Synthesis,Characterization And Catalytic Properties Of Bismuth-based Compound Micro-/Nano-materials

As an important type of semiconductor materials, bismuth-based nanomaterials show splendid physicochemical properties and prospective applications in various fields. Consequently, the synthesis methods and interesting properties of bismuth-based micro-/nano-materials have been receiving extensive research interest in the past decades. So far, bismuth-based micro-/nano-materials have been successfully prepared by many research groups through various approaches. However, high reaction temperature, expensive precursors and a series of complex procedures are generally needed in these above techniques. To overcome these disadvantages, we designed a simple, facile and energy-efficient approach for the large fabrication of uniform bismuth-based micro-/nano-structures. In addition, some factors influencing the formation of the final products, such as temperature, solvents and surfactants were also systematically investigated. Till now, bismuth-based micro-/nano-materials were found to exhibit some unique properties and possess great potential for applications in many fields, including photoresponse device, Li+ battery and the electrochemical hydrogen storage capacity, etc. Obviously, it is still necessary and challenging to explore new properties. In this dissertation, our interest have been focused on the application of the as-obtained bismuth-based products as new-types of catalysts for the reduction of some aromatic nitrocompounds in an excess NaBH4 aqueous system. The main contents are summarized as follows:1. The flowerlike Bi2S3 microspheres have been successfully synthesized via a facile wet chemical route in air at 110℃ for 10 min, employing bismuth nitrate and thiourea in a molar ratio of 1:2 as the starting reactants, ethylene glycol as the reaction medium and polyvinylpyrrolidone (PVP) as the structure-directing reagent. Some factors influencing the formation of flowerlike Bi2S3 microspheres were also investigated, including the reaction temperature, the sort and amount of the surfactant. The experiments showed that the Bi2S3 micro-/nano-structures prepared in the present work could be used as new-type catalysts for the reduction of some aromatic nitro compounds, such as 4-nitroaniline,2-nitrophenol and 4-nitrophenol. It was found that the as-obtained flowerlike Bi2S3 microspheres contributed to the best catalytic activity.2. The flowerlike Bi2Se3 microstructure were synthesized by a simple solvothermal reaction of bismuth nitrate as the Bi source, selenium powder as the Se source and sodium sulfite as the reductant in a mixed solution with a volume ratio of V(diethylenetriamine/ triethylenetetramine/tetraethylenepentamine):V(deionzed water) =1:1, respectively. Simultaneously, some factors influencing the formation of flowerlike Bi2Se3 were also investigated, including the sort of the reaction medium. It was evidenced from the experiments that the as-prepared Bi2Se3 with different flowerlike shapes could be utilized as catalysts for the reduction of 4-nitrophenol.3. We developed a simple and facile magnetic stirring method at room temperature to synthesis BiPO4. Under the assistance of β-cyclodextrin and nitric acid in the deionized water, employing bismuth nitrate and sodium dihydrogen phosphate or disodium hydrogen phosphate in a molar ratio of 1:1 as the starting reactants respectively, various shapes of BiPO4 were prepared. Furthermore, the experiments showed that β-cyclodextrin was the structure-directing reagent. The experiments also revealed that the as-obtained BiPO4 with various shapes in this present work could be used as new-type catalysts for the reduction of some aromatic nitrocompounds.