Synthesis-Dependent Surface Acidity and Structure of SrTiO3Nanoparticles

Chemisorption of pyridine and atmospheric CO 2 followed by means of visible Raman and DRIFT spectroscopy were employed to investigate the surface acidity and structure of as-prepared SrTiO 3 (STO) samples synthesized using three different approaches, solid-state reaction, molten salt, and sol-precipitation–hydrothermal treatment. Samples prepared via solid-state reaction consisted of irregularly shaped polycrystalline grains with a BET surface area of ∼2 m 2 /g, whereas those obtained via molten salt synthesis and sol-precipitation–hydrothermal treatment were single-crystalline nanocubes with the {100} faces primarily exposed and BET surface areas of ∼10 and 20 m 2 /g, respectively. Pyridine and atmospheric CO 2 chemisorption demonstrated that the differences in surface acidity between samples synthesized using different approaches are rather slight with a mixture of SrO-based and TiO-based terminations observed in all cases. In contrast, the typology of surface carbonate species arising from the reactive adsorption of atmospheric CO 2 varied significantly between samples, indicating the atomic structure of STO surfaces depends strongly on the synthetic method employed. The presence of coordinatively unsaturated Ti 4+ acid centers and highly nucleophilic O 2− anions is particularly relevant in the perspective of employing morphology-controlled perovskite nanoparticles as supports in catalytic applications such as the oxidation of hydrocarbons.