Self-assembled isolated monodisperse NiO1+γ nanoparticles as catalytic templates for nanomaterials synthesis

We present the self-organization of isolated monodisperse nickel oxide (NiO1+γ) nanoparticles on surfaces of arbitrary area sizes. Ni films deposited on titanium oxynitride support films are annealed in a nitrogen/air environment at atmospheric pressure for various annealing times. After the annealing treatments, randomly distributed spatially isolated NiO1+γ nanoparticles that are anchored to the support film are observed with a site-density of 11 ± 1 μm−2 and with dimensions of 16 ± 2 nm in height and 82 ± 10 nm in diameter. The anchored nanoparticles, once formed, are immobile during further annealing, even for annealing times of 40 min or annealing temperatures of 800 °C, making the nanoparticle formation a well-controlled process that yields templates suitable for further processing at elevated temperatures. We demonstrate the utilization of these NiO1+γ nanoparticle templates as nucleation sites for carbon nanotubes at temperatures of around 680 °C.