Comparison of Pt/TiO2 nanocomposite films prepared by sputtering and pulsed laser deposition

Pt/TiO2 nanocomposite films were prepared by sputtering and pulsed laser deposition (PLD). The Pt/Ti atomic ratios in the films deposited by the PLD were smaller than those in the ablation targets and those in the films prepared by sputtering. At low Pt concentration, Pt is deposited as PtO2 in the films prepared by sputtering, whereas metallic Pt is deposited in the films prepared by PLD. The Pt nanoparticle size in the as-deposited Pt/TiO2 nanocomposite films prepared by PLD was about 30 nm, which is quite large compared to the 1–2-nm size in the sputter-deposited films. Pt nanoparticles were produced in the growth processes via surface diffusion, which can be reflected by the kinetic energy of the chemical species spread from the target. It can be inferred from the optical measurements of heated Pt/TiO2 nanocomposite films that new energy levels are produced in the band gap of TiO2 by the homogeneous dispersion of Pt nanoparticles in the TiO2 matrix.