Structures and properties of Pd nanoparticles intercalated in layered TiO2: A computational study

The properties of spherical 1-nm Pd43 nanoparticles confined between single layers of lepidocrocite-TiO2 are studied by means of Density Functional Theory calculations. Sandwich-like intercalation is then compared to the adsorption on a single oxide layer in terms of metal-oxide bond strength, structural distortion of the metal particle and charge transferred from the metal to the oxide. Then, a Pd(111) slab is put in contact to lepidocrocite-TiO2 on either one side or both sides, simulating the creation of extended interfaces. This permits to compare the behavior of small reactive metal particles to their more inert bulk counterpart. It results that intercalated Pd43 species are bound more strongly to the oxide support compared to those adsorbed on a single oxide layer, resulting in more pronounced structural changes and larger charge transfer, a fact with presumable direct consequences on the catalytic activity. The conclusions drawn for small Pd particles are confirmed also in the case of extended interfaces, even though up to a smaller extent.