Growth, Structure, and Stability of Au on Ordered ZrO₂(111) Thin Films

The growth, electronic properties, and thermal stability of Au nanoparticles on ordered ZrO 2 (111) thin film surfaces were investigated by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and synchrotron radiation photoemission spectroscopy (SRPES). The thin ZrO 2 (111) films were grown on a Pt(111) substrate. At room temperature, Au initially grows as 2D islands on the ZrO 2 (111) thin films up to 0.1 ML, followed by 3D growth with a number density of ∼1.4 × 10 12 particles/cm 2 . The binding energy of the Au 4f peaks shifts monotonically toward a higher binding energy with decreasing the Au particle size by 0.4 eV, which can be attributed to the contribution from both the initial- and final-state effects. Au atoms most likely form Au δ− initially and become metallic states as the coverage increases. Thermal annealing experiments demonstrate that Au particles experience significant sintering before desorption from the ZrO 2 (111) surface. In addition, Au particles are more thermally stable on the sputtered ZrO 2 (111) surface than on the pristine ZrO 2 (111) surface due to the stronger bonding of Au atoms on the surface defect sites. Moreover, large Au particles are more thermally stable than small ones on the ZrO 2 (111) surface.