三维有序大孔CdS/TiO2薄膜的制备及其可见光催化性能

采用胶体晶体模板辅助溶胶-凝胶法以及S2-离子交换法合成了三维有序大孔CdS/TiO₂膜.结果表明,该薄膜材料在可见光催化降解污染水中罗丹明B和对氯苯酚的反应中表现出高活性.这可归因于修饰剂CdS的光敏化作用实现可见光催化,CdS-TiO₂之间形成了异质结,促进了电子和空穴的分离; 另一方面,有序大孔结构有利于光的利用以及反应物的扩散和吸附.     

CdS Reinforced with CoSX/NiCo-LDH Core-shell Co-catalyst Demonstrate High Photocatalytic Hydrogen Evolution and Durability in Anhydrous Ethanol

At present, inefficient charge separation of single photocatalyst impedes the development of photocatalytic hydrogen evolution. In this work, the CoS_X/NiCo-LDH core-shell co-catalyst was cleverly designed, which exhibit high activity and high stability of hydrogen evolution in anhydrous ethanol system when coupled with CdS. Under visible light (λ≥420 nm) irradiation, the 3 %Co/NiCo/CdS composite photocatalyst exhibits a surprisingly high photocatalytic hydrogen evolution rate of 20.67 mmol g⁻¹ h⁻¹, which is 59 times than that of the original CdS. Continuous light for 20 h still showed good cycle stability. In addition, the 3 %Co/NiCo/CdS composite catalyst also shows good hydrogen evolution performance under the Na₂S/Na₂SO₃ and lactic acid system. The fluorescence (PL), ultraviolet-visible diffuse reflectance (UV-vis) and photoelectrochemical tests show that the coupling of CdS and CoS_X/NiCo-LDH not only accelerates the effective transfer of charges, but also greatly increases the absorption range of CdS to visible light. Therefore, the hydrogen evolution activity of the composite photocatalyst has been significantly improved. This work will provide new insights for the construction of new co-catalysts and the development of composite catalysts for hydrogen evolution in multiple systems.     

Macroporous SiC?MoSi2 ceramics from templated hybrid MoCl5–polymethylsilane

A molybdenum‐containing preceramic polymer, MoPMS, was synthesized for the first time by HCl elimination of polymethylsilane (PMS) and MoCl₅ at room temperature in tetrahydrofuran. The insoluble MoPMS prepared was embedded into the void spaces of a silica colloidal crystal template within the pot life of the polymer and successfully transformed to a three‐dimensionally long‐range‐ordered macroporous SiC? MoSi₂ ceramic after pyrolysis at 1400 °C in an argon atmosphere followed by template removal in HF. The bead‐inverse macroporous SiC? MoSi₂ ceramic, with a ceramic yield of about 88%, exhibits high temperature stability, high BET surface area, and semiconducting behavior. In addition, the macroporous SiC? MoSi₂ ceramic was used as a catalyst carrier for platinum–ruthenium coated on the surface of the pores. The preceramic polymer and the ceramic were characterized by IR, thermogravimetric analysis, X‐ray diffraction, scanning and transmission electron microscopy, and BET surface area. Copyright © 2005 John Wiley & Sons, Ltd.     

Formation of organically and inorganically passivated CdS nanoparticles in reverse microemulsions

This paper is focused on the formation of organically and inorganically passivated cadmium sulfide (CdS) nanoparticles in two different types of microemulsions. On the one hand, we used a ternary inverse microemulsion consisting of water, heptanol, and 3-(N,N-dimethyldodecylammonio)propanesulfonate and on the other hand, a poly(ethyleneimine)-based quaternary microemulsion containing water, toluene, pentanol, and sodium dodecylsulfate. UV-vis measurements confirm the formation of CdS-ZnS core-shell nanoparticles in the ternary microemulsion. Using the quaternary microemulsion template phase, polymer capped luminescent CdS nanoparticles can be formed. After a complete solvent evaporation, the nanoparticles are redispersed in water and characterized by means of dynamic light scattering and transmission electron microscopy. From the ternary microemulsion, well-stabilized CdS-ZnS core-shell nanoparticles with diameters of about 5 nm can be redispersed, but from the quaternary microemulsion, only nanoparticle aggregates of about 100 nm.     

Synthesis of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene-silica core-shell particles with a self-templating method and their fluorescent properties

Sub-micrometer particles with poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV) cores coated by silica-based shells were prepared with a self-templating method and their fluorescent properties were investigated in this paper. The characteristic of this method was that all reactions could be finished in one-pot, which exempted from removing the template and reduced reaction steps compared to the conventional process. Emission wavelength of the resultant core-shell particles can readily be tuned through chemical modification of MEH-PPV, which was carried out via regulating the conjugation length of the polymer. In addition, the size of MEH-PPV/SiO₂ core-shell particles could be controlled by altering reaction conditions. The obtained particles had clear core-shell structure and may be used as biolabeling materials. The morphologies, particle size distribution and fluorescent properties of MEH-PPV/SiO₂ particles were characterized by transmission electron microscopy (TEM), particle size analyzer and fluorescence emission spectra, respectively.     

One-pot hydrothermal synthesis of willow branch-shaped MoS2/CdS heterojunctions for photocatalytic H2 production under visible light irradiation

Willow branch-shaped MoS₂/CdS heterojunctions are successfully synthesized for the first time by a facile one-pot hydrothermal method. The as-prepared samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption measurements, diffuse reflectance spectroscopy, and photoelectrochemical and photoluminescence spectroscopy tests. The photocatalytic hydrogen evolution activities of the samples were evaluated under visible light irradiation. The resulting MoS₂/CdS heterojunctions exhibit a much improved photocatalytic hydrogen evolution activity than that obtained with CdS and MoS₂. In particular, the optimized MC-5 (5 at.% MoS₂/CdS) photocatalyst achieved the highest hydrogen production rate of 250.8 μmol h^-1, which is 28 times higher than that of pristine CdS. The apparent quantum efficiency (AQE) at 420 nm was 3.66%. Further detailed characterizations revealed that the enhanced photocatalytic activity of the MoS₂/CdS heterojunctions could be attributed to the efficient transfer and separation of photogenerated charge carriers resulting from the core-shell structure and the close contact between MoS₂ nanosheets and CdS single-crystal nanorods, as well as to increased visible light absorption. A tentative mechanism for photocatalytic H₂ evolution by MoS₂/CdS heterojunctions was proposed. This work will open up new opportunities for developing more efficient photocatalysts for water splitting.     

Preparation of temperature-sensitive polymer particles having different lower critical solution temperatures

Preparation of temperature-sensitive core-shell composite polymer particles was carried out by seeded emulsion copolymerization of dimethylaminoethyl methacrylate and ethylene glycol dimethacrylate with submicron-sized polystyrene seed particles as core. The lower critical solution temperature (LCST) of the core-shell composite was about 35°C, while the LCST could be controlled toward higher or lower temperatures by copolymerizing the shell layer with hydrophilic/hydrophobic vinyl comonomer.     

多层核-壳结构P(AM-co-MAA)/W/UF复合微球制备研究

以反相悬浮聚合技术合成的丙烯酰胺(acrylamide,AM)和甲基丙烯酸(methacrylic acid,MAA)共聚高分子微凝胶P(AM-co-MAA)为模板,通过离心沉积法将微米级钨粉沉积于高分子微凝胶表面,得到具有核-壳结构的P(AM-co-MAA)/W复合微球材料;再以P(AM-co-MAA)/W复合微球为模板,通过控制甲醛和尿素的缩聚反应在模板与油/水相界面进行,制备得到了具有多层核-壳结构的高分子/钨/脲醛树脂[P(AM-co-MAA)/W/Urea-formaldehyde resin]复合微球材料.利用扫描电子显微镜(SEM)、红外(FT-IR)、X射线衍射(XRD)和热分析(TGA)等手段对复合微球进行了表征.实验结果表明,外壳层脲醛树脂的包覆量、复合微球的表面形貌可通过改变甲醛和尿素溶液的浓度、甲醛和尿素的物质的量之比等因素进行控制.复合微球的导电性测试结果表明,P(AM-co-MAA)/W复合微球表面壳层脲醛树脂包覆前后,其电导率由1.9×10-3降低为0.9×10-8S·m-1.该研究获得的三层核-壳复合微球材料其外层脲醛树脂的包覆较为完整、致密,其导电性接近于绝缘材料,为含钨复合微球作为电子元件的抗辐射涂层材料打下了基础.     

聚合物-二氧化硅复合基材中CdS纳米晶的合成

本文报道在Sol-gel基材中制备由聚合物稳定的CdS纳米晶的新方法， 即通过甲基丙烯酸镉与甲基丙烯酸羟乙酯共聚合合成了含有Cd 2+的聚合物微凝胶, 在聚合物微凝胶网络中原位聚合正硅酸乙酯形成聚合物互穿的Sol-gel复合基材. 再向该聚合物/二氧化硅复合基材中通入H2S气体得到CdS纳米晶. 在聚合物网络中原位聚合正硅酸乙酯可以降低纯二氧化硅材料的脆性; 另一方面, 二氧化硅可以作为增强剂增加聚合物材料的强度. 因此, 在我们合成的聚合物/二氧化硅复合基材中制备的CdS纳米晶将具有很好的应用前景.     

Core-shell structure CdS/TiO2 for enhanced visible-light-driven photocatalytic organic pollutants degradation

CdS modified mesoporous titania core-shell spheres (CdS/CS-TiO₂) with enhanced visible-light activity were synthesized by an in situ method. This method included two steps: planting CdO into the framework of anatase TiO₂ core-shell spheres and then converting it to CdS by ion-exchange. The physicochemical properties of the obtained samples were investigated by X-ray diffraction, scanning electron microscopy, transmission electronic micrograph, UV–vis diffuse reflectance spectra and nitrogen sorption. The in situ strategy resulted in CdS quantum dots highly dispersed in CS-TiO₂ without destroying the mesoporous core-shell structure. Compared with CS-TiO₂, the as-synthesized samples exhibited stronger visible-light absorption capability and greatly enhanced photocatalytic activity toward the degradation of Rhodamine B and 4-chlorophenol aqueous solution under visible light irradiation (λ > 420 nm).     

核-壳结构P(AM-co-MAA)-W-Ag复合微球的制备

以丙烯酰胺(acrylamide, AM)和甲基丙烯酸(methacrylic acid, MAA)的共聚微凝胶(P(AM-co-MAA))为模板, 通过离心沉积法将钨粉沉积于高分子微凝胶表面, 得到具有核-壳结构的P(AM-co-MAA)-W复合微球; 再以经聚乙烯基吡咯烷酮(PVP)修饰的P(AM-co-MAA)-W复合微球为模板, 在硝酸银溶液中充分溶胀后, 通过向反相悬浮体系中缓慢通入氨气, 制备得到了具有核-壳结构的P(AM-co-MAA)-W-Ag双金属复合微球材料. 实验发现, 通过改变制备过程中AgNO3的初始浓度和PVP的用量等条件, 可以改变复合微球表面银的沉积量; 并结合实验结果初步提出了银的形成机理, 即PVP的存在, 不仅可以作为稳定剂固定Ag+离子, 同时可以作为还原剂促进Ag+还原为Ag的反应.     

Coordinated organogel templated fabrication of silver/polypyrrole composite nanowires

A new method to fabricate metal/conducting polymer composite nanowires is presented by taking silver/polypyrrole composite nanowires as an example.A silver(Ⅰ)-coordinated organogel as template was prepared firstly,and redox-polymerization of pyrrole took place on the gel fiber,giving product of silver/polypyrrole nanowires.The silver/polypyrrole nanowires were characterized by multiple techniques.This strategy could be carried out in one-step procedure at room temperature,and it proves the utility of coordinated organogels in template synthesis of polymer nanostructures.     

Fabrication of Ordered Macroporous CdS and ZnS by Colloidal Crystal Template

Ordered macroporous semiconductors CdS and ZnS with regular arrays of spherical pores have been fabricated by poly (styrene-acrylic) (PSA) colloidal crystal template. It was found that the exact three-dimensional (3D) structure of the template had been imprinted in the final material.     

PDA/SiO2大孔复合材料固定化荧光假单胞菌脂肪酶

以具有三维骨架结构的大孔聚合物为模板制备SiO_2大孔材料,通过多巴胺在SiO_2大孔材料孔道表面的原位聚合制得聚多巴胺表面功能化修饰的二氧化硅大孔材料(PDA/SiO_2)。应用SEM、EDX、MIP、BET、TG-DTA和FTIR等技术对修饰前后的材料进行表征。以PDA/SiO_2为载体固定荧光假单胞菌脂肪酶(PFL),优化固定化条件并对比游离脂肪酶和固定化脂肪酶的性质。结果表明SiO_2大孔材料具有三维连续贯通的孔道结构,孔径分布在300~500 nm,聚多巴胺修饰后形成聚多巴胺/二氧化硅复合纳米薄膜构筑的大孔材料。在固定化时间为14 h、p H值为8、初始脂肪酶浓度为0.4 mg·m L-1时,固定化效果最佳,酶活回收率达246%。与游离脂肪酶相比,固定化脂肪酶有更宽的温度和p H适用范围、热稳定性显著提高,并展现出良好的储存稳定性和操作稳定性,固定化脂肪酶的Km低于游离脂肪酶的,酶与底物的亲和性较好。     

CdS@g-C3N4复合核壳纳米微粒的制备与光催化性能

采用水热法,在乙二胺和EDTA-2Na作用下,成功制备了CdS@g-C3N4复合核壳纳米微粒,并探讨了其生长机理。结果显示:CdS@g-C3N4复合核壳纳米微粒的比表面积是纯CdS纳米颗粒的14.0倍,具有良好的光催化活性和光稳定性。当反应条件为180℃、4 h、CdS/g-C3N4质量比1.9∶1时,CdS@g-C3N4的可见光催化性能最好,300 W氙灯光照2 h,RhB的降解率达95.2%,明显高于纯CdS。重复使用3次后,CdS@g-C3N4形貌、结构及光催化性能无明显变化。     

In-situ preparation and electrochromic properties of TiO2/PTPA-HTAN core-shell nanocomposite film

A new star-shaped structure conjugated microporous polymers, poly (2,8,14-tri[4-diphenyl-benzene]-hexaazatrinaphthylene) (PTPA-HATN), was designed and in-situ electrochemically polymerized on the surfaces of FTO electrodes with a directional alignment TiO₂ nanorod array to obtain TiO₂/PTPA-HATN core-shell nanocomposite films. Compared with the PTPA-HATN film, the TiO₂/PTPA-HATN composite film exhibits higher optical contrast and faster response time, with contrast of 57% at 783 nm, coloring time of 3.62 s and discoloring time of 2.55 s (43%, 4.63 s and 4.77 s for PTPA-HATN film, respectively). After 400 cycles, the contrast of nanocomposite film decreased by 28%, while the PTPA-HATN film basically lost its electrochromic properties. A simple three-layer EC prototype device based on TiO₂/PTPA-HATN nanocomposite film constructed with hydrogel electrolyte clearly shows color changes at different voltages. On the one hand, the formation of core-shell porous nanostructure of TiO₂/PTPA-HATN composite film provides a larger ion doping/de-doping interface, shortening the average diffusion length of ions. On the other hand, the large indented polymer-nanorods contact interface makes it difficult for the polymer to detach from the electrode, thus significantly improving the cyclic stability of the composite film.     

Synthesis,Characterization and Electrorheological Properties of Polyaniline/Titanate Core-Shell Composite

In this study, a facile method was developed for the preparation of a new conducting polymer composite with core-shell structure. The surfaces of layered titanate (K₂Ti₄O₉) particles were first modified with 3-aminopropyltriethoxysilane, and then a polyaniline/titanate (PANI/K₂Ti₄O₉) composite was synthesized via chemical oxidative polymerization. The resulting composites were characterized by SEM, XRD, FTIR and TG measurements. The results indicated that the PANI deposited on the surface of K₂Ti₄O₉ particles resulted in the formation of the composite with a core-shell structure. TG analysis showed that the composite containing 28.7 wt% PANI had better thermal stability than that of pure PANI. Further, the PANI/K₂Ti₄O₉ composite particles were adopted as a dispersed phase in silicone oil for electrorheological (ER) investigation. Suspension of the composite particles exhibited typical ER behavior subjected to an external electric field under steady and dynamic oscillatory shear.     

光还原Pt掺杂三维有序大孔ZrO2复合材料的光降解与光解水制氢

采用胶晶模板技术结合光还原方法制备了Pt掺杂复合材料三维有序大孔Pt/ZrO2(3DOM Pt/ZrO2)。通过X-射线衍射(XRD)、X-射线光电子能谱(XPS)、扫描电子显微镜(SEM)、紫外–可见漫反射吸收光谱(UV–Vis/DRS)和氮气吸附–脱附等测试方法对纳米复合材料3DOM Pt/ZrO2的晶相、组成、结构、形貌以及表面物理化学性质等进行表征。结果表明,Pt掺杂复合材料3DOM Pt/ZrO2与单体ZrO2的晶相相一致,其形貌呈现三维有序大孔结构,且孔结构排列整齐有序,孔壁为介孔结构。经光还原作用后该复合材料中Pt主要以单质形式存在,并且均匀分布在三维有序复合材料表面。同时,与单体ZrO2相比,纳米复合材料3DOM Pt/ZrO2的BET比表面积显著增大,光吸收性能发生改变,在240–350 nm间呈现强吸收。另外,在多模式光降解实验中,3DOM Pt/ZrO2的光活性明显增强。同时,其光解水制氢性能差不多是P25的2.5倍。     

Preparation and formation mechanism of three-dimensionally ordered macroporous (3DOM) MgO, MgSO4, CaCO3, and SrCO3, and photonic stop band properties of 3DOM CaCO3

Three-dimensionally ordered macroporous (3DOM) magnesium (Mg) oxide (MgO), MgSO₄, calcium (Ca) carbonate (CaCO₃), and strontium (Sr) carbonate (SrCO₃) were prepared using a colloidal crystal of polymer spheres as a template. Ethanol or ethanol-water solution of metal salts (acetate or nitrate) and citric acid was infiltrated into the void of the colloidal crystal template of a monodispersed poly(methyl methacrylate) (PMMA) sphere. Heating of this PMMA-metal salt-citric acid composite produced the desired well-ordered 3DOM materials with a high pore fraction, which was confirmed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and ultraviolet-visible (UV-vis) diffuse reflectance spectra. The presence of citric acid is crucial for production of the 3DOM structures. Reaction of citric acid with metal salt produces metal citrate solid in the void of PMMA spheres, which is necessary to maintain the 3DOM structure during the calcination process. 3DOM CaCO₃ shows opalescent colors because of it's photonic stop band properties.     

Photoconducting composite,polyester polymer-cds powder

The relation between electrical, photoelectrical and electrophotographical properties of polyester polymer–CdS composites as a function of component weight ratio, electric field strength and light intensity were investigated. Cl and Cu activated CdS_a powder as well as unactivated CdS powder were added to polyester polymer. It has been shown that the composite containing from 60 to 70 wt-% of CdS_a has the best photoelectric properties. The electrophotographical layers of this composite exhibited a photosensitivity as high as 1.25 (Lx · s)⁻¹. The results have been explained in terms of the reduction in interparticle barrier height assisted by the localized trapping of photoexcited or field-excited holes.