Metal organic CVD of nanostructured composite TiO2-Pt thin films: A kinetic approach

Nanostructured composite TiO2-Pt thin films at different Pt/Ti ratios were obtained by chemical vapor deposition (CVD) using titanium tetraisopropoxide (TTIP) and platinum bisacetylacetonate (Pt(acac)(2)) as precursors in the presence of oxygen. The single growth process was kinetically controlled for TiO2 and diffusion limited for Pt under the same experimental conditions. Co-deposition (growth temperature 673 K, total pressure 80 Pa) did not change the individual growth kinetics, in the sense that the sum of the two distinct growth models developed respectively for TiO2 and Pt fitted the experimental co-deposition results quite closely The platinum incorporation was well reproducible and the atomic Pt/Ti ratio in the films was varied in the range 1:1 to 1:20 by changing the evaporation rates of the precursors. The obtained composite films are biphasic and nanostructured with a regular, smooth surface. The time dependence of the platinum bis(acetylacetonate) sublimation rate can give rise to a gradient of Pt concentration into the film, which can be properly modulated for specific applications.