Interaction of hydrogen with metal nitrides and imides

The pursuit of a clean and healthy environment has stimulated much effort in the development of technologies for the utilization of hydrogen-based energy. A critical issue is the need for practical systems for hydrogen storage, a problem that remains unresolved after several decades of exploration. In this context, the possibility of storing hydrogen in advanced carbon materials has generated considerable interest. But confirmation and a mechanistic understanding of the hydrogen-storage capabilities of these materials still require much work. Our previously published work on hydrogen uptake by alkali-doped carbon nanotubes cannot be reproduced by others. It was realized by us and also demonstrated by Pinkerton et al. that most of the weight gain was due to moisture, which the alkali oxide picked up from the atmosphere. Here we describe a different material system, lithium nitride, which shows potential as a hydrogen storage medium. Lithium nitride is usually employed as an electrode, or as a starting material for the synthesis of binary or ternary nitrides. Using a variety of techniques, we demonstrate that this compound can also reversibly take up large amounts of hydrogen. Although the temperature required to release the hydrogen at usable pressures is too high for practical application of the present material, we suggest that more investigations are needed, as the metal-N-H system could prove to be a promising route to reversible hydrogen storage.     

水合物生成影响因素与实验研究

对影响水合物生成的反应条件进行了实验研究，利用高压水合物生成装置测定了纯水与添加剂溶液以及不同温度与压力条件下，水合物生成过程及其特性，通过实验数据与结果分析得出表面活性剂SDS不但可以加快水合物生成速度，同时还可以提高其含气量，而温度与压力对水合物生成具有制约性，低温高压虽利于反应进行，但会增加生产成本，应综合考虑两者的最佳值，这些因素的研究对解决实际生产问题具有直接的指导意义，将促进气体水合物储气应用技术的发展。     

液相有机氢载体的催化研究与应用

氢能清洁高效、能量密度高，是理想的能源载体，也是公认的未来能源发展方向之一。氢气的存储是氢能利用的关键环节，目前仍没有完美适配所有场景的储氢材料，储氢技术的选择势必要以使用场景为导向。液相有机氢载体（liquid organic hydrogen carriers，LOHCs）作为一种液相储氢材料，在运输方面具有独特的应用优势。本文介绍了常见的液相有机储氢材料，重点探讨了适用于运输工具（车、船、航空器等）的LOHCs，综述其加氢/脱氢的催化研究进展、应用技术难点，并展望了其应用前景。     

Active control of slow light on a chip with photonic crystal waveguides

It is known that light can be slowed down in dispersive materials near resonances. Dramatic reduction of the light group velocity-and even bringing light pulses to a complete halt-has been demonstrated recently in various atomic and solid state systems, where the material absorption is cancelled via quantum optical coherent effects. Exploitation of slow light phenomena has potential for applications ranging from all-optical storage to all-optical switching. Existing schemes, however, are restricted to the narrow frequency range of the material resonance, which limits the operation frequency, maximum data rate and storage capacity. Moreover, the implementation of external lasers, low pressures and/or low temperatures prevents miniaturization and hinders practical applications. Here we experimentally demonstrate an over 300-fold reduction of the group velocity on a silicon chip via an ultra-compact photonic integrated circuit using low-loss silicon photonic crystal waveguides that can support an optical mode with a submicrometre cross-section. In addition, we show fast (approximately 100 ns) and efficient (2 mW electric power) active control of the group velocity by localized heating of the photonic crystal waveguide with an integrated micro-heater.     

Molecular dynamics study on the structure I helium hydrate

A 368- water molecule structure I gas hydrate, encased by the number of helium (He) molecules ranging from two to twenty-two, are calculated by molecular dynamical simulations. The potential TIP4P (transferable intermolecular potentical with four sites) is used for water interactions and Lennard-Jones for He-He and He-water interactions. He molecules do not affect the water lattice and can stabilize the hydrate when their concentration is small. A trough signature of He encased is found at 80～90 meV in the phonon density of states. He molecules prefer to be more off-center in 51262 cages. Heavier isotope He are energetically favorable to be filled in cages.     

CO2水合物喷雾合成的生长特性实验研究

利用自行设计的可视化喷雾强化水合物制备实验系统,分析和比较了不同初始温度和初始压力条件下,喷雾合成CO2水合物的耗气量和反应釜内温度的变化,研究其生长特性.实验结果表明,初始压力越高,或者初始温度越低,那么诱导时间越短,单位时间内CO2耗气量越多,水合物生成速率越快.同时,通过对水合物生长过程的摄像在线观察,发现CO2水合物在接触界面紧贴反应釜壁面的两相接触处最先诱导成核并迅速扩展,生成水合物后,随着反应进行,吉布斯自由能差增大,水合物颗粒由圆滑状向数枝状变化.     

Recent advances in additive-enhanced magnesium hydride for hydrogen storage

The discovery of new hydrogen storage materials has greatly driven the entire hydrogen storage technology forward in the past decades. Magnesium hydride, which has a high hydrogen capacity and low cost, has been considered as one of the most promising candidates for hydrogen storage. Unfortunately, extensive efforts are still needed to better improve its hydrogen storage performance, since MgH2 suffers from high operation temperature, poor dehydrogenation kinetic, and unsatisfactory thermal management. In this paper, we present an overview of recent progress in improving the hydrogenation/de-hydrogenation performance of MgH2, with special emphases on the additive-enhanced MgH2 composites. Other widely used strategies (e. g. alloying, nanoscaling, nanoconfinement) in tuning the kinetics and thermodynamics of MgH2 are also presented. A realistic perspective regarding to the challenges and opportunities for further researches in MgH2 is proposed.     

三种缺陷碳纳米管储氢性能分子动力学模拟研究

采用分子动力学（MD）方法对3种含有缺陷的椅式（5，5）、椅式（6，6）和齿式（10，0）碳纳米管储氢能力进行了模拟研究，考查了缺陷大小、缺陷位置、碳纳米管直径和螺旋性以及温度对碳纳米管储氢性能的影响．模拟结果表明；碳纳米管在80K时的储氢能力明显高于298K时的储氢能力；在相同条件下，直径较大的碳纳米管储氢性能优于直径较小的；当碳纳米管上的缺陷孔较小时，碳纳米管在室温下即可达到较高的储氢量，且缺陷位于碳纳米管端部时的储氢量大于缺陷位于管壁时的储氢量，而碳纳米管的螺旋性对储氢量影响较小；当缺陷孔的尺寸变大时，碳纳米管的储氢量明显下降，与此同时，碳纳米管的螺旋性对碳纳米管储氢量的影响趋于明显，而缺陷所在位置对储氢量的影响则相应减弱．     

喷雾式天然气水合物储气系统的实验研究

利用自行设计的喷雾式天然气水合物储气实验系统,研究了喷雾强化措施下的水合物制备所形成水合物的形态特征,考察在不同初始压力和初始温度条件下水合物形成过程的压力变化特性及其对水合物生成速率和生成量的影响,并且分析和比较了间歇进气与连续进气两种不同进气方式下水合物的生成特性.实验结果表明,初始压力越高、初始温度越低,反应生成水合物的速率越快,生成的量越多;在进气方式比较方面,连续式进气生成水合物的速率比间歇式进气要快,能耗要低,因而连续式进气比间歇式进气具有更好的速率和效率.     

镁基固态储氢材料研究进展

 镁基储氢材料具有储氢量高、镁资源丰富以及成本低廉等优点,被认为是极具应用前景的一类固态储氢材料。利用镁基储氢材料供氢主要有热分解放氢和水解产氢2种途径。MgH₂的热分解放氢焓值高（75 kJ/mol H₂）,造成其放氢温度较高、动力学差; MgH₂的水解过程中,由于常温水解产物Mg（OH）₂逐渐包裹在MgH₂表面,阻隔了MgH₂与水的接触,从而导致水解产氢效率较低。近年来,大量研究工作聚焦于改善MgH₂的热解/水解供氢性能及实际应用,已经取得了大量成果。针对目前国内外镁基固态储氢材料的研发,总结了材料/结构改性、反应条件对镁基储氢材料的热解/水解性能的影响,重点阐述了固态镁基储氢材料组成成分-微观结构-储放氢性能之间的关系,并对镁基储氢系统及实际应用场景进行了归纳。未来通过镁基固态储运氢技术的发展,将实现氢气的高安全、高效及大规模储运,助力中国氢能产业的发展。     

Applying Study of Hydrogen Storage Alloy

Hydrogen is an important source of energy.The natural resouces of hydrogen is plenty and it gives us lots of heat, and it is dean. One of difficulties of developing hydrogen sources of energy is hydrogen storage. Hydrogen storage tank is either dangous or a little of capacity. Liquid hydrogen occupys small space. Liquefaction temperature of hydrogen is -253℃ and need better heat insulation protection, the volumn and weight of heat insulation layer are equal to hydrogen storage tank. Hydrogen storage utillizing hydrogen storage material is a very safety, economical and effective method. Hydrogen storage material is either a medium of sofid hydrogen storage or is negative pole active material of Ni-H battery,and is the one of key technoloy of fuel and Ni-H battery, it is an important material of new sources of energy too.Nanotechnology is introduced Mg-matrix hydrogen storage alloy and is achieved progress gteatly,but hydrogen storage alloy need be mode further improvment on applying investigation.     

二元系过渡金属贮氢合金材料的形成规律

利用模式识别的偏最小二乘法对过渡金属二元合金氢化物的形成和贮氢性能进行分析，结果表明：利用化学健参数－模式识别方法可以建立过渡金属二元合金贮氢材料形成的数学模型，是贮氢材料设计的一种用方法。     

ZrCr0.6Fe1.2M0.2贮氢性能的研究

ＺｒＣｒ０．６Ｆｅ１．４是一种性能优良的贮氢条件,以其为母合金,通过对不同取代Ｍ制备的ＺｒＣｒ０．６Ｆｅ１．４贮氢合金氢平台压力,平台斜率及其贮氢过程热力学的研究,比较了不同取代元素对母合金贮氢性能的影响。     

笼型甲烷水合物中单、双水分子缺位后的结构与稳定性

采用量子化学计算方法,对甲烷水合物基本空腔(H₂O)₂₀缺失水分子后形成的(H₂O)₁₉ 和(H₂O)₁₈ 笼型结构特征及其甲烷水合物的稳定性等进行了深入探讨。结果表明,只有相邻且同面的两个水分子缺失,甲烷才有溢出笼型的可能,笼型结构中O—O边长的变化主要源于氢键键长的改变,O—H共价键键长以及H—O—H 键角的变化很小;同类结构异构体的稳定性主要由水分子间的结合能决定,非同类异构体的稳定性主要取决于相邻五元环的个数,而相邻四元环数目的增加将降低其稳定性。     

Improvement in hydrogen storage performance of Mg by mechanical grinding with molten salt etching Ti3C2Clx

Mg-based materials are currently a hot research topic as hydrogen storage materials due to their considerable theoretical hydrogen storage capacity. However, the kinetic performance of hydrogen absorption and desorption of Mg is too slow and requires high temperature, which seriously hinders the application of this material. MXene is a new type of two-dimensional material with significant role in improving thermodynamics and kinetics. In this experiment, a two-dimensional layered MXene containing Cl functional group was prepared by molten salt etching using the Ti-containing MAX phase as the raw material. Then different ratios of Ti₃C₂Cl_x were uniformly dispersed onto the surface of Mg by high energy ball milling. The samples were characterized by hydrogen absorption and desorption kinetics, SEM, XRD, XPS, and DSC to investigate the effect of Ti₃C₂Cl_x on the hydrogen absorption and desorption performance of Mg. The onset hydrogen absorption temperature can be reduced to room temperature and the hydrogen release temperature is reduced by 200 ​°C by doping Ti₃C₂Cl_x. And there is also 5.4 ​wt% hydrogen storage in the isothermal hydrogen absorption test at 400 ​°C. The results of DSC demonstrate that the E_a of Mg+15 ​wt% Ti₃C₂Cl_x was reduced by 12.6% compared to pristine Mg. The ΔH is almost invariable. The results of XPS show that the presence of multivalent Ti promotes electron transfer and thus improves the conversion between Mg²⁺/Mg and H⁻/H. This study provides a guideline for further improving the hydrogen absorption and desorption performance of Mg-based hydrogen storage materials.     

Light-induced conversion of an insulating refractory oxide into a persistent electronic conductor

Materials that are good electrical conductors are not in general optically transparent, yet a combination of high conductivity and transparency is desirable for many emerging opto-electronic applications. To this end, various transparent oxides composed of transition or post-transition metals (such as indium tin oxide) are rendered electrically conducting by ion doping. But such an approach does not work for the abundant transparent oxides of the main-group metals. Here we demonstrate a process by which the transparent insulating oxide 12CaO x 7Al(2)O(3) (refs 7-13) can be converted into an electrical conductor. H(-) ions are incorporated into the subnanometre-sized cages of the oxide by a thermal treatment in a hydrogen atmosphere; subsequent irradiation of the material with ultraviolet light results in a conductive state that persists after irradiation ceases. The photo-activated material exhibits moderate electrical conductivity (approximately 0.3 S cm(-1)) at room temperature, with visible light absorption losses of only one per cent for 200-nm-thick films. We suggest that this concept can be applied to other main-group metal oxides, for the direct optical writing of conducting wires in insulating transparent media and the formation of a high-density optical memory.     

镁基合金与碳纳米纤维复合储氢材料的制备与性能研究(Ⅰ)--以化学镀Ni碳纳米纤维为前驱物热扩散法合成Mg2Ni-CNFs复合储氢材料

利用金属Mg易热扩散制合金的特性，以化学镀Ni的碳纳米纤维(Ni-CNFs)为前驱物，制备出了Mg-Ni合金与CNFs的复合储氢材料．并测试了其电化学性能，提出了镁基储氢合金与CNFs复合储氢材料的储氢机理．     

笼状热电材料p型和n型Ba8Ga16Ge30单晶之间载流子的调谐研究

本研究首次实现了p型和n型Ba_8Ga_(16)Ge_(30)(BGG)单晶之间载流子类型的相互转换.采用以对方单晶为前驱体的再合成调制方法,再次制备了Ba_8Ga_(16)Ge_(30)(BGG)单晶笼状热电材料,利用物理属性测量系统(PPMS)测量单晶样品的变温电阻率并对其载流子类型进行了评价.结果表明:p型和n型Ba_8Ga_(16)Ge_(30)(BGG)单晶之间载流子类型可以成功地进行相互转换,且n型转换为p型样品时前驱体状态及成分配比的不同可导致改性后样品电阻率及载流子浓度不同.以单晶为前驱体的晶体再生长以及载流子调节对于制备珍贵同位素替代的大块单晶具有指导意义,有益于材料内部笼内及笼上原子的非简谐振动研究,并对热电材料的再生利用也具有重要意义.     

一种对文件系统透明的网络存储系统

提出了一种基于TCP／IP协议的对文件系统透明的网络存储系统．其透明性体现在两个方面：a．对用户透明，用户象访问本地磁盘一样访问远程网络存储空间；b．文件系统对存储服务器透明，存储服务器只针对数据块进行处理，从而减轻了用户和服务器的存储管理负担．在实现单用户对多存储空间、多用户对同一存储空间技术的基础上，系统具有数据备份、共享存储的基本功能，为实现复杂的网络存储提供了一个开发平台。     

水合物分离二氧化碳气体的研究

气体水合物是在一定的温度和压力下由气体分子填充水分子产生的晶格而形成的一种笼形晶体.这种水结晶体具有高密度的特性使其成为诸多基于气体水合物应用技术的基础.利用气体水合物生成的原理,将空气中的二氧化碳分离出来,并以气体水合物的形式储存在海洋深处.对二氧化碳气体水合物的生成过程和表面活性剂的促进作用进行了实验研究.选取十二烷基硫酸钠(SDS)、十二烷基苯磺酸钠(SDBS)、对甲苯磺酸(p-TSA)三种表面活性剂进行了二氧化碳气体水合物生成的促进研究,确定了促进气体水合物生成的机理与途径.结果表明:三种表面活性剂在一定的程度上都能缩短气体水合物生成的诱导时间,提高了气体水合物的生成速率.