title: Carbon-metal interfaces analyzed by aberration-corrected TEM: how copper and nickel nanoparticles interact with MWCNTs.
abstract: Experimental confirmation for the stronger interaction of Ni with multi-walled carbon nanotubes (MWCNTs) compared to Cu with MWCNTs is presented. The interfaces between Cu (Ni) nanoparticles side-on oriented onto MWCNTs are analyzed with high spatial resolution electron energy-loss spectroscopy (EELS) of the carbon K-edge. The EEL spectra reveal a rehybridization from sp(2) to sp(3) hybridized carbon of the outermost MWCNT layer at the Ni interface, but no such rehybridization can be observed at the Cu interface. The EELS results are supported by transmission electron microscopy (TEM) images, which show a better wetting behavior of Ni and a smaller gap at the Ni-MWCNT interface, as compared to the corresponding Cu interfaces. The different behavior of Cu and Ni can be explained in terms of differing valence d-orbital occupancy. For the successful experimental demonstration of this effect the use of a soft chemical metal deposition technique is crucial.
authors.affiliation: Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland; Laboratory for Multifunctional Materials, Department of Materials, ETH Zürich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland. Electronic address: gabriele.ilari@empa.ch.
authors.forename: Gabriele M
authors.initials: GM
authors.lastname: Ilari
authors.affiliation: SuperSTEM Laboratory, STFC Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, UK.
authors.forename: Fredrik S
authors.initials: FS
authors.lastname: Hage
authors.affiliation: Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland.
authors.forename: Yucheng
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland.
authors.forename: Marta D
authors.initials: MD
authors.lastname: Rossell
authors.affiliation: SuperSTEM Laboratory, STFC Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, UK.
authors.forename: Quentin M
authors.initials: QM
authors.lastname: Ramasse
authors.affiliation: Laboratory for Multifunctional Materials, Department of Materials, ETH Zürich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Niederberger
authors.affiliation: Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland.
authors.forename: Rolf
authors.initials: R
authors.lastname: Erni
keywords: Carbon nanotubes; Copper; Electron energy-loss spectroscopy; Interfaces; Nickel; Transmission electron microscopy