Preparation and properties of Eu and Dy co-doped strontium aluminate long afterglow nanomaterials

The long afterglow nanomaterials of strontium aluminate co-doped by Eu and Dy have been synthesized by co-precipitation combined hydrothermal method. The effects of hydrothermal time, calcination time, pH value, the amount of aluminum nitrate, activator, co-activator and flux H₃BO₃ on the fluorescence properties of the product were investigated by means of single factor optimization experiment. Then the orthogonal experiment was employed to obtain the optimal synthesis conditions that are as follows: n_Dy/n_Eu = 2.5, t_c = 2.5?h, n_Eu/n_Sr = 0.02, t_h = 8?h. Subsequently, the optimal synthesis conditions were verified by three repeated experiments, and the obtained products were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and fluorescence spectrometer. The results showed that the synthesized target products all were the mixed crystal phase of SrAl₂O₄ and Sr₄Al_l4O₂₅. The particles presented regular spherical-like with size ~ 100?nm. The dopants Eu and Dy were confirmed existed in the SrAl₂O₄ powders. The fluorescence and afterglow data of the target products were better than that in the orthogonal experiment scheme. The primary emission spectra band was in the range of 400–600?nm with characteristic peak located at ~ 460?nm corresponding to the transitions of Eu²⁺ ions from 4f⁶5d→4f⁷, and the blue light can be observed by naked eyes. The similar fast-decaying and slow-decaying processes were displayed in all the afterglow curves, and the initial afterglow brightness of the target product is apparently higher than that of products synthesized by the orthogonal experiment. The synthesized target products, which show excellent long afterglow performance, present a great application prospects in the aspects of ceramics, plastics, arts and crafts, ink and coating.     

海洋非成岩天然气水合物原位快速制备实验及评价

我国的海洋天然气水合物（以下简称水合物）资源主要分布在沿海大陆架水深介于300～3 000 m的深水区，具有弱胶结、非成岩的特征，为了测试和研究该类型水合物必须原位、大量、快速制备样品，而目前常用的搅拌法、喷淋法、鼓泡法等制备技术却存在着生成速度慢、储气密度低等问题。为此，自主设计、研制了1 062 L非成岩水合物快速制备釜，针对我国南海非成岩水合物的物性特征，开展了搅拌法、鼓泡法、喷淋法单一制备方法及“三合一”法（上述3种方法相结合）水合物制备实验，测试了实验过程中温度、压力、电阻率及反应时间等数据，分析比较了几种不同制备方法的水合物生成情况与制备效率。实验结果表明：①搅拌法、鼓泡法、喷淋法制备水合物过程中，生成的水合物均缓慢增加并逐渐铺满整个液面；②搅拌法制备过程中可以观测到明显的诱导期，而喷淋法、鼓泡法及“三合一”法却无明显的诱导期；③单一制备方法及“三合一”法制备水合物过程中，电阻率均随反应时间的增加而增加，其变化趋势亦与水合物制备速率基本一致；④“三合一”法的制备周期明显短于单一制备方法（搅拌法、喷淋法、鼓泡法单一方法的制备时间分别约为“三合一”法的5.14倍、3.59倍、3.16倍）。结论认为，所研制的1 062 L水合物快速制备釜能够实现海洋非成岩水合物样品的原位、快速制备；较之于单一制备方法，“三合一”法大大提高了水合物的制备效率。     

石墨烯增强铜基复合材料的制备技术及发展

石墨烯由于其独特的二维结构和优异的物化性能,在改善复合材料的力学性能、电学性能和热学性能等方面具有很大的潜力,已成为金属基复合材料较理想的增强体。铜合金具有优异的导电导热性能和良好的延展性,但是其强度较低、不耐磨及高温下易变形的特点阻碍了其应用和发展。因此,结合石墨烯和铜的性能特点,将石墨烯作为增强体添加到铜中,制备性能优异的石墨烯增强铜基复合材料成为目前研究的热点之一。综述了目前石墨烯增强铜基复合材料的制备方法,并对各方法的特点进行了分析比较,提出未来可采用的制备工艺的方向以及在制备过程中面临的问题和挑战,并对其未来的研究方向进行了展望。     

Effects of preparation conditions on the morphology and performance of palladium nanostructures

Three-dimensional palladium nanoflowers (PdNF) composed of ultrathin Pd nanosheets had been synthesized by a solvothermal approach in our previous work. Here, the effects of preparation conditions on the morphology and electrochemical performance of palladium nanostructures were investigated. The explored conditions are as follows: the ratio of reducing agent to capping agent, the concentration of PdCl₂ precursor, the amount of HCl (used for PdCl₂ dissolution), the reaction temperature and time. Only when these conditions are strictly controlled, the obtained Pd material displays a uniformly nanoflower-like morphology, otherwise the Pd samples with nanoparticles or incomplete flowers can only be obtained. Then, the relationship between the morphology of Pd and its electrocatalytic activity was further studied. The results indicate that the Pd with perfect nanoflowers morphology possesses superior activity for formic acid electro-oxidation, while the Pd with incomplete flowers and ordinary (or irregular) particle morphology shows moderate and inferior activity. Therefore, the morphology-dependent electrocatalytic activity has been demonstrated in this work.     

An excellent universal catalyst support-mesoporous silica: Preparation,modification and applications in energy-related reactions

As a kind of versatile, excellent catalyst carriers, mesoporous silicas (mSiO₂) have been widely applied for preparing various supported catalysts with ideal catalytic properties due to their uniform and regular channels, adjustable medium pore size, big surface area, controllable wall composition, high hydrothermal stability, easy functional modification and good accessibility of larger reactant molecules. mSiO₂ not only enhances the dispersity of the active phase and generates more active sites for superior catalytic activity but also improves resulted selectivity and cyclic lifespan for enhanced interaction. And high adsorption capacity of mSiO₂ also increases the reactant molecule enrichment. In addition, mesoporous feature of the mSiO₂ pore wall can ensure diffusion of the substrate molecules and prevent leaching of active components. Thus, related investigation and application have been rapidly growing in the past decades. In this review, the development of mesoporous silica based catalysts on preparation, modification, pore size tune and energy-related applications, especially in hydrogenation reaction, esterification reaction, hydrogen production by alkane dry reforming and alcohol steam reforming and photocatalytic water splitting, is introduced in detail and the design ideas, preparation strategies and corresponding mechanism of different composite catalysts are discussed.     

纳米TiO_2的光催化活性及应用

对纳米 Ti O2 的制备、光催化机理、光催化活性的提高以及应用进行了综合评述 ,并揭示了存在问题及今后的研究方向     

非晶态纳米Fe—W—B合金粉末的制备及结构

用ＫＢＨ４化学还原ＦｅＳＯ４和Ｎａ２ＷＯ４制备了ＦｅＷＢ合金粉末。研究了改变溶液中的金属盐比例及ＫＢＨ４浓度对制备的影响。Ｘ射线衍射及电镜分析表明，合金粉末为３０～１００ｎｍ球形粉末，结构为非晶态。实验表明，有些粉末中有明显的非晶氧化物存在。     

高纯微细钛酸钡粉体制备方法进展

介绍了高纯微细钛酸钡粉体在特种陶瓷业竞争中的重要地位，以及国内外的发展概况，还比较详细地叙述了高纯微细钛酸钡粉体的各种制备方法。草酸盐共沉淀法和水热法是目前世界上普遍采用的工业规模制取优质钛酸钡粉体的两种液相法。     

矿物药应用研究中的问题及对策

矿物药是中医药的一个重要组成部分 ,是中华民族的文化瑰宝。但在其定名、使用、炮制、药理学和毒理学研究中存在着诸多问题。通过讨论 ,本文提出了对矿物药要根据其成分统一命名 ,科学使用 ,建立国家矿物药质量标准和质量认定体制等具体办法。同时对矿物药新的发展趋势进行了总结     

西山矿区重介质选煤技术应用分析

介绍了重介质旋流器选煤技术在西山煤电集团公司的使用情况，分析和探讨了存在的问题，并提出了针对性的解决办法。