Preparation and Characterization of Cu_3V_2O_7(OH)_2·2H_2O Hollow Spheres from Na_2V_6O_16·3H_2O Nanobelts

Monoclinic Cu3V2O7（OH）2·2H2O（copper polyvanadate） hollow spheres were prepared with Na2V6O16·3H2O nanobelts as V-precursor by hydrothermal method. The purity and structure of the products were characterized by X-ray powder diffraction（XRD）, Fourier transform infrared（FTIR） spectroscopy, Raman spectroscopy, thermogravimetric analysis（TGA） and X-ray photoelecton spectroscopy（XPS）. The morphology and size were observed by scanning electron microscopy（SEM）. We found that the Kagomé staircase-structural copper polyvanadate hollow spheres with an average diameter of 7 μm could be easily synthesized via the reaction of Na2V6O16·3H2O nanobelts with sufficient copper sulfate. The dielectric property of the copper polyvanadate demonstrates that dielectric loss hardly changes when the frequency of applied electric field is higher than 100 kHz. The formation process of the hollow spheres is discussed in detail by the observation of a series of products prepared for different reaction time.

Template Polymerization Based on Stober Method:an Improved Method for Fabrication of Hollow Polysiloxane Spheres

A modified Stober method has been developed which permits the controlled growth of spherical hollow spheres with diameters between 197 and 208 nanometers by consecutively cocondensed methyltrimethoxysilane and dimethyldimethoxysilane monomers onto microemulsion of polydimethylsiloxane and subsequently removing the templated polydimethylsiloxane by exposure to solvents. Ammonia was used as a morphological catalyst. The morphology of the polymer spheres was demonstrated by transmission electron micrographs （TEM） and atomic force microscopy （AFM）.

Supermolecular template route to fabrication of well crystallized hollow antimony microspheres

Hollow spheres of elemental antimony (Sb) with good crystallinity, high contrast and thin wall were prepared in the solutions of poly(ethylene glycol) (PEG) and oleic acid(OA) associations at the refluxed temperature. The complexes of Sb3+ with tartaric acid were used as precursors, which can avoid the hydrolysis of SbCl3 and the resulting impurity of products. The average diameter and thickness of the as-prepared hollow sphere are about 300 nm and less than 20 nm, respectively. The formation of hollow spheres depends on the template function of PEG and OA associations, which can be confirmed through the theoretical analysis and results of control experiments. The specific surface area reaches 34.669 m2/g.

Preparation and performance of CeO_2 hollow spheres and nanoparticles

CeO_2 hollow spheres were synthesized by polystryrene sphere（PS） templates and CeO_2 nanoparticles were prepared by a facile method. The as-obtained products were characterized by scanning electron microscopy（SEM）, N_2 adsorption-desorption, X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FTIR） and UV-vis diffuse reflectance spectra. The results showed that the structure of the obtained CeO_2 hollow spheres was hollow microsphere with a diameter of 380 nm and the average particle size of CeO_2 nanoparticles was about 1700 nm. The two samples＇ Brunauer-Emmett-Teller（BET） surface area was 67.1 and 37.2 m^2/g. The CeO_2 hollow spheres had a better performance than nanoparticles at UV-shielding because of higher surface area and the structure of hollow sphere.

Nanostructured hollow spheres of hydroxyapatite： preparation and potential application in drug delivery

A solvothermal method has been successfully used to prepare nanostructured hydroxyapatite （HA） hollow spheres with average diameters of about 500 nm and shell thicknesses of about 100 nm in a glycerin/water mixed solvent. Transmission electron microscopy （TEM） and field-emission scanning electron microscopy （FESEM） images show that the shells of the HA hollow spheres are actually composed of nanosheets with thicknesses of about 10 nm. By tuning the glycerin/water volume ratio, two other kinds of HA solid spheres with average diameters of about 6 or 20 pm were assembled from nanoflakes. The properties of the different kinds of spheres as drug delivery carriers were evaluated. Ibuprofen （IBU） was chosen as the model drug to load into the HA samples. The nanostructured HA samples showed a slow and sustained release of IBU. The HA hollow spheres exhibited a higher drug loading capacity and more favorable release properties than the HA solid spheres and thus are very promising for controlled drug release applications.

Preparation of Hollow ZrB_2 Spheres by a Combined Sol-gel and Boro/carbothermal Reduction Method

Carbon microspheres were firstly prepared using glucose （C6H12O6 ） as the starting materials by hydrotherreal carbonization. Then hollow ZrB2 spheres were successfully synthesized using zirconium oxychloride （ ZrClO2 · 8H2O）, boric acid （ H3BO3 ） by a combined solgel and boro/carbothermal reduction method, and the prepared carbon microspheres as the template. The effects of the reaction temperatures （1 200, 1 300, 1 400 and 1 500 ℃, respectively） and contents of carbon microspheres （ n （ C ） ： n （ ZrO2 ＋ B2O3） is 5. 0, 5. 5, 6. 0 and 6. 5, respectively） on the synthesis of hollow ZrB2 spheres were studied. The prepared carbon microspheres have smooth sugrace and good hollow structure by hydrothermal nitridation. Increase of reaction temperature and excessive carbon microspheres can greatly promote the formation of hollow ZrB2 spheres. The optimized reaction temperature and molar ratio of n （C）/ n （ ZrO2 ＋ B2O3 ） were 1 500 ℃ and 6.5, respectively.

Fabrication of functional hollow carbon spheres with large hollow interior as active colloidal catalysts

In this study, we have established a facile method to synthesize functional hollow carbon spheres with large hollow interior, which can act as active colloidal catalysts. The method includes the following steps： first, hollow polymer spheres with large hollow interior were prepared using sodium oleate as the hollow core generator, and 2,4-dihydroxybenzoic acid and hexamethylene tetramine （HMT） as the polymer precursors under hydrothermal conditions; Fe3＋ or Ag＋ cations were then introduced into the as-prepared hollow polymer spheres through the carboxyl groups; finally, the hollow polymer spheres can be pseudomorphically converted to hollow carbon spheres during pyrolysis process, meanwhile iron or silver nanoparticles can also be formed in the carbon shell simultaneously. The structures of the obtained functional hollow carbon spheres were characterized by TEM, XRD, and TG. As an example, Ag-doped hollow carbon spheres were used as colloid catalysts which showed high catalytic activity in 4-nitrophenol reduction reaction.

Simultaneous formation of a C/N-TiO_2 hollow photocatalyst with efficient photocatalytic performance and recyclability

Herein,we report a unique approach towards the preparation of C-modified and N-doped TiO2 hollow spheres(C/N-TiO2).TEM,SEM,and XPS analyses were used to confirm that the carbon and nitrogen co-decorated TiO2 photocatalyst was formed.Carbon-decoration improves the visible-light absorption and speeds up the separation of the photo-generated electron-hole pairs.C/N-TiO2 not only narrows the band gap of TiO2,but also exhibits excellent photocatalytic activity for the degradation of tetracycline and tetracycline hydrochloride.In addition,the C/N-TiO2 photocatalyst shows excellent recyclability for water decontamination,making it a promising candidate to purify aquatic contaminants.

Regeneration of Simulated Deactivated Hollow Titanium Silicate Zeolite by Secondary Crystallization in the TPAOH Solution

It is of paramount importance to improve the utilization efficiency of hollow titanium silicate(HTS) zeolite catalyst used in the cyclohexanone ammoxidation process. To achieve this aim, the regeneration of simulated deactivated HTS zeolite by post-synthesis was carried out in an aqueous TPAOH solution under hydrothermal conditions. It was found that the catalytic performance for phenol hydroxylation over regenerated HTS zeolite was as high as that of fresh one.Judging from the BET measurements, electron micrography and XRD analysis results, it was confirmed that the topological and morphological structure was repaired. The chemical state of Ti species was detected by the UV-Vis and ^(29)Si MAS NMR spectroscopy. No acidic amorphous TiO_2-SiO_2 oxide was formed, and the extraframework Ti species could be reincorporated into the framework of HTS zeolite thanks to the tetrahedral coordination by the condensation between Ti-OH and Si-OH groups. In order to confirm this conclusion, the fresh HTS zeolite was treated under the NH_3·H_2O hydrothermal and thermal conditions for several times. The catalytic activity of both uncalcined and calcined simulated deactivated HTS zeolite samples could be regenerated without the formation of Br?nsted acid sites. It was concluded that the highly dispersed Ti species could be reincorporated into the framework of zeolite by hydrated condensation of Si-OH and Ti-OH groups after secondary hydrothermal synthesis.

Nanohollow Carbon for Rechargeable Batteries:Ongoing Progresses and Challenges

Among the various morphologies of carbon-based materials,hollow carbon nanostructures are of particular interest for energy storage.They have been widely investigated as electrode materials in different types of rechargeable batteries,owing to their high surface areas in association with the high surface-to-volume ratios,controllable pores and pore size distribution,high electrical conductivity,and excellent chemical and mechanical stability,which are beneficial for providing active sites,accelerating electrons/ions transfer,interacting with electrolytes,and giving rise to high specific capacity,rate capability,cycling ability,and overall electrochemical performance.In this overview,we look into the ongoing progresses that are being made with the nanohollow carbon materials,including nanospheres,nanopolyhedrons,and nanofibers,in relation to their applications in the main types of rechargeable batteries.The design and synthesis strategies for them and their electrochemical performance in rechargeable batteries,including lithium-ion batteries,sodium-ion batteries,potassium-ion batteries,and lithium–sulfur batteries are comprehensively reviewed and discussed,together with the challenges being faced and perspectives for them.

Templated synthesis of imine-based covalent organic framework hollow nanospheres for stable potassium-ion batteries

Covalent organic frameworks(COFs), as highly tunable porous crystalline materials, have promising applications in potassium-ion batteries(PIBs) due to their abundant charge carrier transport channels and excellent structural stability. However, the excessive stacking of interlayer electron clouds makes it difficult to expose internal active sites. Strategies to design functional COFs with controllable morphology and copious active sites are promising but still challenging. Herein, by utilizing the condensation between1,3,5-triformylbenzene(TFB) and p-phenylenediamine(PPD) and using amino-modified SiO_(2) nanospheres as templates, we synthesize core-shell NH_(2)-SiO_(2)@TP-COF. Through NaOH etching of NH_(2)-SiO_(2)@TP-COF, we obtain imine-based TP-COF hollow nanospheres, which shows excellent potassium storage performance when applied to the anode for PIBs. Ex-situ analysis and density functional theory calculations reveal that C=N groups and benzenes are active sites for K^(+) storage.

Constructing a hollow core-shell structure of RuO_(2) wrapped by hierarchical porous carbon shell with Ru NPs loading for supercapacitor

Hollow core-shell structure nanomaterials have been broadly used in energy storage, catalysis, reactor,and other fields due to their unique characteristics, including the synergy between different materials,a large specific surface area, small density, large charge carrying capacity and so on. However, their synthesis processes were mostly complicated, and few researches reported one-step encapsulation of different valence states of precious metals in carbon-based materials. Hence, a novel hollow core-shell nanostructure electrode material, RuO_(2)@Ru/HCs, with a lower mass of ruthenium to reduce costs was constructed by one-step hydrothermal method with hard template and co-assembled strategy, consisting of RuO_(2) core and ruthenium nanoparticles(Ru NPs) in carbon shell. The Ru NPs were uniformly assembled in the carbon layer, which not only improved the electronic conductivity but also provided more active centers to enhance the pseudocapacitance. The RuO_(2) core further enhanced the material’s energy storage capacity. Excellent capacitance storage(318.5 F·g^(-1)at 0.5 A·g^(-1)), rate performance(64.4%) from 0.5 A·g^(-1)to 20 A·g^(-1), and cycling stability(92.3% retention after 5000 cycles) were obtained by adjusting Ru loading to 0.92%(mass). It could be attributed to the wider pore size distribution in the micropores which increased the transfer of electrons and protons. The symmetrical supercapacitor device based on RuO_(2)@Ru/HCs could successfully light up the LED lamp. Therefore, our work verified that interfacial modification of RuO_(2) and carbon could bring attractive insights into energy density for nextgeneration supercapacitors.

Facile fabrication of CeO_2 hollow microspheres with yeast as bio-templates

CeO2 hollow microspheres were prepared through a facile method by using yeast cells as bio-templates. The yeast pro- vided a solid flame for the deposition of cerium hydroxide to form the hybrid Ce（OH）3@yeast precursor. The resulting CeO2 hollow microspheres were obtained by calcining the precursor. The products were characterized by field emission scanning electron micros- copy （FE-SEM）, transmission electron microscopy （TEM）, X-ray powder diffraction （XRD）, fourier transform infrared spectroscopy （FTIR）, N2 adsorption/desorption analysis, X-ray photoelectron spectrum （XPS） and H2 temperature programmed reduction （H2-TPR） It was found that the products fully retained the morphology of the yeast cells and the size of the hollow microspheres was about 1.5-2 μm. The catalytic test results showed that the as-obtained hollow CeO2 microspheres possessed a higher catalytic activity in CO oxidation than the commercial CeO2, which attributed to their higher surface area, hollow structure and superior reducibility. This study provided a promising route for the preparation of a variety of other inorganic hollow microspheres.

Scalable synthesis of sub-lO0 nm hollow carbon nanospheres for energy storage applications

Sub-100 nm hollow carbon nanospheres with thin shells are highly desirable anode materials for energy storage applications. However, their synthesis remains a great challenge with conventional strategies. In this work, we demonstrate that hollow carbon nanospheres of unprecedentedly small sizes （down to - 32.5 nm and with thickness of - 3.9 nm） can be produced on a large scale by a templating process in a unique reverse micelle system. Reverse micelles enable a spatially confined Stober process that produces uniform silica nanospheres with significantly reduced sizes compared with those from a conventional Stober process, and a subsequent well-controlled sol-gel coating process with a resorcinol-formaldehyde resin on these silica nanospheres as a precursor of the hollow carbon nanospheres. Owing to the short diffusion length resulting from their hollow structure, as well as their small size and microporosity, these hollow carbon nanospheres show excellent capacity and cycling stability when used as anode materials for lithium/sodium-ion batteries.

Template synthesis of imine-based covalent organic framework core-shell structure and hollow sphere:a case of COFTTA-DHTA

Controllably synthesizing well-dispersed covalent organic frameworks （COFs） with uniform both morphology and size is still a challenge. Herein, we report the template-directed synthesis of COFTTA-D.rA-based core-shell hybrids under solvothermal conditions by using amino-functionalized SiO2 microspheres as templates coupled with stepwise addition of initial monomer molecules. The modified amino groups on the surfaces of SiO2 templates play an important role in the formation of well-defined NH2-f-SiO2@COFTTA-DHXA core-shell hybrids. COFTTA-DHTA hollow spheres can be obtained by etching SiO2 cores of NH2-f-SiO2@COFTTA-DHTA. Both the NH2-f-SiO2@COFTTA-I）HTA and COFxTA-DHVA hollow spheres possess the well-defined morphology, high crystallinity and porosity, excellent dispersion property and high chemical stability. The template synthesis method demonstrated in this work provides a general method for the shape-controlled synthesis of COF-based materials, which is important for the further applications in the fields such as energy storage, drug delivery and catalysis.

空心纳米合金NiPdCu催化硝酸盐电还原合成氨的研究

硝酸盐是工业生产和民用生活废水中的重要污染源,电催化还原硝酸盐制备化工原料氨可实现绿色节能减排。以Ni纳米球为模板合成空心纳米合金NiPdXCu100-X,利用XRD、TEM、XPS等对催化剂微观形貌、比表面积和化学态进行表征,并将NiPdXCu100-X用于电催化硝酸盐还原合成氨反应(NO_(3)RR)。结果表明,在-0.53 V(vs.RHE)电压下,NiPd_(50)Cu_(50)产NH_(3)法拉第效率为94.2%,NH_(3)产率为2166.8 mg/(h·gcat)(NH_(3)产率是NiPd的1.87倍)。NiPd_(50)Cu_(50)优异的电催化硝酸盐还原合成氨活性和稳定性源于金属间协同催化和独特的空心结构。

Facile Template-free Synthesis of Carbonated Hydroxyapatite Spheres in Aqueous Solution

Prickly carbonated hydroxyapatite（CHAp） spheres were obtained via a facile template-free self-assembly method with Na2HPO4 and self-made cubic CaCO3 as reactants. X-ray diffraction results of the product revealed CHAp with high crystallinity could be successfully prepared in a short reaction time. A nucleation mechanism was proposed according to the results of characterizing the resultant powders and analyzing the growth process. It shows that the self-made CaCO3 particles play an important role in the template-free synthesis of prickly spheres.

空心球壳材料的制备研究进展

空心球壳材料的制备通常采用硬模板法或软模板法,评述了它们在制备空心球壳材料时的机理和优缺点,并综述了国内外应用模板法制备各种空心球壳材料(无机材料、金属、高分子材料以及无机-有机复合材料)的研究进展。

新型氧化铝空心球的制备及表征

以胶体碳球为模板,廉价的硝酸铝为铝源,成功制备出了新型的大小可控的氧化铝空心球.通过透射电子显微镜(TEM)、扫描电子显微镜(SEM)、能量扩散X射线(EDX)、X射线粉末衍射(XRD)等手段对合成产品进行了表征,并考察了不同合成条件对空心球形貌的影响.实验结果表明,合成的氧化铝空心球大小均一,粒径及壁厚均可调节.在该实验条件下,硝酸铝浓度及吸附时间的改变对产品结果没有明显的影响,而吸附温度的改变引起了产品表面光滑度及壁厚的改变.

自催化还原制备超细空心镍粉的形成过程研究

超细空心粉末由于其特殊结构和性能而受到研究者的广泛关注.对自催化还原法制备空心镍球的形成过程进行了较深入的研究,认为反应产物的粒径和粒度分布主要取决于原始胶核的形态以及反应孕育期的长短.通过控制工艺参数,可以得到不同结构的空心金属镍粉末或是包含有细小核心的粉末.