Fabrication and enhanced photocatalytic activity of inorganic core-shell nanofibers produced by coaxial electrospinning

Despite the interesting properties and potentially exciting applications of multifunctional one-dimensional nanoscale heterostructures that will likely impact areas such as optoelectronics, the fabrication of high-quality one-dimensional coaxial nanostructures in a simple, cost-effective, and scalable manner still remains challenging. Herein, we demonstrate that highly uniform SnO2/TiO2 coaxial nanoscale fibers with a tunable internal morphology can be prepared in one step by means of coaxial electrospinning. Specifically, by varying the concentration of the tin precursor solution, the interior of these fibers can be tuned in terms of morphologies, ranging from filled solid to peapod-like, and even to hollow tubes. The diameters of the fiber core and the overall dimensions of the fibers were noted to be in the range of 30-160 and 200-300 nm, respectively, depending upon precursor concentration and electrospinning conditions. In particular, the photocatalytic activity of tubular SnO2/TiO2 coaxial nanofibers was found to be higher than that of commercial TiO2 photocatalysts, an observation which could be attributed to the formation of a seamless heterojunction between SnO2 and TiO2 as well as the inherent advantages of a one-dimensional tubular structure. Overall results suggest that coaxial electrospinning can be employed as a novel, facile route for the large-scale synthesis of one-dimensional inorganic coaxial nanoscale heterostructures used for a broad range of applications.