PtRu particles in PtRu/CNTs-PhSH appeared agglomeration and the average PtRu particle size was 2.6 nm.The electrooxidation of methanol on the PtRu/CNTs-Ph(SSPh)nNH2 and PtRu/CNTs-PhSH catalysts was studied.The PtRu/CNTs-Ph(SSPh)nNH2 catalyst showed higher catalytic activity than that of PtRu/CNTs-PhSH catalyst.The peak current of methanol oxidation for PtRu/CNTs-Ph(SSPh)nNH2 was 520.4 mA mg-1Pt,which was 1.6 times higher than that of PtRu/CNTs-PhSH catalyst.