Efficiency of sensitizing nano-titania with organic dyes and peroxo complexes

Abstract

A new method of sensitizing titania by treatment of the reaction mixture with Methylene Blue, Methyl Red or hydrogen peroxide is developed; the sensitizer was introduced into the reaction mixture while synthesizing nanosize TiO 2 from titanyl sulfate. The samples prepared by this method are compared to the samples prepared by cold impregnation of Methylene Blue, Methyl Red or hydrogen peroxide on titania, pre-synthesized by sulfate method, or commercial Degussa P25 and Hombikat UV100. The samples were characterized by X-ray diffraction; their photocatalytic activity was studied in the model reaction of Methyl Orange decomposition in aqueous solution under UV and visible light. The highest photocatalytic activity under visible light was found for titania, sensitized with titanium peroxo complexes by the new method. It is also active for photodegradation of salicylic acid under visible light.

Introduction of peroxo groups into titania: preparation, characterization and properties of the new peroxo-containing phase

“…by hydrolysis of titanyl sulfate. 28 Appearance of additional resonances in the pre-edge region of the XANES spectra (Fig. 3) indicates occurring of the pentacoordinated TiO 5 polyhedra.…”

“…27 Recently, we have found decolouration of methyl orange for the samples prepared by cold impregnation and by introduction of H 2 O 2 solutions into reaction mixtures while preparing TiO 2 from solvated TiOSO 4 . 28 The purpose of the work was to prepare titania containing peroxo groups both on the surface and in the bulk of titania nanoparticles and to find correlations between conditions of preparing samples of nano-titania modified with H 2 O 2 , their characteristics and properties.…”

Associating low crystallinity with peroxo groups for enhanced visible light active photocatalysts

“…phenylurea) [6], phenol [7][8][9][10][11], pharmaceuticals (e.g. paracetamol, diclofenac, ethenzamide) [12,13], organic dyes [14][15][16], furthermore the reactive free radicals formed during the photocatalytic process can also be used efficiently in the removal of various bacteria [17][18][19]. Besides water purification the utilization of TiO 2 in other areas is also extensively investigated for instance air cleaning [20], production of self-cleaning [21] and antibacterial surfaces [22,23], application as dye-sensitized solar cells [24], lithium ion batteries [25], moreover it has great potential to be used for photocatalytic assisted organic synthesis [26], or for the production of hydrogen, an alternate green energy source [27,28].…”

Photosensitization of titanium dioxide with 4′-dimethylaminoflavonol

“…titanium dioxide) with various metal ions or non-metal dopants [1][2][3][4]. Another way of titanium dioxide sensitization encompasses application of dyes [5][6][7][8], including the systems photosensitized according to the photoinduced electron transfer (PET) and optical electron transfer (OET) mechanisms [9]. In the PET mechanism the photon absorption by the adsorbed dye generates its excited state capable of an electron injection into the conduction band (or, alternatively, a hole injection into the valence band).…”