A Facile Peroxo-Precursor Synthesis Method and Structure Evolution of Large Specific Surface Area Mesoporous BaSnO₃

Abstract

In this paper, we propose a facile and efficient strategy for synthesizing mesoporous BaSnO₃ with a surface area as large as 67 m²/g using a peroxo-precursor decomposition procedure. As far as we know, this is the largest surface area reported in literature for BaSnO₃ materials and may have a potential to greatly promote the technological applications of this kind of functional material in the area of chemical sensors, NO_<i>x</i> storage, and dye-sensitized solar cells. The structure evolution of the mesoporous BaSnO₃ from the precursor was followed using a series of techniques. Infrared analysis indicates large amount of protons and peroxo ligands are contained in the peroxo-precursor. Although the crystal structure of the precursor appears cubic according to the analysis of X-ray diffraction data, Raman and Mössbauer spectroscopy results show that the Sn atom is offset from the center of [SnO₆] octahedron. After calcination at different temperatures, the precursor gradually transforms into BaSnO₃ by release of water and oxygen, and the distortion degree of [SnO₆] octahedral decreases. However, a number of oxygen vacancies are generated in the calcined samples, which are further confirmed by the physical property measurement system, and they would lower the local symmetry to some content. The concentration of the oxygen vacancies reduces simultaneously as the calcination temperature increases, and their contributions to the total heat capacity of the sample are calculated based on theoretical analysis of heat capacity data in the temperature region below 10 K