No abstract

Uma sistema catalítico heterogêneo de peroxotungstato realizado em líquido iônico (IL) tipo escova foi sintetizado e aplicado na oxidação seletiva de sulfetos a temperatura ambiente e usando peróxido de hidrogênio 30 wt.% como oxidante terminal e água como solvente. Nenhum cosolvente orgânico ou outro aditivo foi necessário e a reação ocorre com uma quantidade de 1,5-2,0 mol% (baseado no W) de catalisador. Sulfetos alifáticos e aromáticos foram transformados de maneira eficiente e seletiva em seus respectivos sulfóxidos ou sulfonas pelo controle dos equivalentes de peróxido de hidrogênio. Grupos funcionais sensíveis à oxidação, tais como ligações duplas e hidroxila, não foram afetados mesmo com excesso de peróxido de hidrogênio. O catalisador foi recuperado após a reação via filtração e reutilizado pelo menos oito vezes sem perda significativa de atividade.An efficient and reusable heterogeneous catalytic assembly of peroxotungstate held in a ionic liquid (IL) brush was synthesized and an environmentally-friendly procedure was developed for selective oxidation of sulfides at room temperature using 30 wt.% hydrogen peroxide as the terminal oxidant and water as a sole solvent. No organic co-solvent or other additive was needed. A 1.5-2.0 mol% (based on W atom) loading catalyst was found to be sufficient for a smooth and clean reaction. Both aliphatic and aromatic sulfides were efficiently and selectively transformed into their respective sulfoxides or sulfones by simply controlling of equivalents of hydrogen peroxide. In addition to the high catalytic activity, the catalyst exhibits excellent chemoselectivity. Sensitive functional groups, such as double bond and hydroxyl, remained under the oxidation conditions the reaction even with an excess hydrogen peroxide. The catalyst was easily recovered (via simple filtration) and reused at least eight times without a noticeable loss of activity.

The NiO thin films were preapred by reactive radio frequency magnetron sputtering method on glass substrates. The influence of sputtering power on the crystal structure, surface morphological, optical and electrical properties was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectrophotometer (UV-VIS) and Hall effect tester, respectively. The as-preapred NiO thin films are polycrystalline with preferred orientation growth along (200) plane and have very high optical transmittances more than 60 %. All samples have a columnar structure with growth perpendicular to the film surface, and are dense, and homogeneous. With the increase of the sputtering power, a growth mode transformation appears from island growth to layer growth. The lowest resistivity of 2.4 Ω·cm could be obtained in our samples. An optimization electrical properties of the films can be achieved by the variation of crystal quality arises from the sputtering power.

Sulfoxides and sulfones have broad applications in pharmaceutical agents and pesticide due to their biologically activities and they are important synthetic intermediates in C-C bond formation and various molecular rearrangements. The selective oxidation of sulfides is a straightforward and frequently used method to obtain sulfoxides and sulfones. Among various oxidizing agents, hydrogen peroxide as benign oxidant has attracted organic chemists' attention for a long time. This review summarizes the recent and important catalytic systems of metal and nonmetal in this area. The catalytic effect of different catalytic systems is briefly discussed herein.

Nickel (Ni) film electrodes were deposited onto FTO by the magnetron sputtering method. The influence of sputtering power on the morphology and electrochemical performances of the as-prepared films has been investigated in this work. The surface crystal structure and morphology of the prepared films were investigated by using X-ray diffraction (XRD) and scanning electron microscope (SEM). The results have shown that with the increase of the sputtering power from 80 W to 140 W, the increases of the film surface roughness and porosity. The films deposited at sputtering power of 140 W possess the highest specific surface area and abundant pore structure, leading to better electrochemical performance of Ni film.