Construction And Catalyst Design Based On Nano Composites System

In recent years, energy shortages and environmental pollution have become ahuman health, the ecological balance, and one of the biggest challenges facing socialand economic development with the progress of human society. In today’s society, mostof the materials are produced by catalytic reaction. Therefore, the development of newcatalytic material is an effective way to realize sustainable development. Photocatalytictechnology, which is green and environmental protection, can make the use of visiblelight. The photocatalytic reaction is not only high efficiency, fast speed, but also caneffectively degradation of a variety of organic pollutants. At the same time, in thechemical industry, efficient catalysts are the only dream of people. Therefore, the use ofnanomaterials for the preparation of new type of environmentally friendly, high efficientcatalysts is an important subject that is broad-based and valued research in application.In this thesis, we used the simplest chemical method for the preparation ofnanomaterials in catalysis, which can be control by the size and morphology.（1） A series of high performance Ag@Ag salts photocatalysts were designed andfabricated. In this catalyst system （metal@metal salts）, the positive charge center is thekey factor, and its stability determines the photocatalyst activity. Further tuning thephotocatalytic ability of this kind of catalysts can be realized by altering the negativecharged ions: higher stability and higher charged anions lead to the strongerphotocatalytic ability.（2） We have demonstrated a facile chemical etching method for the fabrication ofmesoporous black TiO2nanocrystals. The obtained mesoporous black TiO2nanocrystalsconsist of two phases: a crystalline TiO2nanocrystal in interior, and a highly disorderedsurface layer. This kind of mesoporous black TiO2nanocrystals has a pore size of about5.3nm and a high BET specific surface area. Furthermore, we demonstrated that themesoporous black TiO2nanocrystals exhibit high photoelectrical responses undersimulated sunlight irradiation, and enhanced photocatalytic activity in the visible region. （3） Y2O3nanoparticles with strong red luminescence was synthesized via simplehydroxylation of yttrium nitrate using hexamethylenetetramine as an additive; the redluminescence is emitted from oxygen-related defects of pure Y2O3nanoparticles, and istunable by altering the additive. While we presented a very simple and efficientchemical route to prepare highly luminescent Y₂O₃:Eu³⁺nanocrystals within5nm. Theas-synthesized uniform Y₂O₃:Eu³⁺nanocrystals are well stabilized againstagglomeration, well dispersed and water-soluble.（4） Nanosized polyaniline, as heterogeneous catalyst directly, possesses excellentcatalytic ability for selective oxidation of cyclohexene with H₂O₂as oxidant at60℃.Systematic experiments confirm that the catalytic activity of nanosized PANI isdependent on particle size and redox state, which is responsible for the catalyticdecomposition of H₂O₂.（5）A one-step method was developed for the controllable construction ofmetal–graphene core–shell structures, hollow graphene nanospheres, and a high densityof metal nanoparticles supported on graphene. The metal–graphene core–shellnanostructures as nanocatalysts show excellent catalytic ability for the selectiveoxidation of cyclohexene.（6）(Pt-C₆₀)@SiO₂nanocomposites with a core–shell structure have beensuccessfully synthesized by a step-by-step method. These hollow nanocomposites arecapable of reversible hydrogen storage at appropriate temperature and atmosphericpressure, with a capacity of around1.8wt%(based on C₆₀).