Rhodium thin film-carbon nanotube nanostructures: Synthesis, characterization and electron transfer properties

• Pulsed laser synthesis used to deposit rhodium thin films onto carbon nanotubes.
• Smooth and porous rhodium films verified by electron microscopy analyses
• Electron transfer properties studied in sulfuric acid solution

Rh thin films have been synthesized onto carbon nanotubes by pulsed laser deposition under vacuum and under 266 Pa of helium background pressure. Field emission scanning electron microscopy revealed two types of Rh films: (i) Rh film fabricated under vacuum was smooth and of closed structure and (ii) Rh prepared at 266 Pa of He was porous. Transmission electron microscopy showed that the smooth Rh film was made of highly interconnected particles of 2 nm diameter, whereas the porous film had a morphology of particles arranged into columns with particles having an average diameter of 5 nm. In addition, using high resolution transmission electron microscopy images, the Rh film thickness could be estimated to be about 20 nm. X-ray diffraction pattern showed well-crystallized thin films with a (111) intense orientation. X-ray photoelectron spectroscopy confirmed the presence of metallic Rh at the surface of the carbon nanotubes. Preliminary evaluation of the electron transfer properties showed that porous Rh-carbon nanotubes exhibited reduced oxophilicity than smooth Rh. In addition, the porous Rh film offered larger electrochemical stability window between the onset of hydrogen adsorption and Rh oxide formation. Such interesting properties have important implications in many electroanalytical applications.