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Allylic oxidation of cycloalkenes is a promising route to generate α,β-unsaturated ketones but encounters difficulties in selectivity control. Here, it is demonstrated that ruthenium nanoparticles (1–2 nm sized) decorated on TiO2 nanomaterials with different morphologies (nanoparticles, nanotubes and nanofibers) are demonstrated highly efficiency and selectivity for the selective aerobic oxidation of cyclohexene and indane. The as-prepared Ru/TiO2 nanofibers (NFs) represents higher activity for the allylic oxidation of cyclohexene (conv. 95%) with 78% selectivity toward 2-cyclohexen-1-one at 75 °C under 4 bar O2. Whereas, Ru/TiO2 nanoparticles (NPs) and Ru/TiO2 nanotubes (NTs) show 92 and 84% conversion, respectively. Upon switching to Al2O3 support, catalytic activity with Ru/Al2O3 is decreased significantly to 27%. Very high activity for indane (conv. 70%) toward 2,3-dihydro-1H-inden-1-one (selectivity 85%) has also been observed by using Ru/TiO2 NFs. Ru/TiO2 nanomaterials possess higher catalytic efficiency as compared to Ru NPs and TiO2 nanomaterials individually, representing a positive synergetic effect. Moreover, these reported results suggest that the higher activities of Ru/TiO2 NPs and Ru/TiO2 NFs are related to the crystalline structure, pore volume and surface area of the supports. [ABSTRACT FROM AUTHOR]

In(OH) 3 /In 2 O 3 nano-objects (plates and tubes) were prepared under controlled mild reaction conditions by simple basic thermal hydrolysis of 1-(2-methoxy-ethyl)-3-methyl imidazolium tetrachloro-indate (BMIOMe·InCl 4) ionic liquid (IL). As the reaction temperature increased from 10 °C to 80 °C, there was not only an increase in concentration of In 2 O 3 but the growth of nano-tubes (NTs) also increased. At 10 °C, 30 °C, 50 °C, and 80 °C, 25.2 ± 7 nm sized nanoplates (NPls), small nanotubes (26.6 ± 6 nm in length and 8 ± 2 nm in width), NTs with a length of 25.9 ± 6 nm, and larger nanotubes (49.2 ± 18 nm) were obtained, respectively. The surface concentration of In(OH) 3 decreased with the augmentation of the reaction temperature (from 100% at 10 °C to 5.1% at 80 °C). The nano-objects displayed a band gap of 5.4 eV, which is in the range expected for photo-catalytic activity to generate hydrogen from alcoholic solutions. Remarkably, In(OH) 3 /In 2 O 3 catalyst prepared at 30 °C revealed 3.72 μmol h−1 of rate of hydrogen with apparent quantum yield of 16.3%, yielding a total H 2 productivity of 57.6 μmol (5.76 mmol/g) after 32 h. This is the most active semiconductor photocatalysts reported so far of bare indium-based. The presence of In 2 O 3 inside the nano-tubes is also important for the photacatalytic activity of the In(OH) 3 based semiconductor. The presence of the IL layer not only acts as a template to control the structure of the nano-objects, but its presence also induces H 2 generation. Image 1 • In(OH) 3 /In 2 O 3 nano -plates and -tubes were prepared by thermal hydrolysis of indate ionic liquid. • Photoreforming by small sized In(OH) 3 /In 2 O 3 (1:1) nanotubes yields H 2 up to 3.72 μmol h−1. • Presence of IL on the nano-objects surface is the driving force for enhancing of the H 2 generation. [ABSTRACT FROM AUTHOR]

Abstract: Photo-induced reforming of methanol, ethanol, glycerol and phenol at room temperature for hydrogen production was investigated with the use of ultra-small Pt nanoparticles (NPs) loaded on TiO2 nanotubes (NTs). The Pt NPs with diameters between 1.1 and 1.3 nm were deposited on TiO2 NTs by DC-magnetron sputtering (DC-MS) technique. The photocatalytic hydrogen rate achieved an optimum value for a loading of about 1 wt% of Pt. Apparent quantum yield for hydrogen generation was measured for methanol and ethanol water solutions reaching a maximum of 16% under irradiation with a wavelength of 313 nm in methanol/water solution (1/8 v/v). Pt NPs loaded on TiO2 NTs represented also a true water splitting catalyst under UV irradiation and pure distilled water. DC-MS method appears to be a technologically simple, ecologically benign and potentially low-cost process for production of an efficient photocatalyst loaded with ultra-small NPs with precise size control. [Copyright &y& Elsevier]