Preparation And Characterization Of Electroless Coatings On Carbon Nanofibers And Nano Or Micro Structures By Using Template Method

Recently, researches of surface coatings and surface modification have arousedconsiderable interest. Among them, research of metallic coatings on carbon nanofiersurfaces has been given more and more attention. In view of novel physical andchemical properties, metal coated carbon nanofibers have exhibited vast promisingapplication in composite materials, electric materials, electromagnetic wave absorbingmaterials, catalysis materials and so on. Concerning industrial applications, electrolessplating is the preferred method of surface metallization of carbon nanofibers. Up tonow, the systemic research work in preparing metal coatings onto carbon nanofibersvia electroless plating is still inadequate, especially in the relations of coatingcomposition, structure and properties. Morever, it has proved some supremacy toprepare nanoscale or microscale materials with hollow structure and nanocompositecoating materials via electroless plating.In this paper, the processes of electroless Ni-P, Ni-Fe-Co-P and Ni-Co-B platingwere investigated by using graphite pieces as samples first, and then Ni-P, Ni-Fe-Co-Pand Ni-Co-B coatings were deposited onto carbon nanofibers by using the selectedelectroless processes. The composition, structure of the coatings and the properties ofthe metal-coated carbon nanofibers were also studied. By using electroless platingprocess on the surfaces of non-metal materials, a new method of preparing nanoscaleor microscale materials with hollow structure was investigated. And finally, one-stepprocess of electroless nanocomposite plating was also researched. The main resultsare concluded as follows:(1) The pretreatment process is the key step to obtain continuous and uniformcoatings on carbon nanofibers. (2) Ni-P coated carbon nanofibers exhibit fine magnetic and electromagnetic waveabsorbing properties. In comparison to the uncoated carbon nanofibers, thewave-absorbing peak moves to lower frequency, and the wave absorbing abilityincreases a little. As a new type of supported catalyst, Ni-P coated carbon nanofibers,with high phosphonium content and amorphous structure, exhibit high catalyticactivity and stability in the reaction of nitrobenzene hydrogenization in liquid phase.(3) Ni-Fe-Co-P coated carbon nanofibers exhibit fine magnetic and electromagneticwave absorbing properties. In comparison to the Ni-P coated carbon nanofibers, theelectromagnetic wave absorbing ability and the frequency bandwidth increaseobviously.(4) Ni-Co-B coated carbon nanofibers exhibit best magnetic properties among thethree type coated carbon nanofibers. The electromagnetic wave absorbing ability ofthe Ni-Co-B coated carbon nanofibers is obviously higher than that of the Ni-P andNi-Fe-Co-P coated carbon nanofibers. But its frequency bandwidth is in the middle(5) Metal nanotubes were prepared by heating metal-coated carbon nanofibers inthe air to remove carbon nanofiber templates. This method is much more simple andeffective than other method of preparing metal nanotubes.(6) Metal coatings were deposited onto hollow glass microspheres via electrolessplating first, and then removed the hollow glass microsphere templates by dissolvingmethod, hollow metal microspheres were obtained. This method is much more simpleand effective than other method of preparing hollow metal microspheres. AmorphousNi-P alloy hollow microspheres exhibit excellent catalytic activity and stability in thereaction of nitrobenzene hydrogenization in liquid phase.(7) One step method of preparing electroless Ni-P-TiO₂ nanocomposite coatingshas provided a new route to develop nanocomposite coating technique in view of itsresolving the dispersion problem of nanoparticles both in electroless bath and incomposite coatings effectively.