The activity and stability of Au/TiO2 catalysts depend on several different factors such as the anchoring strength of the Au particles at the TiO2 surface, the particle sintering, and the surface mobility of individual gold atoms and/or gold particles. Au/TiO2 catalysts can be made resistant to sintering by atomic layer deposition (ALD) of a layer of SiO2 onto the catalysts. In this study, first-principles density-functional calculations are used to investigate how the stability of Au nanoparticles is modified when a partial monolayer of SiO2 is deposited on a Au/TiO2 catalyst. We find that SiO2 structures deposited on a pure TiO2 substrate exhibit lattice-mismatch instabilities that result in the formation of additional strong anchoring sites for Au atoms/nanoparticles. An atomic-scale roughness introduced by a partial monolayer of SiO2 can slow the atomic surface diffusion and inhibit Au nanoparticle growth/sintering, in agreement with previous experimental results.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films