碳化硅纳米材料的溶剂热合成

本文综述了溶剂热法制备一系列碳化硅纳米材料的研究,包括一维纳米线、纳米带、纳米棒、二维纳米片及空心球等;同时,碳源过量时可形成碳包覆碳化硅的复合材料。使用废塑料作为碳源合成了碳化硅纳米材料,为废塑料的回收再利用提供了新途径。通过使用碘、硫等添加剂,有效降低了合成温度,显示出溶剂热技术在制备碳化硅方面的独特优势。     

新型功能材料的溶剂热合成及反应

由中国科技大学钱逸泰院士主持的国家自然科学基金重点项目“新型功能材料的溶剂热合成及反应机理”在新型功能材料制备方面取得了突出进展。他们用溶剂热合成不仅能够使反应在相对低的温度下进行,实现了其它常规条件难以实现的新的化学反应,获得各种新物相、亚稳相和不定比化合物及三元、四元等复合物纳米材料,并且控制生长一维纳米材料,从而为新材料探索打下基础。该项目发表SCI论文200余篇。获得2001年国家自然科学二等奖,2000年中国科学院自然科学一等奖各一项。发展了水热合成技术,通过水热制备了薄单晶Te纳米带和纳米管,尤其是制备了Te纳米带的手性右螺旋结构以及含有该结构的纳米管,揭示了纳米管的一种新形成机理,Adv.Mater.上审稿人对此工作做以下评价:“这篇论文提出了合成新颖的纳米结构的方法,化学路线设计巧妙,所得结论非常重要(top10%ofpa鄄pers),建议在AdvancedMaterials发表。总之,这是一项非常好的工作。”另外,他们利用水热合成技术,制备了Ni纳米带,并对其磁学性质进行研究,相关工作发表在Adv.Mater.上。探索了低维硫属化合物纳米材料的溶剂热合成方法。用聚合物控制硫化物的生长溶剂热制...     

离子液体在制备金属氧化物纳米材料中的应用

总结了近年来在离子液体中制备金属氧化物纳米材料的新方法以及离子液体在金属氧化物纳米材料制备方面的应用及发展趋势.目前,对于制备纳米金属氧化物,离子液体主要是作为电解液、表面活性剂;其未来的发展趋势是离子热合成和集模板-溶剂-反应物于一身的离子液体反应.     

稀土氟化物微纳米材料制备方法的研究进展

稀土氟化物纳米材料由于其特殊的光、电、磁性质,在光学器件、显示、生物标记、光学晶体等领域有着广泛的应用,已成为材料科学领域的研究热点之一。目前研究者已用沉淀法、微乳液法、水热与溶剂热法、溶胶-凝胶法、微波法、超声波法、前驱体热解法、静电纺丝法等成功地制备出了纳米颗粒、纳米线、纳米膜、多面体纳米晶、复合结构纳米晶、核壳结构纳米材料等稀土氟化物纳米材料。本文总结了上述几种制备方法的研究进展,讨论了其优缺点,并结合课题组在稀土氟化物纳米材料制备方面的工作,对纳米稀土氟化物制备方法的发展方向做了展望。     

离子液体在无机纳米材料合成上的应用

室温离子液体作为一种新型的绿色环保溶剂,在无机纳米材料合成中的应用引起越来越多研究者的注意。目前,已经利用室温离子液体合成出了纳米多孔材料、纳米粒子和中空球、一维纳米材料等。与传统的溶剂相比,离子液体在合成过程中体现出了很多优势,且合成的产物也不同,为无机纳米材料的合成开辟了一条新途径。本文就近年来国内外相关研究进展,对离子液体在无机纳米材料合成中的应用进行综述。     

四硫化三铁纳米粒子的制备及应用

近些年来磁性Fe3S4纳米粒子由于其独特的物理化学性质,如量子尺寸效应、电磁学特性,在环境治理、能源储存、催化剂、生物医学应用等方面展示出了其巨大的潜力。本文总结了近10年来国内外Fe3S4纳米粒子的制备方法及对比了不同合成方法的优缺点,主要包括：共沉淀法、水热法(溶剂热法)、热分解法和模板法。并且综述了Fe3S4纳米材料在环境治理、能源储存、生物医学等方面的应用。最后,分析了Fe3S4纳米材料在制备中存在的一些问题,并对其的发展方向进行了展望。     

微纳米稀土氯氧化物的合成研究进展

稀土氯氧化物作为一种重要的发光基质,具有较高的光吸收效率和传能效率,在彩色显示、催化、生物医药、光电转换、气敏等领域均有广泛的应用,已成为光功能材料领域的研究热点之一。目前研究者已用固相法、沉淀法、液相-高温焙烧法、水热与溶剂热法、前驱体热解法、溶胶-凝胶法、静电纺丝法等方法成功地制备了稀土氯氧化物微米颗粒,纳米颗粒、纳米条、纳米片、纳米棒、纳米针、纳米纤维、纳米带、纳米管等稀土氯氧化物微纳米材料。总结了各种制备方法的研究进展及优缺点,并结合本课题组在稀土氯氧化物纳米材料方面的研究工作,对稀土氯氧化物微纳米材料的制备方法的发展方向进行了展望。     

基于配位聚合物的纳米材料的可控合成研究进展

本文围绕近年来基于配位聚合物的纳米材料,包括配合物纳米材料和以其为前体制备的各种氧化物、硫化物等半导体材料和磁性材料的可控合成研究工作,总结了配合物纳米材料的制备方法,主要有液相法、微乳法、扩散法、界面反应法、水热/溶剂热法、高温裂解法等,以及应用方面的研究进展,并展望了配合物纳米材料今后可能的发展方向。     

水热微乳法合成La(OH)3纳米棒的形貌控制研究

自1991年Iijima发现碳纳米管以来,一维纳米材料如纳米管、纳米线、纳米棒和纳米纤维等由于其具有独特的光、电、磁等性质及其潜在的应用前景而引起全世界的广泛关注,一维纳米材料的制备方法有化学气相沉积法、溶胶一凝胶法、催化剂辅助法、固相化学反应法、模板法、溶剂热法、微乳法和水热,微乳法等,其中水热,微乳法是近年来兴起的一种很有发展前途的制备一维纳米材料的方法。     

纳米NCS在电化学能量转换和储存中的制备和应用

镍-钴双金属硫化物(NiCo_2S_4)具有典型的AB_2O_4尖晶石结构,NiCo_2S_4的电导率比NiCo_2O_4电导率高两个数量级,在室温下的电导率高达1.25×10~6S·m~(-1)。此外,NiCo_2S_4可提供比相应的单组分硫化物更有效的氧化还原反应,由于其独特的纳米结构和电化学性能,具有很大的应用潜力。本文系统地综述了不同结构纳米NiCo_2S_4的制备及其在电化学能量转换和储存中的应用,介绍了NiCo_2S_4纳米材料的形貌特征、物化特性以及合成方法。预处理条件、制备方法和生长基体都会对NiCo_2S_4纳米结构的形貌和性能产生影响,不同纳米结构(如纳米针、纳米线、纳米棒、纳米管、纳米盒、纳米片、纳米板和层次结构)的NiCo_2S_4可通过多种方法制得(如水热法和溶剂热法、低温合成法、阴离子交换法、蒸气转换法、电沉积方法、共沉淀法和自组装等),其中最常用的是水热和溶剂热法,因为它们成本低、易于处理且适合大规模制造。同时,总结了NiCo_2S_4纳米材料在电催化、超级电容器和锂离子电池领域中的应用现状;分析和比较其不同纳米结构的制备工艺、方法和应用,希望能促进NiCo_2S_4纳米材料在电化学能量转换和储存领域的发展;最后提出NiCo_2S_4纳米材料的发展及应用方向。     

Preparation of nanomaterials from aqueous solutions imitating the hydrometallurgy waste

A technique was developed for synthesis of precursors of nanomaterials from artificial mixtures of aqueous salt solutions, based on flotation extraction followed by reduction of the precursors in direct micelles in view of a surfactant structure. This technique imitates preparation of nanomaterials from hydrometallurgy waste. The resulting materials containing platinum nanoparticles were tested for their ability to catalyze oxidation of carbon monoxide.     

Possibility of a 2D SiC monolayer formation on Mg(0001) and MgO(111) substrates

The geometrical characteristics of a 2D SiC monolayer on Mg(0001) and MgO(111) plates regarded as potential materials for growing two-dimensional silicon carbide were studied. The most favorable positions of the atoms of 2D SiC on the substrates were determined. In the 2D SiC/Mg(0001) system, unlike in 2D SiC/MgO(111), the deviation of the carbon atom from the silicon carbide monolayer was insignificant (0.08 Å). Consequently, magnesium can be used as a substrate for growing two-dimensional silicon carbide. The use of MgO(111) is not recommended because of a significant distortion of the 2D SiC surface.     

Solid Base Assisted Dual-Promoted Heterogeneous Conversion of PVC to Metal-Free Porous Carbon Catalyst

Polyvinyl chloride (PVC) is widely used in daily life, but its waste has become a serious environmental problem. A solid base assisted low-temperature solvothermal dehalogenation was developed in this work to sustainably and efficiently transform PVC into high-value dimethylamine hydrochloride (DMACl) chemical and N,O co-doped carbon monolith with hierarchically porous structure. The synergistic promotion of solid-base catalyst and solvent decomposition with the removal of HCl can shift forward the chemical equilibrium to promote the dechlorination of PVC and increase the carbon yield. Meanwhile, the solid-base catalyst can also act as a pore-forming additive to fabricate the carbon monolith with hierarchical pores. Induced by the high specific surface area, hierarchical pores and N,O co-doped structure, the generated carbon monolith exhibits superior electrocatalytic performance towards H₂ evolution. These discoveries shed light on the design of synergistically coupled solvent and solid catalyst to promote the heterogeneous conversion of waste chlorinated plastics into high-value chemicals for a sustainable future.     

Structural investigations on pyrolysed polycarbosilanes

The combination of combustion analysis, IR-spectroscopy and Raman spectroscopy yields information about the chemical state of carbon in polycarbosilanes or silicon carbide. A stable polycarbosilane can be found where carbon is bonded in a network of silicon, carbon and hydrogen. In the temperature range between 700 and 800°C, the polycarbosilane is transformed into an amorphous silicon carbide with a small excess of carbon. During the crystallisation of the amorphous silicon carbide, which takes place at temperatures above 1100°C, glassy carbon is found by Raman-spectroscopy and combustion analysis. Finally after pyrolysis temperatures above 1500°C only silicon carbide exists; this may be caused by the reaction of free carbon with oxygen impurities in the samples.     

A novel sacrificial interlayer-based method for the preparation of silicon carbide membranes

A novel method is presented based on the use of sacrificial interlayers for the preparation of nanoporous silicon carbide membranes. It involves periodic and alternate coatings of polystyrene sacrificial interlayers and silicon carbide pre-ceramic layers on the top of slip-casted tubular silicon carbide supports. Membranes prepared by this technique exhibit single gas ideal separation factors of helium and hydrogen over argon in the ranges 176–465 and 101–258, respectively, with permeances that are typically two to three times higher than those of silicon carbide membranes prepared previously by the more conventional techniques. Mixed-gas experiments with the same membranes indicate separation factors as high as 117 for an equimolar H₂/CH₄ mixture. We speculate that the improved membrane characteristics are due to the sacrificial interlayers filling the pores in the underlying structure and preventing their blockage by the pre-ceramic polymer. The new method has good promise for application to the preparation of a variety of other inorganic microporous membranes.     

不同活性炭负载的镍基催化剂上废塑料裂解制碳纳米管性能

以椰壳炭、竹炭和木炭三种活性炭为载体,采用浸渍法制备炭负载金属镍的催化剂,考察其在废塑料裂解制备碳纳米管过程中的催化反应性能;采用X射线衍射、扫描电镜、透射电镜、拉曼光谱仪、同步热分析仪、比表面积分析仪等手段分析了催化剂和产物碳纳米管的形貌和结构。结果表明,椰壳活性炭为载体制备的镍基催化剂上碳纳米管产量最高、石墨化程度最好。以椰壳活性炭为载体制备的镍基催化剂为例,研究了反应温度和镍负载量对其催化性能的影响。     

高频红外碳硫分析仪测定含碳化硅耐火材料中碳化硅含量

采用对试样进行灼烧预处理的方法,除去游离碳,用锡粒、纯铁、钨粒作为助熔剂,并以钢铁标准样品校正仪器,高频燃烧红外吸收法测定含碳化硅耐火材料中的碳化硅含量,测定结果的相对标准偏差为1.07%(n=6),该法与化学法的测定结果较接近,精密度和准确度均满足化学分析的要求。     

有机-无机杂化一维纳米材料的合成及其二次转化

近十年来,随着纳米科技的发展,有机．无机杂化一维纳米材料的设计合成与应用成为了自然科学领域的研究热点．本文综述了由有机小分子与无机组分杂化而成的一维纳米材料的合成方法,包括水热／溶剂热法、共沉淀法、非水相溶胶凝胶法、模板法、后嵌入法等．并对有机一无机杂化一维纳米材料的二次转化,如通过二次转化获得功能性一维氧化物、碳氮化物、硫属化合物及高分子杂化纳米材料,进行了讨论与展望．     

Determination of organohalogen compounds and organic carbon as sum parameter in electronic waste

Metal-containing devices in electronic waste such as printed circuit boards can be recycled for the recovery of noble metals such as gold, silver, platinum or palladium using a thermal process. In this process the plastics are burned and more than 90% of the noble metals are transfered into a copper matrix. Finally the pure metals are refined by electrolysis. Because of the content of brominated flame retardants and chlorinated polymers in the plastics, formation of halogenated dibenzo-p-dioxins and dibenzofurans cannot be excluded. The use of modern filter techniques minimizes the emission of these substances. As a precaution the electronic waste is controlled for its content of organohalogen compounds and organic carbon. This work describes an analytical method for the determination of the sum of organohalogen compounds and organic carbon in electronic waste. The investigation of different charges of electronic waste in the fraction of particle size<0.1 mm show concentrations for the sum of organobromine compounds in the range of 0.2–4.8% originating from brominated flame retardants in the plastics. The total content of organochlorine compounds is <0.01–0.13%, showing that chlorinated plastics were efficiently removed before the thermal process. The content of organic carbon is between 13 and 27%. Because of the portion of fine particle size in relation to the total sample amount, the results have to be multiplied by a factor of about 0.25 to 0.3.