Novel electrospun bilayered composite fibrous membrane endowed with tunable and simultaneous quadrifunctionality of electricity–magnetism at one layer and upconversion luminescence–photocatalysis at the other layer

Abstract

A novel, electricity–magnetism-upconversion (UC) luminescence–photocatalysis, quadrifunctional [polyaniline (PANI)/Fe₃O₄/polyacrylonitrile (PAN)]/[Bi₂WO₆:Yb³⁺,Er³⁺/PAN] bilayered composite fibrous membrane (BLCFM) has been successfully synthesized via layer-by-layer electrospinning. PANI, Fe₃O₄ nanoparticles (NPs), and Bi₂WO₆:Yb³⁺,Er³⁺ nanofibers were incorporated into PAN and electrospun into the obtained fibrous membrane with [Bi₂WO₆:Yb³⁺,Er³⁺/PAN] nanofibers as one layer and [PANI/Fe₃O₄/PAN] nanofibers as the other layer. The composition, morphology, magnetism, UC luminescence and electrical conductivity of the composite fibrous membrane were evaluated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), vibrating sample magnetometry (VSM), photoluminescence spectroscopy (PL), and digital four-point probe tester. In addition, the degradation of rhodamine B (Rh B) was used to characterize the photocatalytic activity of the BLCFM. The results indicate that the BLCFM is simultaneously endowed with excellent UC luminescence, electrical conduction, magnetism and photocatalysis, and furthermore, UC luminescence intensity, photocatalysis, electrical conductivity and magnetic properties of BLCFM can be respectively tuned by adding various amounts of Bi₂WO₆:Yb³⁺,Er³⁺ nanofibers, PANI and Fe₃O₄ NPs. Moreover, the as-prepared, bilayered, fibrous membrane can not only achieve the order of 10⁻² S cm⁻¹ of conductivity, but also presents bright green UC luminescence under 980 nm excitation. The well-designed BLCFM demonstrates better performance than its PANI/Fe₃O₄/Bi₂WO₆:Yb³⁺,Er³⁺/PAN monolayered composite fibrous membrane (CFM) counterpart. The novel quadrifunctional BLCFM has promising applications in many areas, such as electromagnetic interference shielding, magnetic resonance imaging and environmental remediation.