Efficient photocatalytic degradation of persistent cationic dye pollutants under visible light is possible with Fe2O3 nanoparticles formed by solvent-less synthesis using macromolecular precursor design.

A controlled physical method without any solvent was developed to growth Ag nanoparticles on TiO 2 through using mercaptoacetic acid as bifunctional surface modifier. The fabricated Ag-TiO 2 particles were proposed as an innovative photocatalytic material. The particle size, chemical nature, morphology and chemical bonding between the mercaptoacetic acid, silver and titania have been characterized by UV-vis Absorption Spectroscopy, Powder X-Ray Diffraction, Raman Spectroscopy, Transmission Electron Microscopy and Field Emission Scanning Electron Microscopy. Combining the photocatalytic activity of titania with the excellent electron acceptor abilities and visible absorption of small spherical silver nanoparticles, it was possible to demonstrate an efficient photo-induced degradation of cationic organic pollutant under UV-Vis light. The nanocatalyst material obtained at 30s of sputtered time under simulated sunlight provides almost complete degradation (97%) of methylene blue after 120 min. The particle-size and distribution of silver nanoparticles have been achieved for the first time by a physical method using controlled chemical bonding to bifunctional surface modifiers and the sputter deposition time.

A solid-state phase control of TiO 2 by the use of different macromolecular complex precursors is reported for the first time. During the formation of TiO 2 nanoparticles, chitosan and Poly(styrene-co-4-vinylpyridine) polymers act as solid-state template producing areas after carbonization, where the TiO 2 nucleates. It seems that the location of metal centres through the polymeric chain (i.e. distance between the metal centres) strongly influence the morphology and particle size of the photocatalyst. To demonstrate the application value of our different TiO 2 structures, photocatalytic behavior was explored. The efficient photocatalytic decoloration of methylene blue on different polymorphic forms of nanostructured TiO 2 is confirmed. The best photocatalyst achieved 86% of discoloration rate in only 25 min, improving the efficiency of the standard photocatalyst Degussa P25 without the addition of other phases or dopants. The novelty of the present work is that by means of an appropriate synthesis, can be tuned simultaneously the three main factors (morphology, size and crystalline phase) that allow modulating the photocatalytic response of titania material. This control has allowed an advance in the properties of the material, managing to increase the photo-response in a short time.

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In an effort to discover new inorganic UV absorbers, titania included into silica was prepared 27 using a solvent-less solid state method involving the pyrolysis of the as prepared precursor 28 Chitosan (TiOSO 4 )/SiO 2 , as an alternative and versatile way to using these compounds for practical applications. The new TiO 2 /SiO 2 composite was characterized by PXRD, SEM-30 EDS, TEM and UV-vis absorption analysis. The SEM-EDS mapping images show a uniform 31 distribution of TiO 2 into the silica matrix. The optical properties of the composite have shown 32 an interesting result related to high absorption of UVB rays and an improved absorption of 33 UVA rays than pure TiO 2 . Efficient suppression of photocatalytic behavior of TiO 2 , when is 34 incorporated into silica, was evidenced from 85% to 31%, suggesting it material as alternative 35 inorganic UV absorber to remains the properties of the methylene blue dye. These results 36 reveal their potential use in practical textile industry and UV protection agent to avoid human 37 damage.