CTAB-assisted synthesis and photocatalytic property of CuO hollow microspheres

CuO hollow microspheres have been fabricated through a simple hydrothermal method in the presence of cetyltrimethylammonium bromide (CTAB). The products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The effects of reaction temperature, surfactant, and the molar ratio of Urea/Cu(Π) on the morphologies of the resulting products were investigated. The possible formation mechanism of CuO hollow dandelion-like architectures was proposed. The hierarchical CuO hollow microspheres exhibited a high photocatalytic activity for decolorization of Rhodamine B (RhB) under UV-light illumination.     

Facile synthesis of amino-functionalized hollow silica microspheres and their potential application for ultrasound imaging

By using the positive charged polystyrene (PS) microsphere as template, mono-disperse amino-(-NH(2)) functionalized hollow silica microspheres (HSMS-NH(2)) with ~1310 nm in diameter and uniform shells were successfully prepared with a modified sol-gel process. The amino functionalized silica were coated on the PS microspheres via ammonia catalysis, co-hydrolysis and condensation of TEOS and APTES, and then the PS templates were selectively dissolved in THF solution to form the functional hollow microspheres. The controllable thickness (35-85 nm) and amino density (2.46×10(-5)-6.18×10(-5) mol/g) of the shells could be facilely tuned by changing the amount of TEOS and APTES. In vitro ultrasound images of as-prepared HSMS-NH(2) with different concentrations in the physiological saline solution were further investigated. The obvious signal enhancement indicates that as-prepared HSMS-NH(2) has a great potential application for ultrasound imaging.     

高活性Ag修饰TiO2空心八面体光催化剂的简易模板诱导合成

贵金属修饰的TiO2空心纳米光催化材料由于具有大的比表面积、低的质量密度、良好的表面渗透性、强的光吸收能力以及界面电荷的快速转移,因而表现出优异的光催化性能.为了制备结构可控且精良的贵金属修饰TiO2空心纳米光催化材料,人们先后采用湿化学法、高温固相法、声化学法及光化学沉积法等.由于在制备过程中涉及多种异相材料的合成和结构控制,因此上述合成方法通常需要复杂且多步过程(有些过程甚至很容易导致结构破坏),从而限制了其在光催化领域的实际应用.本文开发了一种简单的模板诱导法,成功制备了Ag纳米粒子修饰的TiO2空心八面体光催化剂.合成过程包括模板指导沉积和原位模板溶解.以Ag2O八面体为模板, TiF4水溶液为前驱体,首先通过TiF4水解形成TiO2纳米粒子沉积在Ag2O模板表面,而TiF4水解产生的酸性HF水溶液可原位溶解碱性的Ag2O模板,从而一步制得TiO2空心八面体.同时,利用Ag2O以及Ag+离子的光敏特性,在光照条件下使Ag2O和Ag+离子生成Ag纳米颗粒,直接沉积在TiO2空心八面体的内外表面,得到Ag/TiO2光催化剂.由此可见,该合成方法具有明显的步骤少的优点.扫描电镜、透射电镜、能量散射和紫外-可见光谱等表征结果表明成功制得内外Ag纳米粒子修饰的TiO2空心八面体光催化剂,其中TiO2空心八面体的壁厚约为25 nm,边长约为1μm,而修饰在其表面的Ag纳米粒子尺寸仅为5–10 nm.此外,通过控制TiF4前驱体浓度,还可制备核壳结构的Ag2O@TiO2八面体以及不同壁厚Ag修饰的TiO2空心八面体,表明该方法在Ag/TiO2形貌合成上的多样性和可控性.为了获得良好的光催化活性,对制备的Ag纳米粒子修饰的TiO2空心八面体光催化剂进行了不同温度的热处理. X射线衍射结果表明,即使在600 oC高温下,制备的Ag/TiO2空心八面体光催化剂依然能够保持原有的特殊形貌和锐钛矿TiO2晶型.该温度明显高于TiO2从锐钛矿向金红石转变的温度.这说明合成的Ag/TiO2能在保持高活性锐钛矿相的同时获得更好的结晶性.这可能是由于分散在TiO2原始晶粒周围的Ag纳米粒子能阻止其进一步长大,从而抑制了其晶型转变.不同样品光催化降解甲基橙的结果表明,经600oC高温热处理的样品表现出最高的光催化活性,相应的反应速率常数为0.11 min？1.这应得益于该光催化剂具有以下三个特点：(1) TiO2空心八面体的薄壁结构能够缩短光照条件下光生电子和空穴从内部扩散到表面的距离;(2)由于贵金属Ag纳米粒子沉积在TiO2薄壁的内外两个表面以及TiO2和Ag形成肖脱基势垒,因此在它们接触的界面上能够发生更快的界面电荷转移;(3)高温处理导致TiO2良好的晶化以及高活性锐钛矿TiO2晶型的保持.     

Self-assembled mesoporous hierarchical-like In2S3 hollow microspheres composed of nanofibers and nanosheets and their photocatalytic activity

Novel template-free hierarchical-like In(2)S(3) hollow microspheres were synthesized using thiosemicarbazide (NH(2)NHCSNH(2)) as both a sulfur source and a capping ligand in a ethanol/water system. In this study, we demonstrate that several process parameters, such as the reaction time and precursor ratio, strongly influence the morphology of the final product. The In(NO(3))(3)/thiosemicarbazide ratios were found to effectively play crucial roles in the morphologies of the hierarchical-like In(2)S(3) hollow microsphere nanostructure. With the ratios increasing from two to four, the In(2)S(3) crystals exhibited almost spherical morphologies. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffused reflectance spectroscopy (UV-vis DRS). XRD analysis confirmed the tetragonal structure of the In(2)S(3) hollow microspheres. The products show complex hierarchical structures assembled from nanoscale building blocks. The morphology evolution can be realized on both outside (surface) and inside (hollow cavity) the microsphere. The surface area analysis showed that the porous In(2)S(3) possesses a specific surface area of 108 m(2)/g and uniform distribution of pore sizes corresponding to the size of pores resulting from the self-assembled structures with flakes. The optical properties of In(2)S(3) were also investigated by UV-vis DRS, which indicated that our In(2)S(3) microsphere samples possess a band gap of ～1.96 eV. Furthermore, the photocatalytic activity studies revealed that the synthesized In(2)S(3) hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading aqueous methylene blue dye solution under visible light irradiation. These results suggest that In(2)S(3) hollow microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light radiation.     

Facile synthesis of hollow palladium/copper alloyed nanocubes for formic acid oxidation

Hollow PdCu alloyed nanocubes were successfully synthesized by a novel one-pot template-free strategy through tuning the surface energy difference of the crystal planes by alloying. Compared with the solid nanoparticles, the hollow nanocubes exhibit superior electrocatalytic activity and stability for formic acid oxidation.     

Facile synthesis of coordination polymer nanocubes and their conversion into mesoporous single crystal-like Y203 nanocubes

Mesoporous single crystal-like Y2O3 nanocubes have been prepared through a coordination-based self- assembly process. Firstly, a uniform nanocube-like Y-lysine precursor was simply prepared with hydrothermal treatment. After the simple thermal treatment process, nanocube-shaped yttrium oxides with the morphology inherited from the Y-lysine precursor were successfully prepared. The phase, morphology, size and crystalline structure were well characterized by XRD, SEM and TEM. N2 adsorption-desorption demonstrates the mesoporous characteristics of the Y2O3 nanocubes, showing a relatively high surface area of 60 m^2/g.     

Hydrothermal synthesis and photocatalytic property of porous CuO hollow microspheres via PS latex as templates

Porous copper oxide (CuO) hollow microspheres have been fabricated through a simple hydrothermal method using PS latex as templates. The as-obtained samples were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR). The influences of the mole ratio of Ethylenediamine (C₂H₈N₂) and copper acetate (Cu(Ac)₂·H₂O), hydrothermal temperature and time on the size and morphologies of the final products have been investigated. The possible formation mechanism of porous CuO hollow microspheres has been proposed and the specific surface area of the hollow microspheres with 81.71 m²/g is measured by BET method. The band gap value calculated from a UV–vis absorption spectrum of porous CuO hollow microspheres is 2.71 eV. The as-synthesized product exhibits high photocatalytic activity during the photodegradation of an organic dyestuff, rhodamine B (RhB), under UV-light illumination.     

Facile synthesis and high d33 of single-crystalline KNbO3 nanocubes

Single-crystalline KNbO(3) nanocubes with orthorhombic phase were prepared in a large scale by a simple one-step molten salt route without using any surfactant as template; the nanostructures exhibited high piezoelectric properties such as d(33)=105 pC/N and k(p)=0.34 as piezoelectric materials.     

Bismuth titanate pyrochlore microspheres: Directed synthesis and their visible light photocatalytic activity

Bismuth titanates, Bi₂Ti₂O₇ (BIT), with well-defined spherical structures were synthesized by a facile hydrothermal process without the use of any surfactant or template. XRD and SEM studies have shown that spheres could be fabricated in high yields by simply manipulating the concentrations of hydroxide ions. In this case, hydroxide ions seem to play a pivotal role in controlling the formation of seeds and growth rates of the BIT particles. On the basis of structural analysis of samples obtained at different concentrations of OH⁻, we also proposed a plausible mechanism to account for the formation of these distinctive morphologies under different conditions. The as-prepared BIT microspheres with good stability exhibited higher photocatalytic activities in the degradation of Rhodamine B (RhB) under visible light irradiation than that in commercial P25 TiO₂. Furthermore, the enhanced photocatalytic performance for RhB degradation was also investigated with assistance of a small amount of H₂O₂.     

Facile method for synthesis of hollow porous magnetic microspheres with controllable structure

Hollow porous magnetic microspheres with strong magnetization and controllable structure were prepared via a facile electrostatic self-assembly of the positively charged Fe(3)O(4) nanoparticles onto the surface of the negatively charged poly(N,N'-methylenebisacrylamide-co-methacrylic acid) (P(MBAAm-co-MAA)) microspheres with subsequent removal of the polymer core through calcination at high temperature. The shell thickness was facilely tuned through the ratio between Fe(3)O(4) and polymer, and the void space was conveniently changed through the size of polymer microspheres. The hollow magnetic microspheres possessed high saturation magnetization value (51.38 emu/g) and porous structure with high specific surface area (108.04 m(2)/g). Based on these properties, the drug loading and release behaviors were investigated, which indicated that the hollow magnetic microspheres exhibited a controlled release process.     

Sonochemical synthesis of Ag/AgCl nanocubes and their efficient visible-light-driven photocatalytic performance

A novel one-step sonochemical approach to synthesize a plasmonic photocatalyst of AgCl nanocubes (ca. 115 nm in edge length) with a small amount of Ag metal species is presented. The nanoscale Ag/AgCl hybrid photocatalysts with cubic morphology are readily formed under ambient ultrasonic conditions and neither external heat treatment nor reducing agents are required. The size of the Ag/AgCl photocatalysts could be controlled by changing the concentrations of Ag(+) ions and polyvinylpyrrolidone molecules in precursor solutions. The compositions, microstructures, influencing factors, and possible growth mechanism of the Ag/AgCl hybrid nanocubes were systematically investigated. The Ag/AgCl photocatalysts show excellent photocatalytic performance for degradation of various dye molecules under visible light.     

Facile synthesis of hollow Co3O4 microspheres and its use as a rapid responsive CL sensor of combustible gases

The hollow Co(3)O(4) microspheres (HCMs) were prepared by the carbonaceous templates, which did not need the surface pretreatment. The chemiluminescence (CL) and catalytic properties for CO oxidation over these hollow samples were evaluated. The samples were characterized by scanning electron microscopy (SEM), energy disperse spectra (EDS), transmission electron microscopy (TEM), selected area electron diffraction (ED), X-ray diffraction (XRD), temperature-programmed desorption (TPD) and N(2) adsorption. The influences of filter' band length, flow rate of gas, test temperature, and particle structure on CL intensities were mainly investigated. It was found that compared with the solid Co(3)O(4) particles (SCPs), HCMs had a stronger CL intensity, which was ascribed to its hollow structure; and that CL properties of the catalysts were well correlated with their reaction activities. Moreover, HCMs were used to fabricate a highly sensitive gas detector, which is a rapid and effective method for the selection of catalysts or the detection of environmental deleterious gases.     

酵母模板合成CuO空心微球及其催化性能研究

以酵母作为生物模板合成了氧化铜空心微球。X-射线粉末衍射、电子扫描电镜、氮气吸附-脱附、紫外-可见光漫反射光谱对产品的物化结构和性能进行了表征。电子扫描电镜分析表明氧化铜产物具有空心结构,粒径为2.2-2.9μm。X射线粉末衍射表明CuO空心微球具有很好的单斜晶型结构。氮气吸附-脱附表明CuO空心微球的比表面积是8.15 m2/g,壳体表面具有多孔性,中孔尺寸分布在2.0-35.4 nm。紫外-可见光漫反射光谱证实产物的能隙是1.38 ev。傅里叶红外、热重-差热以及X射线能谱分析监控了合成过程中组分及化学键的变化,据此提出了空心氧化铜的合成机理。进一步利用差热分析,研究了空心氧化铜催化热分解高氯酸铵的反应,证实了该空心氧化铜产品具有很高的催化活性。     

Template-free synthesis of mesoporous N-doped SrTiO(3) perovskite with high visible-light-driven photocatalytic activity

An effective, template-free synthesis methodology has been developed for preparing mesoporous nitrogen-doped SrTiO(3) (meso-STON) using glycine as both a nitrogen source and a mesopore creator. The N-doping, large surface area and developed porosity endow meso-STON with excellent activity in visible-light-responsive photodegradation of organic dyes.     

Facile synthesis of polyaniline-modified CuS with enhanced adsorbtion and photocatalytic activity

Novel hierarchical polyaniline-modified CuS (PANI–CuS) has been synthesized by simple assembling PANI on the surface of flower-like CuS spheres. The PANI modification enhances the adsorption properties of flower-like CuS. The prepared PANI–CuS composites exhibit higher visible-light-driven photocatalytic activities in degradation of rhodamine B (RhB) than that of neat CuS. The unusual photocatalytic activity could be attributed to the great adsorptivity of dyes, the extended photoresponse range, and the high migration efficiency of photoinduced electrons, which may effectively suppress the charge recombination. This work not only provides a simple strategy for fabricating highly efficient and stable CuS-based composites, but also proves that these unique structures are excellent platforms for significantly improving their visible- light-driven photoactivities, holding great promise for their applications in the field of purifying polluted water resources.     

Facile one-pot hydrothermal synthesis of B/N-codoped TiO2 hollow spheres with enhanced visible-light photocatalytic activity and photoelectrochemical property

B/N-codoped TiO₂ hollow spheres (B/N-THs) were synthesized by facile one-pot hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), N₂ adsorption-desorption isotherms, UV–vis diffuse reflectance spectrum (DRS) and X-ray photoelectron spectroscopy (XPS). The B/N-THs have large surface areas (up to 172.1 m² g⁻¹). The photocatalytic activities of as-prepared THs were evaluated by degradation of Reactive Brilliant Red dye X-3B solution under visible light irradiation. The results showed that B/N-THs exhibited the highest photocatalytic activity due to their high surface area and synergetic effect of B/N-codoped. A photocurrent–time spectrum was examined by anodic photocurrent response to characterize the electron-transferring efficiency in the process of photocatalysis reaction.     

Facile synthesis of monodisperse microspheres and gigantic hollow shells of mesoporous silica in mixed water-ethanol solvents

Mesoporous silica materials with a variety of morphologies, such as monodisperse microspheres, gigantic hollow structures comprising a thin shell with a hole, and gigantic hollow structures consisting of an outer thin shell and an inner layer composed of many small spheres, have been readily synthesized in mixed water-ethanol solvents at room temperature using cetyltrimethylammonium bromide (CTAB) as the template. The obtained mesoporous silica generally shows a disordered mesostructure with typical average pore sizes ranging from 3.1 to 3.8 nm. The effects of the water-to-ethanol volume ratio (r), the volume content of tetraethyl orthosilicate TEOS (x), and the CTAB concentration in the solution on the final morphology of the mesoporous silica products have been investigated. The growth process of gigantic hollow shells of mesoporous silica through templating emulsion droplets of TEOS in mixed water-ethanol solution has been monitored directly with optical microscopy. Generally, the morphology of mesoporous silica can be regulated from microspheres through gigantic hollow structures composed of small spheres to gigantic hollow structures with a thin shell by increasing the water-to-ethanol volume ratio, increasing the TEOS volume content, or decreasing the CTAB concentration. A plausible mechanism for the morphological regulation of mesoporous silica by adjusting various experimental parameters has been put forward by considering the existing state of the unhydrolyzed and partially hydrolyzed TEOS in the synthesis system.     

Facile synthesis of hollow polymer microspheres with movable cores with the aid of hydrogen-bonding interaction

Poly(divinylbenzene-co-acrylic acid) (poly(DVB-co-AA)) hollow microspheres with movable poly(DVB-co-AA) cores were prepared by a facile route. In this approach, poly(DVB-co-AA) microspheres were first used as templates to synthesize poly(DVB-co-AA)@PAA core-shell particles with a non-crosslinked PAA shell by distillation precipitation polymerization in acetonitrile. In situ polymerization to prepare poly(DVB-co-AA)@PAA@poly(DVB-co-AA) trilayer microspheres was then developed, in which the hydrogen-bonding interaction between the carboxylic acid groups played a key role as the driving force for the formation of monodisperse trilayer structure polymer microspheres. After removal of the non-crosslinked poly(acrylic acid) (PAA) midlayer of the poly(DVB-co-AA)@PAA@poly(DVB-co-AA) microspheres in ethanol under basic conditions, poly(DVB-co-AA) hollow microspheres with movable poly(DVB-co-AA) cores were obtained. Functional poly(DVB-co-AA) cores could be released successfully when the hollow structure was destroyed. The resultant core-shell, trilayer polymer microspheres and hollow polymer microspheres with movable cores were characterized by transmission electron microscopy (TEM), dynamic laser scattering (DLS), and Fourier transform infrared (FT-IR) spectra.