中空MOFs的研究进展

中空金属有机骨架材料MOFs因其具有高的比表面积、密度低、中空结构等优点受到人们广泛的关注,是近年来MOFs材料的一个重要研究方向。本文概括了中空结构MOFs(H-MOFs)制备方法的研究进展,重点介绍了聚苯乙烯牺牲剂和Cu_2O自我牺牲剂模板法、乳液型液-液和液-气界面的软模板法、Ostwald Ripening、Kirkendall效应等自组装方法的无模板法,并对其优缺点进行了讨论;探讨了中空MOFs在气体吸附和分离、催化方面的应用性能及在生物医药、磁性分离及环境保护方面的潜在应用;并提出今后H_MOFs研究的主要方向是合成新型H_MOFs、制备形貌多样、结晶性能好的新型高稳定性材料、精确控制壳层厚度以及开发新的H_MOFs制备方法。     

牺牲模板法制备中空微纳米结构材料的研究进展

中空结构材料密度低、比表面积大、具有较高的容载能力,在环境保护、生物医药、能量存储等领域具有广泛的应用。牺牲模板法由于模板本身作为反应物参与壳材料的构造过程,不需要进行模板修饰及模板去除工作,被广泛用于制备中空微纳米结构材料。综述了近年来利用化学刻蚀、离子交换、电化学置换和金属盐分解等牺牲模板法制备中空材料的研究进展。     

过渡金属氧化物空心球的制备及催化性能研究进展

过渡金属氧化物空心球由于其高比表面积、低密度及特殊的多级孔结构而受到了研究者的广泛关注,并相应发展出了形式多样的中空结构制备工艺。与此同时,空心球制备技术的进步也为其在催化领域中的应用提供了发展契机。在过去20多年中,中空结构的设计及制备几乎囊括了催化的所有领域。本文总结了作者所在课题组近年来在过渡金属氧化物空心球制备及在催化中应用的研究进展,着重介绍了纳米氧化物空心球的制备思路及催化剂的一些设计理念。     

二氧化钛纳米空心球的制备

中空结构的二氧化钛材料由于制备简单、光催化能力好,使得其具有较高的应用前景。文章概述了二氧化钛纳米空心球的制备方法,包括模板法、喷雾反应法、自组装法以及其他方法。     

渗透诱导结构演化的微流控双重乳液为模板合成聚合物微颗粒的研究

利用渗透压诱导的水分子跨界面传质过程实现了双重乳液尺寸和结构的调控，并将可控演化的双重乳液液滴作为模板，可控制得到中空结构、孔壳结构等多种结构的功能微颗粒。利用微流控技术产生均一尺寸的双重乳液，通过在双重乳液内部液滴和外部水相中采用不同盐浓度来构建渗透压差，使得双重乳液在渗透压差驱动下经水分子跨界面传质发生收缩/膨胀过程，实现对双重乳液尺寸结构的演化和调控，推导了其在演化平衡时内部水滴尺寸的计算公式。利用不同演化阶段的双重乳液为模板，成功制得了具有中空结构和孔壳结构且壳层具有多孔结构的聚合物微颗粒。该研究为新型聚合物微颗粒的设计和可控构建提供一种有效策略。     

资讯

过程工程所多壳层空心球研究又获进展多壳层空心球由于具有很大的内部空间及厚度在纳米尺度范围内的壳层,在光电器件、化学传感器、能量转换及存储体系、催化、药物输送等领域有广泛的应用前景。在国家自然科学基金和国家重点实验室基金的支持下,中科院过程工程研究所王丹研究员领导的科研团队发展了一种制备金属氧化物多壳层空心球的普适方法——时空多尺度模板法。     

介孔中空二氧化硅微球制备及吸附缓释性能研究

以用分散聚合法制得的不同粒径单分散阳离子型聚苯乙烯球为模板、十二胺为表面活性剂,通过溶胶-凝胶方法,在模板上包裹二氧化硅壳,并通过浸渍和焙烧制备了具有介孔结构的中空二氧化硅微球.TEM,SEM显示微球具有很好的单分散性和中空结构.小角XRD表明球壳上具有六方介孔结构.实验表明控制模板粒子大小可改变介孔中空二氧化硅微球粒径,改变正硅酸乙酯浓度可以调整二氧化硅球壳厚度.通过对丁基罗丹明B染料的吸附装载与释放实验证实了其有很好的渗透性和缓释性能.     

Ni-Mn氧化物纳米空心球的制备及其电化学性能研究

以碳球为模板,通过吸附过渡金属阳离子在空气下煅烧后制备Ni-Mn氧化物纳米空心球.利用XRD、FESEM、TEM以及HRTEM对样品的形貌、结构等进行表征,并利用电化学工作站对样品的电化学性能进行测试.结果表明,Ni-Mn氧化物纳米空心球具有较大的比容量,电流密度为1A/g时的比容量为592 F/g;电流密度为20 A...     

rGO/TiO2双壳空心球纳米材料的制备及光催化性能

以钛酸四丁酯(TBOT)为前驱体、SiO_2为模板,采用溶胶-凝胶法制备了还原氧化石墨烯/二氧化钛双壳空心球纳米复合材料(rGO/TiO_2HS)并通过SEM、XRD、FT-IR对其进行表征。rGO/TiO_2HS纳米复合材料因为rGO与TiO_2的协同作用和独特的双层壳空心球结构,可以抑制光生电子-空穴对的复合、增加比表面积以及提高光利用率,增强了其在紫外光照射下对甲基橙废水的光催化性能,而且具有较好的稳定性。     

氧化镍空心球材料合成方法介绍

当今世界纳米材料的性能研究和结构控制早已经成为全球纳米技术研究的重点和热点。纳米材料的突破点便是去掌控纳米材料的形貌和尺寸,此文便是研究空心球结构纳米材料的。因空心球结构纳米材料相比于其它形貌的纳米材料具有密度小,比表面积大的特性。此文介绍了模板法和水热法制备氧化镍空心球。模板法利用氧化亚铜和胶质碳球为模板,而水热法则是采取两种不同的方法制备纳米空心球。这四种方法各有千秋,希望此文可以对纳米材料空心球的制备有帮助。     

Metal hollow sphere electrocatalysts

Metal micro-/nano hollow spheres have been widely applied in numerous fields during the last decade. This review will only focus on the synthetic strategies to synthesize hollow spherical structures in the enhancement of their electrocatalytic activity, especially the metal hollow spherical materials. We present a comprehensive overview of synthetic strategies for metal hollow spherical structures which have been approached specifically in electrochemical reactions. These synthetic methods are mainly categorized as hard templates, soft templates, sacrificial templates and without templates. The review further includes electrocatalytic approaches of hollow spherical metals in different electrochemical processes, especially the methanol electro-oxidation reaction for methanol fuel cell application and hydrogen and oxygen evolution reactions in water electrolyzer, as metal hollow spherical materials are especially applied in these specific reactions.     

Preparation of cubic and spherical hollow silica structures by polystyrene-poly diallyldimethylammonium chloride and polystyrene-poly ethyleneimine hard templates

In this study, hollow silica structures were synthesized by sol-gel/template technique using two types of hard templates: polystyrene-poly diallyldimethylammonium chloride (PS@PDADMAC) and polystyrene-polyethyleneimine (PS@PEI). The obtained templates were evaluated by zeta potential analysis, FTIR, SEM and EDX techniques. The obtained structures were then assessed by the TEM method. By controlling the ratio of the precursors, two morphologies were obtained: hollow spherical and hollow cubic. The results indicated the successful synthesis of two types of hollow silica spheres with the approximated diameters of 63 and 19 nm as well as two types of hollow cubic silica with approximated dimensions of 830 and 58 nm. SEM, XRD, and BET were used to further study morphology, phase composition, and porosity of the hollow silica spheres prepared by PS@PEI templates.     

酵母菌模板组装Ti-Cr二元空心微球及光催化活性

以酵母菌为生物模板制备出了Ti-Cr二元复合空心微球。SEM表明产品粒径为3.5—3.7μm,呈分散较好的圆形,壳壁强度高。X射线衍射表明,TiO2为锐钛矿,Cr2O3为六角形矿。与TiO2相比,UV-V is图谱红移明显,证实Ti-Cr二元复合空心微球对可见光的响应得到加强。FTIR表明,Ti-Cr二元复合空心微球的形式机理可以概括为二步包裹-模板脱除过程。在光催化降解苯胺黑染料废水中,Ti-Cr二元复合空心微球表现出了较高的光催化活性,催化活性增加的原因在于可见光利用率的提高以及Cr3+的掺杂抑制了电子-空穴对的快速复合。     

柔软的球状和长方体状氧化硅中空结构的制备研究

采用自组装形成的芘纳米结构作为模板,成功地制备了柔软的球状和长方体状氧化硅中空结构.当不同量的芘在十六烷基三甲基溴化铵(CTAB)溶液中自组装时,产生的自组装结构展现出明显的从球状到长方体状的形貌变化.这些结构被用作氧化硅前驱体溶胶-凝胶反应的模板,获得了球状和长方体状氧化硅/芘复合结构.通过乙醇除去模板后,生成了柔软的球状(直径约为400nm)和长方体状(长为0.5—2.5μm)的氧化硅中空结构.这些结果展现了采用有机纳米结构作为模板来合成无机中空结构的优势:合成简便、结构多样以及结构形貌的灵活可控.     

Facile synthesis of multi-shelled MnO2–Co3O4 hollow spheres with superior catalytic activity for CO oxidation

Nano-oxide hollow structures have a wide range of applications in catalysis, but the preparation of multi-shelled composite oxide hollow structures still presents a major challenge. Herein, well-dispersed multi-shelled MnO₂–Co₃O₄ hollow spheres have been successfully prepared via a facile “Kirkendall effect” method employing carbon spheres as sacrifice templates. The shell of the hollow spheres was constructed by interconnected Co₃O₄ nanosheets and catkin-like MnO₂ nanorods. The interdiffusion of Carbon chain and MnO₄^? during synthesis could be the possible formation mechanism for the special morphology. Benefiting from the hierarchical porous structure, high surface area and strong synergistic effect between Co₃O₄ and MnO₂ was obtained, the as-prepared Co–Mn composite hollow spheres showed reliably high activity and recycle stability for CO oxidation, achieving the complete CO conversion at 137 °C without significant decrease in activity after five cycles and 10h constant-temperature reaction. We believe that this work will provide a new method for the preparation of multi-shell composite hollow spheres.     

Synthesis of porous hollow silica spheres using functionalized polystyrene latex spheres as templates

Uniform sized and integrated hollow silica spheres with porous shells were prepared by using sulfuric and carboxylic acid-functionalized polystyrene latex spheres as templates, sodium silicate as a precursor, and cetyltrimethylammonium bromide as a shell structure-directing agent. When polystyrene-methyl acrylic acid latex spheres were used as the templates, the pores in the shells of the resultant hollow silica spheres were composed of both micropores and mesopores. The pores in the shells of the hollow silica spheres were mainly composed of mesopores when sulfonated polystyrene-methyl acrylic acid latex spheres were used as the templates. The shell thickness and the specific surface area of the hollow silica spheres increased with the increase in the surface acidity of the latex spheres.     

Spherical silica micro/nanomaterials with hierarchical structures: synthesis and applications

This paper reviews the progress made recently in synthesis and applications of spherical silica micro/nanomaterials with multilevel (hierarchical) structures. The spherical silica micro/nanomaterials with hierarchical structures are classified into four main structural categories that include (1) hollow mesoporous spheres, (2) core-in-(hollow porous shell) spheres, (3) hollow spheres with multiple porous shells and (4) hierarchically porous spheres. Due to the complex structures and being focused on spherical silica micro/nanomaterials, some novel methods based on the combination of two routine methods or two surfactants, and some special synthetic strategies are proposed to produce the spherical silica micro/nanomaterials with hierarchical structures. Compared with the same-sized solid, porous or hollow silica spheres, these fantastic spherical silica micro/nanomaterials with hierarchical structures exhibit enhanced properties which may enable them to be used in broad and promising applications as ideal scaffolds (carriers) for biological, medical, and catalytic applications.     

Visible-light photocatalytic activity of SiC hollow spheres prepared by a vapor–solid reaction of carbon spheres and silicon monoxide

SiC hollow spheres are obtained by a vapor–solid reaction using carbon spheres as templates. The prepared SiC hollow spheres are characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, and UV–vis diffuse reflectance spectra. The visible-light photocatalytic activity is evaluated by photocatalytic decomposition of the methylene blue in aqueous solution. Results show that the diameter of SiC hollow spheres ranges from 200 to 300 nm and the shell thickness is about 50 nm. The SiC hollow spheres have a high surface area of 83.5 m²/g and exhibit a mesoporous structure characteristic. The photo-response of the SiC hollow spheres expand to visible-light region with band gap energy of 2.15 eV. The SiC hollow spheres exhibit a significantly enhanced photocatalytic activity due to their high surface area as well as large light-harvesting efficiencies.     

Preparation of hollow porous Cu2O microspheres and photocatalytic activity under visible light irradiation

Cu₂O p-type semiconductor hollow porous microspheres have been prepared by using a simple soft-template method at room temperature. The morphology of as-synthesized samples is hollow spherical structures with the diameter ranging from 200 to 500 nm, and the surfaces of the spheres are rough, porous and with lots of channels and folds. The photocatalytic activity of degradation of methyl orange (MO) under visible light irradiation was investigated by UV-visible spectroscopy. The results show that the hollow porous Cu₂O particles were uniform in diameters and have an excellent ability in visible light-induced degradation of MO. Meanwhile, the growth mechanism of the prepared Cu₂O was also analyzed. We find that sodium dodecyl sulfate acted the role of soft templates in the synthesis process. The hollow porous structure was not only sensitive to the soft template but also to the amount of reagents.     

Facile Preparation of Strontium Tungstate and Tungsten Trioxide Hollow Spheres

A simple and low-cost technique was developed to produce unique SrWO₄ and WO₃ hollow spheres. The SrWO₄ hollow spheres were prepared via a precipitation reaction between SrCl₂ and Na₂WO₄ in the presence of polymethacrylic acid, and the synthesis of WO₃ spheres used the as-prepared SrWO₄ hollow spheres as both precursors and templates. After soaking in HNO₃ and calcinations, the SrWO₄ were completely transformed into WO₃ while the hollow structures were perfectly retained. The "polymer-cation template" model was proposed to describe the formation of the SrWO₄ hollow spheres. This technique is feasible in fabricating other inorganic hollow-structured materials.