Excitation dependent recombination studies on SnO2/TiO2 electrospun nanofibers

Abstract

Poly(vinyl acetate) (PVAc)/TiO₂ nanofibers, PVAc/SnO₂ nanoribbons and PVAc/SnO₂–TiO₂ nanoribbons were produced via electrospinning. TiO₂ nanofibers and SnO₂ nanoribbons were obtained by removal of the polymeric matrix (PVAc) after calcination at 450 °C. Interestingly, PVAc/SnO₂–TiO₂ nanoribbons were transformed into SnO₂–TiO₂ nanofibers after calcination under the similar conditions. Fiber morphology and elemental mapping confirmed through SEM and TEM microscope techniques respectively. The X-ray diffraction measurements suggested the presence of anatase TiO₂ and rutile SnO₂ and both were present in the SnO₂–TiO₂ mixed system. Systematic photoluminescence studies were performed on the electrospun nanostructures at different excitation wavelengths (λ_ex1 = 325, λ_ex2 = 330, λ_ex3 = 350, λ_ex4 = 397 and λ_ex5 = 540 nm). We emphasize that the defects in the SnO₂–TiO₂ based on the defect levels present in TiO₂ and SnO₂ and anticipate that these defect levels may have great potential in understanding and characterizing various semiconducting nanostructures.