A review is given of the nucleation and growth processes occurring in thin film formation. Emphasis is given to quantitative nucleation theories and to the role of electron microscopy and surface techniques in providing data to test such theories. The relations between the thermodynamics of adsorption and the kinetics of crystal growth is stressed. Experimental examples are taken from the island growth, layer plus island (or Stranski-Krastanov) and layer growth modes. The shapes of growing crystallites are briefly discussed.

No abstract

Palladium nanoparticles are grown on TiO2 nanotubes by atomic layer deposition (ALD), and the resulting three-dimensional nanostructured catalysts are studied for ethanol electrooxidation in alkaline media. The morphology, the crystal structure, and the chemical composition of the Pd particles are fully characterized using scanning and transmission electron microscopies, X-ray diffraction, and X-ray photoelectron spectroscopy. The characterization revealed that the deposition proceeds onto the entire surface of the TiO2 nanotubes leading to the formation of well-defined and highly dispersed Pd nanoparticles. The electrooxidation of ethanol on Pd clusters deposited on TiO2 nanotubes shows not only a direct correlation between the catalytic activity and the particle size but also a steep increase of the response due to the enhancement of the metal-support interaction when the crystal structure of the TiO2 nanotubes is modified by annealing at 450 °C in air.