The self-terminating
chemistry of atomic layer deposition (ALD)
ideally enables the growth of homogeneously distributed materials
on the atomic scale. This study investigates the ALD of zinc oxide
(ZnO) on mesoporous zirconium oxide (ZrO2) using zinc acetylacetonate
[Zn(acac)2] and synthetic air in a fixed-bed powder ALD
reactor. A broad variety of methods, including thermogravimetry analysis,
scanning electron microscopy with energy-dispersive X-ray spectroscopy,
low-energy ion scattering, X-ray absorption near-edge structure, X-ray
photoelectron spectroscopy, in-situ diffuse reflectance infrared Fourier
transform spectroscopy–mass spectrometry, and density functional
theory calculations, were used to analyze the reactant and the resulting
samples. The factors affecting the zinc loading (wt %) on ZrO2 were investigated by varying the ALD reaction temperature
(160–240 °C), the calcination temperature of zirconium
oxide (400–1000 °C), and the ALD cycle number (up to three).
The studied process showed self-terminating behavior with the areal
number density of zinc of approximately two atoms per square nanometer
per cycle. Zinc was distributed throughout ZrO2. After
the Zn(acac)2 reaction, acac ligands were removed using
synthetic air at 500 °C. In the following cycles, already-deposited
ZnO acted as nuclei for further ZnO growth. This study demonstrates
the potential of Zn(acac)2 as an ALD reactant and provides
an initial understanding of ZnO growth via ALD on high surface area
porous particles as an example for catalytic applications.