| Size- and shape-controlled SrTiO3 nanoparticles were synthesized using two different approaches: molten salt and sol-precipitation--hydrothermal treatment. As-prepared nanoparticles were characterized chemically, structurally, and morphologically at both the bulk and surface levels. SrTiO3 samples synthesized via molten salt and sol-precipitation--hydrothermal treatment consisted of nonporous, single-crystalline, cubic-shaped nanoparticles having the (100) crystal planes primarily exposed, average edge lengths of 120 and 60 nm, and surface areas of 10 and 20 m2/g, respectively. Nanoparticles obtained via sol-precipitation--hydrothermal treatment exhibited narrower particle size distribution, regular and uniform cubic shape, and reduced interparticle agglomeration. A comparative study of the surface acidity showed rather slight differences between SrTiO3 nanoparticles synthesized using different approaches, with a mixture of SrO-based and TiO-based terminations observed in all cases.;Functionalization of the surface of SrTiO3 nanoparticles obtained via sol-precipitation--hydrothermal treatment was attempted via thermal and chemical--thermal treatments of the SrTiO3 surface, and via deposition of platinum clusters using SrTiO3 nanoparticles as support. Thermal and chemical treatments consisted of high-temperature annealing under oxidizing atmosphere and acid lixiviation of the SrO surface layers, respectively. These treatments had opposite effects on the chemical composition of the surface: high-temperature annealing resulted in Sr-enrichment, whereas acid lixiviation produced Tienriched surfaces. From the standpoint of the morphology, the stabilization of the (110) relative to the (100) crystal plane was observed upon annealing at high temperatures.;Platinum nanoparticles were deposited on SrTiO3 nanoparticles via atomic layer deposition. Their chemical composition, morphology, and catalytic activity for propane oxidation were investigated. Platinum nanoparticles consisted of a mixture of Pt0 and PtIIO, the latter species becoming predominant as the particle size decreases. They exhibited sizes ranging from 1 to 5 nm, single-crystalline character, and excellent spatial dispersion over the support. Finally, their catalytic performance for propane oxidation was significantly superior to that of a standard Pt/gamma-Al 2O3 catalyst, in terms of both activity and stability.;Results presented in this Thesis demonstrate that synthetic approaches based on soft chemistry coupled to atomic layer deposition offer potential for the preparation of metal oxide--metal nanoparticles with homogeneous and well-defined chemical composition, structure, and morphology at both the bulk and surface levels. |
