Nanosurface-confined nucleation and patterned growth of Pt and TiO ₂

The nanosurface-confined nucleation and growth processes of Pt and TiO ₂ were investigated when Pt was sputter deposited and TiO ₂ was sol-gel coated on a unique surface-designed substrate. The substrate was an anodic aluminum oxide (AAO) film with self-assembled grouped nanopores (SGNPs). The SGNPs gave rise to unique nucleation sites comprising very small-sized boundaries and nanopores. Pt sputter deposition onto the SGNPs showed restricted growth of nanogranules. The TiO ₂ sol-gel coating onto the SGNPs resulted in unique formations of nanopore and network structures. The unique nucleation phenomena of Pt and TiO ₂ on the nanometer-sized surfaces are explained by a combination of two effects: confinement of the degree of freedom at the nucleation sites and growth direction. This is different from conventional surface nucleation that yields the growth of islands, layer-by-layer deposition, and epitaxy.