Synthesis And Properties Of Hierarchically Hollow Nanofibers Supported Catalysts

As we know,the catalytic science plays an indispensable role for the rapid development of social economy.At present,the development of new catalyst materials has attracted much attention in catalysis field.Nano-materials have been widely used in energy,environment,sensors,photoelectric devices and catalysis due to their unique small size effect,quantum size effect,surface effect and macroscopic quantum tunneling effect.However,the small nanoparticles are easy to agglomerate,resulting in a remarkable reduction in their activities.Moreover,small nanoparticles are very difficult to be removed and recycled from the reaction media,which also limits their applications.Therefore,the rational design and synthesis of high efficient and easy-separation catalysts is urgently desirable in catalysis field.Electrospinning technique is one of the most important methods for preparing one-dimensional nanofiber materials.The electrospun nanofibers not only possess the unique properties of nano-size materials with a large specific surface area,but also can be easily separated by gravitational sedimentation.Thus,the electrospun nanofibers can be used as the support to obtain the supported catalysts with the characteristic of high catalytic activity,and easy separation and recycle.In this paper,we have prepared composites nanofibers by combining electrospinning technique,calcination,hydrothermal method and chemical reduction method.The morphology and structure of samples were characterized by Transmission Electron Microscope?TEM?,Scanning Electron Microscope?SEM?,X-ray Diffraction Analysis?XRD?and X-ray photoelectron spectroscope?XPS?.The catalytic properties and recycling features have also been investigated.The main results are list as follows:?1?Hierarchical double-walled nickel silicate?NiSiO?hollow nanofibers have been successfully fabricated by a simple hydrothermal treatment by using SiO₂ hollow nanofiber as the sacrificial template.Furthermore,the Ni/NiSiO nanocomposites were obtained by in situ reduction under hydrothermal conditions.The reduction of 4-nitrophenol?4-NP?was used as a model system to evaluate the catalytic performance of the Ni/NiSiO nanocomposites.The results showed that the as-prepared sample had good catalytic activity and cyclic stability,and can be separated and recycled by gravitational sedimentation.?2?Hierarchical double-walled cobalt oxide?Co₃O₄?hollow nanofibers assembled by ultrathin nanosheets have been successfully fabricated by combination of hydrothermal method and post-treatment by using SiO₂ hollow nanofiber as the hard template.On this basis,the highly dispersed Pt nanoparticles were immobilized on the surface of Co₃O₄ through insitu reduction.The catalytic test demonstrated that the prepared Pt/Co₃O₄ had a high catalytic performance on CO oxidation.?3?Hierarchical double-walled tin dioxide?SnO₂?hollow nanofibers assembled by ultrathin nanosheets have been successfully fabricated by combination of solvothermal method and post-treatment by using SiO₂ hollow nanofiber as the hard template.On this basis,the highly dispersed Pt nanoparticles were immobilized on the surface of SnO₂ through chemical reduction.The catalytic test demonstrated that the prepared Pt/SnO₂ had a good catalytic activity and cyclic stability.