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Activated carbon (AC) has been widely used in the prevention and control of air and water pollution due to its excellent adsorption ability. However, the adsorption capacity of AC for targeting organic compounds is reduced because of the competitive adsorption of water molecules. The current study proposes hydrophobic modification and regeneration of waste AC as a solution to these issues. Using waste AC as raw material, SiO2 particles were introduced to increase its surface roughness and micropores of AC. Nonpolar alkyl chain groups were grafted on the surface of AC to improve its hydrophobic performance, and high-temperature regeneration was used to increase its specific surface area. The experimental results showed that the water contact angle of AC increased from 30° (hydrophilic) to 142° (hydrophobic) after modification, and it maintained an angle of 139° even after high-temperature regeneration. The specific surface area of hydrophobic AC increased from 290 to 1075 m2 g−1 and the equilibrium adsorption capacity of hydrophobic AC for methylene blue is 425.4 mg g−1 after regeneration. AC-adsorbed methylene blue also has excellent hydrophobicity (145°) and high specific surface area (1250 m2 g−1) after being modified and regenerated by the same methods. After being exposed to air for 600 days, the modified AC still has good hydrophobicity (125°). This indicates that our method of hydrophobic modification combined with regeneration has great significance to the recovery and utilization of waste AC.

Various ZrO2 with pure tetragonal, monoclinic, and mixed phases were used as carriers of gold nanoparticles for an exploration to production of propylene oxide (PO) in co-presence of propylene with H2 and O2. Catalysts with similar gold dispersion (2–5 nm gold particles) were prepared by a deposition–precipitation method. 100% selectivity to PO was obtained for the first time over non-titanium-supported Au catalysts on both tetragonal and monoclinic ZrO2 supports, which needs a good match of nanogold and active sites (quite possible hydroxyls connected with Zr4+). However, Au/tetragonal ZrO2 benefits PO formation that could be accelerated by hydroxyl groups while Au/monoclinic ZrO2 generates more acrolein and suppresses CO2 formation. The active sites for the production of PO are speculated to be Au and Zr-O rectangular pyramids in ZrO2, similar to that on TiO2 and acrolein appears on the Au near oxygen vacancies.

Gold nanocatalysts have been reported to be active in the selective hydrogenation of acetylene. In this paper, a series of Au/Ce1−xZrxO2 (x = 0.03 to 0.5) supported catalysts with different ratios of Ce to Zr were prepared and their catalytic performance for selective hydrogenation of acetylene was investigated. The structure and surface defects of the catalyst can be changed by altering the amount of Zr incorporation. Compared to both Au/CeO2 and Au/ZrO2, the synthesized Au/Ce1−xZrxO2 showed the higher catalytic activity with keeping almost 100% ethylene selectivity at 300 °C. The TEM observation indicated that the incorporation of Zr led to the formation of hollow spherical solid solutions. The specific surface area also has a certain influence on the catalytic activity. Considering the catalytic activity of Au/Ce1−xZrxO2 and their characterizations by XPS and Raman, the concentration of Ce4+ and the oxygen vacancy of the Ce1−xZrxO2 support play an important role in the selective hydrogenation of acetylene.

Supported gold nanoparticles are highly selective catalysts for hydrogenation of acetylene, but low activity and heavy coke effect have been major concern for the Au-based catalysts. Based on a modified impregnation-calcination strategy, a series of MgOx-Al2O3 composite oxides with different crystal structures from mixed phase to pure spinel was prepared. Due to its crystal defect and synergetic effect, Au nanoparticles on MgOx-Al2O3 components treated at 550 °C (abbreviated as Au/3%MgOx-Al2O3-550) with well controlled smaller particle size gave an enhanced activity for the selective acetylene hydrogenation. The conversion rate was nearly twice as high as that of all other samples at 250 °C. The H2-TPR and XPS results indicate the partially positive charged Au species (Auδ+) played a crucial role in facilitating the adsorption of the C C group. Both the temperature programmed oxidation and Raman scattering also indicated that the Au/3%MgOx-Al2O3-550 showed better decoking effect than Au/Al2O3. This report opens up promising possibilities on engineering the crystal phase of support for the highly efficient heterogeneous gold catalysts.

In order to clarify the nature of cooperation effect of gold–copper in CO oxidation without disturb of substrate materials, in this work we prepared nano-sized copper and cuprous oxide with different morphologies followed by the deposition of gold nanoparticles. The reaction of CO oxidation under both hydrogen-rich and oxygen-rich streams was investigated over as-prepared CuO/Cu2O materials and the corresponding supported gold catalysts. The characterizations reveal that in the unreduced Au/Cu2O samples, Au+–Cu2+ assembles are dominant on the surface of Cu2O substrate due to the spontaneous oxidation–reduction reaction of Au3+ and Cu+, while both of Au3+-Cu2+ and Au+-Cu2+ entireties are existed in the unreduced Au/CuO sample and the former is dominant. A comprehensive analysis of the catalytic results over these samples for CO oxidation in both oxygen-rich and hydrogen-rich streams demonstrates that the CuO species (not Cu2O) play a more critical role for the oxidation of CO and the improved catalytic activity of the Au/CuO catalyst can be attributed to the strong interactions of CuO support with nanogold particles.

In this paper, core-shell SiO2/polypyrrole (SiO2/PPy) composites were prepared via in situ chemical oxidation of pyrrole monomer on surface of the modified SiO2 by using FeCl3 as the oxidant. Au nanoparticles (NPs) were loaded on SiO2/PPy composites by means of the redox reaction between PPy and gold ions. Several analytical tools, such as TEM, FT-IR, XRD and EDX, were employed to characterize the morphology and structure of the as-prepared SiO2/PPy/Au composites. Their catalytic performances in reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with NaBH4 as the reducing agent were studied. Results showed that the conversion of 4-NP was increased with an decrease of Au loading. The reduction of trace AuCl4− ions in core-shell composites to small Au NPs by NaBH4 in the beginning of the reaction favored the enhancement of catalytic activity.

Supported gold catalysts are highly efficient for selective hydrogenation of acetylene. It has been shown that reducible materials such as ceria may influence the catalytic performance due to its unique charge shift between reduced and oxidized state. However, its role in catalytic performance remains fiercely debated. In this paper, differently morphological CeO2 supported Au catalysts were prepared with pretreatment under air and H2 atmospheres respectively, and evaluated for selective hydrogenation of acetylene. No matter with rod (abbreviated as R) or polyhedral (abbreviated as P) shape, the catalysts of Au/CeO2 reduced in air exhibits better catalytic performance than that in H2 atmosphere. The Au/CeO2 (R)-air catalyst shows the best performance. The C2H2 conversion is about three times of that over the catalyst of Au/CeO2 (R)-H2 at 300 °C. The Raman result and XPS analysis clearly showed a dependence of catalytic activity on the oxygen vacancy concentration of catalysts, revealing the correlation between its defect features and pretreatment atmosphere. Our report not only deepens the knowledge of catalytic performance affected by defect features of catalyst but also provides a possibility for the efficient heterogeneous gold/ceria catalysts by controlling the pretreatment atmosphere.

With increased global warming, the impact of high temperature and humidity (HTH) on human health is increasing. Traditional Chinese medicine describes the Herb Yinchen as a remedy for reducing heat and eliminating dampness. This study focused on the impact of HTH conditions on mice and the potential protective effect of Herb Yinchen. Five male Balb/c mouse groups included two normal control groups, two HTH-exposed groups, and one Yinchen-treated group. For either three or ten days, normal and HTH-exposed mice were housed under normal or HTH (33 ± 2 °C,85% relative humidity) conditions, respectively. Yinchen-treated mice, housed under HTH conditions, received the Herb Yinchen decoction for three days. Metabolite profiles of plasma and liver samples from each group were analyzed using LC–MS/MS. Fecal DNA was extracted for 16S rDNA analysis to evaluate the intestinal microbiome. Spearman correlation analysis was performed on metabolites, bacteria, and bile acids that differed between the groups. We found that HTH altered the host metabolite profiles and reduced microbial diversity, causing intestinal microbiome imbalance. Interestingly, Herb Yinchen treatment improved HTH-mediated changes of the metabolite profiles and the intestinal microbiome, restoring them to values observed in normal controls. In conclusion, our study reveals that HTH causes intestinal bacterial disturbances and metabolic disorders in normal mice, while Herb Yinchen could afford protection against such changes.

This paper explores the effect of emission trading scheme (ETS) policy on carbon emission performance using the setting that China implemented an ETS pilot policy from 2013 to 2014. Adopting the Difference-in-Difference (DID) model, we find that: (1) China's ETS pilot policy can significantly improve the carbon emission performance of listed companies in the pilot provinces. (2) The heterogeneity analysis shows that the carbon emission performance of listed companies in the eastern coastal pilot areas has improved significantly, which is not significant in the central and western pilot areas. (3) We find that China’s ETS pilot policy can significantly improve innovation capabilities of listed companies, suggesting that innovation is a channel for the impact of the China’s ETS pilot policy on carbon emission performance in the pilot provinces. Overall, our study shows that ETS pilot policy has played a governance role in China and improved carbon emission performance. We further highlight some important policy implications with respect to helping companies save energy and reduce emissions, and promoting the further improvement of China’s ETS pilot policy.

The YVO4 nanospindles with well-crystallization were synthesized through a facile and rapid chemical conversion route. The synthesis started with the precipitation of sheet-like yttrium precursor Y2(OH)5NO3∙nH2O at room temperature. With the addition of vanadate, YVO4 nanospindles were formed at the expense of the precursor in less than 10 min at 120 °C. The obtained particle shape and size are insensitive to experimental parameters, such as pH value and reaction temperature. The synthesis route is environment-friendly which involves no template or surfactant, but only relates to facile aqueous conditions at low temperature. We also investigated the luminescence properties of YVO4:Eu3+ and gold functioned Au/YVO4:Eu3+ products. Under UV excitation, both samples show strong red luminescence due to the radiative transitions of Eu3+, while the excitation spectra vary significantly. The interactions between Au nanoparticles (NPs) and the YVO4:Eu3+ NPs were also investiged.

Herein, polystyrene/polyaniline/Au (PS/PANI/Au) composites were prepared by a novel method using self-made Au(en)2Cl3 as the Au source and were used as the catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Before the preparation of PS/PANI/Au, PS microparticles were sulfonated by the copolymerization between styrene and sodium 4-styrenesulfonate (SSS). Then self-made Au(en)2Cl3 was added and Au(en)23+ species were adsorbed on the surface of sulfonated PS particles due to the electrostatic attraction. The Au(en)23+ was then reduced to Au nanoparticles in situ by aniline monomer. After the polymerization of the residual aniline monomer by ammonium persulfate (APS), the PS/PANI/Au composite catalysts were obtained. The morphology and structure of the as-prepared PS/PANI/Au composites were characterized by TEM, FT-IR, XPS and EDX. Their catalytic performance for the reduction of 4-NP by NaBH4 was evaluated by means of UV–vis spectroscopy. The as-prepared PS/PANI/Au composites are very active for the reduction of 4-NP by virtue of the interaction between Au nanoparticles and PANI shell. The catalytic reaction obeys the pseudo-first-order reaction equations and the reaction rate constants are also calculated in this paper.

A novel Au/Fe–V–Ox/Al2O3 catalyst displayed remarkable activity and good stability for CO oxidation in the simulated atmosphere of a CO2 laser with high CO2 levels up to 60 vol% and stoichiometric or even lower O2/CO ratio. The improved surface labile lattice oxygen on the FeOx and VOx modified Al2O3 plays a crucial role in its outstanding performance for the CO oxidation reaction in an oxygen-poor atmosphere.

Well-defined sodium lanthanum molybdate [NaLa(MoO4)2] microcrystals with a variety of morphologies (microspheres, ellipsoids, microspindles, microflowers, etc.) have been fabricated via a mild and controllable solvothermal method. The whole process was carried out without any organic surfactant, template, or catalyst. The morphology and size of the NaLa(MoO4)2 particles can be tuned in a controlled manner by altering the pH value of the initial solution, reaction temperature, and composition of solvent. Upon ultraviolet (UV) or near infrared (NIR) excitation, the as-synthesized NaLa(MoO4)2:Ln3+ phosphors exhibit intense characteristic down-conversion or up-conversion luminescence, respectively. The dependence of NaLa(MoO4)2:Ln3+ luminescence intensity on different particle sizes and morphologies has been also investigated. The facile synthesis strategy may be extended to the synthesis of other well-defined lanthanide molybdate materials.

Uniform and well-dispersed NaTb(MoO4)2 hierarchical nanoflowers have been fabricated via a hydrothermal method by using trisodium citrate as additive. The morphology and particle size of the NaTb(MoO4)2 samples can be tuned in a controlled manner by altering the pH value of the initial solution, reaction temperature, and component of solvent. The Eu3+-doped NaTb(MoO4)2 sample mainly shows the characteristic emission of Eu3+ corresponding to 5D0–7FJ (J=1, 2, 3, 4) transitions due to an efficient energy transfer from MoO42− and Tb3+ to Eu3+. The as-synthesized NaTb(MoO4)2:Eu3+ may be applied as a novel red phosphor in optoelectronic devices or advanced flat panel displays.

We reported a novel and simple strategy to construct core-shell composite microspheres with fly ash (FA) and Au nanoparticles embedded in polypyrrole (PPy) chains. In an acid medium, activation of FA microspheres, synthesization of Au nanoparticles, and polymerization of PPy were synergistically achieved in one-step green process. The physicochemical characteristics of the Au-PPy/FA composite microspheres were studied by SEM, TEM, FTIR, XRD, TGA and VSM. In the presence of NaBH 4 as a reducing agent, the Au-PPy/FA composite microspheres exhibited highly catalytic efficiency in reduction of nitrophenol to aminophenol. The reaction rate constants were calculated through the pseudo-first-order kinetic equation by using the excess amount of NaBH 4 . For the two isomers of nitrophenol, the reduction rates were particularly investigated and followed the order: 4-nitrophenol > 2-nitrophenol. The electronic interaction between Au nanoparticles and PPy chains plays an important role for the highly catalytic efficiency of the Au-PPy/FA. A possible reaction mechanism for the reduction process was also emphasized.

A novel Pd(II) complex immobilized on ethylenediamine-functionalized core–shell magnetic nanoparticles [Fe 3 O 4 @SiO 2 –2N–Pd(II)] was successfully synthesized by a facile procedure, and various characterizations (TEM, XRD, FT-IR, TGA, XPS and VSM) were performed to identify its intrinsic features. The amino groups in two kinds from ethylenediamine-functionalized magnetic nanoparticles (Fe 3 O 4 @SiO 2 –2N) performed as robust anchors and efficient stabilizers during the fabrication of Fe 3 O 4 @SiO 2 –2N–Pd(II). As a heterogeneous phosphine-free Pd(II) complex catalyst, it showed excellent catalytic activity for aerobic oxidation of alcohols, and up to >99% yield of unsymmetrical biaryl ketone was obtained in the carbonylative Suzuki coupling reaction of carbon monoxide, 4-methylbenzeneboronic acid and the 4-iodonitrobenzene. Moreover, the catalyst could be completely recovered by magnetic separation from the reaction mixture and remained unaltered activity even after six repeated cycles.

An orange-like catalyst of Pd nanoparticles supported by magnetic Fe3O4/polypyrrole nanocomposite is facilely prepared. It shows great activity for Suzuki coupling reactions in neat water under atmospheric pressure. This magnetic and water-soluble catalyst avoids the use of toxic solvents in traditional process of coupling reactions and can be easily recovered by mean of a convenient magnetic separation technique, demonstrating in both environmental friendliness and recyclability.

Herein, polystyrene/polyaniline/Pd (PS/PANI/Pd) core-shell composite catalysts were prepared by a facile swelling-diffusion-interfacial polymerization method. PS microparticles were firstly prepared by dispersion polymerization and were swollen by aniline monomer without any surface modification. H2PdCl4 acid was used as palladium precursor. The PdCl42− was adsorbed on the surface of aniline-swollen PS microparticles because of the electrostatic attraction between PdCl42− and anilinium positive ions protonated by H+, which was diffused from the aniline-swollen PS microparticles. Then HCl solution was added to control the diffusion rate of anilinium positive ions and ammonium persulfate (APS) was used to polymerize the anilinium ions to get PANI shell. Due to the redox activity between PANI and Pd ions, Pd nanoparticles can be in situ formed on the surfaces of PS. Therefore, the core-shell PS/PANI/Pd composite catalysts were obtained. The morphology and structure of the obtained composites was characterized by TEM, FT-IR and EDX. Results showed that the products presented excellent catalytic properties for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4 by virtue of the interaction between Pd nanoparticles and conducive PANI shell. The catalytic reaction obeyed the pseudo-first-order reaction equations and the reaction rate constants were also calculated in this article. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 133, 44812.

In this work, Au/Al2O3 and Au/xCeO2-Al2O3 catalysts were prepared by incipient wetness impregnation method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), raman spectroscopy, temperature programmed hydrogen reduction (H2-TPR) and temperature programmed NH3 desorption and C2H2 desorption (NH3-TPD, C2H2-TPD). TEM and XRD results showed that there was no obvious difference for the structures and morphologies compared with Au/Al2O3 and Au/xCeO2-Al2O3. However, enhanced catalytic performance was found in the selective acetylene hydrogenation to ethylene. Raman spectra showed that no coke was obtained for Au/xCeO2-Al2O3. NH3-TPD confirmed that with the increase of CeO2 loading, the surface acidity was decreased and an appropriate CeO2 addition was needed for the improvement of catalytic activity. The charge transfer between metallic Au and CeO2 leads to positively charged Au (Auδ+).The basic character of CeO2 and the positively charged Au may play a positive role in the selective acetylene hydrogenation reaction. A possible reaction mechanism was proposed in this paper.

In stark contrast to the report that phenanthroline is an efficient chelate ligand for lanthanide-based metal–organic framework formation, here it is found that phenanthroline can act as a very useful regent to modulate self-assembly of nano/micro-sized yttrium benzenetricarboxylate (Y–BTC). 1D nanobelts of Y–BTC was firstly produced via a simple, mild one-step approach. Then the morphology was transformed to 3D urchin-like hierarchical architectures with the assistance of phenanthroline. Interestingly, the as-synthesized 3D urchin-like superstructures can be disassembled through simple ultrasonic treatment. Thus a large quantity of 1D nanorods was obtained. Additionally, brilliant-red light of the nanomaterials was realized by doping Eu 3 + ions.

Monodispersed CaWO4 and CaWO4:Mo/Eu, Tb microspheres have been obtained hydrothermally with excellent reproducibility. X-ray diffraction, field-emission scanning electron microscopy and photoluminescence were used to characterize the as-synthesized samples. The results uncover the formation process of the microspheres and the influence of ethylenediamine. Doping proper concentration of Mo into CaWO4 micropheres can extend the excitation range as the incorporation induces obvious redshift. We have also tuned the color from blue to pink blue, white and green only by varying the relative content of Eu-Tb in the CaWO4 host. (C) 2011 Elsevier B.V. All rights reserved.

A novel tunable full-color-emitting Sr3Gd(PO4)3:Eu2+,Mn2+ phosphor system was successfully developed. Its excitation wavelength ranging from 230 to 450 nm fits well with the characteristic emission of UV light-emitting diode (LED) chips. The color emission of these phosphors can be tuned across almost the entire visible light spectrum resulting in white light emission with varied hue and correlated color temperature (CCT) by varying the molar ratios of Eu2+ and Mn2+. Moreover, the efficient energy transfer from Eu2+ to Mn2+ was demonstrated via a dipole–quadrupole mechanism by the luminescence spectra and the fluorescence decay dynamics based on the Inokuti–Hirayama theoretical model. These results indicate that the developed phosphor may be promising as a single-component white-light-emitting phosphor for white LEDs.

A series of single-component Sr3Lu(PO4)3:Eu2+,Mn2+ phosphors were successfully synthesized by solid-state reaction, and their photoluminescence properties were investigated. The Sr3Lu(PO4)3:Eu2+,Mn2+ phosphor system was efficiently excited at wavelength ranging from 250 to 420 nm, which is well-matched with ultraviolet (UV) light-emitting diode (LED) chips. As a result of fine-tuning of the emission composition of the Eu2+ and Mn2+ ions, warm white light emission can be realized by combining the emission of Eu2+ and Mn2+ in a single host lattice under UV light excitation. Efficient resonant energy transfer from the Eu2+ to Mn2+ ions was demonstrated to be a dipole–quadrupole mechanism in such system, and the energy transfer efficiency increases with an increase in the Mn2+ doping content, which was confirmed by the luminescence spectra and fluorescence decay curves. In addition, the energy transfer efficiency and critical distance were also calculated. The results indicate that the developed phosphor can ...

YBO(3) micropancakes and NaYF(4) nanorods were synthesized through a two-step hydrothermal chemical conversion route. The uniform sheetlike yttrium precursor was first hydrothermally prepared. Well-crystallized YBO(3) and NaYF(4) were then obtained at the expense of the precursor. The two steps were both carried out in aqueous conditions without any template, surfactant, or catalyst. The formation mechanisms of our samples are both governed by the dissolution-recrystallization. During the recrystallization, oriented attachment attributes most to the final morphology of our products. We have investigated the relation between their growth habits and inherent crystal structures in detail for the first time and the results afford some guidance for the green synthesis of other inorganic nano-/micro-materials with specific morphology. We have also investigated the luminescence properties of Tb(3+) doped YBO(3) and NaYF(4), which preserved the same morphology as the undoped samples.

Hierarchically nano/microstructured coordination polymer Pr(1,3,5-BTC)(H2O)6 architectures with different crystal splitting forms have been successfully prepared on a large scale via direct precipitation in the solution phase. The as-obtained samples present highly crystallinity in spite of the moderate reaction conditions. The morphology and size of the products strongly depend on the concentration, molar ratio of reactants, reaction temperature, solvent, surfactant, and static reaction; thus, 3D flower, straw-sheaf, chrysanthemum-sheaf, dendrite-sheaf, fan, bundle without fantails, broccoli, embryo superstructures, and 1D nanorod of the coordination polymer can be perfectly manipulated by controlling the above reactions parameters rationally.

Lanthanide-based coordination polymer Dy(1 3 5-BTC)(H(2)O)(6) nanobelts were successfully synthesized on a large scale through an extremely simple approach at room temperature the size of the nanobelts can be easily tuned from several to several hundred micrometers in length 70-600 nm in width and 10-100 nm in thickness by varying concentrations solvent and surfactant reasonably In addition the as-obtained dysprosium benzenetricarboxylate nanobelts exhibit the characteristic emission of the Dy(3+) ions making the belt-like coordination polymer have potential applications in building minioptoelectronic devices (C) 2010 Elsevier Masson SAS All rights reserved

NaYF4:Yb,Er micro/nanocrystals with different sizes and morphologies such as nanospheres, short flexural nanorods, and half opened microtubes, were synthesized in reverse microemulsion under solvothermal condition using the quaternary reverse microemulsion system, CTAB/1-butanol/cyclohexane/aqueous solution. The X-ray diffraction analysis confirmed that cubic phase NaYF4:Yb,Er can completely transform to hexagonal phase with increasing reaction time. The scanning electron microscope and transmission electron microscope images revealed that the morphology of the product can be tailored by varying the reaction time. A possible crystalline growth process of the NaYF4:Yb,Er micro/nanocrystals was discussed. The obtained half opened microtubes exhibited an intense green upconversion luminescence, which may be attractive in novel optoelectronic devices.

Nano/micro-sized coordination polymer La(1,3,5-BTC)(H2O)(6) with controllable morphologies have been successfully prepared on a large scale via a simple solution phase method at room temperature. By rationally adjusting the synthetic parameters such as concentration, molar ratio of reactants, surfactant, and solvent, the La(1,3,5-BTC)(H2O)(6) with 3D flowerlike, wheatearlike, spherical, sheaflike, taillike, bundlelike hierarchical architectures, and 1D nanorods can be selectively prepared. More interestingly, the photoluminescence color of codoped Eu3+ and Tb3+ lanthanum 1,3,5-benzenetricarboxylate phosphors can be easily tuned from red, orange, yellow, green-yellow to green by changing co-doping concentration of activator ions, making the material has potential applications in building minioptoelectronic devices, biomedicine, and color display fields. (C) 2010 Elsevier Inc. All rights reserved.

NaCaPO4:Ce3+,Tb3+ phosphors were prepared by a solid-state reaction. Their luminescence properties reveal that an efficient energy transfer from the Ce3+ to Tb3+ ions occurs, and its mechanism is a resonant type by means of a dipole-quadrupole reaction. The critical distance of the energy transfer has been calculated by concentration-quenching and spectral-overlap methods. The varied emitted color of the phosphors from blue 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 NaCaPO4:Ce3+,Tb3+ is potentially useful as a highly efficient, green-emitting, UV-convertible phosphor for white-light-emitting diodes. Moreover, the accurate oscillator strength ratio of the electric quadrupole-to-dipole transitions for the Tb3+ ion was obtained to be about 10(-3), which may be of much significance in the estimate of the critical distance of the dipole-quadrupole interaction between Ce3+ and Tb3+ ions through Dexter's energy-transfer theory.

Highly uniform pancake-like YBO(3) hierarchical architectures have been successfully prepared by a designed two-step hydrothermal method. Yttrium precursor microprisms were first synthesized according to a simple hydrothermal route. Subsequently, nearly monodisperse multilayered YBO(3) products with a pancake-like shape were synthesized at the expense of the precursor during the hydrothermal process. The whole process was carried out under aqueous conditions without the use of any organic solvent, surfactant, or catalyst. The conversion process from the precursor to YBO(3) products has been investigated by time-dependent XRD experiments. Extending this method, other LnBO(3) (Ln=Ho, Er, Tm, Yb) samples with well-defined shape and dimensionality have also been obtained by a similar synthetic process. The luminescence colors of YBO(3) samples co-doped with Eu(3+) and Tb(3+) under ultraviolet or low-voltage electron beam excitation can be tuned from red, through yellow and green-yellow, to green by simply adjusting the relative doping concentrations of the activator ions. This merit of multicolor emissions in the visible region endows materials of this kind with potential application in the fields of light-display systems and optoelectronic devices.

Y4O(OH)9NO3:Eu3+ nanotubes and nanobundles were successfully synthesized from nanolamellar precursors in large quantities with a direct hydrothermal method. Different choices of solvents led to different products with distinct morphologies. Nanosheet precursors were obtained using water as the solvent while Y4O(OH)9NO3:Eu3+ nanotubes and nanobundles were produced by introducing ethylene glycol into the solvent. The observations of scanning and transmission electron microscopy are in good agreement with the proposed “rolling mechanism” and the effects of solvents on the morphology changes were discussed. The Y2O3:Eu3+ nanotubes and nanobundles were obtained by subsequent calcinations of the corresponding Y4O(OH)9NO3:Eu3+ precursors. The photoluminescent properties of the phosphors have been discussed in detail.

The facile, rapid, and effective synthesis of coordination polymer La(1,3,5-BTC)(H2O)6 has been realized via direct precipitation at room temperature. It is found that the crystal structure is of monoclinic, space group Cc. The doped Eu3+ or Tb3+ ions samples have the same phase and exhibit red and green emissions under UV light excitation, respectively.

The multi-morphological coordination polymer La(1,3,5-BTC)(H2O)6 has been prepared through simple and mild one-step approaches at room temperature on a large scale (1,3,5-BTC = 1,3,5-benzenetricarboxylate). The delicate sheaflike, broccolilike, urchinlike, and fanlike hierarchical architectures made of uniform nanorods were obtained through splitting crystal growth. More interestingly, these three dimensional architectures can exhibit tunable white-light emission by codoping Tb3+ and Eu3+.

Large-scale GdVO4:Eu3+ nanowires with diameters of about 15 nm and lengths of several micrometers were achieved by a facile hydrothermal method in the presence of disodium ethylenediamine tetraacetate (Na2H2L). The influences of several parameters, such as pH value, reaction temperature, and molar ratio of Na2H2L to Gd3+ on the final products were investigated. The formation mechanism of the as-obtained GdVO4:Eu3+ nanowires is proposed on the basis of time-dependent experiments. It is found that the organic additive Na2H2L, which acts as a shape modifier, has a dynamic effect by adjusting the growth rates of different facets, resulting in the formation of the GdVO4:Eu3+ nanowires. The luminescent spectrum of GdVO4:Eu3+ nanowires shows the strong characteristic dominant emission of the Eu3+ ions at 614 nm.

Hierarchically nanostructured coordination polymer Ce(1,3,5-BTC)(H2O)6 architectures with tunable morphologies have been successfully prepared on a large scale via a simple and rapid solution phase method at room temperature. The as-synthesized products are characterized by X-ray diffraction, thermogravimetric analysis, energy dispersive X-ray (EDX) analysis, scanning electron microscopy, and transmission electron microscopy, respectively. A possible splitting formation mechanism for the interesting architectures has been proposed to interpret the growth process. By rationally adjusting the synthetic parameters such as concentration, reaction temperature, surfactant, solvent, static, and ultrasonic treatment, Ce(1,3,5-BTC)(H2O)6 with straw-sheaflike, flowerlike, wheatearlike, strawlike, bundlelike, and urchinlike architectures, and nanorods can be selectively obtained. This facile, rapid, mild, cost-effective, reproducible, and environment-friendly growth strategy has considerable potential, and could rea...

Sheaflike terbium phosphate hydrate hierarchical architectures composed of filamentary nanorods have been fabricated by a hydrothermal method. The X-ray diffraction patterns and thermogravimetric/d...

Uniform NaLuF(4) nanowires and LuBO(3) microdisks have been successfully prepared by a designed chemical conversion method. The lutetium precursor nanowires were first prepared through a simple hydrothermal process. Subsequently, uniform NaLuF(4) nanowires and LuBO(3) microdisks were synthesized at the expense of the precursor by a hydrothermal conversion process. The whole process was carried out in aqueous condition without any organic solvents, surfactant, or catalyst. The conversion processes from precursor to the final products have been investigated in detail. The as-obtained Eu(3+) and Tb(3+)-doped LuBO(3) microdisks and NaLuF(4) nanowires show strong characteristic red and green emissions under ultraviolet excitation or low-voltage electron beam excitation. Moreover, the luminescence colors of the Eu(3+) and Tb(3+) codoped LuBO(3) samples can be tuned from red, orange, yellow, and green-yellow to green by simply adjusting the relative doping concentrations of the activator ions under a single wavelength excitation, which might find potential applications in the fields such as light display systems and optoelectronic devices.

The nonstoichimetric Ba0.92Y2.15F8.29 submicrospheres that piled up by nanoparticles have been prepared via a solution-based method in a hydrothermal environment. The size distribution of the submicrospheres could be tuned by varying the amount of BaCl2. The fluoride source NaBF4 plays an important role in the formation of the submicrospheres. The chelator ethylenediaminetetraacetic acid regulates the growth of the primary nanoparticles as well as the aggregated submicrospheres. The photoluminescence properties of different concentrations of Eu3+-doped Ba0.92Y2.15F8.29 were investigated and the results revealed that the 8% concentration of Eu3+ ions is the optimum doping concentration and the Y3+ ions occupy the site of inversion symmetry.

Uniform octahedral YVO4:Eu3+ microcrystals have been successfully prepared through a designed two-step hydrothermal conversion method. One-dimensional precursor Y4O(OH)9NO3 was first prepared through a simple hydrothermal process without using any surfactant, catalyst or template. Subsequently, well-defined octahedral YVO4 was synthesized at the expense of the precursor during a hydrothermal conversion process. XRD results demonstrate that the diffraction peaks of the final product can be well indexed to the pure tetragonal phase of YVO4. The SEM and TEM images indicate that the as-prepared YVO4 sample has regular octahedral shape with sharp corners and well-defined edges. The as-obtained YVO4:Eu3+ phosphor shows strong red emission under ultraviolet excitation or low-voltage electron beam excitation. Furthermore, this facile and general conversion method may be of much significance in the synthesis of many other lanthanide compounds with uniform morphology.

Novel one-dimensional europium benzene-1,3,5-tricarboxylate compressed nanorods have been synthesized on a large scale through direct precipitation in solution phase under moderate conditions without the assistance of any surfactant, catalyst, or template. The obtained nanorods have widths of about 50−100 nm, thicknesses of 10−20 nm, and lengths ranging from a few hundred nanometers to several micrometers. X-ray powder diffraction, elemental analysis, Fourier transform infrared studies, and thermogravimetric and differential thermal analysis show that the nanorods have the structural formula of Eu(1,3,5-BTC)·6H2O. Upon UV excitation, these nanorods exhibit a highly efficient luminescence, which comes from the Eu3+ ions. Moreover, Eu2O3 nanorods could also be obtained via a thermal decomposition method using the corresponding complex as a precursor. This synthetic route is promising for the preparation of other one-dimensional crystalline nanomaterials because of its simplicity and the low cost of the star...

Uniform MF/YVO4:Ln(3+) (Ln = Eu, Dy, and Sm) composite microspheres have been prepared via a simple and economical wet-chemical route at ambient pressure and low temperature. Monodisperse micrometer-sized melamine formaldehyde (MF) colloidal particles were first fabricated by a condensation process of melamine with formaldehyde. Subsequently, well-dispersed YVO4 nanoparticles were successfully grown onto the MF microspheres to form core-shell structured composite particles in aqueous Solution. The as-obtained composite microspheres with perfect spherical shape are uniform in size and distribution, and the thickness and roughness of the YVO4 shells on MF cores could be tuned by varying the reaction temperature. The MF/YVO4:Ln(3+) composite phosphors show strong light emissions with different colors coming from different activator ions under ultraviolet excitation, which might find potential applications in fields such as light phosphor powders and advanced flat panel displays.