Persistent deNOx Ability of CaAl2O4:(Eu, Nd)/TiO2-x N y Luminescent Photocatalyst

Abstract  

CaAl₂O₄:(Eu, Nd)/TiO_2-x N _y composite luminescent photocatalyst was successfully synthesized by a simple planetary ball milling process. Improvement of photocatalytic deNOx ability of TiO_2-x N _y , together with the persistent photocatalytic activity for the decomposition of NO after turning off the light were realized, by coupling TiO_2-x N _y with long afterglow phosphor, CaAl₂O₄:(Eu, Nd). The novel persistent photocatalytic behavior was related to the overlap between the absorption wavelength of TiO_2-x N _y and the emission wavelength of the CaAl₂O₄:(Eu, Nd). It was found that CaAl₂O₄:(Eu, Nd)/TiO_2-x N _y composites provided the luminescence to persist photocatalytic reaction for more than 3 h after turning off the light.     

Morphology of polyacetylene and doped polyacetylene

A detailed study of the morphology of polyacetylene and iodine and arsenic pentafluoride doped polyacetylene has been carried out using scanning electron microscopy and transmission electron microscopy techniques. The results reveal a variety of fibrillar and rod-like morphologies for trans-polyacetylene. The samples retain this morphology upon doping, with, in many cases, a significant increase in the diameter of these structures. Larger increases in diameter were observed for the AsF₅ doped samples than in iodine doped samples. Energy dispersive X-ray analysis and back-scattered electron imaging were used to determine dopant distribution. Both iodine and arsenic distributions were uniform across the film surfaces to a resolution of 5000 Å. In addition, both dull and shiny sides of the films are shown to have approximately the same dopant concentration. This demonstrates that nonuniformity of the doping occurs, if at all, at a much finer scale. Finally, we have determined that small crystals, presumably arsenic trioxide, form on the surface of AsF₅ doped polyacetylene upon even moderate exposure to air.     

Third-order nonlinear optical properties and two-photon absorption in polymers doped with p-phenyl sydnone

We report the measurements of the third-order susceptibilities and two-photon absorption in three different polymers doped with p-phenyl sydnone moiety viz., 2-benzylhydrazono-5-(3-p-tolylsydnone-4-yl)1,3,4,-thiadiazine, which is recently synthesized and characterized, with the prospective of reaching a good compromise between processability and high nonlinear optical properties. The measurements were done using nano second Z-scan at 532nm. The Z-scan spectra reveal a large negative nonlinear refraction coefficient n₂ of the order 10⁻¹⁴ cm²/W and a two-photon absorption β, which is determined to be the order of cm/GW. The absorption cross section is 10⁻⁴⁶ cm⁴ s/photon. The molecular second-order hyperpolarizability in PMMA matrix was calculated to be 1.47 × 10⁻³¹ esu, comparable with stilbazolieum derivatives, a well-known class of optical materials for photonics and biophotonics applications. The chromophore shows its optical power limiting behavior in all the three polymer matrices. All these results suggest that this moiety has potential for the application of all-optical limiting and switching devices. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Highly transparent antibacterial hydrogel-polymeric contact lenses doped with silver nanoparticles

Biocompatible polymers such as poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) are used to prepare hydrogels for biomedical applications, including optical applications such as the manufacture of sensing devices, cosmetic and smart, and medical contact lenses, among others. In this study, three contact lenses were prepared by doping PVP-PVA supportive hydrogel with 0.1, 0.5, and 1 wt% of laboratory-manufactured Ag NPs. The work demonstrates the evaluation of vision correction through each lens and the effect of changing the concentration of silver on its refractive index. The simulation involved the design and simulation of an aberrated human eye based on the Liou and Brennan model (LBM), and the insertion of the contact lenses for vision correction using the ZEMAX optical design program. This work also included a study of the antimicrobial properties of the resulting hydrogel contact lenses doped with Ag NPs. The resulting refractive index of one PVP-PVA-Ag lens was relatively high at 532 nm = 1.604, which made the lens provide the highest image contrast (the lowest MTF curve degradation) of 0.883 ± 0.027 at 20 cycles/mm and an RMS nearly the Airy disc diameter of 3.983 μm. PVA was used in combination with PVP for stabilizing Ag NPs to give the contact lenses an antibacterial property. Finally, the optimum contact lens with a 1 wt% Ag NPs concentration showed the highest inhibition activity.     

Synthesis and nonlinear optical characterization of copolymers containing alternating 3,4‐dialkoxythiophene and (1,3,4‐oxadiazolyl)benzene units

We report the synthesis and linear and third‐order nonlinear optical (NLO) characterization of two novel copolymers containing alternating 3,4‐dialkoxythiophene and 1,4‐bis(1,3,4‐oxadiazolyl)benzene units. The copolymers were synthesized with a precursor polyhydrazide route. Both copolymers exhibited fluorescence around 430 nm under the irradiation of UV light. The NLO measurements were made with the single‐beam Z‐scan technique with Nd:YAG nanosecond laser pulses at 532 nm. The nonlinear refractive index of the investigated copolymers was negative, and the magnitude was as high as 10^?10 esu. The samples exhibited strong reverse saturation absorption and very good optical limiting properties at the wavelength used. The concentration dependence of third‐order NLO parameters was studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Luminescent thermometry based on Ba4Y3F17:Pr3+ and Ba4Y3F17:Pr3+,Yb3+ nanoparticles

New effective luminescence thermometers based on novel host Ba₄Y₃F₁₇ doped with Pr³⁺ and Pr³⁺/Yb³⁺ in 80–320 K temperature range were studied. The absolute temperature sensitivity (S_a) of both Ba₄Y₃F₁₇: Pr³⁺(0.1 mol %) and Ba₄Y₃F₁₇: Pr³⁺(0.1 mol.%): Yb³⁺(10.0 mol.%)nanothermometers based on luminescence intensity ratio (LIR) between two Pr³⁺ emission bands (³P₁-³H₅ and ³P₀-³H₅) demonstrate a notable value (0.011 K⁻¹ at 300 K) in the 200–320 K range. The Ba₄Y₃F₁₇: Pr³⁺(0.1 mol.%): Yb³⁺(10.0 mol.%)nanothermometers based on LIR between ³P₀→³H₄ of Pr³⁺ and ²F_5/2→ ²F_7/2 of Yb³⁺ emission bands demonstrate high S_a into the 80–200 K range with maximal S_a = 0,0778 K⁻¹ at 100 K. The stability of the phosphors was revealed by thermo-cycling experiments.     

NLO active Pd(II)-based organometallic side-chain polymers with C,N or N,O-chelating chromophoric ligands

Three organometallic homopolymers and three copolymers have been obtained, by reacting, respectively, cyclopalladated dinuclear complexes with a polymeric backbone, and by radical copolymerization of cyclopalladated acrylic monomers and methyl methacrylate. Taking into account thermal behaviour and solubility, the copolymers, which display good second order nonlinear optical activity, seem to be the most promising for applications within the new metallated macromolecules. Macroscopic nonlinear optical coefficients d₃₃ have been determined on spin-coated corona-poled thin films by means of Second Harmonic Generation (SHG) measurements at the wavelength of 1064 nm.     

铝铋离子掺杂对ZnO量子点荧光性能的影响研究

以二水合醋酸锌作为前驱体,无水乙醇作为溶剂,聚乙二醇(PEG-400)作为分散稳定剂,利用一种简单温和的方法制备Al~(3+)、Bi~(3+)掺杂氧化锌量子点,分别研究Al~(3+)、Bi~(3+)单掺,共掺对量子点荧光光谱性能的影响。结果表明:在紫外灯照射下,量子点颜色为绿色。在360 nm的激发下,ZnO量子点在524 nm附近有较的发射峰。随着掺杂离子用量的增加,ZnO量子点可见光区发射峰形状不变,单掺和共掺Al~(3+)、Bi~(3+)都使ZnO量子的荧光峰值减弱,但单掺Al~(3+)使荧光峰发生了红移。     

发光Lyocell纤维的制备

以可再生的α-纤维素为基体,粉末发光颗粒作为添加物,利用Lyocell纤维技术制备出发光性能合格的蓄光型自发光纤维。发光Lyocell纤维继承了稀土铝酸盐粉末优异的发光性能,含10%发光材料的纤维其余辉达到了德国的执行标准(DIN67510),10min余辉亮度>20mcd/m2,60 min余辉亮度>2.8 mcd/m2,而其有效余辉(>0.3 mcd/m2)时间大于10h。与无添加的Lyocell纤维相比,其断裂强度下降了17.6%,断裂伸长率上升了25%。     

掺杂炭黑电催化剂氧还原性能研究

碳纳米材料由于其良好的结构和功能特性,常做为氧还原反应中电催化剂的载体或直接做为氧还原反应的电催化剂。本文从具有良好导电性和高比表面积的炭黑(BP2000)出发,在对其进行表面氧化的基础上分别通过高温氨化和Fe(NO3)3溶液浸渍/高温煅烧进行了掺氮(N-BP2000)和掺铁(Fe-BP2000),对比考察了掺氮和掺铁对所得催化剂氧还原性能的影响。结果表明,所制备的掺氮炭黑(N-BP2000)和掺铁炭黑(Fe-BP2000)电催化剂的氧还原活性均较BP2000电催化剂提高显著。其中,Fe-BP2000电催化剂,表现出了最佳的氧还原活性,其半波电位为0.774 V,分别比N-BP2000与BP2000电催化剂正22、108 mV,同时其也表现出最佳的长程稳定性。     

Pure and (zinc or iron) doped titania powders prepared by sol-gel and used as photocatalyst

Pure and doped (zinc and iron) nanocrystalline titania powders were prepared by the sol-gel route. Doping tends to change the existing crystalline phases and their degree of crystallinity, but particle size distribution and morphology of the particles are also affected. In the pure titania system, the main crystalline phase is anatase but rutile is also present. The doped (Zn and Fe) titania crystallizes only as anatase. The undoped titania shows a bimodal distribution of particles size: fine (20-40 nm) and coarse (300-500 nm) grains. The doped TiO₂ powder also exhibits a much more uniform particle size distribution, with all grains under 40 nm.The photocatalytic efficiency of suspended powders was tested on the decolouration of Orange II aqueous solutions under visible artificial light irradiation. The maximum decolouration reached by the pure TiO₂ was 81% at a rate of 3.6 × 10⁻³ min⁻¹. Iron doping decreases the photocatalytic activity; the maximum dye degradation was only 43% at a rate of 1.3 × 10⁻³ min⁻¹. On the contrary, the performance of Zn-doped titania was better, having a decolouration rate of 17.7 × 10⁻³ min⁻¹.     

Photoinduced birefringence properties of poly‐Schiff bases containing triphenylamine

Anisotropy was induced in poly‐Schiff bases containing triphenylamine with linearly polarized light at 488 nm. Both writing and relaxation processes were described with a biexponential function. The alignment process involved two response modes: a fast response mode and a slow one. The fast response mode was associated with angular‐dependent trans–cis photoisomerization, whereas the slow one was attributed to the position adjustment of the rigid main chains used to obtain well‐aligned monodomains. The writing rate increased with an increase in the light intensity at a low intensity of the irradiation light. Structural factors such as main‐chain rigidity seemed to play important roles in the remaining stored information. The two polymers had large photoinduced birefringence values (0.01 and 0.0015, respectively). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2274–2279, 2004     

Synthesis and performances of 9,9-bis(perfluorohexylethyl propionate) fluorene copolymers

2,7-dibromo-9,9-bis(perfluorohexylethyl propionate) fluorene was synthesized by Michael addition reaction using 2,7-dibromofluorene and perfluorohexyl ethyl acrylate as the reactants. 9,9-Bis(perfluorohexylethyl propionate) fluorene copolymers were then synthesized by Suzuki coupling reaction with 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborane-diyl)-9,9 -dioctyl fluorene, 2,7-dibromo-9,9-dioctyl fluorene and 2,7-dibromo-9,9-bis(perfluorohexylethyl propionate) fluorene as the monomers. The fluorinated fluorene copolymers were characterized and investigated via Fourier infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance spectroscopy (¹HNMR), ultraviolet absorption spectroscopy (UV–vis), cyclic voltammetry (CV) and photoluminance spectroscopy (PL). Because of the long fluorine-containing alkyl side chain, the ultraviolet absorption peak of 9,9-bis(perfluorohexylethyl propionate) fluorene is blue-shifted compared with poly(9,9-dioctylfluorene)(PF8). The LUMO energy level increases and the energy band gap of copolymers widens. Due to the self-assembly of the long fluoroalkyl side chain, the photoluminance spectra of 9,9-bis(perfluorohexylethyl propionate) fluorene copolymers exhibit a new excimer emission peak at 550 nm. The photoluminance stabilities of the copolymers under irradiation and humid conditions are significantly improved due to protective effect from the long fluoroalkyl side chain. After being irradiated under 500 W iodine tungsten lamp or kept under 70% relative humid conditions, the 9,9-bis(perfluorohexylethyl propionate) fluorene copolymers showed much better photoluminance stability than that of poly(9,9-dioctylfluorene) (PF8). These show that introducing long fluoroalkyl side chain into conjugated polymer main chain is a promising strategy to improve environmental stability of devices based on organic conjugated polymers.     

Formation of low-resistance contact between titanium and lightly doped polycrystalline diamond using highly doped interlayer

A low-resistance ohmic contact between lightly doped polycrystalline diamond (poly-C) and metal was achieved for piezoresistive sensor applications using highly doped poly-C thin interlayer in the contact area for the first time for poly-C. Two Trimethylboron (TMB) doping concentrations were used during the growth of poly-C films using microwave plasma chemical vapor deposition (MPCVD), which yielded a 0.2 μm highly doped layer on top of 1.8 μm lightly doped layer. The resistivities of the highly and lightly doped poly-C layers are 0.022 and 151 Ω cm, respectively. The contacts were defined by partially etching the highly doped poly-C layer beyond the contact area. Kelvin bridges are fabricated to test the contact resistance. It is demonstrated that the contact resistivities are 0.0028 and 0.0083 Ω cm² for contacts with and without interlayer, respectively. This method reduced the contact resistance to one third of the original value and improved the performance of the piezoresistive sensor.     

Luminescent properties and energy transfer mechanism of NaGd(MoO4)2:Sm3+, Eu3+ phosphors

Sm³⁺ singly doped NaGd(MoO₄)₂ and Sm³⁺, Eu³⁺ co-doped NaGd(MoO₄)₂ phosphors by using sodium citrate as chelating agent were synthesized via hydrothermal method. The structure and morphology were characterized by means of X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). During the synthesis process, the Na₃Cit concentration plays a crucial role in determining the morphology and particle size of the products. The optimal doping concentration in Sm³⁺ singly doped NaGd(MoO₄)₂ phosphor was confirmed. The relevant parameters of energy transfer in the NaGd(MoO₄)₂: Sm³⁺, Eu³⁺ phosphors have been calculated based on the fluorescent dynamic analysis. Finally, on the analysis of luminescent spectra and fluorescent dynamics, the main energy transfer mechanism between Sm³⁺ and Eu³⁺ in NaGd(MoO₄)₂ phosphor is confirmed to be electric dipole-dipole interaction, and energy transfer pathway is from ⁴G_5/2 state of Sm³⁺ to ⁵D₀ state of Eu³⁺ rather than ⁵D₁ of Eu³⁺ ions.     

Formation of thermosensitive water‐soluble copolymers with phosphinic acid groups and the thermosensitivity of the copolymers and copolymer/metal complexes

Thermosensitive and water‐soluble copolymers were prepared through the copolymerization of acryloyloxypropyl phosphinic acid (APPA) and N‐isopropyl acrylamide (NIPAAm). The thermosensitivity of the copolymers and copolymer/metal complexes was studied. The APPA–NIPAAm copolymers with less than 11 mol % APPA moiety had a lower critical solution temperature (LCST) of approximately 45°C, but the APPA–NIPAAm copolymers with greater than 21 mol % APPA moiety had no LCST from 25 to 55°C. The APPA–NIPAAm copolymers had a higher adsorption capacity for Sm³⁺, Nd³⁺, and La³⁺ than for Cu²⁺, Ni²⁺ and Co²⁺. The APPA–NIPAAm (10:90) copolymer/metal (Sm³⁺, Nd³⁺, or La³⁺) complexes became water‐insoluble above 45°C at pH 6–7, but the APPA–NIPAAm (10:90) copolymer/metal (Cu²⁺,Ni²⁺, or Co²⁺) complexes were water‐soluble from 25 to 55°C at pH 6–7. The temperature at which both the APPA–NIPAAm copolymers and the copolymer/metal complexes became water‐insoluble increased as the pH values of the solutions increased. The APPA–NIPAAm copolymers were able to separate metal ions from their mixed solutions when the temperature of the solutions was changed; this was followed by centrifugation of the copolymer/metal complexes after the copolymers were added to the metal solutions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 116–125, 2004     

Synthesis of PEGylated chitosan copolymers as efficiently antimicrobial coatings for leather

In this work, poly(ethylene glcycol)‐grafted chitosan (PEG‐g‐CS) was synthesized by conjugating PEG to the chitosan (CS) backbone. Such PEGylated CS copolymer was further characterized by FTIR and ¹H NMR, and the results demonstrated the successful synthesis. After PEGylation, the water solubility of CS was significantly improved due to the hydrophilicity of the PEG polymer. Therefore, this PEGylated CS was prepared as water borne coating for leather surface. The morphology and hydrophilicity of this coating on leather was studied by SEM and water contact angle measurement. Furthermore, the antimicrobial activity of PEGylated CS coating was investigated by measuring its minimum inhibitory concentration and the inhibition zone of coated leather against Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus, respectively. Compared to CS coating, such PEG‐g‐CS coating exhibited better antimicrobial property, which indicated the synergetic effect of the antimicrobial property of CS and the antiadhesive property of PEG. Thus, this PEGylated CS copolymer can be used as efficiently antimicrobial coating for leather product. © 2016 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43465.     

Thermo‐ and pH‐ responsive copolymers: Poly(n‐Isopropylacrylamide‐co‐IAM) copolymers

Poly(N‐isopropylacrylamide) (NIPAAm) is well known as a smart material with good thermal sensitivity and favorable biocompatibility. A series of new smart hydrogels, NIPAAm copolymerized with IAM (itaconamic acid; 4‐amino‐2‐methylene‐4‐oxobutanoic acid), were synthesized through radical solution polymerization in this work. Poly(NIPAAm‐co‐IAM) can respond to the changes of temperature as well as pH value. Such a characteristic is due to the fact that IAM contains not only a hydrophilic acrylic acid moiety but also an acrylamide moiety to be thermal and pH sensitive. The experimental results show that the lower critical solution temperature (LCST) of the copolymer increases as the molar fraction of IAM increases. Moreover, based on the current experimental data, 3 wt % of Poly(NIPAAm‐co‐IAM) aqueous solution in this study exhibits a phase transition temperature (37.8°C) close to the human body temperature in the buffer solution of pH 7 possibly to be useful in drug delivery. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42367.     

Acrylic acid‐doped polyaniline sensitive to ammonia vapors

Acrylic acid and HCl‐doped polyanilines were synthesized by chemical oxidative polymerization. The synthesized materials were used as sensors for ammonia. Comparison of the responses of the two polymers reveal that the acrylic acid‐doped polymer exhibits higher sensitivity and reversibility. Further, the resistance is observed to decrease on exposing the acrylic acid‐doped polyaniline to saturated ammonia vapors. A reversed trend is observed in the case of HCl‐doped polyaniline. The results are explained in terms of the differences in the chemical interactions of the two polymers with respect to ammonia vapors. The proposed mechanism is further supported by the X‐ray diffraction and FTIR analysis. The X‐ray diffractogram of acrylic acid‐doped polymer shows an enhancement in the crystallinity on exposure to ammonia vapors, while the HCl‐doped polymer exhibits a loss in crystallinity. The FTIR spectra shows a higher doping level in acrylic acid doped polymer as observed from the intense peak of the dopant ion at 1158 cm⁻¹, which is seen to be shifted to a lower wavenumber i.e. ∼1128 cm⁻¹ on exposing the polymer to ammonia vapors. On the other hand, in HCl‐doped polyaniline, the peak of the dopant ion ∼1120 cm⁻¹ is initially less intense, which is further suppressed on exposure to ammonia. Conductivity measurements show a large vapor‐induced increase in conductivity, in the case of ammonia‐exposed acrylic acid‐doped polyaniline, which results in the formation of a more crystalline‐conducting phase. Exactly the opposite results were obtained in the case of HCl‐doped polyaniline exposed to ammonia. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1994–1998, 2001     

碱土金属掺杂对SrTiO3:Pr3+,Na+体系荧光粉发光性能的影响

采用高温固相法在还原气氛下制备了MxSr1-xTiO3∶Pr3+,Na+荧光粉.用X射线衍射分析测定了MxSr1-xTiO3∶Pr3+,Na+荧光粉的晶体结构,具体研究了碱土金属M(M=Mg、Ca)掺杂对SrTiO3∶Pr3+,Na+体系荧光粉发光性能的影响.结果表明,碱土金属Mg2+,Ca2-的掺杂未改变SrTiO3∶Pr3+,Na+荧光粉的立方晶系结构.随着碱土金属加入量的增加,各体系中激发峰或发射峰均有不同程度的红移或蓝移.