A Raman spectroscopic study on the allocation of ammonium adsorbing sites on H2Ti3O7 nanofibre and its structural derivation during calcination

Abstract

The adsorption behaviour of ammonium ions and the structural features of layered proton trititanate were characterised by using Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy. It revealed that the intensity of the Raman band at 309 cm−1, assigned to very long Ti–Obonds (0.22 nm), reduced, whereas the band at 890 cm−1, assigned to very short Ti–O bonds (0.17 nm), increased slightly after the adsorption of ammonium ions (NH4+). The adsorption of ammonium ions enlarged the interlayer distance of the (200) plane. Ammonium ions were located at the corner of the TiO6 octahedral slabs. This was further confirmed by XRD, with an increased intensity of the (201¯) plane being observed.