Hollow TiO2/Poly (Vinyl Pyrrolidone) Fibers Obtained via Coaxial Electrospinning as Easy-to-Handle Photocatalysts for Effective Nitrogen Oxide Removal

Abstract

Herein, we present a method for fabricating hollow TiO2 microfibers from Ti (OBu)4/poly (vinyl pyrrolidone) sol-gel precursors and their effects on denitrification as a photocatalyst for air purification. Various sizes of hollow TiO2 fibers were developed using coaxial electrospinning by controlling the core flow rate from 0 to 3 mL h−1. At higher flow rates, the wall layer was thinner, and outer and core diameters were larger. These features are correlated with physical properties, including specific surface area, average pore diameter, and crystalline structure. The increase in the core flow rate from 0 to 3 mL h−1 leads to a corresponding increase in the specific surface area from 1.81 to 3.95 µm and a decrease in the average pore diameter from 28.9 to 11.1 nm. Furthermore, the increased core flow rate results in a high anatase and rutile phase content in the structure. Herein, hollow TiO2 was produced with an approximately equal content of anatase/rutile phases with few impurities. A flow rate of 3 mL h−1 resulted in the highest specific surface area of 51.28 m2 g−1 and smallest pore diameter size of ~11 nm, offering more active sites at the fiber surface for nitrogen oxide removal of up to 66.2% from the atmosphere.