Characterization of gold nanoclusters deposited on HOPG by atmospheric plasma treatment

The interest of gold nanoparticles in the field of nanocatalysis and nanosensors is growing. For example, carbon nanotubes covered with gold nanoclusters could present interesting properties in catalysis or/and in devices based on catalytic reaction such as chemical gas sensor. Unfortunately, the characterization of nanoparticles deposited onto a substrate is generally not a trivial exercise. Indeed, in many cases, the amount and size of material deposited is in the range of the sensitivity limits and the spatial resolutions of the techniques used. In that respect, our system, i.e. gold deposited onto a carbon support, is a favourable case, due to the high difference between the atomic numbers of gold and carbon. In this work, gold nanoparticles were deposited onto a HOPG (Highly Oriented Pyrolitic Graphite) substrate using an atmospheric plasma. In this preliminary study, HOPG sample has been used as a model surface that could present the same chemical properties as multiwall carbon nanotubes (MWCNTs). The surface composition was analysed using X‐ray photoelectron spectroscopy (XPS). Narrow region electron spectra were used to extract the chemical‐state information from the C 1s, O 1s and Au 4f peaks. The Au 4f spectral line shape was also analysed using the QUASES–Tougaard software package in order to obtain the in‐depth concentration profile of the resulting nanomaterial. This result evidences a good agreement between experiment and modelling. Indeed, field emission scanning electron microscope (FE‐SEM) and atomic force microscopy (AFM) images highlight a homogeneous distribution of 10 nm‐size gold clusters with a surface coverage of 12% on the HOPG surface, both in agreement with the results obtained with the Tougaard and coworkers method. Copyright © 2008 John Wiley & Sons, Ltd.