基于材料基因工程的储氢材料数据库构建及其应用

高密度储氢材料的加速研发对于我国能源经济转型、早日实现双碳目标至关重要.集成高通量计算、数据库及机器学习预测的数据驱动材料研发新范式有望缩短研发周期并降低研发成本.由于组分、结构、工艺及形貌等多重复杂性,目前储氢材料相关的数据驱动性能预测研究较少,尚缺乏一个较为系统的性质性能数据库.因此,本文中我们开发了智能化的数据挖掘引擎,通过已发表的学术论文中发掘储氢材料热力学、动力学储氢性能数据,以及现有的材料基因工程数据库数据中获取含氢材料物理化学性质,并结合高通量第一性原理计算数据,构建了储氢材料性质性能数据集.基于所构建的数据集进一步建立了储氢材料数据库,并应用晶体图形神经网络等机器学习方法对储氢材料的吸放氢质量、吸放氢温度进行预测.相关工作将数据驱动的材料研发新模式与储氢材料相结合,为发展实用高效的新型储氢材料提供有效的平台支持、数据支撑、方法指引.     

纳米PbO/Ti电极催化还原偏硼酸锂制备硼氢化锂

在乙二醇甲醚溶液中电解铅片,制备了铅醇盐配合物,然后将溶液直接水解、凝胶,再通过提拉法涂抹在钛丝表面,450 ℃煅烧2 h制备纳米PbO/Ti电极。 将PbO/Ti电极在0.2~1.0 mol/L LiOH+0.1~0.5 mol/L LiBO2溶液测试催化还原性能,研究了影响电解还原LiBO2制备硼氢化锂(LiBH4)的主要因素,如LiBO2和LiOH浓度等。 通过X射线粉末衍射和扫描电子显微镜对PbO/Ti电极和LiBH4进行了表征。 实验表明,纳米PbO/Ti电极表面颗粒分散较好,修饰电极催化性能稳定,放电电流较大,产率和电流效率分别达15.6%和25.3%。     

新型储氢材料及其热力学与动力学问题

氢能作为一种理想的二次能源受到了国内外科研工作者的广泛关注,研制可以在室温和较低压力下方便、安全、高效地储存氢能的材料是氢能发展的瓶颈.到目前为止,固态储氢材料以能量密度高及安全性好等优势被认为极具应用前景,其中以轻质元素构成的氢化物(包括硼氢化物/铝氢化物(可用通式A(MH4)n表示,其中A是碱金属(Li,Na,K)或碱土金属(Be,Mg,Ca);M是硼或铝;n=1～4)、氨基氢化物(如LiNH2等))、氨硼烷(NH3BH3)、金属有机骨架材料(MOFs)是新型储氢材料研究领域的热点,本文将着重就目前这几类储氢材料的研究当中所涉及到的一些热力学及动力学问题进行总结探讨.     

纳米结构储氢材料的计算研究与设计

对B原子掺杂的石墨烯、碳纳米管和富勒烯、MB2纳米管和ca表面覆盖的纳米管体系的氢气吸附和存储性能进行了第一原理计算,结果表明在表面曲率比较大的碳材料体系中掺B可以增强其对H2的吸附作用;过渡金属原子与H2由于Kubas作用而表现出很大的H2吸附能;碱土金属Ca离子化后的带电电荷的材料体系,由于与H2发生极化作用,也会增强氢气的吸附性能．综合我们的结果和储氢材料研究的最新进展,讨论了影响储氢材料性能的相关因素,就如何增强材料与H2之间的相互作用,使H2吸附能在0．2～0．4eV之间,能够在温和的条件下吸／放氢,并且具有较大的重量和体积储氢量等问题作了简要论述,这些原理对纳米结构储氢材料的设计有一定的指导意义．     

h-BN负载纳米NbH对LiBH_4放氢性能的协同改性作用

制备了h-BN负载纳米NbH改性剂(NbH@h-BN),并采用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)以及X射线能谱(EDS)等测试手段对其进行表征,分析了NbH@h-BN对LiBH_4放氢反应的掺杂改性作用及机理.结果表明:经NbH@h-BN掺杂改性后,LiBH_4的放氢峰值温度和表观活化能分别降低至380℃和142.31kJ/mol,放氢动力学性能也得到大幅改善.分析认为:NbH@h-BN具备协同改性LiBH_4的放氢性能是因为NbH@h-BN可以生成稳定的粒径为5~10nm的NbH颗粒,并且可以避免纳米NbH在掺杂改性过程和放氢过程中发生团聚,能够充分发挥纳米NbH和h-BN各自的改性作用.     

Li-Mg-N-H体系储氢材料的热力学和动力学调控

Mg（NH₂）₂-2LiH体系储氢材料具有较高的储氢容量和较适宜的热力学性能,并且其吸放氢过程完全可逆,是目前最有望实现大规模应用的固态储氢材料之一。然而,由于该体系在吸放氢过程中具有较高的动力学壁垒,导致其在200℃以上才能实现快速地吸放氢。因此,国际上对该体系储氢材料的研究主要集中在热力学和动力学的调控方面。本文从成分调变、纳米化和掺杂改性等方面,详细综述了Mg（NH₂）₂-2LiH体系储氢材料热力学和动力学调控的研究现状,并提出了其中存在的问题和相应对策,同时指出了将来的研究方向。     

纳米镁储氢材料吸放氢动力学性能的研究进展

综述近十年来国内外有关纳米镁储氢材料吸放氢动力学的研究现状和发展趋势.众多研究表明,应用高能球磨法制备纳米镁复合储氢材料,并以过渡金属氧化物为催化剂,或者用ABx型储氢合金与镁复合,都能显著改善镁的吸放氢动力学性能.     

储氢材料的研究与进展

本文详细介绍了氢作为一种洁净二次能源载体的优点及发展潜力，综合描述了金属储氢材料、矿物多孔储氢材料、有机液态储氢材料的储氢特性及最新研究状况。最后就储氢材料的发展提出自己的见解。     

纳米储氢合金

作为一种新型的清洁能源,氢能在日益严峻的能源危机中越来越重要。纳米储氢合金因其优异的性能,被认为是下一代重要的储氢材料。本文介绍了储氢合金的原理、储氢合金的动力学和热力学以及各种储氢材料性能。基于储氢合金的最新研究进展,本文综述了提高纳米合金储氢性能的措施、纳米储氢合金的制备方法及其优缺点,进一步探讨了影响纳米合金储氢性能的因素,对储氢合金的进一步发展进行了展望。     

储氢材料的研究与进展

本文详细介绍了氢作为一种洁净二次能源载体的优点及发展潜力,综合描述了金属储氢材料、矿物多孔储氢材料、有机液态储氢材料的储氢特性及最新研究状况.最后就储氢材料的发展提出自己的见解.     

硼氢化钠催化水解制氢*

硼氢化钠（NaBH₄）催化水解制氢是一项具备车载氢源应用前景的储氢/制氢一体化技术。本文介绍了该技术催化水解制氢的原理,综述了制氢催化剂、反应动力学、反应机理、反应装置的设计和反应副产物回收利用的最新研究进展,讨论了该技术研发中需解决的问题。水解制氢系统的实际应用需研发高效、耐久性负载型催化剂。制氢装置的设计应考虑反应热的综合利用、燃料电池产生的水循环利用及膜分离技术的应用。NaBH4的高效再生将降低其生产成本,实现NaBH4基水解制氢系统的商业化应用。     

金属硼氢化物基固态储氢体系

氢气储存仍是制约氢经济推行的关键问题,开发一种高效、安全的储氢技术仍面临着巨大挑战。近年来,利用固态氢化物的化学吸附储氢技术由于可靠、结构紧密和高储氢容量的特点,被视为最有潜力的储氢手段之一。在众多固态氢化物储氢材料中,金属硼氢化物由于其极高的重量和体积储氢密度而备受关注。然而,金属硼氢化物热力学稳定,动力学缓慢,导致其吸/放氢温度高、速率慢、可逆性及循环稳定性差。本文从替代、复合、掺杂、纳米结构限域及相应的反应机理等角度总结了金属硼氢化物储氢材料的最新改性研究和应用,并提出了其中存在的问题和相应对策,同时指出了未来的研究方向。     

Fe_2O_3-Modified Hydrogen Storage Alloys as Electrocatalyst for Borohydride Oxidation

The effects of hot alkaline treatment and Fe₂O₃ modification of hydrogen storage alloy on the electrocatalytic activity for oxidation of borohydride have been investigated using linear sweep voltammetry. The performance of borohydride electrochemical oxidation was significantly influenced by the hot alkaline treatment and Fe₂O₃ modification of the hydrogen storage alloy. The results showed that the current density of the Fe₂O₃‐modified hot alkaline‐treated hydrogen storage alloy electrode containing 5 wt% Fe₂O₃ reached 125 mA·cm^?2 in 0.10 mol·L^?1 NaBH₄ and 2 mol·L^?1 NaOH solution at ?0.55 V vs. saturated Ag/AgCl, KCl electrode.     

Thermodynamics of Electrochemical Lithium Storage

The thermodynamics of electrochemical lithium storage are examined by taking into account that it is the point defects that enable storage. While the Li defects are mobile, most of the other point defects have to be considered as frozen owing to the performance temperature being low compared to the melting point of the electrode materials. The defect chemistry needs to be considered to fully understand equilibrium charge/discharge curves. On this basis, single phase and multiphase storage mechanisms can be discussed in terms of theoretical storage capacity and theoretical voltage. Of paramount interest in the field of Li batteries are metastable materials, in particular nanocrystalline and amorphous materials. The thermodynamics of storage and voltage, also at interfaces, thus deserve a special treatment. The relationship between reversible cell voltage and lithium content is derived for the novel job‐sharing mechanism. With respect to the classic storage modes, thermodynamic differences for cathodes and anodes are elaborated with a special attention being paid to the search for new materials. As this contribution concentrates on the equilibrium state, current‐related phenomena (irreversible thermodynamics) are only briefly touched upon.     

Synergetic Effects of In Situ Formed CaH2 and LiBH4 on Hydrogen Storage Properties of the Li–Mg–N–H System

Hydrogen storage properties and mechanisms of the Ca(BH₄)₂‐doped Mg(NH₂)₂–2 LiH system are systematically investigated. It is found that a metathesis reaction between Ca(BH₄)₂ and LiH readily occurs to yield CaH₂ and LiBH₄ during ball milling. The Mg(NH₂)₂–2 LiH–0.1 Ca(BH₄)₂ composite exhibits optimal hydrogen storage properties as it can reversibly store more than 4.5 wt % of H₂ with an onset temperature of about 90 °C for dehydrogenation and 60 °C for rehydrogenation. Isothermal measurements show that approximately 4.0 wt % of H₂ is rapidly desorbed from the Mg(NH₂)₂–2 LiH–0.1 Ca(BH₄)₂ composite within 100 minutes at 140 °C, and rehydrogenation can be completed within 140 minutes at 105 °C and 100 bar H₂. In comparison with the pristine sample, the apparent activation energy and the reaction enthalpy change for dehydrogenation of the Mg(NH₂)₂–2 LiH–0.1 Ca(BH₄)₂ composite are decreased by about 16.5 % and 28.1 %, respectively, and thus are responsible for the lower operating temperature and the faster dehydrogenation/hydrogenation kinetics. The fact that the hydrogen storage performances of the Ca(BH₄)₂‐doped sample are superior to the individually CaH₂‐ or LiBH₄‐doped samples suggests that the in situ formed CaH₂ and LiBH₄ provide a synergetic effect on improving the hydrogen storage properties of the Mg(NH₂)₂–2 LiH system.     

硼氢化钠水解制氢

质子交换膜燃料电池技术的迅速发展大大促进了对氢的廉价制取和高效储存的研究。作为一种安全、方便的新型制氢技术,硼氢化钠水解制氢成为当前燃料电池氢源研究中的热点课题之一。本文介绍了硼氢化钠制氢原理,综述了硼氢化钠水解催化剂和反应动力学研究进展,并对硼氢化钠制氢技术实用化前景进行了展望。     

Local Disorder in Hydrogen Storage Compounds: The Case of Lithium Amide/Imide

Amides and imides of alkali metals are a very promising class of materials for use as a hydrogen‐storage system, as they are able to store and release hydrogen via a chemical route at controllable temperatures and pressures. We critically revise the present picture of the atomic structure of the lightest member (LiNH₂/Li₂NH) by using a combined computational and experimental approach. Specifically, ab initio path integral molecular dynamics simulations and solid‐state ¹H NMR techniques are combined. The results show that the presently assumed local structure might be inconsistent or at least incomplete and needs considerable revision. In particular, the Li atoms turn out to be more mobile and more disordered than suggested by structural data obtained from X‐ray scattering. Also, the configuration of the hydrogen atoms, which is accessible via the NMR experiment and the corresponding first‐principles calculations, is different from the previously assumed data. The computed and experimentally observed ¹H NMR parameters are in very good mutual agreement and illustrate the unusual chemical environment of the hydrogen atoms in this system. Incorporating our results on the new lithium data, we show that the effect of nuclear quantum delocalization for the hydrogen atoms is considerably reduced compared to the perfect crystal structure.     

Improved Dehydrogenation Properties of LiBH4 Using Catalytic Nickel‐ and Cobalt‐based Mesoporous Oxide Nanorods

Lithium borohydride (LiBH₄) with a theoretical hydrogen storage capacity of 18.5 wt % has attracted intense interest as a high‐density hydrogen storage material. However, high dehydrogenation temperatures and limited kinetics restrict its practical applications. In this study, mesoporous nickel‐ and cobalt‐based oxide nanorods (NiCo₂O₄, Co₃O₄ and NiO) were synthesized in a controlled manner by using a hydrothermal method and then mixed with LiBH₄ by ball milling. It is found that the dehydrogenation properties of LiBH₄ are remarkably enhanced by doping the as‐synthesized metal oxide nanorods. When the mass ratio of LiBH₄ and oxides is 1:1, the NiCo₂O₄ nanorods display the best catalytic performance owing to the mesoporous rod‐like structure and synergistic effect of nickel and cobalt active species. The initial hydrogen desorption temperature of the LiBH₄‐NiCo₂O₄ composite decreases to 80 °C, which is 220 °C lower than that of pure LiBH₄, and 16.1 wt % H₂ is released at 500 °C for the LiBH₄‐NiCo₂O₄ composite. Meanwhile, the composite also exhibits superior dehydrogenation kinetics, which liberates 5.7 wt % H₂ within 60 s and a total of 12 wt % H₂ after 5 h at 400 °C. In comparison, pure LiBH₄ releases only 5.3 wt % H₂ under the same conditions.