Pingfan Du

Preparation and the luminescent properties of Tb3 + -doped Gd2O3 fluorescent nanofibers via electrospinning

Tb(3+)-doped Gd(2)O(3) (Gd(2)O(3):Tb(3+)) nanofibers were prepared via a simple electrospinning technique using poly(ethylene oxide) (PEO) and rare-earth acetate tetrahydrates (Ln(CH(3)COO)(3)·4H(2)O (Ln = Gd, Tb)) as precursors. The obtained nanofibers have an average diameter of about 80 nm and are composed of pure cubic Gd(2)O(3) phase. A possible formation mechanism for the nanofibers is proposed on the basis of the experimental results, which reveals that PEO acts as the structure directing template during the whole electrospinning and subsequent calcination process. The luminescent properties of the nanofibers were investigated in detail. The nanofibers exhibit a favorable fluorescent property symbolized by the characteristic green emission (545 nm) resulting from the 5D4-->7F5 transition of Tb(3+). Concentration quenching occurs when the Tb(3+) concentration is 3 at.%, indicating that the Gd(2)O(3):Tb(3+) nanofibers have an optimum luminescent intensity under such a doping concentration.

Photocatalytic degradation of Rhodamine B using electrospun TiO2 and ZnO nanofibers: a comparative study

TiO2 and ZnO nanofibers were fabricated through a facile electrospinning method. The obtained nanofibers were characterized by a variety of analytical means including FESEM, TEM, SAED, XRD, UV–Vis, and PL. Compared with nanoparticles, nanofibers can be recycled more easily when they are used as photocatalysts. The photocatalytic activities of these two nanofibers were investigated and compared by evaluating the photodegradation of hazardous dye Rhodamine B. Although, ZnO nanofibrous photocatalyst exhibits better initial activity than TiO2 nanofibrous counterpart, its photocatalytic performance is inferior to that of the latter on the whole. The photo-instability arising from photocorrosion may be responsible for its rapid deterioration in activity. The difference in the photocatalytic properties between TiO2 and ZnO nanofibers was discussed, and a possible photodegradation mechanism of organic dyes in the presence of the nanofibrous photocatalyst was proposed. This work offers a direct insight into the comparison of photocatalysis of electrospun TiO2 and ZnO nanofibers.

Optimization of the Photoluminescence Properties of Electrodeposited Y2O3 : Eu3 + Thin-Film Phosphors

In this work, electrodeposition is proved to be a promising method to prepare Y 2 O 3 :Eu 3+ thin-film phosphors. The photoluminescence (PL) property of the Y 2 O 3 :Eu 3+ thin-film phosphor strongly depends on different factors such as the crystal structure of host materials, annealing temperature, and doping concentration of Eu 3+ . The best PL performance of the Y 2 O 3 :Eu 3+ thin-film phosphor is achieved for a sample annealed at 600°C with a Eu 3+ doping concentration of 1.85 atom %.

A photovoltaic smart textile and a photocatalytic functional textile based on co-electrospun TiO2/MgO core–sheath nanorods: novel textiles of integrating energy and environmental science with textile research

TiO2/MgO core–sheath structured nanofibers (NFs) were fabricated through co-electrospinning (i.e., coaxial electrospinning), and then the long TiO2/MgO NFs were converted into short TiO2/MgO nanorods (NRs) by ultrasonic treatment. Based on the TiO2/MgO NRs, two novel technical textiles, that is, a photovoltaic smart textile integrating flexible dye-sensitized solar cells and a photocatalytic functional textile immobilizing photocatalyst, were developed. The effect of the insulating MgO sheath on the semiconducting TiO2 core was discussed. Compared with the pure TiO2 NR counterparts, the TiO2/MgO NR-based photovoltaic and photocatalytic textiles exhibit better performances. The common reason for the performance enhancements is that the charge recombinations occurring in both photovoltaic and photocatalytic processes are greatly suppressed when TiO2 is coated by MgO. Finally, the potential applications of these two types of textiles were proposed. This work offers a unique insight into the development of special textiles through the combination of new energy and environmental technologies and traditional textile research.

Study on the Photoluminescence Properties of Electrodeposited Y2O3 : Tb3 + Thin-Film Phosphor

In this work, photoluminescence properties of Y 2 O 3 :Tb 3+ thin-film phosphors were studied in detail. Y 2 O 3 :Tb 3+ thin-film phosphors were prepared by a two-step process: electrodeposition followed by an annealing process. Photoluminescence properties of the Y 2 O 3 :Tb 3+ thin-film phosphors strongly depend on the atomic content of Tb 3+ . The strongest photoluminescence emission was achieved with the atomic content of Tb 3+ of 5.02 atom %. The photoluminescence decay behavior of the Y 2 O 3 :Tb 3+ thin-film phosphors was also studied to understand the concentration quenching behavior. Based on the results and calculations, the concentration quenching of Tb 3+ was caused by the dipole―dipole interaction between Tb 3+ ions.

A facile preparation and the luminescent properties of Eu{sup 3+}-doped Y{sub 2}O{sub 2}SO{sub 4} nanopieces

The europium(III)-doped yttrium oxysulfate (Y2O2SO4:Eu3+) nanopieces have been prepared via electrospinning followed by calcination at 1000 °C in mixed gas of sulfur dioxide and air. Based on the experimental results, a possible formation mechanism for the nanopieces is that the nanopieces are determined by the directing template of electrospun nanoribbons and the multilayer crystal structure of Y2O2SO4. Besides, the nanopieces show excellent luminescent properties with emissions at 581, 589, 597, 653, 619, and 697 nm resulting from the 5D0 → 7FJ (J = 0, 1, 2, 3, 4) transition of Eu3+. The peaks of charge transfer and 5D0 → 7F2 transition of Eu3+ obviously have red shifts comparing to those of both Y2O3:Eu3+ nanoribbons and commercial Y2O3:Eu3+. Moreover, the nanopieces exhibit stronger intensities than the Y2O3:Eu3+ in excitation and emission spectra. Concentration quenching in the nanopieces occurs when Eu3+ concentration is 11 mol%, indicating that the nanopieces have an optimum luminescent intensity under this doping concentration.

Preparation and luminescent properties of Tb3+ doped Y2O2SO4 microflakes

Abstract Tb3+ doped Y2O2SO4 (Y2O2SO4:Tb3+) microflakes were prepared by a combination method of electrospinning and calcination. The two-dimensional microflakes had smooth surface and high radial/axial ratio. Crystal structures of the Y2O2SO4:Tb3+ microflakes resulted in layer by layer growth in axial direction. A possible formation mechanism was proposed on the basis of experimental results, which indicated that poly(vinyl pyrrolidone) played the role of the nanostructure directing template and revealed the growth priority in radial direction. The microflakes showed a favourable fluorescent property symbolised by the characteristic green emission (541 nm) resulting from the 5D4→7F5 transition of Tb3+ ions under 229 nm ultraviolet excitation. The maximum intensity of Tb3+ emission of the Y2O2SO4:Tb3+ microflakes was 2·3 times stronger than that of the Y2O2SO4:Tb3+ bulk powders with the same doping concentration.

Highly Improved Photoluminescence Properties of Electrodeposited Y2O3:Eu3+ Thin-Film Phosphors by the Addition of Li+ Ions

In this work, Y 2 O 3 :Eu 3+ thin-film phosphors were prepared by an electrodeposition method. The effect of Li + ions on the photoluminescence properties of Y 2 O 3 :Eu 3+ thin-film phosphor was studied in detail. The addition of Li + ions could improve the photoluminescence intensity by around 3.5 times. The greatly improved photoluminescence intensity may be caused by different factors. The most likely factors are the improved crystallinity and the increased optical volume caused by the flux effect of Li + ions.