Please cite this article as: E. Albiter, M.A. Valenzuela, S. Alfaro, G. Valverde-Aguilar, F.M. Martínez-Pallares, Photocatalytic deposition of Ag nanoparticles on TiO 2 : metal precursor effect on the structural and photoactivity properties, Journal of Saudi Chemical Society (2015), doi: http://dx.Abstract A series of 1 wt. % Ag-TiO 2 photocatalysts were obtained by photodeposition using different organic (acetylacetonate, Ag-A) and inorganic (nitrate, Ag-N, and perchlorate, Ag-C) silver precursors in order to determinate the influence of the silver precursor on the final properties of the photocatalysts. The resulting photocatalytic materials were characterized by different techniques (UV-Vis DRS, TEM/HRTEM and XPS) and their photocatalytic activity was evaluated in the degradation of rhodamine B (used as model pollutant) in aqueous solution under simulated solar light. The photocatalytic reduction of Ag species to Ag 0 on TiO 2 was higher with silver nitrate as precursor compared to acetylacetonate or perchlorate. All the Ag-modified TiO 2 photocatalysts exhibited a surface plasmon resonance effect in the visible region (400-530 nm) indicating different metal particle size depending on the Ag precursor used in their synthesis. A higher photocatalytic activity was obtained with all the Ag/TiO 2 samples compared with nonmodified TiO 2 . The descending order of photocatalytic activity was as follows: Ag-A/TiO 2 ≈ Ag-N/TiO 2 > Ag-C/TiO 2 > TiO 2 -P25. The enhanced photoactivity was attributed to the presence of different amounts Ag 0 nanoparticles homogeneously distributed on Ag 2 O and TiO 2 , trapping the photogenerated electrons and avoiding charge recombination.

The photosensitized oxidation of 9,10-dimethylanthracene with singlet oxygen in acetonitrile was investigated using a safranin O/silica composite as an heterogeneous delivery system of the photosensitizer. The only detected product was the corresponding endoperoxide (9,10-endoperoxianthracene) and its formation rate depended on the initial concentration of DMA, the light intensity and the amount of the composite. The kinetics of this reaction was compared with that of the reported kinetic model of photosensitized oxidations of organic compounds in homogeneous reactions. It was found that both reactions followed the same model, suggesting that the actual reaction between photoproduced singlet oxygen and 9,10-dimethylanthracene was performed in homogeneous media and the surface of the composite was not involved in the reaction.

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In this work, we present an investigation concerning the evaluation of the catalytic properties of Ni nanoparticles supported on ZrO2, SiO2, and MgAl2O4 for CO2 hydrogenation to methane. The supports were prepared by coprecipitation and sol-gel, while Ni was incorporated by impregnation (10–20 wt %). X-ray diffraction, nitrogen physisorption, temperature-programmed reduction, H2 pulse chemisorption, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy were the main characterization techniques employed. A laboratory fixed-bed reactor operated at atmospheric pressure, a temperature range of 350–500 °C, and a stoichiometric H2/CO2 molar ratio was used for catalyst evaluation. The most outstanding results were obtained with nickel catalysts supported on ZrO2 with CO2 conversions of close to 60%, and selectivity to methane formation was 100% on a dry basis, with high stability after 250 h of reaction time. The majority presence of tetragonal zirconia, as well as the strong Ni–ZrO2 interaction, were responsible for the high catalytic performance of the Ni/ZrO2 catalysts.

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