Ti<Superscript>3+</Superscript>-doped TiO<Subscript>2</Subscript> hollow sphere with mixed phases of anatase and rutile prepared by dual-frequency atmospheric pressure plasma jet

A novel method of synthesizing Ti³⁺-doped TiO₂ was proposed. Ti³⁺-doped TiO₂ hollow spheres were prepared with different thickness of carbon shell by using atmospheric pressure plasma jet generated by dual-frequency power sources. The as-synthesized Ti³⁺-doped TiO₂ hollow microspheres were characterized by X-ray diffraction (XRD) pattern, scanning electron microscope (SEM) images, high-resolution transmission electron microscopy (HRTEM) images, Raman spectra, X-ray photoelectron spectroscopy (XPS), and UV–vis spectra. These results indicated that these samples had mixed phases of anatase and rutile and the structure of hollow sphere varied with different thickness of carbon shell. The Ti-O-C chemical bond was the connection between the TiO₂ hollow sphere and carbon layer. Amount of Ti³⁺ ions were found, which were accompanied with the formation of oxygen vacancies. Meantime, the as-synthesized catalysts also display strong absorption in the visible light region and have a narrow band energy gap. Optical emission spectroscopy (OES) was used to observe different excited species in the discharge area. These results showed that the oxygen content had a significant impact on the number of oxygen vacancies. Finally, the photocatalytic activities of as-prepared samples were evaluated by decomposition of rhodamine B aqueous solution, which showed better photocatalytic activity under UV–vis light irradiation.     

Morphology transformation of Cu<Subscript>2</Subscript>O by adding TEOA and their antibacterial activity

Cu₂O polyhedral particles and hollow spheres were successfully synthesized by adjusting the concentration of triethanolamine (TEOA). The as-prepared samples were structurally characterized by the scanning electron microscope (SEM), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). The results revealed that the solid polyhedral Cu₂O with sizes ranging from 70 to 150 nm was in good crystallization. The diameter of the hollow Cu₂O spheres increased to 350–450 nm. It was found that the sizes and morphologies of the products could be significantly affected by the concentration of TEOA. And the morphology of Cu₂O transformed from solid polyhedrons to hollow spheres with the further enrichment of TEOA concentration. A possible mechanism was proposed to explain the formation of the hollow Cu₂O spheres. In addition, we investigated the antibacterial activities of the samples. It was demonstrated that the hollow Cu₂O sphere exhibited better antibacterial activities for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) compared with the solid polyhedral Cu₂O.     

聚(N-异丙基丙烯酰胺)模板法制备二氧化硅中空微球

以在50 oC水溶液中析出的聚(N-异丙基丙烯酰胺) (PNI-PAM)聚集体作为软模板,使正硅酸乙酯吸附在PNIPAM聚集体表面进行水解缩合,原位生成二氧化硅包裹PNIPAM的核壳结构微球;进一步冷却至室温使PNIPAM溶解在水中除去内核,从而成功合成出SiO₂中空微球．实验表明,只有在足够的PNIPAM和正硅酸乙酯含量以及正硅酸乙酯水解时间下,才能形成稳定的SiO₂中空微球．用TEM、SEM和FTIR对合成的SiO₂中空微球进行了表征,结果表明,微球尺寸为150 nm左右,并且由于PNIPAM上酰胺基团和正硅酸乙酯水解出来的硅醇间具有静电相互作用,使得SiO₂壳层上依然有PNIPAM残留.     

Synthesis and formaldehyde sensing performance of LaFeO3 hollow nanospheres

Metal oxide semiconductors with hollow structure and morphology have attracted considerable attentions because of their promising application on gas sensors. In this paper, LaFeO₃ hollow nanospheres have been prepared by using carbon spheres as templates in combination with calcination. Based on the observation of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and transmission electron microscope (TEM), the structure and morphology of the products were characterized. It has been revealed that as-prepared LaFeO₃ samples have a uniform diameter of around 300 nm and hollow structures with thin shells of about 30 nm consisting of numerous nanocrystals and nanopores. Owing to the hollow and porous structure, large surface area and more surface active sites, the sensor based on LaFeO₃ hollow nanospheres exhibited high response, good selectivity and stability to formaldehyde gas (HCHO). It suggests that the as-prepared LaFeO₃ hollow nanospheres are promising candidates for good performance formaldehyde sensor.     

A room-temperature synthesis of nanocrystalline vanadium nitride

Vanadium nitride was synthesized by the reaction of VCl₄ and NaNH₂ at room temperature. X-ray powder diffraction could be indexed as cubic VN with the lattice constant of a=4.134 Å. Transmission electron microscopy image showed particle and hollow sphere morphology. The optical properties of the as-prepared VN were investigated.     

Fabrication of porous BaSnO3 hollow architectures using BaCO3@SnO2 core-shell nanorods as precursors

We present a strategy to synthesize porous BaSnO₃ hollow architectures with that were 150-300 nm in diameter and 1.5-5 μm in length using precursor of BaCO₃@SnO₂ nanorods prepared by hydrothermal treatment. BaCO₃@SnO₂ nanorods, consisting of a BaCO₃ core and a SnO₂ shell, could be used effectively for the solid-state synthesis of polycrystalline BaSnO₃ powder at 800 °C (lower than convention for BaCO₃ and SnO₂ mixtures). The core/shell structure of the precursor could play a role as a structural directing template for preparing BaSnO₃ hollow architectures during the calcination process. The X-ray diffractometer (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) are employed to characterize the structures and morphologies. When applied to DSSC, the porous BaSnO₃ hollow architectures exhibit distinct photovoltaic effect.     

Shape‐Tunable Selective Synthesis of Bismuth Fluoride Nanostructures for Versatile Applications

A facile approach for shape‐tunable synthesis of bismuth fluoride nanoparticles is reported. The approach is based on the homogeneous precipitation of precursor materials in mixed solvents (H₂O and ethylene glycol) and only ethylene glycol. The influencing factors on the morphology of the particles, i.e., solvent ratio, F/Bi ratio, and ethylenediaminetetraacetic acid, are studied in detail, and are schematically illustrated. The morphology, crystallinity, structure, and optical properties of the prepared samples are characterized by using a field‐emission scanning electron microscope, transmission electron microscope, X‐ray diffractometer, Fourier transform infrared spectrometer, and spectrofluorometer, respectively. The hollow sphere‐shaped nanoparticle doped with Eu³⁺ ions exhibit reddish orange emission under ultraviolet illumination due to the symmetric environment around the dopant ions. Subsequently, the effect of dopant concentration on the optical properties is also evaluated. The temperature‐dependent photoluminescence emission spectra reveal good thermal stability. The obtained results provide an efficient strategy for synthesizing the shape‐tunable nanoparticles with excellent optical properties.     

利用聚乙烯亚胺修饰的CaCO3仿生模板合成3D花朵型二氧化硅微球

利用聚乙烯亚胺(PEI)修饰的碳酸钙仿生模板合成了具有3D花朵型形貌的SiO₂微球.通过调整碳酸钙微粒表面不同浓度PEI的吸附量实现SiO₂微球的形貌控制呈现花朵或刀锋的形状. 用XPS和SEM对制备的SiO₂微粒进行表征. 结果表明,不用浓度的PEI修饰可以较好地控制3花朵型DSiO₂微球的形貌.     

Study on the surface erosion route to the fabrication of TiO2 hollow spheres

Three-dimensional (3D) architecture of TiO₂ hollow sphere has many excellent and interesting performances that attract significant attention nowadays. In this paper, a simple surface erosion approach to the fabrication of TiO₂ hollow spheres via the hydrothermal process has been developed. The morphologies and the phase were characterized by scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The results indicate that the anatase-type TiO₂ hollow spheres with a diameter of ∼1 μm are successfully synthesized. The shell thickness of TiO₂ hollow spheres is ∼150 nm and the size of hollow cavity is ∼600 nm. By the control experiments, the influence of ammonium fluoride and hydrogen peroxide on the hollow spherical structures was studied. Hydrogen peroxide acts as both the oxidant and the bubble generator, ammonium fluoride is crucial for the erosion and dissolution of titanium, the detailed dissolution-crystallization mechanism for the formation of TiO₂ hollow spheres was also proposed.     

α-Fe2O3 and Fe3O4 hollow nanospheres as high-capacity anode materials for rechargeable Li-ion batteries

α-Fe₂O₃ and Fe₃O₄ hollow nanospheres of size 30?±?2 nm were synthesized by using polymeric micelles as a soft template for the first time. The hollow nanospheres were thoroughly characterized by transmission electron microscope, superconducting quantum interference device, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential thermal analysis, cyclic voltammogram, and nitrogen sorption analyses. The α-Fe₂O₃ and Fe₃O₄ hollow nanospheres were used as anode materials in lithium-ion rechargeable batteries to investigate their electrochemical properties. The hollow particle-based electrodes exhibit high capacity, stable cycling performance, and good rate capability at different current densities. The α-Fe₂O₃ and Fe₃O₄ hollow nanospheres with nanosized shell domain favors fast lithium insertion/extraction processes during the repeated charge/discharges.     

BiVO4空心微球的合成及其光催化降解亚甲基蓝的性能研究

以BiNO₃·5H₂O和NH₄VO₃为原料,柠檬酸为络合剂,成功合成了BiVO₄空心纳米球．采用TEM、XRD、UV-Vis等测试技术对样品的形貌、相结构以及光吸收性能等进行了表征．结果表明,所制备的BiVO₄空心微球在紫外区和可见区均有较强的光吸收,空心球平均粒径为160 nm,空腔直径为10～80 nm．以亚甲基蓝染料溶液的脱色降解实验为模型反应研究了样品的光催化性能．光催化实验结果表明,在可见光照射下,反应150 min后,样品对亚甲基蓝溶液的脱色率可达到95%以上．此外,考察了柠檬酸添加量对空心球形貌的影响,并提出了BiVO₄空心纳米球的可能形成机理．     

Synthesis of Br-doped TiO<Subscript>2</Subscript> hollow spheres with enhanced photocatalytic activity

The Br-doped hollow TiO₂ photocatalysts were prepared by a simple hydrothermal process on the carbon sphere template following with calcination at 400 °C. The structure and properties of photocatalysts were characterized by X-ray diffraction, Raman spectrum, scanning electron microscope, transmission electron microscopy, N₂ desorption–adsorption, UV–Vis spectroscopy, and X-ray photoelectron spectroscopy. The TiO₂ hollow spheres are in diameter of 500 nm with shell thickness of 50 nm. The shell is composed of small anatase nanoparticles with size of about 10 nm. The TiO₂ hollow spheres exhibit high crystalline and high surface area of 89.208 m²/g. With increasing content of Br doping, the band gap of TiO₂ hollow spheres decreased from 2.85 to 1.75 eV. The formation of impurity band in the band gap would narrow the band gap and result in the red shift of absorption edge from 395 to 517 nm, which further enhances the photocatalytic activity. The appropriate Br doping improves the photocatlytic activity significantly. The TiO₂ hollow spheres with 1.55% Br doping (0.5Br-TiO₂) exhibit the highest photocatalytic activity under full light. More than 98% of RhB, MO, and MB can be photodegraded using 0.5Br-TiO₂ with concentration of 10 mg/L in 40, 30, and 30 min, respectively. The degradation rate of Br-doped photocatalysts was 40% faster than undoped ones.

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Synthesis of Ni1−xZnxO hollow structures by a facile method

By a sol–gel method, we obtained Ni_1−xZn_xO polycrystalline powders. The obtained Ni_1−xZn_xO was characterized by scanning electron microscope and transmission electron microscope techniques. The characterized results showed that the obtained Ni_1−xZn_xO showed hollow structure. The grain sizes of the obtained hollow Ni_1−xZn_xO were quite uniform, typically in the range of 400–500 nm. This method is a simple and effective method for large-scale synthesis of hollow Ni_1−xZn_xO quasi-spheres. The present method is very promising for large-scale production because the method is only involves commercial Zn(AC)₂·2H₂O and NiCl₂·6H₂O powders and the reaction is achieved in an open system free of autoclave and organic chemical reagents. This template-free method is facile but effective and therefore it is very promising for large-scale industrial production.     

Preparation, characterization and photocatalytic activity of the neodymium-doped TiO2 hollow spheres

Nd-doped titania hollow spheres were prepared using carbon spheres as template and Nd-doped titania nanoparticles as building blocks. The Nd-doped titania nanoparticles were synthesized at low temperature. The prepared hollow spheres were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectrum (DRS). The effects of Nd content on the physical structure and photocatalytic activities of doped titania hollow sphere samples were investigated. Results showed that there was an optimal Nd-doped content (3.9 at.%) for the photocatalytic degradation of dye X-3B (C.I. Reactive Red 2). The apparent rate constant of the best one was almost 9 times as that of P25 titania. The mechanism of photocatalytic degradation of dyes under visible light irradiation was also discussed.     

Synthesis and structural characterization of perovskite 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 nanotubes

We report the synthesis and structural characterization of 0.65Pb(Mg_1/3Nb_2/3)O₃-0.35PbTiO₃ (PMN-PT) nanotubes prepared by a novel sol-gel template method. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) investigations demonstrated that the postannealed (650 °C for 1 h) PMN-PT nanotubes were polycrystalline with perovskite crystal structure. The field emission scanning electron microscope (FE-SEM) shows that as prepared PMN-PT nanotubes were hollow with diameter to be about 200 nm. High resolution transmission electron microscope (HRTEM) analysis confirmed that the obtained PMN-PT nanotubes made up of nanoparticles (10-20 nm) which were randomly aligned in the nanotubes. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the stoichiometric 0.65Pb(Mg_1/3Nb_2/3)O₃-0.35PbTiO₃. The possible formation mechanism of PMN-PT nanotubes was proposed at the end.     

Insight in the 3D morphology of silica-based nanotubes using electron microscopy

Amorphous silica-based nanotubes (SBNTs) were synthesized from phosphoryl triamide, OP(NH₂)₃, thiophosphoryl triamide, SP(NH₂)₃, and silicon tetrachloride, SiCl₄, at different temperatures and with varying amount of the starting material SiCl₄ using a recently developed template-free synthesis approach. Diameter and length of the SBNTs are tunable by varying the synthesis parameters. The 3D mesocrystals of the SBNTs were analyzed with focused ion beam sectioning and electron tomography in the transmission electron microscope showing the hollow tubular structure of the SBNTs. The reconstruction of a small SBNT assembly was achieved from a high-angle annular-dark field scanning transmission electron microscopy tilt series containing only thirteen images allowing analyzing beam sensitive material without altering the structure. The reconstruction revealed that the individual nanotubes are forming an interconnected array with an open channel structure.     

Hollow glass microspheres coated with CoFe2O4 and its microwave absorption property

Spinel CoFe₂O₄ coating on the surface of hollow glass microspheres of low density was synthesized by co-precipitation method. The phase structures, morphologies, particle size, shell thickness, chemical compositions of the composites have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy dispersive X-ray spectroscopy (EDS). The results show that CoFe₂O₄ coating on hollow glass microspheres can be achieved, and the coating layers are constituted by CoFe₂O₄ nanoparticles of mean size ca. 10 nm. The as-synthesized powder materials were uniformly dispersed into the phenolic cement, then the mixture was pasted on metal plate with the area of 200 mm×200 mm as the test plate. The test of microwave absorption was carried out by the radar-absorbing materials (RAM) reflectivity far field radar cross-section (RCS) method. The results indicate that the coated CoFe₂O₄/hollow glass microspheres composites can be applied in lightweight and strong absorption microwave absorbers.     

Preparation and surface encapsulation of hollow TiO nanoparticles for electrophoretic displays

Hollow black TiO nanosparticles were obtained via deposition of inorganic coating on the surface of hollow core-shell polymer latex with Ti(OBu)₄ as precursor and subsequent calcination in ammonia gas. Hollow TiO particles were characterized by scanning electron microscope, transmission electronic microscopy, X-ray diffraction, and thermogravimetric analysis. Encapsulation of TiO via dispersion polymerization was promoved by pretreating the pigments with 3-(trimethoxysilyl) propyl methacrylate, making it possible to prepare hollow TiO-polymer particles. When St and DVB were used as polymerization monomer, hollow TiO-polymer core-shell particles came into being via dispersion polymerization, and the lipophilic degree is 28.57%. Glutin-arabic gum microcapsules containing TiO-polymer particles electrophoretic liquid were prepared using via complex coacervation. It was founded that hollow TiO-polymer particles had enough electrophoretic mobility after coating with polymer.     

Dual Template Engaged Synthesis of Hollow Ball‐in‐Tube Asymmetrical Structured Ceria

Hollow materials with different configurations are of interest due to their unique structural features, which induce interesting properties e.g. catalysis. Here, the synthesis of asymmetrical hollow ball‐in‐tube (HBT) structured CeO₂ is reported, which is achieved using a dual template engaged solid–liquid interfacial reaction. In this reaction, the SiO₂ sphere (hard template)‐embedded Ce(OH)CO₃ nanorod (sacrificial template) composite is first treated with NaOH solution, followed by an acid wash to obtain asymmetrical hollow structured CeO₂. Such HBT structured CeO₂ is demonstrated to be a good support for Au nanoparticles toward CO oxidation as compared to simple hollow CeO₂ nanotubes, leading to significantly increase catalytic activity.     

Graphene-decorated sphere Li<Subscript>2</Subscript>S composite prepared by spray drying method as cathode for lithium-sulfur full cell

In this work, a graphene-decorated Li₂S cathode has been prepared via spray drying method using Li₂SO₄, graphene oxide and sucrose as raw materials. During spray drying, sucrose melts and embeds Li₂SO₄ when Li₂SO₄ were sprayed out with graphene oxide and sucrose, and becomes sphere particles. The as-prepared Li₂S composite was received after a heat treatment under nitrogen atmosphere. X-ray diffraction patterns confirm the cubic structure of Li₂S and scanning electron microscope images reveal that Li₂S and carbon components stay in sphere structure with diameter around 20 μm. The sphere Li₂S composite shows enhanced performance when acts as cathode. Under current density of 100 mA g^?1, a specific discharge capacity of 778 mAh g^?1 has been achieved and the battery cycled over 60 rounds. Furtherly, the sphere composite was coupled with silicon/graphite anode to construct full cell system, suggesting large possibility to work with the current lithium-ion battery anodes.