WO3–TiO2 vs. TiO2 photocatalysts: effect of the W precursor and amount on the photocatalytic activity of mixed oxides

Aiming at producing TiO2-based photocatalytic materials with reduced charge carriers recombination, WO3\u2013TiO2 mixed oxides were synthesized by a sol\u2013gel method employing either an inorganic salt, Na2WO4, or an organic alkoxide, W(OC2H5)6, as tungsten precursor, with different W/Ti ratios. The so-obtained materials were characterized by XRPD, BET, UV\u2013vis reflectance, XPS and EDX analyses and their photoactivity was tested under UV\u2013visible irradiation in both the mineralization of formic acid in aqueous suspension and the gas phase oxidation of acetaldehyde. Both photoactivity results and photocurrent measurements point to a superior performance of photocatalysts obtained from the organic precursor with an optimal tungsten content (3%). The formation of an intimately mixed oxide, as revealed by XRPD analysis, results in photoactivity higher than that of pure TiO2, and also of benchmark P25 TiO2, consequent to a better charge separation due to the migration of photoproduced holes from WO3 domains to TiO2 and of photopromoted electrons in the opposite direction. The persistence of pure anatase phase in W-containing photocatalysts also after calcination at 700 \ub0C and their higher surface area with respect to pure TiO2 also contribute in increasing the photocatalytic activity of the WO3\u2013TiO2 mixed oxides

Solar energy conversion by nanostructured TiO

10.1155/2014/704729International Journal of Photoenergy201470472

Photomedicine with inorganic complexes: a bright future

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Photocatalytic conversion of acetate into molecular hydrogen and hydrocarbons over Pt/TiO2: pH dependent formation of Kolbe and Hofer-Moest products

The photocatalytic generation of H2 and hydrocarbons from aqueous acetic acid has been studied employing TiO2 P25-based photocatalyst particles. The effect of pH on the distribution of reaction products and their formation rates during the photochemical as well as the photoelectrochemical oxidation of acetic acid has been investigated. The photocatalytic formation rates for H2 and hydrocarbons were found to be higher for Pt-loaded TiO2 than for bare TiO2. The major reaction products resulting from the photocatalytic decomposition of aqueous acetic acid, as determined quantitatively in the gas phase, were found to be H2, CO2, and CH4. Furthermore, traces of C2H6, C3H8, CO, CH3CHO, HCHO, CH3OH, C2H5OH, and HCOOH were also detected. After 15 h of illumination, the average formation rates of H2, CO2, CH4, and C2H6 evolved at pH 2 were found to be 22, 65, 35, and 2 ?mol/h, respectively. The ratio of H2 to hydrocarbons strongly depends on the pH values, i.e., at acidic pH the ratio of H2 to CH4 formation was found to be 0.6. On the contrary, at neutral and basic pH values negligible amounts of hydrocarbons were formed and H2 was found to be the main product with formation rates of 12 and 5 ?mol/h at pH 7 and 11, respectively. It is therefore assumed that the hydroxide ion has a significant effect on the reaction pathways. Due to the fact that methanol and ethanol are formed as reaction products, water or hydroxide ions are apparently required for the formation of the major oxidizing agent, that is the hydroxyl radical. Herein, a detailed mechanism for the photocatalytic decomposition of acetic acid at different pH values is presented. ? 2017 Elsevier Inc.119sciescopu

Design and synthesis of imidazole-triphenylamine based organic materials for dye sensitized solar cells

Two imidazole – triphenylamine based organic dyes (SD1 and SD2) configured with donor -donor-π-acceptor (D2-π-A) structures with reported dye material namely TPA B5 were synthesized using different acceptor units and characterized by various spectroscopic techniques. The optical and electrochemical behavior of the dyes was systematically analyzed. The obtained results were compared with TPA B5 and found that, these dyes are considered to have proper electronic energy levels as promising sensitizers in dye sensitized solar cells (DSC’s). This work could facilitate the development of new way to improve the performance of anchoring units