Strongly enhanced interaction between evaporated Pt nanoparticles and functionalized multiwalled carbon nanotubes via plasma surface modifications: Effects of physical and chemical defects

Oxygen and argon plasmas were used to modify multiwalled carbon nanotubes (CNTs) to improve their interfacial interaction with subsequently deposited Pt nanoparticles. In contradistinction to what was found in the case of highly oriented pyrolytic graphite (HOPG), X-ray photoelectron spectroscopy (XPS) confirms the introduction of chemical functionalizations by oxygen plasma treatment; however, as in the case of HOPG, argon plasma treatment produced physical defects. Transmission electron microscopy (TEM) provided visual evidence of the interaction of subsequently evaporated Pt with treated CNTs, showing it to have been enhanced by both plasma treatments. XPS and TEM analyses demonstrate that the enhancement is due to similar interactions of Pt nanoparticles with both types of treated CNTs, although not to the same extent: X-ray photoelectron spectroscopy gives no evidence of chemical bonds formed for either plasma treatment. The morphology of the Pt nanoparticles changes with the deposition rate, which may be influenced by the limited availability of the CNT surface.