Effect of sulfation on the photoactivity of TiO2 sol–gel derived catalysts

✍ Scribed by R Gómez; T López; E Ortiz-Islas; J Navarrete; E Sánchez; F Tzompanztzi; X Bokhimi

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 172 KB
• Volume: 193
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/s1381-1169(02)00473-9

✦ Synopsis

Titania and sulfated-titania were prepared by the sol-gel method using titanium alkoxide as titania precursor. BET specific surface areas on samples calcined at 600 • C were 57 and 62 m 2 /g for titania and sulfated-titania, respectively. FTIR spectra of sulfated samples show the 1360-1370 cm -1 absorption band assigned to S=O vibrations. Moreover, by means of FTIR-pyridine absorption the strength of the sulfate bonded on the TiO 2 surface was studied. Pyridine absorption bands assigned to Lewis and Bronsted acidic sites were identified on sulfated TiO 2 . A diminution of the band gap (E g ) by effect of sulfation was observed by UV-Vis spectroscopy. X-ray diffraction patterns show that sulfate ions stabilize the anatase phase. The photoactivity of the samples determined in the 2,4-dinitroaniline decomposition was found to be higher in sulfated samples. A model is proposed, in which the sulfate anchored to the titania surface acts as an electron trap during photo activation leading to an enhancement of activity.