Photocatalytic degradation of organic molecules on mesoporous visible-light-active Sn(II)-doped titania

• Published in: Journal of catalysis 2011-07, Vol.281 (1), p.156-168
• Main Authors: Boppana, Venkata Bharat Ram, Lobo, Raul F.
• Format: Article
• Language: English
• Subjects: Anatase; aqueous solutions; Biodegradation; Catalysis; Catalysts; Chemistry; chemometrics; chlorine; Colloidal state and disperse state; Cresol; Doping; Exact sciences and technology; General and physical chemistry; hydroxyl radicals; infrared spectroscopy; Photocatalysis; photocatalysts; Photochemistry; photoluminescence; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Porous materials; Raman spectroscopy; reflectance spectroscopy; Rhodamine B; Rutile; semiconductors; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; tin; TiO 2; titanium; titanium dioxide; Visible light; X-ray diffraction; X-ray photoelectron spectroscopy
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2011.04.014

Visible-light-active valence band-hybridized Sn(II)–TiO 2 materials were synthesized possessing unique electronic properties and photocatalytic activities dependent on the hydrothermal synthesis conditions. [Display omitted] ► Mesoporous Sn(II)–TiO 2 photocatalysts synthesized hydrothermally. ► The band gaps decrease to the visible region of the solar spectrum. ► This reduction is associated with the hybridization of Sn 5s with O 2p. ► They are photocatalytically active for the degradation of RhB and cresol. ► Potential applications could be photocatalytic water splitting. We report the first demonstration of visible light photocatalytic activity of Sn 2+-doped TiO 2. The catalysts are prepared from the reaction of titanium butoxide and several tin precursors at 80 °C in aqueous solutions. Samples synthesized with SnCl 2 have lower band gaps (red-shifted to the visible region) with respect to anatase TiO 2. The catalysts are isostructural to anatase TiO 2 even at the highest loadings of Sn 2+. When the precursor is changed to SnCl 4, rutile is the predominant phase obtained but no reduction in the band gap is observed. The materials are investigated using X-ray diffraction, ultraviolet–visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, IR spectroscopy, photoluminescence, Raman spectroscopy, and other techniques. The majority of surface cation sites are tin, with a fraction of tin also incorporated in the bulk particles. The experiments also indicate the presence of chlorine in the samples, also influencing the optical and catalytic properties as confirmed by comparison to materials prepared using bromide precursors. These catalysts are photocatalytically active for the degradation of organic molecules with rates higher than the standards (P25 TiO 2) and also evidenced from the generation of hydroxyl radicals using visible light. This protocol could be extended to incorporate Sn 2+ into other oxide semiconductors to prepare photocatalysts with interesting electronic properties. The analysis of the degradation of rhodamine B dye by a de-ethylation mechanism using multivariate chemometric methods is also described.