Mesoporous ceramic nanofibers provide advantageous chemical and physical properties beneficial for heterogeneous catalysis. Electrospun nanofibers usually have a solid interior and smooth surface. The interest in complex structured fibers with multifunctional, specific properties has been growing over in recent years. In particular, porous core-shell structures are attractive since they integrate different functional components into a single element, thus providing advantageous properties and synergetic effects for different applications such as catalysis, energy storage and conversion. The structure can also provide new strategies for modern material design with higher surface area. Electrospinning (ES) is an effective route to polymer, ceramic and composite fibers of controlled diameters and morphologies.
Core-shell electrospun nanofibers were previously fabricated using coaxial nozzles or emulsion methods. Recently, we synthesized ceramic nanofibers with unique lamellar-like mesoporous structure using a single nozzle ES process, followed by thermal treatment. The fibers morphology consist of inner Fe-Al-O core with elongated mesopores and an outer thin accordion-like Fe-rich shell. A general mechanism for the formation of this morphology is suggested, where the final structure depends greatly on the heating rate stage and chemical composition of the metal oxide precursors and polymer matrix. The proposed mechanism suggests that this structure is possible in the presence of a metal-organic component with low melting point and high volatility below the polymer main decomposition temperature.
Titanium-based materials have been investigated intensively as a stable oxide semiconductor. Nevertheless, new designs with improved properties are necessary to meet the demands and requirements in the energy market. Development of nanostructured titanium-based materials with engineered compositions and morphologies have the potential to provide a breakthrough in this area. Overall, the presented nanofibers are highly promising in material research, especially in applications requiring an accessible high surface area porous media.