Heterostructures Built in Metal Hydrides for Advanced Hydrogen Storage Reversibility

Hydrogen storage is a vital technology for developing on-board hydrogen fuel cells. While Mg(BH₄)₂ is widely regarded as a promising hydrogen storage material owing to its extremely high gravimetric and volumetric capacity, its poor reversibility poses a major bottleneck inhibiting its practical applications. Herein, a facile strategy to effectively improve the reversible hydrogen storage performance of Mg(BH₄)₂ via building heterostructures uniformly inside MgH₂ nanoparticles is reported. The in situ reaction between MgH₂ nanoparticles and B₂H₆ not only forms homogeneous heterostructures with controllable particle size but also simultaneously decreases the particle size of the MgH₂ nanoparticles inside, which effectively reduces the kinetic barrier that inhibits the reversible hydrogen storage in both Mg(BH₄)₂ and MgH₂. More importantly, density functional theory coupled with ab initio molecular dynamics calculations clearly demonstrates that MgH₂ in this heterostructure can act as a hydrogen pump, which drastically changes the enthalpy for the initial formation of B H bonds by breaking stable B B bonds from endothermic to exothermic and hence thermodynamically improves the reversibility of Mg(BH₄)₂. It is believed that building heterostructures provides a window of opportunity for discovering high-performance hydrogen storage materials for on-board applications.     

Complex Hydrides for Energy Storage,Conversion, and Utilization

Functional materials are the key enabling factor in the development of clean energy technologies. Materials of particular interest, which are reviewed herein, are a class of hydrogenous compound having the general formula of M(XH_n)_m, where M is usually a metal cation and X can be Al, B, C, N, O, transition metal (TM), or a mixture of them, which sets up an iono‐covalent or covalent bonding with H. M(XH_n)_m is generally termed as a complex hydride by the hydrogen storage community. The rich chemistry between H and B/C/N/O/Al/TM allows complex hydrides of diverse composition and electronic configuration, and thus tunable physical and chemical properties, for applications in hydrogen storage, thermal energy storage, ion conduction in electrochemical devices, and catalysis in fuel processing. The recent progress is reviewed here and strategic approaches for the design and optimization of complex hydrides for the abovementioned applications are highlighted.     

金属氢化物分离氢同位素

本文介绍了金属氢化物分离氢同位素的基本原理及主要方法,并简要回顾了近年来有关金属氢化物分离氢同位素方面的研究工作。     

B和C对Li-N-H络合氢化物储氢性能的影响

利用机械合金化方法制备了Li-N-H络合氢化物,并研究B、C作为催化剂对其储氢性能的影响. 结果表明：LiNH₂、Li₂NH为Li-N-H络合氢化物的主要储氢相,随B的加入,储氢相的非晶化程度提高. 虽然B、C的添加均使储氢量下降,但n(B)∶n(C)=1∶2的混合添加提高了有效储氢量,同时也提高吸放氢动力学性能;B的添加可有效降低可逆吸放氢温度,适当增加球磨时间,有利于提高可逆吸放氢量.     

镁基储氢材料研究现状

从镁基储氢材料体系、制备方法及其应用研究等方面对该类材料进行了综述,归纳分析了影响镁基储氢材料吸放氢性能的因素,明确了镁基储氢材料未来的研究方向。     

利用储氢金属分离回收氢的研究进展

系统地介绍了储氢金属分离回收氢的技术及它们的最新发展状况，提出了今后的发展重点     

新型储氢材料的中子衍射研究

利用高灵敏度中子粉末衍射对新型储氢材料Li2NH,LiNH2,Li4BN3H10和BH3NH3的晶体结构进行了研究.通过对中子衍射数据的拟合分析得到了材料的晶格参数,原子占位和键长等数据.研究发现测量的氢原子占位结果与X-光衍射测量的结果有明显差别.结果表明储氢材料的氧释放温度与材料中的N-H或B-H键的键长成对应关系.通过将不同的储氢材料,例如LiBH4和LiNH2,进行复合改变材料中N-H和B-H氢键的强度,可以合成新的材料,有望达到储氢的目标.     

储氢材料研究进展

氢能作为一种新型的能量密度高的绿色能源,正引起世界各国的重视。储存技术是氢能利用的关键。储氢材料是当今研究的重点课题之一,也是氢的储存和输送过程中的重要载体。本文综述了目前已采用或正在研究的储氢材料,如金属(合金)储氢、碳基储氢、有机液体储氢、络合物储氢、硼烷氨储氢等材料,比较了各种储氢材料的优缺点,并指出其发展趋势。     

Reaction Kinetics of C60 Fullerene Ozonation

Abstract

It has been verified that the reaction between O₃ and C₆₀ follows the general second order reaction rate which is valid for all the reactions between ozone and unsaturated olefinic bonds: v = k[C?C][O₃]. The reaction rate constant k has been measured ≈(1.5 ± 0.3) × 10⁴ L mol^?1 s^?1. The value of this rate constant has the same order of magnitude of the rate constant measured for instance in the ozonation of 1,4‐diphenylbutadiene.     

Reaction Kinetics of C60 Fullerene Ozonation

It has been verified that the reaction between O₃ and C₆₀ follows the general second order reaction rate which is valid for all the reactions between ozone and unsaturated olefinic bonds: v = k[C=C][O₃]. The reaction rate constant k has been measured ≈(1.5 ± 0.3) × 10⁴ L mol^-1 s^-1. The value of this rate constant has the same order of magnitude of the rate constant measured for instance in the ozonation of 1,4-diphenylbutadiene.     

轻质金属-铝氢化物贮氢材料的研究进展

介绍了几种轻质金属-铝氢化物贮氢材料的吸放氢机理和研究进展.轻质金属-铝氢化物贮氢密度高,但存在动力学性能差、放氢温度高、可逆反应程度低等缺点,目前主要通过掺杂催化剂、降低材料的颗粒尺寸等方法来创提高吸放氢的速率和效率.随着研究的深入,轻质金属-铝氢化物在贮氢方面将有广阔的发展前景.     

贮氢合金的开发与应用

本文对贮氢合金的分类、基本性能、发展过程、研究现状、应用情况以及发展趋势进行了综合论述。     

镀覆处理对LaNiAl合金贮氢性能影响*

用化学镀法和酸性镀法在ＬａＮｉ４.７５Ａｌ０.２５材料颗粒表面镀覆铜膜，然后压制成块。处理后材料的放氢速率、导热性能、抗粉化效果有显著提高，其中酸性镀得到的颗粒与化学镀得到的颗粒在元素分布、成分、吸氢量、抗粉化效果等上有较大差别，因此压块的放氢动力学和抗粉化效果也不同。     

Hydrogen absorption/desorption properties of Li–Al–N–H composite

Li₃AlH₆ and LiNH₂ at a 1:3 molar ratio were mechanically milled to yield a Li–Al–N–H composite. The hydrogen storage properties of the composite were studied using thermogravimetry, differential scanning calorimetry, mass spectrometry, and X-ray diffraction. Addition of LiNH₂ lowered the decomposition temperature of Li₃AlH₆. The Li–Al–N–H composite began to release hydrogen at around 110 °C, which was 90 °C lower than the initial desorption temperature of Li₃AlH₆. About 7.46 wt% of hydrogen was released from the composite after heating from room temperature to 500 °C. A total hydrogen desorption capacity of 8.15 wt% was obtained after accounting for hydrogen released in the ball-milling process. The resulting dehydrogenated composite absorbed 3.56 wt% of hydrogen at 400 °C under a hydrogen pressure of 110 bar. The hydrogen absorption capacity and kinetic properties of the Li–Al–N–H composite significantly improved when CeF₃ was added to the composite. A maximum hydrogen absorption capacity of 4.8 wt% was reached when the composite was doped with 2 mol% CeF₃.     

镁基储氢材料研究进展

从气固反应的角度对近几年镁基储氢材料研究中的新技术和新方法进行了综述。主要包括球磨法、晶态及非晶态改性、烧结法和添加添加剂等方法。并简要对各种方法的工艺条件及所制备产物的吸放氢性能进行了讨论。     

碳纳米管储氢

近年来,碳纳米管由于其独特的力学、电学等性能以及在众多方面的潜在应用,越来越受到世界各国科学家的关注.最近,碳纳米管由于其大表面积和中空的结构,被应用于氢气储存.本文介绍了该领域最新的一些研究结果     

新型纳米结构炭材料的储氢研究

氢能是一种清洁的可再生能源。由于传统的储氢材料和储氢技术达不到氢燃料电池电动车的实用要求,储氢问题已成为氢能应用中最急需解决的关键问题。近年来,各种新型纳米结构炭材料的储氢已成为国际上的一个研究热点,引起了人们的广泛关注。但在这一研究领域中一直存在着许多争议和很大的分歧。通过综述国内外近几年来各种新型纳米结构炭材料如单壁碳纳米管、多壁碳纳米管、石墨纳米纤维以及炭纳米纤维等的储氢研究进展,指出了这一领域中需要解决的问题如储氢测试方法的标准化、纳米结构炭材料的评价以及储氢机制和吸附位的研究等。