TiO 2 films organofunctionalized with 2-aminothiazole ligand and adsorbed Pd(II) ions applied in the photocatalytic degradation of phenol in an aqueous medium Valtair M. Cristante a , Sônia M.A. Jorge b , José P.S. Valente b , Margarida J. Saeki c , Ariovaldo O. Florentino b , Pedro M. Padilha b, ⁎ a Instituto de Química, Departamento de Química Analítica/UNESP, P.O. box-355, 14800–900, Araraquara, SP, Brazil b Instituto de Biociências, Departamento de Química e Bioquímica/UNESP, P.O. box-510, 18618–000, Botucatu, SP, Brazil c Faculdade de Ciências de Bauru, Departamento de Química, P.O. box-473, 17033360, Bauru, SP, Brasil Received 2 May 2006; received in revised form 29 November 2006; accepted 11 January 2007 Available online 23 January 2007 Abstract This paper describes the preparation of thin titanium films via sol–gel route and their subsequent chemical modification by anchoring with 2- aminothiazole ligand and Pd(II) ion sorption, aiming to maximize the photocatalytic activity. The material was characterized by diffuse reflectance infrared Fourier transform spectroscopy, ultraviolet and visible spectrometry, X-ray diffractometry, and scanning electronic microscopy. The amount of palladium adsorbed on the film's surface, determined by graphite furnace atomic absorption spectrometry, showed a value of 2.69 × 10 16 atoms cm - 2 . The photocatalytic tests indicated that the functionalization with 2-aminothiazole and the adsorption of palladium (II) were determinants in the semiconductor's enhanced photocatalytic activity. © 2007 Elsevier B.V. All rights reserved. Keywords: TiO 2 films; Photocatalysis; 2-aminothiazole; Sensitizer 1. Introduction Organic compounds that persist in residuary or natural waters, such as organochlorines, phenols and chlorinated pesticides, are considered carcinogenic and mutagenic to mammals and aquatic life [1]. The Environmental Protection Agency (EPA — USA) [2] lists many of these compounds as top priority pollutants, and they are strictly controlled by legislation and by international agencies [3–5]. The conven- tional biological or physicochemical processes for treating water bodies are ineffective in destroying these persistent organic compounds in the short time [1]. Therefore, processes using more efficient materials must be developed to extinguish these pollutants and their precursors. Heterogeneous photo- catalysis using semiconductors has been studied since 1972 [6] and has proved to be a suitable tool for decontaminating water bodies [7,8]. The advantage of this process is that it leads to the complete mineralization of the contaminants, whether they are composed of simple or of complex molecules [9–11]. Different semiconductor materials have been tested under the same conditions and with the same pollutants for photode- gradation; however, titania (anatase phase) has proved to be the most active material. Furthermore, titania possesses photo- stability, is biologically inert, inexpensive, and displays chemical stability within a wide range of pH, limiting the choice of other semiconductors [12]. Among the various forms of titania employed is Degussa's® P25 catalyst (specific surface area of 50 ± 5 m 2 g - 1 composed of 80% anatase phase and 20% rutile phase), which has exhibited the greater activity in degrading organic pollutants [13]. The photocatalysis mechanism is based on the activation of a semiconductor, by sunlight or artificial light (ultraviolet visible radiation). The interaction of light with the semiconductor excites electrons in the valence band toward the conduction band. This excitation produces holes (h + ) in the valence band Thin Solid Films 515 (2007) 5334 – 5340 www.elsevier.com/locate/tsf ⁎ Corresponding author. Tel./fax: +55 14 3811 6255. E-mail address: padilha@ibb.unesp.br (P.M. Padilha). 0040-6090/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.tsf.2007.01.023