A novel strategy to directly fabricate flexible hollow nanofibers with tunable luminescence–electricity–magnetism trifunctionality using one-pot electrospinning

Abstract

Novel photoluminescent–electrical–magnetic trifunctional flexible Eu(BA)₃phen/PANI/Fe₃O₄/PVP (BA = benzoic acid, phen = phenanthroline, PANI = polyaniline, PVP = polyvinylpyrrolidone) hollow nanofibers were fabricated by a one-pot electrospinning technique using a specially designed coaxial spinneret for the first time. Very different from the traditional preparation process of hollow fibers via coaxial electrospinning, which needs to firstly fabricate the coaxial fibers and followed by removing the core through high-temperature calcination or solvent extraction, in our current study, no core spinning solution is used to directly fabricate hollow nanofibers. The morphology and properties of the obtained hollow nanofibers were characterized in detail using X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, fluorescence spectroscopy, Fourier-transform infrared spectroscopy, a 4-point probe resistivity measurement system and vibrating sample magnetometry. The Eu(BA)₃phen/PANI/Fe₃O₄/PVP hollow nanofibers, with outer diameters of ca. 305 nm and inner diameters of about 140 nm, exhibit excellent photoluminescence performance, electrical conductivity and magnetic properties. Fluorescence emission peaks of Eu³⁺ are observed in the Eu(BA)₃phen/PANI/Fe₃O₄/PVP hollow nanofibers and assigned to the ⁵D₀ → ⁷F₀ (580 nm), ⁵D₀ → ⁷F₁ (592 nm) and ⁵D₀ → ⁷F₂ (616 nm) energy level transitions of Eu³⁺ ions, and the ⁵D₀ → ⁷F₂ hypersensitive transition at 616 nm is the predominant emission peak. The electrical conductivity of the hollow nanofibers reaches up to the order of 10⁻³ S cm⁻¹. The luminescent intensity, electrical conductivity and magnetic properties of the hollow nanofibers can be tuned by adding various amounts of Eu(BA)₃phen, PANI and Fe₃O₄ nanoparticles. The new-type photoluminescent–electrical–magnetic trifunctional flexible hollow nanofibers hold potential for a variety of applications, including electromagnetic interference shielding, microwave absorption, molecular electronics and biomedicine. The design conception and synthetic strategy developed in this study are of universal significance to construct other multifunctional hollow one-dimensional nanomaterials.