Paper NS-TuP2
Deposition of Gold Nanoparticles on HOPG using Atmospheric Plasma

Tuesday, October 16, 2007, 6:00 pm, Room 4C

The interest for gold nanoparticles in the field of nanocatalysis and of nanosensors is growing. Nanotubes covered with gold nanoclusters could present interesting properties in these fields. However, due to the weak carbon-gold bond, the adhesion of this metal to carbon is not trivial. It is generally accepted that the carbon surface must be activated, either by the creation of surface defects and/or by the adsorption of reactive species, such as oxygen containing groups. Most of the time, activation is done using wet chemistry techniques, such as hot nitric acid solutions. Some studies present activation and deposition experiments realized using vacuum techniques, with ion guns, low pressure plasmas, and/or thermal evaporators. In this preliminary study, we used highly oriented pyrolitic graphite (HOPG) as a model surface that could present the same chemical properties as the one of carbon nanotubes. An atmospheric plasma torch was used to activate the HOPG surface and to realize the gold deposition. The atmospheric plasma torch runs in the RF mode (13,56 MHz), using argon as the main gas. Oxygen was added as secondary gas, in order to provide the active species able to activate the surface. The plasma post discharge was spatially characterized by optical emission spectrometry. Immediately after activation, metal particles were injected into the plasma post-discharge. The surface Au/C elemental composition was analysed using XPS and shows the presence of gold, whereas field emission gun scanning electron microscopy allowed to study the size distribution of the gold particles on the surface as a function of the plasma parameters. This work is financially supported by the Nano2Hybrids (EC-STREP-033311) and PAI 7/3 (Plasma surface interactions - Belgian federal government) projects.