Co-reporter:Chunming Yang, Guimei Gao, Zhifeng Guo, Litao Song, Junzhou Chi, Shucai Gan
Applied Surface Science 2017 Volume 400(Volume 400) pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.apsusc.2016.12.194
•Unique chrysanthemum-like Co3O4/Bi2O2CO3 photocatalyst was synthesized by two-step hydrothermal process.•The Co3O4/Bi2O2CO3 composites showed superior photocatalytic activity and stability.•The mechanism of the high performance was proposed as well.A hierarchical flower-like Co3O4/Bi2O2CO3 composite photocatalyst with a p-n heterojunction semiconductor structure has been synthesized via two-step hydrothermal process. The composite photocatalyst have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM), BET surface area, UV–vis diffuse reflectance spectra (DRS), electron spin resonance (ESR) and photoluminescence spectroscopy (PL). The photocatalyst exhibits enhanced photocatalytic activity for methyl orange (MO) degradation under visible light irradiation. The ESR results reveal that the superoxide radicals (O2−) were the main active species in the photocatalytic system. The 0.6 wt% Co3O4/Bi2O2CO3 exhibits the highest photocatalytic activity as compared with other samples because of the formation of the p-n junction between p-Co3O4 and n-Bi2O2CO3, which effectively suppresses the recombination of photoinduced electron-hole pairs and increase of the concentration of superoxide radicals (O2−) involving in the photodegradation process. Moreover, the mechanism of the enhanced photocatalytic properties was proposed.Download high-res image (123KB)Download full-size image
Co-reporter:Chunming Yang;Guimei Gao;Junjun Zhang;Ruiping Liu;Ruicheng Fan;Ming Zhao;Yongwang Wang;Shucai Gan
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 22) pp:14431-14441
Publication Date(Web):2017/06/07
DOI:10.1039/C7CP02136D
A CdWO4/Bi2O2CO3 core–shell heterostructure photocatalyst was fabricated via a facile two-step hydrothermal process. Flower-like Bi2O2CO3 was synthesized and functioned as the cores on which CdWO4 nanorods were coated as the shells. Photoluminescence (PL) spectra and electron paramagnetic resonance (EPR) demonstrate that the CdWO4/Bi2O2CO3 core–shell heterostructure photocatalyst possesses a large amount of oxygen vacancies, which induce defect levels in the band gap and help to broaden light absorption. The photocatalyst exhibits enhanced photocatalytic activity for Rhodamine B (RhB), methylene blue (MB), methyl orange (MO), and colorless contaminant phenol degradation under solar light irradiation. The heterostructured CdWO4/Bi2O2CO3 core–shell photocatalyst shows drastically enhanced photocatalytic properties compared to the pure CdWO4 and Bi2O2CO3. This remarkable enhancement is attributed to the following three factors: (1) the presence of oxygen vacancies induces defect levels in the band gap and increases the visible light absorption; (2) intimate interfacial interactions derived from the core–shell heterostructure; and (3) the formation of the n–n junction between the CdWO4 and Bi2O2CO3. The mechanism is further explored by analyzing its heterostructure and determining the role of active radicals. The construction of high-performance photocatalysts with oxygen vacancies and core–shell heterostructures has great potential for degradation of refractory contaminants in water with solar light irradiation.
Co-reporter:Yimai Liang, Na Guo, Linlin Li, Ruiqing Li, Guijuan Ji and Shucai Gan
New Journal of Chemistry 2016 vol. 40(Issue 2) pp:1587-1594
Publication Date(Web):30 Nov 2015
DOI:10.1039/C5NJ02388B
Three-dimensional (3D) flower-like Ag/ZnO heterostructures with different Ag content were prepared using a facile two-step method. The samples structure, morphology and optical properties were well-characterized using XRD, SEM, EDS, XPS, DRS, PL and ICP-AES techniques. The results demonstrated the successful deposition of Ag nanoparticles on a flower-like ZnO surface. The photocatalytic performance was evaluated by the photocatalytic degradation of rhodamine B (RhB) under ultraviolet and visible light. The results showed that the Ag/ZnO heterostructures had superior photocatalytic activity compared to the pure ZnO samples and the commercial photocatalyst TiO2 (Degussa, P25). The enhanced photocatalytic activity was attributed to the effective separation of electron/hole pairs on flower-like ZnO by employing Ag nanoparticles as a conductor. Furthermore, 3D flower-like Ag/ZnO microspheres exhibited good recycling stabilities over several separation cycles photodegradation.
Co-reporter:Zhihua Leng, Linlin Li, Yali Liu, Nannan Zhang, Shucai Gan
Journal of Luminescence 2016 Volume 173() pp:171-176
Publication Date(Web):May 2016
DOI:10.1016/j.jlumin.2016.01.010
Dy3+ and Eu3+ codoped KSr4(BO3)3 phosphors were successfully synthesized by solid-state reaction process. Under near-ultraviolet (near-UV) excitation, individual Dy3+ or Eu3+ ion activated sample exhibits characteristic emissions in their respective regions. In KSr4(BO3)3:Dy3+, xEu3+ phosphors, the energy transfer from Dy3+ to Eu3+ was revealed to be resonant type by dipole–dipole mechanism. And the critical distance RDy–Eu was calculated to be 13.95 Å. The energy transfer efficiency of KSr4(BO3)3:Dy3+, xEu3+ reached about 20% when the concentration of Eu3+ was 0.035. Moreover, the emitting colors of Dy3+ and Eu3+ codoped samples can be adjusted from the edge of white area to warm white via tuning the activator (Eu3+) doped concentration. More significantly, the chromaticity coordinates (0.334, 0.351) of KSr4(BO3)3:0.005Dy3+, 0.015Eu3+ sample are extremely adjacent to standard white light (0.33, 0.33). The quantum efficiency of the KSr4(BO3)3:0.005Dy3+, 0.015Eu3+ phosphor with 389 nm excitation is found to be 42%, demonstrating that the obtained single-component white-emitting phosphor exhibits potential applications for solid state lighting.
Co-reporter:Junjun Zhang, Tianqi Zhao, Lianchun Zou, Shucai Gan
Journal of Photochemistry and Photobiology A: Chemistry 2016 Volume 314() pp:35-41
Publication Date(Web):1 January 2016
DOI:10.1016/j.jphotochem.2015.08.009
•PbMoO4:Eu3+ phosphors were produced via ultrasound-assisted precipitation route.•Bright red light could be observed from PbMoO4:Eu3+ under the excitation line at 466 nm.•The Egap values decrease with increasing Eu3+ ions doping concentrations.Herein, PbMoO4 and PbMoO4:Eu3+ nanocrystals (NCs) with homogeneous grain size were successfully prepared via a simple but effective ultrasound-assisted precipitation process. These NCs samples were analyzed by X-ray diffraction (XRD), ultraviolet-visible (UV–vis) absorption spectroscopy, field-emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), photoluminescence (PL) and decay curve measurements. XRD patterns indicated that the PbMoO4 NCs present a scheelite-type tetragonal structure without the presence of secondary phases. UV–vis absorption spectra of the prepared PbMoO4 NCs indicate they had absorption in the UV region. The Egap values decrease with increasing Eu3+ ions doping concentrations. An intense PL emission at room temperature was observed in these PbMoO4 NCs when they were excited with a 300 nm wavelength. The luminescence spectra showed that PbMoO4:Eu3+ phosphors can be effectively excited by the blue light, and exhibited strong red emission around 613 nm attributed to the 5D0 → 7F2 transition. It was also found that the process of energy transfer among the nearest neighbor ions plays an important role in quenching luminescence of Eu3+ ions.PbMoO4 and PbMoO4:Eu3+ NCs were successfully synthesized via a facile ultrasound-assisted precipitation method. The luminescence spectra showed that PbMoO4:Eu3+ phosphors can be effectively excited by the blue light.
Co-reporter:Yali Liu, Chunming Yang, Hailong Xiong, Nannan Zhang, Zhihua Leng, Ruiqing Li, Shucai Gan
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 502() pp:139-146
Publication Date(Web):5 August 2016
DOI:10.1016/j.colsurfa.2016.05.006
•Modified the morphology of YVO4 nanocrystals by varying the pH value of solution.•Using different surfactants to obtain the products with different morphology.•Study the luminescent properties of YVO4:Ln3+ nanoparticles.•Comparison of PL intensity of different morphologies.YVO4 nano/microcrystals with multiform morphologies were successfully synthesized via a facile hydrothermal method using NH4VO3 as vanadium source. The samples were characterized by XRD, FT-IR, SEM, EDX and photoluminescence (PL) spectroscopies. The experimental results indicate that the shape and size of as-prepared architectures can be rationally modified by controlling the reaction conditions, such as reaction time, different organic additives and the pH value of solution. Multiform morphologies YVO4:Eu3+ sample have been obtained with the sodium citrate reagent (Cit3−), macrogol (PEG), polyvinylpyrrolidone (PVP) and cetyl trimethyl ammonium bromide (CTAB) were employed as surfactant. When Cit3− added to solution, YVO4:Eu3+ has the highest PL intensity. In addition, the luminescent properties of the YVO4:Ln3+ (Ln = Eu, Dy and Sm) have been systematically investigate. Upon ultraviolet excitation, the obtained YVO4:Ln3+ exhibit red, light blue, orange red, emission, respectively.
Co-reporter:Ruiqing Li, Yali Liu, Nannan Zhang, Linlin Li, Lu Liu, Yimai Liang and Shucai Gan
Journal of Materials Chemistry A 2015 vol. 3(Issue 16) pp:3928-3934
Publication Date(Web):04 Mar 2015
DOI:10.1039/C5TC00371G
A series of Tb3+ and Eu3+ activated orthorhombic yttrium oxyfluoride, Y7O6F9 (denoted as V-YOF hereafter) phosphors were synthesized through a facile two-step hydrothermal synthesis route followed by heat treatment for the first time. The phase, morphologies, sizes and photoluminescence properties of as-prepared samples were investigated by means of XRD, SEM, and luminescence spectroscopy. A series of characteristic emission originated from the f–f transitions of Eu3+ and Tb3+ can be observed and multicolour emissions from green to yellow and then to red have been achieved in the V-YOF:Tb3+,Eu3+ samples under 378 nm irradiation. The energy transfer process from Tb3+ to Eu3+ was studied and demonstrated to be a quadrupole–quadrupole interaction mechanism. These results show that the V-YOF phosphors have potential applications in field-emission displays.
Co-reporter:Ruiqing Li, Linlin Li, Yimai Liang, Nannan Zhang, Yali Liu and Shucai Gan
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 33) pp:21485-21491
Publication Date(Web):21 Jul 2015
DOI:10.1039/C5CP03421C
In this study, monodisperse and uniform LaOF hollow spheres were successfully synthesized through a novel facile synthetic route employing a La(OH)CO3 sphere as a sacrificial template followed by a subsequent calcination process. The structure, morphology, formation process, and luminescence properties were well investigated using various techniques. The possible formation mechanism of evolution from the La(OH)CO3 spheres to the LaCO3F precursor, and to the final LaOF hollow spheres can be attributed to the Kirkendall effect and the decomposition of the LaCO3F precursor. Under ultraviolet excitation, the LaOF:Ln3+ (Ln = Eu,Tb) hollow spheres show their characteristic f–f emissions and exhibit red, green emissions, respectively. Moreover, by codoping the Tb3+ and Eu3+ ions into the LaOF host and tuning their relative concentration ratio, multicolor tunable emissions are obtained due to the efficient energy transfer from Tb3+ to Eu3+ at 378 nm excitation. This material may find potential application in color display fields.
Co-reporter:Lu Liu, Yimai Liang, Linlin Li, Lianchun Zou and Shucai Gan
CrystEngComm 2015 vol. 17(Issue 40) pp:7754-7761
Publication Date(Web):10 Sep 2015
DOI:10.1039/C5CE01118C
White light-emitting NaGdF4 phosphor samples based on efficient energy transfer between Tb3+ and Eu3+ were synthesized via a conventional hydrothermal reaction process. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra and lifetime measurement were performed to characterize the samples. The energy transfer process between Tb3+ and Eu3+ was demonstrated to be a resonant type via a dipole–dipole interaction mechanism. Furthermore, for NaGdF4:Tb3+,Eu3+, white light emission can be realized in the single-phase NaGdF4 host by reasonably adjusting the relative doping concentrations of Tb3+ and Eu3+ under ultraviolet excitation. Due to their excellent PL properties and good CIE chromaticity coordinates, the as-prepared Tb3+, Eu3+ co-doped NaGdF4 nanocrystalline phosphors have potential application in field-emitting displays.
Co-reporter:Lu Liu, Nannan Zhang, Zhihua Leng, Yimai Liang, Ruiqing Li, Lianchun Zou and Shucai Gan
Dalton Transactions 2015 vol. 44(Issue 14) pp:6645-6654
Publication Date(Web):02 Mar 2015
DOI:10.1039/C5DT00581G
This paper describes a simple and environmentally-friendly approach that allowed for the facile synthesis of a gadolinium-based core/shell/shell nanotube structure with a set of lanthanide ions incorporated into separated layers. In addition, by the rational design of a core/shell structure we systematically investigated the luminescence properties of different lanthanide ions in NaGdF4 host, and efficient down-conversion emission can be realized through gadolinium sublattice-mediated energy migration. The Gd3+ ions play an intermediate role in this process. By changing the doped lanthanide ions, we generated multicolour emissions from the luminescent Ln3+ centers via energy transfer of Ce3+→Gd3+→Ln3+ and Ce3+→Ln3+ (Ln = Eu, Tb, Dy and Sm) in separated layers. Due to the strong absorption of ultraviolet (UV) irradiation by Ce3+ ions, the luminescence efficiency could be enhanced after doping Ce3+ ions in the shell. In NaGdF4:5% Eu3+@NaGdF4@NaGdF4:5% Ce3+ core/shell/shell nanotubes, with increasing the NaGdF4 interlayer thickness, a gradual decrease in emission intensity was observed for the Eu3+ activator.
Co-reporter:Ruiqing Li, Nannan Zhang, Linlin Li, Yimai Liang, Yali Liu and Shucai Gan
New Journal of Chemistry 2015 vol. 39(Issue 9) pp:7019-7025
Publication Date(Web):02 Jul 2015
DOI:10.1039/C5NJ01119A
A series of undoped and Eu3+ doped YOF and Y1−xGdxOF (x = 0–0.7) crystals were prepared via a urea based homogeneous precipitation method followed by a heat treatment process. After Gd3+ doping, we observed the crystal phase transition, morphology transformation, and greatly enhanced luminescence properties of the YOF crystals. The results reveal that the addition of Gd3+ can promote the phase transition from the hexagonal phase to the rhombohedral phase and the morphology transformation from spheres, though a mixture of rods and spheres, to spheres. The luminescence properties of Eu3+ doped YOF phosphors were investigated upon UV excitation and the quenching concentration of Eu3+ was found to be 10 mol%. More importantly, the luminescence intensity after doping a certain amount of Gd3+ increased by 31 times compared to that of the Gd3+ free sample, which may be due to the modification of the crystal field and the crystal phase of YOF, providing an effective way to gain numerous Gd3+ doped luminescent materials. These results show that the Gd3+ doped red phosphors have potential applications in white light emitting diodes.
Co-reporter:Ruiqing Li, Linlin Li, Wenwen Zi, Junjun Zhang, Lu Liu, Lianchun Zou and Shucai Gan
New Journal of Chemistry 2015 vol. 39(Issue 1) pp:115-121
Publication Date(Web):10 Sep 2014
DOI:10.1039/C4NJ01136H
YOF:Ln3+ (Ln = Eu, Tb, Dy, Tm) nano-/microcrystals with high uniformity, monodispersity and a variety of well-defined morphologies, such as submicro spheres, ellipsoids, nanorods, microspindles and spindle nanorod bundles, have been successfully synthesized via a urea based homogeneous precipitation method followed by a heat-treatment process. The influence of pH values, fluoride sources and reaction time on the sizes and morphologies of the as-prepared precursor was systematically investigated and discussed. The possible formation mechanism for the precursor has been presented. Upon ultraviolet excitation, the YOF:Ln3+ (Ln = Eu, Tb, Dy, Tm) submicro spheres show their characteristic f–f emissions and give red, green, yellow, and blue emission, respectively. Moreover, a novel single-phased and near-UV-pumped white-light-emitting phosphor YOF:Tm3+,Dy3+ was also successfully fabricated by singly varying the doping content of Dy3+ with a fixed Tm3+ content through the principle of energy transfer. This merit of multicolor emissions in the visible region endows materials of this kind with potential application in field-emission display devices and white light-emitting diodes.
Co-reporter:Junjun Zhang, Yali Liu, Linlin Li, Nannan Zhang, Lianchun Zou and Shucai Gan
RSC Advances 2015 vol. 5(Issue 37) pp:29346-29352
Publication Date(Web):18 Mar 2015
DOI:10.1039/C5RA03913D
In this paper, Bi2MoO6:Eu3+ phosphors were successfully synthesized via a facile, efficient hydrothermal synthesis process followed by a further calcination treatment without using any surfactants. The samples were analyzed by XRD, UV-vis absorption spectroscopy, photoluminescence (PL) and decay curve measurements. XRD patterns reveal that all the diffraction peaks could be indexed to well-crystallized orthorhombic structures. UV-visible diffuse reflection spectra of the prepared Bi2MoO6 and Bi2MoO6:Eu3+ indicate that they had absorption in the UV-light region. The luminescence spectra showed that Bi2MoO6:Eu3+ phosphors can be effectively excited by UV light (328 nm), and exhibited strong red emission around 613 nm attributed to the Eu3+ 5D0 → 7F2 transition. Effects of Eu3+ concentration on lattice constants and PL were presented.
Co-reporter:Nannan Zhang, Hailong Xiong, Yali Liu, Ruiqing Li, Zhihua Leng, Shucai Gan
Applied Surface Science 2015 Volume 357(Part A) pp:255-261
Publication Date(Web):1 December 2015
DOI:10.1016/j.apsusc.2015.09.058
Highlights
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The luminescence properties of Bi2O2CO3:Eu3+ are studied for the first time.
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The photoluminescence intensity is related to crystallinity and size uniformity.
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Different morphologies of Bi2O2CO3 are obtained by urea-based precipitation method.
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Uniform nanosheet phosphor shows strongest red light than the other two shapes.
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The CIE coordinate of prepared red phosphor is close to the standard (0.67, 0.33).
Co-reporter:Yimai Liang, Na Guo, Linlin Li, Ruiqing Li, Guijuan Ji, Shucai Gan
Applied Surface Science 2015 Volume 332() pp:32-39
Publication Date(Web):30 March 2015
DOI:10.1016/j.apsusc.2015.01.116
Highlights
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Unique porous 3D flower-like Ag/ZnO composites were successfully synthesized.
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No pore-directing reagents or surfactants are used in the synthesis of the Ag/ZnO.
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Compared with Degussa P25, the Ag/ZnO exhibited superior photocatalytic activity.
Co-reporter:Yimai Liang, Na Guo, Linlin Li, Ruiqing Li, Guijuan Ji and Shucai Gan
RSC Advances 2015 vol. 5(Issue 74) pp:59887-59894
Publication Date(Web):22 Jun 2015
DOI:10.1039/C5RA08519E
Porous 3D Ce-doped ZnO microflowers were prepared by a hydrothermal method followed by a low temperature annealing process. The effects of Ce doping on the structural and photocatalytic properties of porous ZnO microflowers were investigated in detail. The samples were characterized using XRD, SEM, EDS, XPS, DRS, PL spectra and BET surface area measurements. According to the XRD analysis, both of the crystalline structures of the synthesized pure ZnO and Ce-doped ZnO samples are hexagonal wurtzite. The XPS results demonstrated the successful synthesis of Ce4+ doped ZnO. In addition, the SEM morphologies showed the unique porous 3D flower-like structure of the Ce-doped ZnO. Compared with the porous ZnO microflowers, the Ce-doped ZnO samples exhibit improved photocatalytic performance in the decomposition of Rhodamine B (RhB). It is proposed that the special structural feature with a porous 3D structured and Ce modification lead to the rapid photocatalytic activity of the Ce-doped ZnO microflowers.
Co-reporter:Linlin Li, Yali Liu, Ruiqing Li, Zhihua Leng and Shucai Gan
RSC Advances 2015 vol. 5(Issue 10) pp:7049-7057
Publication Date(Web):08 Dec 2014
DOI:10.1039/C4RA15643A
A series of Tm3+- and Dy3+-codoped LiLa(MoO4)x(WO4)2−x phosphors were prepared via the conventional solid-state reaction method. It was discovered that the optimum single doped concentrations of both Tm3+ and Dy3+ are 0.04 for the LiLa(WO4)2 host; moreover, LiLa(WO4)2:0.04Tm3+ and LiLa(WO4)2:0.04Dy3+ emit blue and yellow light, respectively. On the other hand, the emission colors of Tm3+- and Dy3+-codoped LiLa(WO4)2 could be tuned from blue to white by tuning the energy transfer. With increase in the Dy3+ doped concentration, the energy transfer efficiency of LiLa(WO4)2:0.005Tm3+,yDy3+ increased gradually and reached as high as 88% when the concentration of Dy3+ was 0.05. The energy transfer from Tm3+ to Dy3+ was revealed to be resonant via the quadrupole–quadrupole mechanism. As for LiLa(MoO4)x(WO4)2−x:0.005Tm3+,0.03Dy3+ phosphors, the emission intensities of both Tm3+ and Dy3+ were found to reach a maximum when the molar ratio of Mo/W was 0:2. In addition, with increase in the proportion of MoO42−, the location of the chromaticity coordinates changed from the edge to the center of the white area. When the relative ratio of Mo/W was 2:0, the chromaticity coordinates were much closer to the standard chromaticity coordinates for white light. The results indicate that these phosphors may have potential applications in the fields of UV-excited white light-emitting diodes.
Co-reporter:Junjun Zhang, Tianqi Zhao, Bingnan Wang, Linlin Li, Lianchun Zou, Shucai Gan
Journal of Physics and Chemistry of Solids 2015 Volume 79() pp:14-22
Publication Date(Web):April 2015
DOI:10.1016/j.jpcs.2014.11.003
•CdMoO4: Tb3+ phosphors have been synthesized by PEG-assisted hydrothermal synthesis.•The possible formation process of the CdMoO4 microspheres structures was discussed.•The Tb3+-doped CdMoO4 microspheres exhibit strong green emissions.•The influence of reaction conditions on the formation of the products is investigated.In the presence of polyethylene glycol (PEG), we first investigate a facile hydrothermal process to fabricate CdMoO4:Tb3+ green phosphor. The morphology and size of the products can be controlled by simply tuning the PEG amounts and the reaction time. The XRD results show that the CdMoO4:Tb3+ can be indexed to CdMoO4 phase. FE-SEM results revealed that the pure CdMoO4 was a sphere with a diameter of about 2.6 μm. The photoluminescence (PL) properties of CdMoO4:Tb3+ phosphors indicated energy transfer from MoO42- groups to Tb3+. PL spectra indicated the phosphors emitted green light centered at 544 nm under ultraviolet excitation. Simultaneously, this novel and efficient pathway could open new opportunities for further investigating about the properties of molybdate materials.3D well-defined CdMoO4:Tb3+ microspheres have been successfully synthesized using a facile hydrothermal synthesis route in the presence of PEG. Photoluminescence spectra indicated the phosphors emitted strong green light centered at 544 nm under ultraviolet light excitation.
Co-reporter:Hong YU, Jinlei CHEN, Yong PU, Tiejun ZHANG, Shucai GAN
Journal of Rare Earths 2015 Volume 33(Issue 4) pp:366-370
Publication Date(Web):April 2015
DOI:10.1016/S1002-0721(14)60428-2
Sr2MgSi2O7:Tb3+,Ce3+ phosphors were synthesized by solid-state reaction and placed in a muffle furnace in a reducing atmosphere at 1300 °C for 3 h. Photoluminescence properties and energy transfer were investigated. The Ce3+/Tb3+ energy transfer was thoroughly investigated by their emission/excitation spectra and photoluminescence lifetime, there was shortened lifetime of Ce3+ (from 51.31 to 50.06 ns) which could support evidence of energy transfer from Ce3+ to Tb3+ in the host. The varied emitted color of Sr1.97–yMgSi2O7:0.03Tb3+, yCe3+ phosphors could be achieved by altering the concentration of Ce3+, the chromaticity coordinates (x, y) varied from (0.225, 0.376) to (0.172, 0.231). In Sr1.96MgSi2O7:0.03Tb3+,0.01 Ce3+ phosphors, the results indicated that Sr2MgSi2O7:Tb3+,Ce3+ might be useful as tunable phosphors for ultraviolet white-light-emitting diodes.Photoluminescence emission (λex=332 nm) spectra of Sr2–x–yMgSi2O7:xTb3+, yCe3+ (The inset shows the excitation and emission spectra of Sr1.99MgSi2O7:0.01Ce3+)
Co-reporter:Fengying Guo;Wenwen Zi;Guijuan Ji;Lianchun Zou
Journal of Polymer Research 2015 Volume 22( Issue 4) pp:
Publication Date(Web):2015/04/01
DOI:10.1007/s10965-015-0660-3
Co-reporter:Zhihua Leng, Nannan Zhang, Yali Liu, Linlin Li, Shucai Gan
Applied Surface Science 2015 330() pp: 270-279
Publication Date(Web):1 March 2015
DOI:10.1016/j.apsusc.2015.01.046
•Pancake-like/flower-like/leaf-like GdBO3 were obtained via a hydrothermal method.•Gd(OH)3 nanorods and borates were used as the precursors for the first time.•A dissolution and recrystallization process was happened induced by the excess borax.•Three products have the similar stacked arrangements to reduce the surface energy.•The luminescence properties of GdBO3:Eu3+ are related to shape and crystallinity.Monodisperse pancake-like/flower-like/leaf-like GdBO3 samples have been successfully synthesized via a designed hydrothermal conversion method using H3BO3, Na2B4O7·10H2O, or NaBO2·4H2O as boron sources, respectively. It was found that different boron sources have crucial influences on the formation and morphology of the products. The Gd(OH)3 nanorods precursors were prepared through a simple hydrothermal process, which then served as sacrificial templates for the fabrication of GdBO3 micropancakes/microflowers/microleaves via a hydrothermal conversion process. FT-IR spectra confirm that vaterite-type GdBO3 can be synthesized by this method. The possible formation mechanisms for different microstructures were put forward on the basis of a series of time-dependent control experiments. The products have similar stacked arrangements driven by the minimization of the interfacial and surface energy of the hydrothermal system. An investigation on the photoluminescence (PL) properties of GdBO3:Eu3+ samples with different morphologies indicates that the PL properties of as-obtained GdBO3:Eu3+ phosphors are strongly dependent on their morphology and crystallinity. The flower-like structure exhibits the strongest red emission.
Co-reporter:Guihong Yu, Shucai Gan
Journal of Molecular Structure 2015 1091() pp: 159-162
Publication Date(Web):
DOI:10.1016/j.molstruc.2015.02.073
Co-reporter:Zhihua Leng, Yali Liu, Nannan Zhang, Linlin Li, Shucai Gan
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 Volume 472() pp:109-116
Publication Date(Web):5 May 2015
DOI:10.1016/j.colsurfa.2015.02.046
•Cake-like and olive-like GdBO3 self-assembled of nanoparticles were synthesized.•This method used Gd(OH)CO3 and NaBO2·4H2O as the precursors for the first time.•When a small amount of ethanol was added, different morphologies can be obtained.Uniform cake-like and olive-like GdBO3 samples have been successfully synthesized for the first time via a simple solution-based hydrothermal method using Gd(OH)CO3 colloid spheres and NaBO2·4H2O as the precursors. It was found that small amount ethanol in the hydrothermal process was responsible for determining the shape of products. The FT-IR analysis indicates that vaterite-type GdBO3 can be synthesized by this method. The obtained cake-like and olive-like GdBO3 with rough surfaces have similar mircostructures which are composed of numerous nanoparticles. Time-dependent experiments were employed to study the possible formation mechanism. The formation of cake-like and olive-like GdBO3 mircostructures self-assembled of nanoparticles can be ascribed to the Ostwald ripening process. A detailed investigation on the photoluminescence (PL) properties of GdBO3:Eu3+ samples with different morphologies indicates that the PL properties of as-obtained GdBO3:Eu3+ phosphors are dependent on their morphologies. The effect of Eu3+ doping concentration on PL intensity was also investigated and the quenching concentration of GdBO3:Eu3+ is 20%.Small amount of ethanol has a favorable effect on controlling the products’ morphology. The formation of cake-like and olive-like GdBO3 microcrystals self-assembled of nanoparticles can be assigned to the Ostwald ripening process.
Co-reporter:Junjun Zhang, Ruiqing Li, Lu Liu, Linlin Li, Lianchun Zou, Shucai Gan, Guijuan Ji
Ultrasonics Sonochemistry 2014 Volume 21(Issue 5) pp:1736-1744
Publication Date(Web):September 2014
DOI:10.1016/j.ultsonch.2014.03.023
•Sphere-like SrMoO4 micro-architectures have been synthesized by sonochemistry process.•The possible formation process of the SrMoO4 hierarchical structures was discussed.•The Ln3+-doped SrMoO4 microspheres exhibit strong light emissions with different colors.•The energy transfer process from host to rare earth ions were investigated systematically.Three-dimensional (3D) well-defined SrMoO4 and SrMoO4:Ln3+ (Ln = Eu, Sm, Tb, Dy) hierarchical structures of obvious sphere-like shape have been successfully synthesized using a large-scale and facile sonochemical route without using any catalysts or templates. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and photoluminescence (PL) spectra were used to characterize the samples. The intrinsic structural feature of SrMoO4 and external factor, namely the ultrasonic time and the pH value, are responsible for the ultimate shape evolutions of the product. The possible formation mechanism for the product is presented. Additionally, the PL properties of SrMoO4 and SrMoO4:Ln3+ (Ln = Eu, Sm, Tb, Dy) hierarchical structures were investigated in detail. The Ln3+ ions doped SrMoO4 samples exhibit respective bright red–orange, yellow, green and white light of Eu3+, Sm3+, Tb3+ and Dy3+ under ultraviolet excitation, and have potential application in the field of color display. Simultaneously, this novel and efficient pathway could open new opportunities for further investigating about the properties of molybdate materials.
Co-reporter:Junjun Zhang, Nannan Zhang, Lianchun Zou and Shucai Gan
RSC Advances 2014 vol. 4(Issue 72) pp:38455-38465
Publication Date(Web):18 Aug 2014
DOI:10.1039/C4RA05038J
In the present work, large-scale uniform CdMoO4 and CdMoO4:Ln3+ (Ln = Pr, Sm, Eu, Dy, Ho, Er) microspheres have been successfully synthesized via a facile sonochemical route. XRD, FE-SEM, EDS, the Brunauer–Emmett–Teller (BET) surface area, and photoluminescence (PL) spectra were used to characterize the samples. The results show that the CdMoO4:Ln3+ can be directly indexed to the tetragonal CdMoO4 phase with high purity. The influence of the reaction time and reactants on the size and shapes of the CdMoO4 microspheres has been studied, and the results revealed that the ultrasonication time and reactants play a crucial role in determining the final morphologies of the samples. Additionally, the PL properties of the CdMoO4 and CdMoO4:Ln3+ (Ln = Pr, Sm, Eu, Dy, Ho and Er) microspheres were investigated in detail. It can be seen that the CdMoO4:Pr3+, Sm3+, Eu3+, Dy3+, Ho3+ and Er3+ samples are located in the red, yellow, red, white, yellow and green regions, respectively. Simultaneously, this novel and efficient pathway could open new opportunities for further investigating the properties of molybdate materials.
Co-reporter:Ruiqing Li, Wenwen Zi, Linlin Li, Lu Liu, Junjun Zhang, Lianchun Zou, Shucai Gan
Journal of Alloys and Compounds 2014 Volume 617() pp:498-504
Publication Date(Web):25 December 2014
DOI:10.1016/j.jallcom.2014.08.118
•We reported a simple route to synthesize the Y2O3 HNSs.•A possible formation mechanism of the Y2O3 HNSs was proposed.•The Ln-doped Y2O3 HNSs exhibit characteristic emission with different colors.•White-light-emitting phosphor Y2O3:Tm3+, Dy3+ was also successfully synthesized.A novel, fast and simple method was developed to synthesize the undoped and lanthanide-doped yttrium oxide hollow nanospheres (Y2O3⋅HNSs) with multicolored downconversion emission under mild conditions by employing poly (acrylic acid sodium salt) microspheres (PAAS MSs) as active templates followed by a subsequent calcination process. The structure, morphology, formation process, and fluorescent properties are well investigated using various techniques. The results show that the samples can be well indexed to the pure cubic phase of Y2O3. The possible formation mechanism of the PAAS MSs, PAA-Y precursor, and Y2O3 HNSs are proposed and discussed in detail. Upon ultraviolet excitation, the obtained Y2O3:Ln3+ (Ln = Eu, Dy, Er, Tm) HNSs exhibit strong red, yellow–green, blue, yellow emission, respectively. Moreover, a novel single-phased and near-UV-pumped white-light-emitting phosphor Y2O3:Tm3+, Dy3+ was also successfully fabricated through optimizing the molar ratio among Tm3+ and Dy3+ in the Y2O3 host. This material may find potential applications in field-emission display devices and white ultraviolet light-emitting diodes (UV LEDs). Furthermore, this synthesis route may be of great significance in the preparation of other hollow spherical materials.
Co-reporter:Lu Liu, Ruiqing Li, Yuefeng Deng, Linlin Li, Shi Lan, Wenwen Zi, Shucai Gan
Applied Surface Science 2014 Volume 307() pp:393-400
Publication Date(Web):15 July 2014
DOI:10.1016/j.apsusc.2014.04.044
Highlights
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OmimPF6 acts not only as a reactant but also as a morphology-directing agent was introduced to prepare uniform LuF3 nanocrystals.
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Morphology and size-controlled synthesis of rare earth doped LuF3 for the first time, different shapes of the orthorhombic LuF3 nanocrystals were obtained in this research.
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The effect of different sizes and morphologies on luminescence properties has also been discussed.
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This study provides more alternatives of rare earth fluorides that exhibit strong characteristic emission, and further complements the exploration of Lu-based nanomaterials, which may have unique properties that the Y/Ln-based nanoparticles do not possess and may serve as versatile luminescent phosphors for further application.
Co-reporter:Na Guo, Yimai Liang, Shi Lan, Lu Liu, Guijuan Ji, Shucai Gan, Haifeng Zou, Xuechun Xu
Applied Surface Science 2014 Volume 305() pp:562-574
Publication Date(Web):30 June 2014
DOI:10.1016/j.apsusc.2014.03.136
Highlights
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Unique hollow structure of TiO2–SiO2 nanosphere was successfully synthesized via a simple sol–gel method.
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The as-synthesized TiO2–SiO2 nanosphere possesses large BET surface area of 1105 m2/g, and an average pore diameter of 2.6 nm.
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The as-prepared samples displayed both high adsorption capability and degradation efficiency of azo dyes and phenol.
Co-reporter:Shi Lan, Lu Liu, Ruiqing Li, Zhihua Leng, and Shucai Gan
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 8) pp:3131
Publication Date(Web):February 4, 2014
DOI:10.1021/ie404053m
Hierarchical hollow structure ZnO (CZ-400) was synthesized successfully by a facile homogeneous precipitation method. Morphology, structure, and optical properties of the as-prepared CZ-400 were characterized by different techniques. The mentioned product possessed hollow core and hierarchical shell morphology, and grew well-crystallinity with high surface area. The CZ-400 exhibited adsorption capacity and photocatalyst activity toward congo red (CR) higher than those of TiO2 P25 and commercial ZnO. This is attributed to the hierarchical structure of CZ-400, which provides the improved charge transport and the reduced recombination rate of photogenerated electron–hole pairs. In addition, the combinatorial effect of adsorption and photodegradation reflected the importance of adsorption in the enhanced photoreactivity. The results indicated that CZ-400 is a potential catalyst and adsorbent material for removal of CR from water samples.
Co-reporter:Shi Lan;Ruiqing Li;Zhihua Leng;Na Guo ;Shucai Gan
Journal of Applied Polymer Science 2014 Volume 131( Issue 20) pp:
Publication Date(Web):
DOI:10.1002/app.40957
ABSTRACT
Poly(barbituric acid) functionalized magnetic nanoparticles with excellent adsorption behavior were facilely synthesized through one-step chemical oxidation polymerization method by using sodium borohydride as the reducing agent. Structure, morphology, and magnetism of the products were thoroughly investigated by means of FTIR, FESEM, EDX, X-ray photoelectron spectra, thermogravimetric analyzer–differential scanning calorimetry, and vibrating sample magnetometer. The products were of a sphere-shaped nanostructure with the saturation magnetization value of 7.5 emu g−1, which make them reusable for adsorption application. Removal capability for heavy metal ions were systematically evaluated using Pd (II) and Cu (II) ions as the models. The maximum sorption capacities by applying the Langmuir equation were calculated to be 166.6 mg/g for Cu (II) and 142.8 mg/g for Pb (II). A recycle test revealed that the PBA-MNPs have above 87.1% for Cu (II) and 82.69% for Pb (II) ion desorption efficiency after the three regeneration cycle process. All the above experimental results demonstrated that barbituric acid-based material could be used as a possible adsorbent for the efficient removal of heavy metals from aqueous solution. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40957.
Co-reporter:Linlin Li, Junjun Zhang, Wenwen Zi, Shucai Gan, Guijuan Ji, Haifeng Zou, Xuechun Xu
Solid State Sciences 2014 Volume 29() pp:58-65
Publication Date(Web):March 2014
DOI:10.1016/j.solidstatesciences.2014.01.003
•Eu3+-activated MRE(MoO4)2 have been successfully prepared via the solid-state method.•The emission intensity was found to decrease with increasing the size of alkali cations.•The emission intensity was found to decrease with decreasing size of rare earth ions.•The emission intensity of the obtained phosphors is much stronger than that of Y2O3:Eu3+.A series of Eu3+-activated double molybdate phosphors MRE(MoO4)2 (M = Li, Na, K; RE = Gd, Y, Lu) have been successfully prepared via the conventional solid-state reaction method. The effects of alkali cations and rare earth ions on the luminescence of MRE(MoO4)2:Eu3+ were investigated in detail. The experimental results show that the emission intensity was found to decrease with increasing the size of alkali cations or decreasing the size of rare earth ions. Under 393 nm light excitation, all compounds exhibited strong red emission at about 613 nm due to 5D0 → 7F2 transition of Eu3+. Compared with the commercially available red phosphor Y2O3:Eu3+, the emission intensity of the obtained phosphors is much stronger than that of Y2O3:Eu3+. Additionally, the excitation spectra of these phosphors implied that the MRE(MoO4)2:Eu3+ phosphors can absorb not only the emission of near UV-LED chips but also that of blue LED chips. The CIE chromaticity coordinates are close to the National Television Standard Committee (NTSC) standard CIE chromaticity coordinate values for red (0.67, 0.33). All the results indicate that these phosphors are promising red-emitting phosphors pumped by near-UV or blue light.
Co-reporter:Junjun Zhang, Linlin Li, Wenwen Zi, Na Guo, Lianchun Zou, Shucai Gan, Guijuan Ji
Journal of Physics and Chemistry of Solids 2014 Volume 75(Issue 7) pp:878-887
Publication Date(Web):July 2014
DOI:10.1016/j.jpcs.2014.03.010
•For the first time, CaMoO4:Eu3+ phosphors were produced via a simple sonochemical route.•The morphology of CaMoO4 and CaMoO4:Eu3+ were found to be manipulated by changing the pH value of precursor solution.•The products have tunable luminescent properties due to their different morphologies.•The synthesis method influences the final properties of the materials.Tetragonal CaMoO4 and CaMoO4:Eu3+ with various novel three-dimensional (3D) hierarchical architectures were successfully synthesized via a facile, efficient sonochemistry process in the absence of any surfactant or template. XRD, EDS, FE-SEM, and photoluminescence (PL) were employed to characterize the as-obtained products. It was found that morphology modulation could be easily realized by changing pH value of the precursor. The pH value of the precursor not only affected the substructures of the hierarchical structures, but also determined the size distributions of the final products. The formation mechanism for different hierarchical architectures was proposed on the basis of time-dependent experiments. The luminescence spectra showed that CaMoO4:Eu3+ phosphors can be effectively excited by the near ultraviolet (UV) (396 nm) and blue (466 nm) light, and exhibited strong red emission around 615 nm, which was attributed to the Eu3+5D0→7F2 transition. Compared with Y2O3:Eu3+ phosphor, CaMoO4:Eu3+ is much more stable, efficient and suitable, therefore, this phosphors could be a promising red component for possible applications in the field of LEDs.The morphology of the samples were found to be manipulated by changing the pH value of the precursor solution. Uniform CaMoO4 3D dumbbell-like microstructure could be trapped at pH 7 and the flower-like and elliptic cylinder microstructures were obtained at pH 5. When the pH value was adjusted to 9, the doughnut-shaped CaMoO4 structures were obtained. When the pH value was adjusted to 11, the peony-shaped CaMoO4 structures were obtained. The luminescence spectra showed that CaMoO4 doped with Eu3+ phosphors can be effectively excited by the near ultraviolet (UV) and blue light.
Co-reporter:Linlin Li;Zhihua Leng;Wenwen Zi;Shucai Gan
Journal of Electronic Materials 2014 Volume 43( Issue 7) pp:2588-2596
Publication Date(Web):2014 July
DOI:10.1007/s11664-014-3152-z
Eu3+ and Sm3+ co-doped SrMoO4 phosphors have been successfully prepared via a simple surfactant-free hydrothermal method. The as-prepared phosphors present dumbbell-like agglomerates and comprise of many nanoparticles of 150–300 nm in diameter. Eu3+ and Sm3+ co-doped SrMoO4 phosphors display all the characteristic excitations and emissions of Eu3+ and Sm3+. The introduction of Sm3+ can generate a strong excitation line at 403 nm, originating from the 6H5/2 → 4K11/2 transition of Sm3+, which significantly broadened the excitation region for matching the near ultraviolet light emitting diodes (∼400 nm). And Sm3+ ions can transfer the absorbed energy to Eu3+ ions efficiently, so the intensity of the main emission peak at 614 nm due to 5D0 → 7F2 transition of Eu3+ are strengthened by the co-doping of Sm3+. The doping concentration of Eu3+/Sm3+ was optimized. In addition, the possible energy transfer mechanism has been investigated and is discussed in detail.
Co-reporter:Fengying Guo;Ruiqing Li;Jijing Xu;Lianchun Zou
Colloid and Polymer Science 2014 Volume 292( Issue 9) pp:2173-2183
Publication Date(Web):2014 September
DOI:10.1007/s00396-014-3234-8
The Gd-, Tb-, and Ho-doped W-type hexagonal ferrite Ba0.85RE0.15Co2Fe16O27 was fabricated by a facile route of low-temperature sol–gel self-propagating combustion. Furthermore, a combination of dielectric loss phase polyaniline and magnetic loss phase Ba0.85RE0.15Co2Fe16O27 as the microwave absorber in a core-shell architecture has been synthesized. The effect of different lanthanide ions Gd, Tb, and Ho on their microstructure, static magnetic properties, electromagnetic properties, and microwave reflection loss have been systematically studied. Our results show that the Ho-doped ferrite has the low microstructure parameters (a, c, and V) and high saturation magnetization (Ms) attributed to its ionic radius and magnetic moment. Moreover, it was found that the Ho-doped composite exhibited excellent microwave absorbing property with a minimum reflection loss (RL) of about −15.1 dB at 9.4 GHz. The reflection loss of composite increases up to almost triple upon the combination of polyaniline and doped ferrite. Such lightweight and highly effective absorbers via combining the organic and inorganic phase into a core-shell architecture are highly desirable for microwave absorber in various applications.
Co-reporter:Na Guo ; Yimai Liang ; Shi Lan ; Lu Liu ; Junjun Zhang ; Guijuan Ji ;Shucai Gan
The Journal of Physical Chemistry C 2014 Volume 118(Issue 32) pp:18343-18355
Publication Date(Web):July 24, 2014
DOI:10.1021/jp5044927
A microscale hierarchical 3D flowerlike TiO2/PANI composite with enhanced photocatalytic activity was synthesized via a sol–gel method, and the as-synthesized samples were characterized by XRD, SEM, TEM, FT-IR, UV–vis adsorption, BJH, and TGA/DSC. The outcome of the photocatalytic experimental demonstrating the TiO2/PANI hybrid with a Ti/ANI (aniline) molar ratio of 1:1 (denoted as T/P) showed high photocatalytic activity upon the degradation of Congo red (CR) and methyl orange (MO) under both UV-light and sunlight irradiation. The unique hierarchical 3D flowerlike structure endows the T/P hybrid with a large surface area of 38.81 m2/g. The intermeshed PANI nanoflakes could make full use of the light resource by multiple reflections between the nanoflakes. Moreover, the intrinsic cavity of the hollow TiO2 nanoparticles can also increase the light-capturing efficiency. The synergistic effect between PANI and TiO2 hollow nanoparticles results in a reduction of the photoinduced electron–hole recombination rate as well as enhanced photocatalytic activity under UV-light and sunlight. Given the unique spatial structure and high photocatalytic characteristics of the T/P composite, there is great potential for applications in water treatment.
Co-reporter:Shi Lan, Zhihua Leng, Na Guo, Xiaomin Wu, Shucai Gan
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 446() pp:163-171
Publication Date(Web):5 April 2014
DOI:10.1016/j.colsurfa.2014.01.054
•Simple, facile, and general approach for the synthesis of Fe3O4@CPS nanocomposites was developed.•The eco-friendly sesbania gum was used as carbon precursor for the first time.•Fe3O4@CPS showed potential application as recyclable adsorbent for heavy metal ions.Magnetic carbonaceous polysaccharide composites (Fe3O4@CPS) with excellent adsorption behavior were facilely synthesized through hydrothermal process by using sesbania gum served as carbon resource. Evidence for the synthesis has been inferred from different techniques like transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET), and Fourier transform infrared (FTIR). The nanocomposites are spherical with the particle size ranged from 10 nm to 16 nm and the surface area of 55 m2 g−1. The removal capability of nanocomposites for metallic ion contaminants was determined by batch adsorption procedure. The isotherms and kinetics of adsorption process were analyzed and discussed in detail. The as-prepared nanocomposites also displayed super-paramagnetic property with a saturation magnetization value of 15 emu g−1, which make the sesbania gum-based magnetic nanocomposites recyclable for adsorption application.Magnetic carbonaceous polysaccharide nanocomposites were synthesized as recyclable adsorbents by a facile hydrothermal method using sesbania gum carbohydrate as carbon precursor, and used for removal of heavy metal ions.
Co-reporter:Zhihua Leng, Lu Liu, Linlin Li, Shucai Gan
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 463() pp:1-7
Publication Date(Web):5 December 2014
DOI:10.1016/j.colsurfa.2014.09.033
•Ellipsoid-like YBO3 were synthesized via a solution-based hydrothermal method.•This method used Y(OH)CO3 and Na2B4O7·10H2O as the precursors for the first time.•Under different molar ratio of Y/B, different morphologies can be obtained.•The quenching concentration of YBO3:Eu3+ and YBO3:Tb3+ is high and is 25% and 20%, respectively.A series of YBO3:Ln3+ (Ln = Eu, Tb) phosphors have been successfully synthesized for the first time via a simple solution-based hydrothermal method using Y(OH)CO3:Ln3+ (Ln = Eu, Tb) colloid spheres and Na2B4O7·10H2O as the precursors. The as-prepared phosphors present uniform ellipsoid-like morphology and have a diameter of about 2.5 μm. FTIR confirms the formation of vaterite-type YBO3 can be synthesized by this method. The molar ratio of Y/B plays an important role in controlling the product morphology. The possible formation mechanism for the ellipsoid-like microcrystals was proposed on the basis of a series of time-dependent experiments. Even in such a simple solution-based hydrothermal reaction system, the formation of YBO3 microcrystals went through complex crystallization and crystal growth processes: a small amount of random shaped particles served as precursors for the crystals initially formed which continuously grew into large flower-like YBO3, the excess borax resulted in the dissolution of flower-like YBO3 and the formation of new YBO3 particles. Moreover, there exists characteristic luminescence of Eu3+ and Tb3+ individually when doping them in the YBO3 host. The quenching concentration of YBO3:Eu3+ and YBO3:Tb3+ is 25% and 20%, respectively.The formation of YBO3 microcrystals went through complex crystallization and crystal growth processes: a small amount of random shaped particles served as precursors for the crystals initially formed which continuously grew into large-sized flower-like morphology, and subsequent increase in borax concentration resulted in the dissolution of flower-like YBO3 and the formation of new YBO3 particles.
Co-reporter:Weiwei Bao, Fengying Guo, Haifeng Zou, Shucai Gan, Xuechun Xu, Keyan Zheng
Powder Technology 2013 Volume 249() pp:220-224
Publication Date(Web):November 2013
DOI:10.1016/j.powtec.2013.08.001
•We synthesize alumina aerogels using oil shale ash as alumina source.•Alumina aerogels were modified by silylation and characterized.•After silylation, the surface property of alumina aerogels changed to hydrophobic.In this study, the hydrophobic alumina aerogels were successfully prepared using oil shale ash (OSA) as a new raw material. The process consisted of two stages, leaching of aluminum and hydrophobic modification. The effects of methyltrimethoxysilane (MTMS) and tetraethylorthosilicate (TEOS) used as surface modifying agents on the physicochemical properties of the alumina aerogels were investigated. The surface chemical group, thermal stability, structure properties and morphological features before and after modification were examined by Fourier transform infrared (FT-IR), Thermogravimetry–differential thermal analysis (TG–DTA), Brunauer–Emmett–Teller (BET) and Scanning electron microscope (SEM) techniques. The experimental results indicated that the obtained alumina aerogels without surface modification had ordered mesoporous structure and flaky morphology with average length of about 200–300 nm. After surface modified with MTMS, the surface property of alumina aerogels changed from hydrophilic to hydrophobic, meanwhile the morphology changed to catkin-like structure. The results obtained in this experiment prove that the OSA can be used to prepare hydrophobic alumina aerogels, which explores a new way for comprehensive utilization of OSA.
Co-reporter:Linlin Li, Lu Liu, Wenwen Zi, Hong Yu, Shucai Gan, Guijuan Ji, Haifeng Zou, Xuechun Xu
Journal of Luminescence 2013 Volume 143() pp:14-20
Publication Date(Web):November 2013
DOI:10.1016/j.jlumin.2013.04.031
•Eu3+-activated MLa(WO4)2 and NaRE(WO4)2 have been prepared via the solid-state method.•The emission intensity was found to decrease with increasing the size of alkali cations.•In NaRE(WO4)2:Eu3+ system the luminescent intensity can be ordered as follows: Lu>Y>Gd.Eu3+-activated double tungstates phosphors MLa(WO4)2 (M=Li, Na, K) and NaRE(WO4)2 (RE=Gd, Y, Lu) have been successfully prepared via the conventional solid-state reaction method. The effects of alkali ions and rare earth ions on the luminescence of MLa(WO4)2:Eu3+ and NaRE(WO4)2:Eu3+ were investigated. In MLa(WO4)2:Eu3+ system the emission intensity was found to decrease with increasing the size of alkali ions, and in NaRE(WO4)2:Eu3+ system the emission intensity can be ordered as follows: Lu>Y>Gd. Moreover, under 393 nm light excitation all compounds exhibited strong luminescence of 5D0→7F2 at 615 nm. The excitation spectra implied that these phosphors can absorb not only the emission of near UV-LED chips but also that of blue LED chips. All the results indicate that these phosphors are promising red-emitting phosphors pumped by near-UV or blue light.
Co-reporter:Wenwen ZI, Tianjie CUI, Hong YU, Linlin LI, Shucai GAN, Xuechun XU
Journal of Rare Earths 2013 Volume 31(Issue 9) pp:871-877
Publication Date(Web):September 2013
DOI:10.1016/S1002-0721(12)60372-X
A novel green-emitting phosphor, Eu2+-doped Ca2−x/2Si1−xPxO4 (0.25≤x≤0.30), was prepared through a conventional solid- state reaction. X-ray diffraction (XRD), photoluminescence (PL) and decay studies were employed to characterize the sample, which was assigned to P63mc space group in the hexagonal system. The effect of P-doping on the α-Ca2SiO4 was studied and P2O5 broken down by the raw material of (NH4)2HPO4 played an important role in stabilizing α-Ca2SiO4 which can only be stable at high temperature. The XRD patterns of the Ca2−x/2Si1−xPxO4 host were found pure and optimized when the mole fraction of P2O5 was 14.5%. The diffuse reflectance spectra of the Ca1.855Si0.71P0.29O4 and Ca1.845Si0.71P0.29O4:0.01Eu2+ covered the spectral region of 230–400 nm, implying that the phosphor was suitable for UV or near-UV LED excitation. The phosphor could be effectively excited in the near UV region with the maximum at 372 nm. The emission spectrum of the Ca1.845Si0.71P0.29O4:0.01Eu2+ phosphor showed an asymmetrical single intensive band centered at 513 nm, which corresponded to the 4f65d1→4f7 transition of Eu2+. Eu2+ ions might occupy two types of Ca2+ sites in the Ca1.855Si0.71P0.29O4 lattice and form two corresponding emission centers, which led to the asymmetrical emission of Eu2+ in Ca1.855Si0.71P0.29O4. The effects of Eu2+-doped concentration in Ca1.855−xSi0.71P0.29O4:xEu2+ on the PL were also discussed, the optimum doping concentration of Eu2+ was 1 mol.% and the critical distance of the energy transfer was also calculated by the concentration-quenching method. The non-radiative energy transfer between Eu2+ seemed to be caused by the multipole-multipole interaction. The fluorescence lifetime of Eu2+ was found to be 0.55711 μs. The results suggested that these phosphors might be promising candidates used for near UV light excited white LEDs.XRD patterns of Ca2−x/2Si1−xPxO4 (x=0.25−0.30)
Co-reporter:Shi Lan, Xiaomin Wu, Linlin Li, Mengmeng Li, Fengying Guo, Shucai Gan
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2013 Volume 425() pp:42-50
Publication Date(Web):20 May 2013
DOI:10.1016/j.colsurfa.2013.02.059
•Hyaluronic acid was successfully immobilized on the magnetic silica submicron-sized particles.•Hyaluronic acid was utilized as adsorbent for the heavy metal removal.•Magnetism and adsorption were perfectly combined into one single entity.Magnetic hyaluronic acid (HA) microspheres were fabricated as a novel adsorbent through the immobilization of hyaluronic acid on the magnetic silica microspheres. The as-prepared microspheres were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray powder diffraction (XRD), and X-ray photoelectron spectra (XPS). The as-synthesized microspheres were evaluated for Cu2+ removal by the adsorption, and the effect of pH value, interferential metal ions, initial Cu2+ concentration, and contact time on adsorption capability was investigated, respectively. The adsorption equilibrium study exhibited that the Cu2+ adsorption of hyaluronic acid-supported magnetic microspheres had a better fit to the Freundlich isotherm model than the Langmuir model. The kinetic date of adsorption of Cu2+ on the synthesized adsorbents was best described by the pseudo-second-order equation. The resultant microspheres also revealed super-paramagnetic behavior, which made these adsorbent magnetically separable after the adsorption performance. This work demonstrates that the synthesized hyaluronic acid-supported magnetic adsorbent can be considered as a potential adsorbent for hazardous metal ions from wastewater.Hyaluronic acid-supported magnetic submicron-sized particles were fabricated as a novel adsorbent for the Cu2+ removal and can be separated magnetically through the application of a magnetic field in shorter time after the adsorption performance.
Co-reporter:Hong Yu;Wenwen Zi;Shi Lan;Shucai Gan;Haifeng Zou;Xuechun Xu;Guangyan Hong
Luminescence 2013 Volume 28( Issue 5) pp:679-684
Publication Date(Web):
DOI:10.1002/bio.2415
ABSTRACT
Sr3MgSi2O8:Ce3+, Dy3+ phosphors were prepared by a solid-state reaction technique and the photoluminescence properties were investigated. The emission spectra show not only a band due to Ce3+ ions (403 nm) but also as a band due to Dy3+ ions (480, 575 nm) (UV light excitation). The photoluminescence properties reveal that effective energy transfer occurs in Ce3+/Dy3+ co-doped Sr3MgSi2O8 phosphors, and the co-doping of Ce3+ could enhance the emission intensity of Dy3+ to a certain extent by transferring its energy to Dy3+. The Ce3+/Dy3+ energy transfer was investigated by emission/excitation spectra, and photoluminescence decay behaviors. In Sr2.94MgSi2O8:0.01Ce3+, 0.05Dy3+ phosphors, the fluorescence lifetime of Dy3+ (from 3.35 to 27.59 ns) is increased whereas that of Ce3+ is greatly decreased (from 43.59 to 13.55 ns), and this provides indirect evidence of the Ce3+ to Dy3+ energy transfer. The varied emitted color of Sr3MgSi2O8:Ce3+, Dy3+ phosphors from blue to white were achieved by altering the concentration ratio of Ce3+ and Dy3+. These results indicate Sr3MgSi2O8:Ce3+, Dy3+ may be as a candidate phosphor for white light-emitting diodes. Copyright © 2012 John Wiley & Sons, Ltd.
Co-reporter:Guanghuan Li, Shi Lan, Linlin Li, Mengmeng Li, Weiwei Bao, Haifeng Zou, Xuechun Xu, Shucai Gan
Journal of Alloys and Compounds 2012 Volume 513() pp:145-149
Publication Date(Web):5 February 2012
DOI:10.1016/j.jallcom.2011.10.008
The NaLa(MoO4)2:Ce3+,Tb3+ phosphors were synthesized by a high temperature solid-state reaction. Co-doping of Ce3+ enhances the emission intensity of Tb3+ greatly by transferring its excitation energy to Tb3+. Through an efficient energy transfer process, the obtained phosphors exhibit both a indigo emission of Ce3+ and a yellowish green emission of Tb3+ with considerable intensity under near-ultraviolet excitation (339 nm). The energy transfer mechanism from Ce3+ to Tb3+ in NaLa(MoO4)2 host was demonstrated to be dipole–quadrupole interaction. The varied emitted color of the phosphors from indigo to yellow-greenish can be achieved by properly tuning the relative ratio of Ce3+ and Tb3+ through the energy transfer from the Ce3+ to Tb3+ ions. These results indicate that the NaLa(MoO4)2:Ce3+,Tb3+ phosphors have potential applications as an UV-convertible phosphor for white light emitting diodes because of its effective excitation in the near ultraviolet range.Graphical abstractHighlights► The optical properties of NaLa(MoO4)2:Ce3+,Tb3+ phosphors have not been reported before. ► The energy transfer from Ce3+ to Tb3+ ions was observed in NaLa(MoO4)2:Ce3+,Tb3+. ► NaLa(MoO4)2:Ce3+,Tb3+ phosphors have potential applications as an UV-convertible phosphor for white light emitting diodes.
Co-reporter:Guijuan Ji, Mengmeng Li, Guanghuan Li, Guimei Gao, Haifeng Zou, Shucai Gan, Xuechun Xu
Powder Technology 2012 Volumes 215–216() pp:54-58
Publication Date(Web):January 2012
DOI:10.1016/j.powtec.2011.09.005
The hierarchical micron flower-like γ-AlOOH and γ-Al2O3 superstructures were synthesized using oil shale ash (OSA) as a new raw material. In order to prepare the better quality alumina with uniform morphology, the effects of ethanol and surfactant CTAB on the formation of alumina particles were investigated and the formation mechanism of flower-like composite particles was also discussed. The structural and morphological properties of the uncalcined and calcined powders were characterized by X-ray diffractometer (XRD), Scanning electron microscope (SEM), Brunauer Emmett Teller (BET) and Fourier transform infrared (FT-IR). The results indicated that uniform flower-like γ-AlOOH and γ-Al2O3 assembled by nanosheets which thickness is less than 100 nm were prepared. After calcined at 600 °C, morphology of the flower-like superstructure was maintained perfectly. The results obtained in this work prove that the oil shale ash can be used for production of hierarchical superstructures alumina and open a new way for comprehensive application of OSA.Highlights►Flower-like γ-AlOOH and γ-Al2O3 superstructures were synthesized using oil shale ash ► The results indicated that as-prepared products assembled by nanosheets ► This work open a new way for comprehensive application of OSA ►
Co-reporter:Guanghuan Li, Linlin Li, Mengmeng Li, Yanhua Song, Haifeng Zou, Lianchun Zou, Xuechun Xu, Shucai Gan
Materials Chemistry and Physics 2012 Volume 133(Issue 1) pp:263-268
Publication Date(Web):15 March 2012
DOI:10.1016/j.matchemphys.2012.01.020
LaPO4: Eu3+, Sm3+ nanorods have been successfully prepared by a designed two-step hydrothermal method. The whole process was carried out under aqueous conditions without the use of any organic solvent, surfactant, or catalyst. The crystal structure, morphology have been characterized by XRD, FT-IR, SEM and TEM, respectively. The detailed conversion process of the product LaPO4 nanorods has been investigated on the basis of time-dependent XRD experiments and SEM experiments. Moreover, the LaPO4 samples doped with Eu3+ and Sm3+ under ultraviolet excitation showed red emission corresponding to the 5D0–7F1 transition of the Eu3+ ions. The doped Sm3+ was found to be efficient to sensitize the emission of Eu3+ and be effective to extend the absorption of near-UV light with wavelength of 400–405 nm. The effect of the concentration of Sm3+ on the emission intensities of the phosphor LaPO4: Eu3+, Sm3+ is also investigated. These samples could be potentially used in the fields of near UV-excited white-light-emitting diode and optoelectronic devices.Graphical abstractLaPO4: Eu3+, Sm3+ nanorods have been successfully prepared by a designed two-step hydrothermal method. The doped Sm3+ was found to be efficient to sensitize the emission of Eu3+ and be effective to extend the absorption of near-UV light with wavelength of 400–405 nm. The effect of the concentration of Sm3+ on the emission intensities of the phosphor LaPO4: Eu3+, Sm3+ is also investigated. These samples could be potentially used in the fields of near UV-excited white-light-emitting diode and optoelectronic devices.Highlights► LaPO4: Eu3+, Sm3+ nanorods have been successfully prepared by a designed two-step hydrothermal method. ► The doped Sm3+ was found to be efficient to sensitize the emission of Eu3+. ► The doped Sm3+ extend the absorption of near-UV light with wavelength of 400–405 nm.
Co-reporter:Linlin Li, Wenwen Zi, Guanghuan Li, Shi Lan, Guijuan Ji, Shucai Gan, Haifeng Zou, Xuechun Xu
Journal of Solid State Chemistry 2012 Volume 191() pp:175-180
Publication Date(Web):July 2012
DOI:10.1016/j.jssc.2012.03.003
Pompon-like NaLa(MoO4)2:Dy3+ phosphors have been successfully prepared via a hydrothermal method using ammonia as pH value regulator. The hydrothermal process was carried out under aqueous condition without the use of any organic solvent, surfactant, and catalyst. The experimental results demonstrate that the obtained NaLa(MoO4)2:Dy3+ phosphor powders are single-phase scheelite structure with tetragonal symmetry. Moreover, the phosphor under the excitation of 390 and 456 nm exhibited blue emission (486 nm) and yellow emission (574 nm), corresponding to the 4F9/2→6H15/2 transition and 4F9/2→6H13/2 transition of Dy3+ ions, respectively. In addition, the yellow-to-blue emission intensity ratio (Y/B) can be changed with the doped concentration of Dy3+ ions. All chromaticity coordinates of the obtained NaLa(MoO4)2:Dy3+ phosphors are located in the white-light region. The results indicate that this kind of phosphor may has potential applications in the fields of near UV-excited and blue-excited white LEDs.Graphical abstractIt can be seen from the SEM images that a pompon-like shape was obtained with an average diameter of about 1 μm, and it is composed of many nanoflakes.Highlights► Pompon-like NaLa(MoO4)2:Dy3+ phosphors have been successfully prepared via a hydrothermal method. ► Blue emission at 486 nm and yellow emission at 574 nm were obtained from the samples. ► The yellow-to-blue emission intensity ratio (Y/B) can be changed with the doped concentration of Dy3+ ions. ► NaLa(MoO4)2:Dy3+ can be efficiently excited by the blue light and the near ultraviolet light.
Co-reporter:Hong Yu, Wenwen Zi, Shi Lan, Shucai Gan, Haifeng Zou, Xuechun Xu, Guangyan Hong
Optics & Laser Technology 2012 Volume 44(Issue 7) pp:2306-2311
Publication Date(Web):October 2012
DOI:10.1016/j.optlastec.2012.02.005
Sr3MgSi2O8:Ce3+, Tb3+ phosphor samples were prepared using a solid-state reaction technique, and the photoluminescence properties and energy transfer were investigated. Effective energy transfer occurred in Ce3+/Tb3+ co-doped Sr3MgSi2O8 phosphors. Co-doping of Ce3+ was found to enhance the emission intensity of Tb3+ to a certain extent by transferring energy to Tb3+. The Ce3+/Tb3+ energy transfer was thoroughly investigated through its emission/excitation spectra and photoluminescence decay behavior. The color emitted by Sr3MgSi2O8:Ce3+, Tb3+ phosphors varied from blue to green and can be controlled by altering the concentration ratio of Ce3+ to Tb3+. These results indicate that Sr3MgSi2O8:Ce3+, Tb3+ may be useful as a green-emitting phosphor for ultraviolet whitelight-emitting diodes.Highlights► Sr3MgSi2O8:Ce3+, Tb3+ phosphors were firstly reported. ► The luminous properties and energy transfer were discussed. ► With Ce3+ co-doping, the fluorescence lifetime of Tb3+ greatly enhanced. ► Sr3MgSi2O8:Ce3+, Tb3+ phosphors may be useful for UV white-light-emitting diodes.
Co-reporter:Guanghuan Li, Yawen Lai, Weiwei Bao, Linlin Li, Mengmeng Li, Shucai Gan, Tao Long, Lianchun Zou
Powder Technology 2011 Volume 214(Issue 2) pp:211-217
Publication Date(Web):10 December 2011
DOI:10.1016/j.powtec.2011.08.012
Uniform YF3 nanocrystals were prepared through a facile ethylene glycol (EG)/ionic liquid interfacial synthesis route in a imidazolium ionic liquids (1-octyl-3-methylimidazolium hexafluorophosphate) with the ionic liquids acting as both reagents and templates. The partial hydrolysis of PF6− was utilized to introduce a fluoride source. X-ray diffraction (XRD), field emission scanning microscopy (FE-SEM) and transmission electron microscopy (TEM) have been used to study the morphologies and crystal structure. The detailed growth mechanism of the YF3 nanocrystals was researched. Furthermore, under ultraviolet exaltation, the phosphor of YF3:Eu3+ and YF3:Tb3+ shows red and green emission, corresponding to 5D0–7F1 transition of Eu3+ and 5D4–7F5 transition of Tb3+. The emission spectrum of YF3:Ce3+ phosphor exhibits one dissymmetrical band extending from 350 to 500 nm with a maximum at about 383 nm. A bright fluorescent yellow emission at 574 nm and blue emission at 487 nm were observed in the YF3:Dy3+. These novel nanocrystals could be potentially used in biolabels and light emitting diodes (LEDs).Uniform YF3 nanocrystals were prepared through a facile ethylene glycol (EG)/ionic liquid interfacial synthesis route in ionic liquids. The detailed growth mechanism of the YF3 nanocrystals was researched. Furthermore, the photoluminescence (PL) properties of YF3:Ln3+ (Ln = Eu, Tb, Ce, Dy) nanocrystals were also studied in detail.Highlights► OmimPF6 was introduced to prepare uniform YF3 nanocrystals in large scale for the first time. ► The detailed growth mechanism of the YF3 nanocrystals was researched. ► The photoluminescence properties of YF3:Ln3+ (Ln= Eu, Tb, Ce, Dy) nanocrystals were studied.
Co-reporter:Lina Miao, Guijuan Ji, Guimei Gao, Guanghuan Li, Shucai Gan
Powder Technology 2011 Volume 207(1–3) pp:343-347
Publication Date(Web):15 February 2011
DOI:10.1016/j.powtec.2010.11.017
Alumina was extracted from oil shale ash which is a solid by-product of oil shale processing. A Box–Behnken statistical design was used to optimize the factors affecting the extraction efficiency of the alumina such as sulfuric acid concentration, reaction time and reaction temperature, and to determine the optimum conditions for the extraction process. The optimal extraction efficiency of 89.71% can be obtained when the conditions are as follows: the temperature of 100 °C, the time of 4 h and the sulfuric acid concentration of 50 wt.%. The result of statistical design shows that the extraction efficiency was in an agreement with the generated model and the experimental results. Further, the ultrafine silica powders were characterized by various techniques. The results show that the purity of alumina reaches 99.80%, which is suitable for the production of aluminum metal. It is evident that the way of extraction of alumina from the oil shale ash is practical and feasible and provides a new solution of the pollution to the environment.Alumina was extracted from oil shale ash which is a solid by-product of oil shale processing. A Box–Behnken statistical design was used to determine the optimum conditions for the extraction process. The experimental results show that with increasing the concentration of sulfuric acid up to 50 wt.%, the extraction efficiency reaches 89.71% at 100 °C for 4 h.Research Highlights► The oil shale ash is a new raw material to extracting alumina. ► Box–Behnken design was firstly used to optimize the extraction process. ► It provides a new way to solve the environment pollution of oil shale ash.
Co-reporter:Jijing Xu, Guijuan Ji, Haifeng Zou, Yuan Zhou, Shucai Gan
Journal of Alloys and Compounds 2011 Volume 509(Issue 11) pp:4290-4294
Publication Date(Web):17 March 2011
DOI:10.1016/j.jallcom.2011.01.027
Z-type hexaferrites doped with Nd3+, Ba3−xNdxCo2Fe24O41 (x = 0, 0.05, 0.10, 0.15, and 0.25), were prepared by solid-state reaction. The effect of the Nd3+ ions substitution for Ba2+ ions on the microstructure and electromagnetic properties of the samples was investigated. The results reveal that an important modification of microstructure, complex permeability, complex permittivity, and static magnetic properties can be obtained by introducing a relatively small amount of Nd3+ instead of Ba2+. SEM image shows that the grains of the ferrites doped with Nd3+ were smaller, more perfect and homogeneous than that of the pure ferrite. The real part (ɛ′) of complex permittivity and imaginary part (ɛ″) increase at first, and then decrease with increasing Nd content. At low frequency, the imaginary part μ″ of complex permeability decreases with Nd content and then increases when frequency is above 7.0 GHz. The magnetization (Ms) and the coercivity (Hc) are 79.38 emu g−1 and 36.94 Oe for Ba2.75Nd0.25Co2Fe24O41. The data of magnetism show that the ferrite doped with Nd3+ ions is a better soft magnetic material due to the higher magnetization and lower coercivity.Graphical abstractThe results obtained reveal that, by introducing a relatively small amount of Nd3+ instead of Ba2+, an important modification of both structure and electromagnetic properties of Ba3−xNdxCo2Fe24O41 can be obtained.Research highlights▶ A Nd-doped Co2Z-type hexaferrites Ba3−xNdxCo2Fe24O41 was firstly reported. ▶The structural, dielectric and magnetic properties of Nd-doped Co2Z-type hexaferrites were successfully discussed. ▶ The results obtained reveal that, by introducing a relatively small amount of Nd3+ instead of Ba2+, an important modification of both structure and electromagnetic properties of Ba3−xNdxCo2Fe24O41 can be obtained. ▶ The novel Nd-doped Z-type ferrites exhibit excellent static magnetic properties such as high saturation magnetization up to 79.3 emu g−1 and low coercivity under 40 Oe.
Co-reporter:Hong Yu, Yawen Lai, Guimei Gao, Li Kong, Guanghuan Li, Shucai Gan, Guangyan Hong
Journal of Alloys and Compounds 2011 Volume 509(Issue 23) pp:6635-6639
Publication Date(Web):9 June 2011
DOI:10.1016/j.jallcom.2011.03.116
The luminescence of SrCaSiO4:Eu2+, Ce3+ is studied as a potential ultraviolet light-emitting diodes (UV-LEDs) phosphor that is capable of converting the ultraviolet emission of a UV-LED into green light with good luminosity. There are two emissions peaks peaking at 420 and 500 nm, respectively. The two emissions come from d–f transitions of Ce3+ and Eu2+, respectively. Effective energy transfer occurs in Ce3+/Eu2+ co-doped SrCaSiO4 due to a part of spectral overlap between the emission of Ce3+ and excitation of Eu2+. Co-doping of Ce3+ enhances the emission intensity of Eu2+ greatly by transferring its excitation energy to Eu2+. The Ce3+/Eu2+ energy transfer, thoroughly investigated by the diffuse reflection emission and excitation spectra, photoluminescence decay curves, is demonstrated to be in the mechanism of electric dipole–dipole interaction.Graphical abstract. The results obtained reveal that, under the excitation of 365 nm, with increased concentration of Ce3+ doped in SrCaSiO4:0.005 Eu2+ could not only increase the emission intensity of Eu2+ but also make the luminous color transfer from yellow-green to blue-green.Highlights► We present a detailed study of the luminescence property and the energy transfer of SrCaSiO4:Eu2+, Ce3+ phosphors. ► With Ce3+ co-doping, the excitation of Eu2+ in UV range is greatly enhanced and its corresponding emission intensity is increased by the excitation energy transferred from Ce3+ the fluorescence lifetime of Eu2+ is also greatly enhanced (from 198 to 611 ns). ► The SrCaSiO4:Eu2+, Ce3+ phosphor can act as a potential green light emitting phosphor for UV-LEDs.
Co-reporter:Guanghuan Li, Mengmeng Li, Linlin Li, Hong Yu, Haifeng Zou, Lianchun Zou, Shucai Gan, Xuechun Xu
Materials Letters 2011 Volume 65(23–24) pp:3418-3420
Publication Date(Web):December 2011
DOI:10.1016/j.matlet.2011.07.050
The Sr2Al2SiO7:Eu2+, Ce3+ phosphors were synthesized by a high temperature solid-state reaction. Effective energy transfer occurs in Ce3+ and Eu2+ co-doped Sr2Al2SiO7 due to large spectral overlap between the emission of Ce3+ and excitation of Eu2+ ions. Co-doping of Ce3+ enhances the emission intensity of Eu2+ greatly by transferring its excitation energy to Eu2+ ions. The critical distance has been estimated to be about 1.83 nm by spectral overlap method. Furthermore, the developed phosphors can generate lights from blue to green region under the excitation of UV radiation by appropriately tuning the activator content. The Sr2Al2SiO7:Eu2+,Ce3+ phosphors are promising phosphors for warm-white-light-emitting diode because of its effective excitation in the near ultraviolet range.The results obtained reveal that, under the excitation of 345 nm, with increased concentration of Eu2+ doped in Sr2Al2SiO7:0.02Ce3+ could not only increase the emission intensity of Eu2+ but also make the luminous color transfer from blue to green.Highlights► The Sr2Al2SiO7:Ce3+Eu2+ phosphors were synthesized by a high temperature solid-state reaction for the first time. ► Co-doping of Ce3+ enhances the emission intensity of Eu2+ greatly. ► The phosphors are promising phosphors for warm-white-light-emitting diode.
Co-reporter:Gui-Mei Gao, Xue-Chun Xu, Hai-Feng Zou, Gui-Juan Ji, Shu-Cai Gan
Powder Technology 2010 Volume 202(1–3) pp:137-142
Publication Date(Web):25 August–10 October 2010
DOI:10.1016/j.powtec.2010.04.028
The silica aerogels based on oil shale ash were successfully synthesized in the presence of different surface modification agents via ambient pressure drying. The organic modification of hydrogels was a crucial step during the processing which preserved mesopores in ambient pressure drying. It was found that the textural properties of silica aerogels dependent on the type of surface modification agents. The hexamethyldisilazane (HMDZ) modified aerogels had much lower tapping density (0.084 cm3), higher specific surface area (980 m2/g) and larger cumulative pore volume (2.42 cm3/g) and higher porosity (96.16%) than those of dimethyldichlorosilane (DMDC) and trimethylchlorosilane (TMCS) modified aerogels. The HMDZ modified aerogel exhibited a narrow pore size distribution and small average pore size, while DMDC and TMCS modified aerogels had relatively wider pore size distributions, bigger average pore sizes and lower porosity. The FT-IR analysis indicated that as the number of alkyl groups present in surface modification agents increased, the intensity of the peaks related to –OH at 3500 and 1600 cm− 1 decreased (HMDZ < TMCS < DMDC).The TG–DTA analysis revealed that all the surface-modified aerogels were found to be thermally stable up to a temperature of 350 °C, the HMDZ and TMCS modified aerogels showed higher thermal stability (∼ 400 °C).The silica aerogels based on oil shale ash were successfully synthesized in the presence of different surface modification agents via ambient pressure drying. The hexamethyldisilazane (HMDZ) modified aerogels had much lower tapping density, higher specific surface area and larger cumulative pore volume than those of dimethyldichlorosilane (DMDC) and trimethylchlorosilane (TMCS) modified aerogels.
Co-reporter:Gui-Mei Gao, Da-Rui Liu, Hai-Feng Zou, Lian-Chun Zou, Shu-Cai Gan
Powder Technology 2010 Volume 197(Issue 3) pp:283-287
Publication Date(Web):25 January 2010
DOI:10.1016/j.powtec.2009.10.005
The silica aerogel with high specific surface area and large pore volume was successfully synthesized using oil shale ash (OSA) via ambient pressure drying. The oil shale ash was burned and leached by sulfuric acid solution, and then was extracted using sodium hydroxide solution to produce a sodium silicate solution. The solution was neutralized with sulfuric acid solution to form a silica gel. After washing with water, the solvent exchange with n-hexane, and the surface modification with hexamethyldisilazane (HMDZ), the aged gel was dried by fluidization technique and also using a furnace to yield silica aerogels. The physical and textural properties of the resultant silica aerogels were investigated and discussed. The results have been compared with silica aerogel powders dried in a furnace. From the results, it is clear that the properties of silica powders obtained in fluidized bed are superior to that of powders dried in the furnace. Using fluidization technique, it could produce silica aerogel powders with low tapping density of 0.0775 g/cm3, high specific surface area (789 m2/g) and cumulative pore volume of 2.77 cm3/g.A novel method for the production of silica aerogel powders, using oil shale ash as a new silica source by fluidized bed drying technique, has been developed. The aerogel dried by fluidized bed exhibited relatively lower tapping densities (0.0775 g/cm3), higher specific surface (789 cm2/g) and larger cumulative pore volume (2.77 cm3/g) than that of the furnace dried aerogel powders.
Co-reporter:Guanghuan Li, Yawen Lai, Tianjie Cui, Hong Yu, Darui Liu, Shucai Gan
Materials Chemistry and Physics 2010 Volume 124(2–3) pp:1094-1099
Publication Date(Web):1 December 2010
DOI:10.1016/j.matchemphys.2010.08.039
Sr3Al2O6:Ce3+ phosphors were synthesized by a solid-state reaction method under mild reducing atmosphere of activated carbon. The effects of H3BO3 flux on the luminescence intensity and the optimum concentration of Ce3+ for luminescence property have been investigated. The effect of a small amount of charge compensators like Li+, Na+, K+ and Rb+ on Sr3Al2O6:Ce3+ phosphor has also been studied. Sr3Al2O6:Ce3+, R+(R = Li, Na, K and Rb) exhibit superior blue emission around 460 nm to Sr3Al2O6:Ce3+ and can be effectively excited by 395 nm light, which implies that efficient charge compensation can promote the luminescence of Ce3+ in Sr3Al2O6. The Sr3Al2O6:Ce3+, R+ (R = Li, Na, K and Rb) have potential application as a blue phosphor for n-UV chip excited white LEDs.
Co-reporter:Gui-Mei Gao, Hai-Feng Zou, Shu-Cai Gan, Zhao-Jun Liu, Bai-Chao An, Ji-Jing Xu, Guang-Huan Li
Powder Technology 2009 Volume 191(1–2) pp:47-51
Publication Date(Web):4 April 2009
DOI:10.1016/j.powtec.2008.09.006
The method of preparing spherical silica nanoparticles from the oil shale ash (OSA) via the ultrasonic technique in the hydrolysis-condensation stage followed by azeotropic distillation, was reported. The effects of ultrasonic and azeotropic distillation on the particle size and distribution have been investigated. Further, the morphology and properties of the silica particles were examined. The X-ray fluorescence spectroscopy (XRF) and Brunauer Emmett Teller (BET) analysis confirmed that the powders consist of silica nanoparticles with high purity, 99.90% and specific surface area of 697 m2/g. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) analysis indicate that the silica nanoparticles are amorphous and that the surface of silica nanoparticles is modified by the organics. The transmission electron microscopy (TEM) images of the sample show that good dispersion and uniform silica particles with an average diameter of about 10 nm are prepared. The results obtained in the mentioned method prove that the oil shale ash (OSA) can be used for production of silica nanoparticles.Graphical abstractA new synthetic method of silica nanoparticles using the OSA as the silica source and the PEG as surfactant via the ultrasonic technique in the hydrolysis-condensation stage followed by azeotropic distillation was developed. This method is a simple and effective route for preparing ultrafine silica powders on a nanometer scale and with homogeneous particle size distribution. The specific surface area is as high as 697 m2/g. It leads to the low cost production of silica nanoparticles for practical applications. Furthermore, it provides a new way to solve the problem of OSA pollution.
Co-reporter:Gui-Mei Gao, Li-Na Miao, Gui-Juan Ji, Hai-Feng Zou, Shu-Cai Gan
Materials Letters 2009 Volume 63(Issue 30) pp:2721-2724
Publication Date(Web):31 December 2009
DOI:10.1016/j.matlet.2009.09.053
The silica aerogels were successfully synthesized using oil shale ash which is a by-product of oil shale processing via ambient pressure drying. The physical and textural properties of the silica aerogels have been investigated and discussed. The results showed that the organic modification of hydrogels was a crucial step during the processing which preserved mesopores in ambient pressure drying. The unmodified hydrogel underwent tremendous shrinkage during the drying and yielded microporous silica aerogel. Using this novel route, it could produce silica aerogel with low tapping density of 0.074 g/cm3, high specific surface (909 m2/g) and cumulative pore volume of 2.54 cm3/g. From the industrial point of view, the present process is quite suitable for a large scale production of powdered silica aerogel. Furthermore, it provides a new way to solve the problem of oil shale ash pollution.
Co-reporter:Gui-Mei Gao, Hai-Feng Zou, Da-Rui Liu, Li-Na Miao, Gui-Juan Ji, Shu-Cai Gan
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009 350(1–3) pp: 33-37
Publication Date(Web):
DOI:10.1016/j.colsurfa.2009.08.030
Co-reporter:Gui-Mei Gao, Hai-Feng Zou, Da-rui Liu, Li-na Miao, Shu-Cai Gan, Bai-Chao An, Ji-Jing Xu, Guang-Huan Li
Fuel 2009 Volume 88(Issue 7) pp:1223-1227
Publication Date(Web):July 2009
DOI:10.1016/j.fuel.2008.12.010
Ultrafine silica powders were synthesized using oil shale ash which is a solid by-product of oil shale processing. Fluidization technique was employed for the drying of wet-gel slurry at an ambient pressure. Box–Behnken statistical design was used to optimize the factors affecting the extraction efficiency of the silica such as concentration of sodium hydroxide, reaction time and reaction temperature, and to determine the optimum conditions for the extraction process. The result of statistical design shows that the extraction efficiency was in an agreement with the generated model and the experimental results. It is observed that the extraction efficiency of silica was increased by increasing the concentration of sodium hydroxide, the reaction time and the reaction temperature. Further, the ultrafine silica powders were characterized by transmission electron microscopy (TEM), X-ray fluorescence spectroscopy (XRF) and nitrogen adsorption (using BET equation). The BET surface area of the ultrafine silica powders obtained in fluidized bed is comparatively higher (652 m2/g) than that of silica powders dried in the furnace (385 m2/g). It is clear that the properties of silica powders obtained in fluidized bed are superior to that of powders dried in the furnace.
Co-reporter:Weiwei BAO, Lu LIU, Haifeng ZOU, Shucai GAN, Xuechun XU, Guijuan JI, Guimei GAO, Keyan Zheng
Chinese Journal of Chemical Engineering (September 2013) Volume 21(Issue 9) pp:974-982
Publication Date(Web):1 September 2013
DOI:10.1016/S1004-9541(13)60529-7
Na-A zeolite was synthesized using oil shale ash (OSA), which is a solid by-product of oil shale processing. The samples were characterized by various techniques, such as scanning electron microscopy, X-ray diffraction and Brunauer Emmet Teller method. The batch isothermal equilibrium adsorption experiments were performed to evaluate the ability of Na-A zeolite for removal of Cu (II) from aqueous solutions. The effects of operating parameters, such as concentration of copper solutions, adsorbent dosages, pH value of solutions and temperature, on the adsorption efficiency were investigated. The equilibrium adsorption data were fitted with Langmuir and Freundlich models. The maximum adsorption capacity of Na-A zeolite obtained from the Langmuir adsorption isotherm is 156.7 mg·g−1 of Cu (II). The increase of pH level in the adsorption process suggests that the uptake of heavy metals on the zeolite follows an ion exchange mechanism. The batch kinetic data fit the pseudo-second order equation well. The thermodynamic parameters, such as changes in Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS), are used to predict the nature of the adsorption process. The negative ΔG values at different temperatures confirm that the adsorption processes are spontaneous.
Co-reporter:Guijuan JI, Weiwei BAO, Guimei GAO, Baichao AN, Haifeng ZOU, Shucai GAN
Chinese Journal of Chemical Engineering (August 2012) Volume 20(Issue 4) pp:641-648
Publication Date(Web):1 August 2012
DOI:10.1016/S1004-9541(11)60229-2
A novel biosorbent was developed by coating chitosan, a naturally and abundantly available biopolymer, on to activated alumina based on oil shale ash via crosslinking. The adsorbent was characterized by various techniques, such as Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric-differential thermal analysis, and X-ray photoelectron spectroscope. Batch isothermal equilibrium adsorption experiments were condcted to evaluate the adsorbent for the removal of Cu(II) from wastewater. The effect of pH and agitation time on the adsorption capacity was also investigated, indicating that the optimum pH was 6.0. The equilibrium adsorption data were correlated with Langmuir and Freundlich models. The maximum monolayer adsorption capacity of chitosan coated alumina sorbent as obtained from Langmuir adsorption isotherm was found to be 315.46 mg·g−1 for Cu(II). The adsorbent loaded with Cu(II) was readily regenerated using 0.1 mol·L−1 sodium hydroxide solution. All these indicated that chitosan coated alumina adsorbent not only have high adsorption activity, but also had good stability in the wastewater treatment process.
Co-reporter:Baichao An, Guijuan Ji, Wenying Wang, Shucai Gan, Jijing Xu, Guimei Gao, Guanghuan Li
Chemical Engineering Journal (15 February 2010) Volume 157(Issue 1) pp:67-72
Publication Date(Web):15 February 2010
DOI:10.1016/j.cej.2009.10.048
A combined process was proposed for the utilization of waste oil shale ash (OSA) in the production of gamma-alumina nanoparticles. The process consisted of two stages, leaching and sintering. The ultrasonic technique followed by a heterogeneous azeotropic distillation process in the presence of polyethylene glycol (PEG) was carried to ensure complete elimination of the residual water in the precipitate. The structural and morphological properties of the calcined nanocrystalline powders were characterized by X-ray diffractometer (XRD), transmission electron microscope (TEM), Brunauer–Emmett–Teller nitrogen-gas adsorption method (BET). The as-prepared precursor hydroxides were analyzed using thermogravimetric–differential thermal analysis (TG–DTA), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The results indicated that the gamma-alumina powder with a uniform particle is well dispersed and the particle size is 20–40 nm; the waste OSA can be utilized to produce gamma-alumina nanoparticles.
Co-reporter:Ruiqing Li, Linlin Li, Yimai Liang, Nannan Zhang, Yali Liu and Shucai Gan
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 33) pp:NaN21491-21491
Publication Date(Web):2015/07/21
DOI:10.1039/C5CP03421C
In this study, monodisperse and uniform LaOF hollow spheres were successfully synthesized through a novel facile synthetic route employing a La(OH)CO3 sphere as a sacrificial template followed by a subsequent calcination process. The structure, morphology, formation process, and luminescence properties were well investigated using various techniques. The possible formation mechanism of evolution from the La(OH)CO3 spheres to the LaCO3F precursor, and to the final LaOF hollow spheres can be attributed to the Kirkendall effect and the decomposition of the LaCO3F precursor. Under ultraviolet excitation, the LaOF:Ln3+ (Ln = Eu,Tb) hollow spheres show their characteristic f–f emissions and exhibit red, green emissions, respectively. Moreover, by codoping the Tb3+ and Eu3+ ions into the LaOF host and tuning their relative concentration ratio, multicolor tunable emissions are obtained due to the efficient energy transfer from Tb3+ to Eu3+ at 378 nm excitation. This material may find potential application in color display fields.
Co-reporter:Ruiqing Li, Yali Liu, Nannan Zhang, Linlin Li, Lu Liu, Yimai Liang and Shucai Gan
Journal of Materials Chemistry A 2015 - vol. 3(Issue 16) pp:NaN3934-3934
Publication Date(Web):2015/03/04
DOI:10.1039/C5TC00371G
A series of Tb3+ and Eu3+ activated orthorhombic yttrium oxyfluoride, Y7O6F9 (denoted as V-YOF hereafter) phosphors were synthesized through a facile two-step hydrothermal synthesis route followed by heat treatment for the first time. The phase, morphologies, sizes and photoluminescence properties of as-prepared samples were investigated by means of XRD, SEM, and luminescence spectroscopy. A series of characteristic emission originated from the f–f transitions of Eu3+ and Tb3+ can be observed and multicolour emissions from green to yellow and then to red have been achieved in the V-YOF:Tb3+,Eu3+ samples under 378 nm irradiation. The energy transfer process from Tb3+ to Eu3+ was studied and demonstrated to be a quadrupole–quadrupole interaction mechanism. These results show that the V-YOF phosphors have potential applications in field-emission displays.
Co-reporter:Chunming Yang, Guimei Gao, Junjun Zhang, Ruiping Liu, Ruicheng Fan, Ming Zhao, Yongwang Wang and Shucai Gan
Physical Chemistry Chemical Physics 2017 - vol. 19(Issue 22) pp:NaN14441-14441
Publication Date(Web):2017/05/03
DOI:10.1039/C7CP02136D
A CdWO4/Bi2O2CO3 core–shell heterostructure photocatalyst was fabricated via a facile two-step hydrothermal process. Flower-like Bi2O2CO3 was synthesized and functioned as the cores on which CdWO4 nanorods were coated as the shells. Photoluminescence (PL) spectra and electron paramagnetic resonance (EPR) demonstrate that the CdWO4/Bi2O2CO3 core–shell heterostructure photocatalyst possesses a large amount of oxygen vacancies, which induce defect levels in the band gap and help to broaden light absorption. The photocatalyst exhibits enhanced photocatalytic activity for Rhodamine B (RhB), methylene blue (MB), methyl orange (MO), and colorless contaminant phenol degradation under solar light irradiation. The heterostructured CdWO4/Bi2O2CO3 core–shell photocatalyst shows drastically enhanced photocatalytic properties compared to the pure CdWO4 and Bi2O2CO3. This remarkable enhancement is attributed to the following three factors: (1) the presence of oxygen vacancies induces defect levels in the band gap and increases the visible light absorption; (2) intimate interfacial interactions derived from the core–shell heterostructure; and (3) the formation of the n–n junction between the CdWO4 and Bi2O2CO3. The mechanism is further explored by analyzing its heterostructure and determining the role of active radicals. The construction of high-performance photocatalysts with oxygen vacancies and core–shell heterostructures has great potential for degradation of refractory contaminants in water with solar light irradiation.
Co-reporter:Lu Liu, Nannan Zhang, Zhihua Leng, Yimai Liang, Ruiqing Li, Lianchun Zou and Shucai Gan
Dalton Transactions 2015 - vol. 44(Issue 14) pp:NaN6654-6654
Publication Date(Web):2015/03/02
DOI:10.1039/C5DT00581G
This paper describes a simple and environmentally-friendly approach that allowed for the facile synthesis of a gadolinium-based core/shell/shell nanotube structure with a set of lanthanide ions incorporated into separated layers. In addition, by the rational design of a core/shell structure we systematically investigated the luminescence properties of different lanthanide ions in NaGdF4 host, and efficient down-conversion emission can be realized through gadolinium sublattice-mediated energy migration. The Gd3+ ions play an intermediate role in this process. By changing the doped lanthanide ions, we generated multicolour emissions from the luminescent Ln3+ centers via energy transfer of Ce3+→Gd3+→Ln3+ and Ce3+→Ln3+ (Ln = Eu, Tb, Dy and Sm) in separated layers. Due to the strong absorption of ultraviolet (UV) irradiation by Ce3+ ions, the luminescence efficiency could be enhanced after doping Ce3+ ions in the shell. In NaGdF4:5% Eu3+@NaGdF4@NaGdF4:5% Ce3+ core/shell/shell nanotubes, with increasing the NaGdF4 interlayer thickness, a gradual decrease in emission intensity was observed for the Eu3+ activator.
![1,3,5-Tris(4'-carboxy[1,1'-biphenyl]-4-yl)benzene](http://img.cochemist.com/ccimg/911900/911818-75-2.png)
![1,3,5-Tris(4'-carboxy[1,1'-biphenyl]-4-yl)benzene](http://img.cochemist.com/ccimg/911900/911818-75-2_b.png)
