Otro
Long-range and short-range structures of cube-like shape SrTiO3 powders: microwave-assisted hydrothermal synthesis and photocatalytic activity
Registro en:
PCCP. Physical Chemistry Chemical Physics, v. 15, p. 12386-12393, 2013.
1463-9076
9848311210578810
7422167106177474
5852409796882171
5321313558714462
6395095165722635
4361220072322558
Autor
Silva, Luís F. da
Avansi, Waldir
Andrés, Juan
Ribeiro, Caue
Moreira, Mário L.
Longo, Elson
Mastelaro, Valmor R.
Resumen
We report herein a detailed study on the influence of microwave-assisted hydrothermal (MAH) treatment time on both long and short range structures around Ti atoms of SrTiO3 powders. Few studies have been carried out on short-order structural properties as well as the relationship between the local order and the SrTiO3 photocatalytic properties. We use X-ray diffraction to determine the long-range structure, while the local environment around the Ti atom is probed with X-ray absorption spectroscopy and the vibration frequencies are investigated by Raman spectroscopy. The faster crystallization of SrTiO3 powders provided by the MAH system resulted in large distortions of Ti–O bond lengths which remain unchanged even for a longer MAH treatment time. Despite the long-range structure being associated with ideal TiO6 clusters, X-ray absorption spectroscopy measurements identified the presence of undercoordinated TiO5 clusters. Compared with the reference bulk SrTiO3, the hierarchical SrTiO3 cube-like shape showed enhanced photocatalytic activity, which was associated with the presence of these TiO5 clusters. Field emission scanning electron microscopy (FE-SEM) revealed that the superstructures based on a cube-like shape are formed by an assembly process, becoming well defined as a function of MAH treatment time. Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)