Synthesis and characterization of Al-, Bi-, and Fe-incorporated mesoporous titanosilicate (MPTS) materials and their hydrophilic properties

Mesoporous titanosilicates (MPTS) including Al, Bi, and Fe ions of three positive oxidation states (Metal3+) were prepared using a common hydrothermal method. The XRD result indicated that these metals (10.0 wt.% per titania amount) are stably incorporated in a titanosilicate framework. The mesopore sizes were distributed in the range of 1.0-6.0 nm in TEM images, and the surface areas obtained were above 300 m2/g in all metal-incorporated MPTSs. The dehydrated amount decreased in the order of Al- > Bi- > Fe- > non-metal MPTS, and the activation energy needed for H2O desorption from the surface of photocatalyst decreased in the order of Al- > Fe- > Bi- > non-metal MPTS. The XPS result showed that the special peak for Ti2p in metal-MPTSs shifted to stronger binding energy than in non-metal MPTS. The O1s (Ti-O, Ti-OH) peaks for metal-MPTSs also shifted to stronger binding energy than those for non-metal MPTS. In particular, the shift to the larger binding energy for the second peak (Ti-OH) was remarkable in Al-MPTS. In H2-TPR, Ti3+ could be more easily transferred into Ti0, which affected the photoreaction, over Al- and Fe-MPTSs compared with non-metal MPTS. The photoluminescence intensity from the contribution of emitted electron decreased in the order: non-metal, Al-, Fe-, and finally Bi-MPTSs. Consequently, these findings indicate that the super-hydrophilicity of Al-MPTS was the best, and that the contact angle for water droplets was below 3° under 120 min UV-radiation.