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The pulsed plasma polymerization of tetramethyltin monomer was studied as a function of the radio frequency (rf) duty cycle employed, all other plasma variables being held constant. Progressive increases in the relative tin content of the plasma deposited films were observed with systematic decreases in the rf duty cycles employed during film formation. The variations in tin content of these films were documented by XPS, FT-IR, TEM, AFM, and electrochemical analyses. A particularly interesting aspect of this work is the microstructure of the films which reveals spherical tin particles of essentially uniform diameters (20-30 nm) independent of the duty cycle during deposition. The increasing metal content in these films with decreasing duty cycle corresponds to increased aggregation of these nanosized particles into progressively larger sized clusters. The results obtained are supportive of the use of the variable duty cycle pulsed plasma deposition technique as a new route to improved nanoscale film chemistry control in the synthesis of organometallic composite films.

The deposition of metal nanoparticles (such as Ag, Cu, Au, Pd, and Pt) on boron-doped, polycrystalline diamond thin films grown on silicon substrates was investigated using Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Nanometer-size metal particles with preferred crystalline textures can be spontaneously deposited on the diamond thin film after a simple immersion in an acidic solution containing metal ions or metal complex ions. The size and distribution of metal deposits can be controlled by adjusting the metal ions concentration, the solution acidity, and the deposition time. The diamond/silicon interfacial ohmic contact was found to be the critical factor for achieving the observed spontaneous metal deposition on the diamond surface. Significant enhancement of hydrogen evolution activity was observed on a diamond electrode modified by 9% coverage of Pd nanoparticles. The results demonstrate a novel route for depositing nanometer-size metal catalysts on a highly corrosion resistant and dimensionally stable polycrystalline diamond support.