Study On Synthesis, Properties And Application Of Different Polyphosphazene-modified Pt Catalysts

Direct methanol fuel cell (DMFC) is an ideal power supply forportable electronic devices and electric vehicles due to its advantages likehigh energy transfer efficiency, non-pollution, the safety for storage,transportation of the fuel, uninterrupted power supply and so on, whichhas attracted much attention of domestic and foreign researchers.However, the commercialization of DMFC is hampered by a majorfactor-that is catalyst, which including the catalyst composition and thecatalyst support. Thus, many researchers have taken effective approachesto solve the catalyst problem like improving anti-poisoning of catalyst aswell as the catalytic activity. Cyclophosphazene is a kind of highlycross-linking micro-material based on the synthesis ofhexachlorocyclotriphosphazene(HCCP) and another function monomer.There are many N=P bonds and function groups in polyphosphazene, which can stabilize metal nanoparticles, and polyphosphazene hasbecome an important material in nanoparticle modification.In this study, we attempt to prepare differentpolyphosphazene-coated carbon nanotubes to support Pt–Co catalyst formethanol oxidation fuel cell. What’s more, the development ofnanotechnology with polymer has given us some instructions to studyhow polyphosphazene stabilize nanoparticles. We systematically studythe stabilizing mechanism between polyphosphazene and nanoparticlesby UV-vis spectroscopy, Fourier transform infrared spectra and so on,providing theory bases for the application in catalysis, optoelectronics,chemical sensors, bioanalysis and so on.The main contents are listed below:1. The composite of polyphosphazene-coated carbon nanotubes isprepared by a simple and efficient synthesis method and regarded as animproved catalyst support for direct methanol fuel cell. Catalyst of Pt-Cosupported on polyphosphazene-coated carbon nanotubes is preparedusing mixed reducing agents. The PZAF/MWCNTs, PZS/MWCNTs,Pt–Co/PZAF-MWCNTs and Pt–Co/PZS-MWCNTs are measured bytransmission electron microscopy, X-ray diffraction and inductivelycoupled plasma. The electrocatalytic activity of Pt-Co/PZAF-MWCNTs,Pt-Co/PZS-MWCNTs catalysts for methanol oxidation has beeninvestigated by cyclic voltammetry. The composite of Pt-Co/PZAF-MWCNTs shows a good distribution, small particle size andhigh mass activity.2. We prepared Pt/PZS, Pt/PZAF by a simple method. We systematicallyexamined the effects of coordination time, and surface characteristics ofthe polyphosphazene microspheres on coordination and and reductionprocess by UV-vis spectroscopy and Fourier transform infrared spectra.The structure and morphology of Pt/PZS, Pt/PZAF are measured bytransmission electron microscopy and X-ray diffraction. Deposition of Ptnanoparticles on polyphosphazenes involves two steps: the negativelycharged Pt precursor coordination with P=N groups firstly and thenreduction by NaBH4. The longer the coordination time it takes, the morestronger interaction between polyphosphazenes with Pt precursor. Due tothe coordination behavior between Pt nanoparticles and PZS, Pt/PZSshows a good distribution and small particle size.