Yonggan Hao,Xiankun Shao,Benxia Li,Luyang Hu,Tao Wang
The Au/TiO 2 hybrid nanofibers composed of mesoporous TiO 2 nanofibers and Au nanoparticles were synchronously fabricated by integrating a facile electrospinning technique and subsequent annealing in air. The Au loading content in the hybrid nanofibers was regulated by varying the dosage of chlorauric acid added in the precursor solution . The compositions, microstructures and optical response properties of the Au/TiO 2 hybrid nanofibers were characterized. The UV–vis spectra of the as-prepared hybrid fibers reveal two absorption bands belonging to the band gap absorption of TiO 2 and the surface plasmon resonance (SPR) of Au nanoparticles. For the catalytic reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride , the apparent reaction rate constant is raised but TOF value of the catalyst decreases, as the Au loading amount in the hybrid fibers increases. This is because the Au nanoparticles with smaller sizes have higher total surface areas at the same weight and therefore show higher catalytic activity . This method for producing Au/TiO 2 hybrid nanofibers is versatile and can be extended to the fabrication of other hybrid nanofibers composed of various noble metal nanoparticles and other mesoporous metal oxide nanofibers, designing of highly efficient catalysts for more important chemical reactions.
Hierarchically mesoporous silica nanorods with well-ordered cubic Fm-3m mesostructure were fabricated for the first time under basic conditions by using cationic surfactant cetyltrimethylammonium bromide (CTAB) as a template with poly(acrylic acid) (PAA) and triblock copolymer Pluronic P123 (PEO20PPO70PEO20) as co-templates. Due to the electrostatic interaction between CTAB and PAA, they would co-assemble to form complex colloids. The nonionic surfactant P123 would also be incorporated into the complex. The CTA/PAA/P123 complex colloids exhibited the morphology of nanorods, and the morphology of the final product inherited from the complex. The ordered mesopores (∼3 nm) of hierarchically mesoporous silica were connected with the secondary mesopores, whose average pore size was about 20 nm. Interestingly, the existence of the secondary mesopores did not disturb the ordered mesostructure of the nanorods and thus all the nanorods remained as single-crystalline mesoporous silica crystals. By varying the average molecular weight of the triblock copolymers, we could obtain hierarchically mesoporous silica with 2-D hexagonal mesostructure, which had a high surface area (∼980 m2 g−1) and large pore volume (∼1.3 cm3 g−1). Au-supported hierarchically mesoporous silica nanorods exhibited much higher reaction rate than that of Au-supported MCM-41 in catalytic reduction of 4-nitrophenol, as a result of its unique hierarchically mesoporous structure.
危险品化学品经营许可证（带存储）