Preparation, characterization and photocatalytic properties of singly and doubly titania-modified mesoporous silicate MCM-41 by varying titanium precursors

A series of titania-modified MCM-41 have been synthesized from varying thre e kinds of titanium precursors [Ti(OBun)(4), Ti(OBun)(3)(acac), Ti(OBun)(2) (acac)(2)] respectively and mesoporous molecular sieve MCM-41, in which tit ania existed as single or double layers. The samples were characterized by powder X-ray diffraction (XRD), nitrogen adsorption-desorption at 77 K, Si- 29 MAS NMR, FTIR and Raman spectroscopy, as well as by solid state diffuse reflectance UV-VIS spectroscopy. The titanium precursor was cocondensed wit h the active silanol groups of MCM-41 via Si-O-Ti bonds and the resulting t itania modified the mesopore walls of MCM-41 after hydrolysis and calcinati on. In the titania-modified MCM-41 samples, although the titania species we re in an amorphous state and in tetrahedral coordination rather than octahe dral coordination, which exists extensively in crystalline titania, they ex hibited high photocatalytic activity for the photodecomposition of phenol a nd the photoreduction of Cr(vi) to Cr(iii).