Indian Journal of Chemistry Vol. 49A, September 2010, pp. 1189-1196 Synthesis, characterization and photocatalytic activity of alkaline earth metal doped titania Balaram Kiran Avasarala a , Siva Rao Tirukkovalluri a * & Sreedhar Bojja b a Andhra University, Department of Inorganic and Analytical Chemistry, Visakhapatnam, India Email: raost@yahoo.com b Indian Institute of Chemical Technology, Inorganic and Physical Chemistry Division, Hyderabad, India Received 17 March 2010; revised and accepted 26 August 2010 The synthesis of beryllium doped titania (Be 2+ –TiO 2 ) at different percentages (0.25, 0.5, 0.75 and 1.0 wt %) by sol-gel method and its characterization by XRD, UV-visible absorption spectroscopy, XPS, SEM and FT-IR techniques are reported. Diffraction peaks of anatase crystalline phase have been observed both in synthesized TiO 2 as well as in Be 2+ –TiO 2 . Presence of Be 2+ ions in the TiO 2 structure causes significant absorption shift towards the visible region. FT-IR and XPS data show the interstitial presence of Be 2+ ion in TiO 2 . The photocatalytic efficiency of the synthesized Be 2+ –TiO 2 and unsubstituted TiO 2 has been evaluated by the degradation of monocrotophos pesticide under visible light irradiation, wherein the degradation rate of MCP by Be 2+ –TiO 2 is found to be higher than by unsubstituted TiO 2 . This may be attributed to the more efficient electron-hole creation in Be 2+ –TiO 2 in visible light, as compared to unsubstituted TiO 2 which can be excited only by UV irradiation. The effect of dopant concentration, pH, catalyst dosage and pollutant concentration have been studied for obtaining optimal degradation conditions. Keywords: Catalysts, Photocatalysts, Titania, Beryllium Water purification by semiconductor photocatalysis is attracting a great deal of interest from research workers and water purification companies. There are several semiconducting materials readily available, amongst which TiO 2 has proven to be most suitable in different media for wide spread applications 1,2 . Although TiO 2 is superior to other semiconductors 3-5 for many practical uses, its high band gap (3.2 eV), which can be excited only by UV light, restricts the efficient usage of the highly available visible light. To circumvent this particular limitation, a number of strategies have been proposed to improve the light absorption features and lengthen the charge-carrier life time characteristics of TiO 2 such as surface chelation 6 , surface derivatisation 7 , platinisation 8 and selective doping 9 . In recent years, impurity doping has been widely used to improve photoactivity 10 . Since metal elements have different valences, metal ions doped in the TiO 2 matrix can be superficial potential traps of photogenerated charge carriers and lengthen the life time of electron-hole pairs and increase photocatalytic activity. Karakitsou and Verykios 11 showed that doping with cations having a valence higher than that of the parent TiO 2 cation results in enhanced light absorption at the near UV region, while doping with lower valence cations exhibit a somewhat enhanced light absorption capacity in the visible range. On the other hand Mu et al., 12 reported that doping with trivalent or pentavalent metal ions was detrimental to the photoactivity even in the UV region. There have been many studies on transition metal, noble and rare earth metal ions as dopants 13,14 . Doping with alkaline earth metal ions has been less explored compared with other metal ions. Also limited literature reports are available that the doped catalyst was tested only in the UV range of radiation 15 . Hence, in the present study doping of TiO 2 with beryllium (Be 2+ ) ion has been taken up. Since beryllium is an acceptor atom, a P-type semiconductor is created on doping with TiO 2 . A P-type semiconductor has Fermi energy levels, which are closer to the valence band and enhance charge transfer during absorption of visible light. Hence, beryllium has been selected as dopant and tested in visible region. The properties and photocatalytic activity of a photocatalyst are greatly influenced by their preparation methods. Previous workers have developed numerous techniques for fine TiO 2