Rapid synthesis of ultrafine K2Ln2Ti3O10 (Ln=La, Nd, Sm, Gd, Dy) series and its photoactivity

Ultrafine-layered lanthanon titanates K2Ln2Ti3O10 (Ln=La, Nd, Sm, Gd, Dy) were fabricated at relatively low temperature by a stearic acid method (SAM). The obtained products were characterized by FT-IR, X-ray diffractometer, DTA–TG, scanning electron microscopy, transmission electron microscopy and BET experiments. The photocatalytic activity of the obtained products was studied and was compared with that of solid-state reaction (SSR) using photodecomposition of methyl orange as the model system. Results showed that by using SAM, the fabricating temperature was lowered (from 1100 to 800 °C) and the reacting time was shortened (from at least 11–2 h). Comparing with the product of traditional SSR, the particle size of K2Ln2Ti3O10 synthesized by SAM is smaller, BET surface area is higher (more than 16.97 m2/g), and photoreactivity is better. It was very interesting to find the difference in d(002) of obtained K2Ln2Ti3O10 for Ln=La, Nd, Sm, Gd, Dy separately and the photoactivity of K2Ln2Ti3O10 is strongly dependent on lanthanide, increasing in the sequence of La