In this paper, core/sheath TiO 2 /SiO 2 nanofibers with tunable sheath thickness were directly fabricated via a facile co-electrospinning technique with subsequent calcination at 500 °C. The morphologies and structures of core/sheath TiO 2 /SiO 2 nanofibers were characterized by TGA, FESEM, TEM, FTIR, XPS and BET. It was found that the 1D core/sheath nanofibers are made up of anatase–rutile TiO 2 core and amorphous SiO 2 sheath. The influences of SiO 2 sheath and its thickness on the photoreactivity were evaluated by observing photo-degradation of methylene blue aqueous solution under the irradiation of UV light. Compared with pure TiO 2 nanofibers, the core/sheath TiO 2 /SiO 2 nanofibers performed a better catalytic performance. That was attributed to not only efficient separation of hole–electron pairs resulting from the formation of heterojunction but also larger surface area and surface silanol group which will be useful to provide higher capacity for oxygen adsorption to generate more hydroxyl radicals. And the optimized core/sheath TiO 2 /SiO 2 nanofibers with a sheath thickness of 37 nm exhibited the best photocatalytic performance.
Direct oxidation of methanol to high value oxygenated chemicals on V2O5/TiO2 based catalysts is a green alternative to the commercial methods. But the V–Ti based catalysts are challenged by the relatively low reactivity. Herein, we demonstrated a facile and practicable strategy to directly fabricate hollow structure VOx/TiO2 nanofibers (VTO-HNF) through the coelectrospinning and calcination method. The effects of V/Ti ratio on the structure, the surface chemistry and methanol oxidation performance were investigated in detail. VTO-HNFs with appropriate V/Ti ratio have hierarchical structure, large surface area, uniform nanoparticles, narrowed grain sizes, and high dispersions of vanadium. Moreover, both the oxidation properties and the acidities of the catalyst were enhanced due to the high content of surface V4+. The VTO-HNF catalysts featured excellent activities and reliable stability for the selective oxidation of methanol to methyl formate (MF) and dimethoxymethane (DMM). The MF yield reached 90% at 150 °C, which is comparable with the noble metal based catalysts. In situ NAP-XPS investigations suggested that the variable valence of vanadium was involved in the oxidation of methanol.
Mohammed A. Al-Baadani,Kendrick Hii Ru Yie,Abdullrahman M. Al-Bishari,Bilal A. Alshobi,Zixin Zhou,Kai Fang,Binwei Dai,Yiding Shen,Jianfeng Ma,Jinsong Liu,Xinkun Shen
The rising popularity of co-electrospinning technique in the field of biomaterial has enabled the possibility of combining various polymers, in which they provide the mechanical properties and the bioactivity for each other. Herein, a series of polycaprolactone/gelatin (PCL/Gel) composite membranes were prepared by co-electrospinning, and their biocompatibility and drug-controlled release ability were evaluated in detail for the first time. The addition of Gel significantly enhanced the adhesion and differentiation of osteoblasts, while the addition of PCL significantly improved the mechanical properties. Moreover, the in vitro degradation and drug release results showed that by adjust the PCL fibers amount and size, the degradation of Gel and the release profile of hydrophilic drugs/proteins could be effectively controlled: in the low PCL groups (PCL/Gel-1 & PCL/Gel-4), the Gel nano-fibers dissolved rapidly, resulting in an early explosive release within 1 week; however, with the increase of PCL content, the drug release rate decreased gradually, and the total release period could be extended to over 2 weeks (PCL/Gel-2, PCL/Gel-3 & PCL/Gel-5) or more (PCL/Gel-6). Therefore, the preparation of a controllable drug delivery system with good biological activity by co-electrospinning of PCL and Gel could provide an effective strategy for bone regeneration.
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