Characterization of RuO2 nanocrystals deposited on carbon nanotubes by reactive sputtering
Abstract We report deposition and characterization of RuO 2 nanocrystals (NCs) on carbon nanotubes (CNTs) by reactive radio frequency magnetron sputtering using a Ru target. Field-emission scanning electron microscopy micrographs showed the surface morphology of the as-deposited RuO 2 varied from nanoparticle-like to tube-like NCs as the oxygen flux increased from 2 to 10 sccm. X-ray diffraction pattern confirmed the formation of pure rutile RuO 2 NCs on CNTs. The transmission electron microscopy image of RuO 2 -coated CNTs revealed that RuO 2 NCs had been deposited on the surface of the CNTs with uniform size distribution and random directions. X-ray photoelectron spectroscopy spectra indicated the coexistence of higher oxidation states of ruthenium in the as-deposited RuO 2 NCs. The red-shifts of the peak positions and broadening of linewidths of the Raman features were attributed to both the size and residual stress effects.