Jun 2011, Volume 6 Issue 2
    

Cover illustration

  • Hydrogen has been considered the best substitute for fossil fuels in future, as it is clean and renewable. Currently, one of the main obstacles of hydrogen economy is the efficient storage, which should have high gravimetric and volumetric density, fast kinetics. However, no existing materials meet all the industry requirements. The interactions between hydrogen and materials are either too weak in physical adsorption or too strong in chemical adsorption. The rational design [Detail] ...


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  • EDITORIAL
    Jun-lin YANG, Qiang SUN
  • REVIEW ARTICLE
    Feng DING, Boris I. YAKOBSON

    In this short review, we will briefly discuss the story of hydrogen storage, its impact on clean energy application, especially the challenges of using hydrogen adsorption for onboard application. After a short comparison of the main methods of hydrogen storage (high pressure tank, metal hydride and adsorption), we will focus our discussion on adsorption of hydrogen in graphitic carbon based large surface area adsorbents including carbon nanotubes, graphene and metal organic frameworks. The mechanisms, advantages, disadvantages and recent progresses will be discussed and reviewed for physisorption, metal-assisted storage and chemisorption. In the last section, we will discuss hydrogen spillover chemisorption in detail for the mechanism, status, challenges and perspectives. We hope to present a clear picture of the present technologies, challenges and the perspectives of hydrogen storage for the future studies.

  • REVIEW ARTICLE
    Li-fang SONG (宋莉芳), Chun-hong JIANG (姜春红), Shu-sheng LIU (刘淑生), Cheng-li JIAO (焦成丽), Xiao-liang SI (司晓亮), Shuang WANG (王爽), Fen LI (李芬), Jian ZHANG (张箭), Li-xian SUN (孙立贤), Fen XU (徐芬), Feng-lei HUANG (黄风雷)

    Hydrogen storage material has been much developed recently because of its potential for proton exchange membrane (PEM) fuel cell applications. A successful solid-state reversible storage material should meet the requirements of high storage capacity, suitable thermodynamic properties, and fast adsorption and desorption kinetics. Complex hydrides, including boron hydride and alanate, ammonia borane, metal organic frameworks (MOFs), covalent organic frameworks (COFs) and zeolitic imidazolate frameworks (ZIFs), are remarkable hydrogen storage materials because of their advantages of high energy density and safety. This feature article focuses mainly on the thermodynamics and kinetics of these hydrogen storage materials in the past few years.

  • REVIEW ARTICLE
    Zhi-wei ZHANG (张志伟), Jian-chen LI (李建忱), Qing JIANG (蒋青)

    This review covers structural, electronic, and hydrogen storage properties of carbon-based materials with doped metals under electric fields with different orientations and intensities, which are determined by density functional theory (DFT) simulations. The special application case is considered in investigating variations of electronic structures, binding, and hydrogen storage properties. External fields that are often met in practical applications lead to changes of the above properties.

  • REVIEW ARTICLE
    Fu-qiang HUANG, Chong-yin YANG, Dong-yun WAN

    As one of the most promising solutions for the green energy, thin-film photovoltaic cell technology is still immature and far from large-scale industrialization. The major issue is getting low cost and stable module efficiency. To solve these problems, a large amount of advanced solar materials have been developed to improve all parts of solar cell modules. Here, some new solar material developments applied in different critical parts of chalcogenide thin-film photovoltaic cells are reviewed. The main efforts are focused on improving light trapping and antireflection, internal quantum efficiency and collection of photo-generated carriers.

  • REVIEW ARTICLE
    Di-hua WU (吴迪华), Zhen ZHOU (周震)

    Computations have been widely used to explore new Li ion battery materials because of its remarkable advantages. In this review, we summarize the recent progress on computational investigation on anode materials in Li ion batteries. By introducing the computational studies on Li storage capability in carbon nanotubes, graphene, alloys and oxides, we reveal that computations have successfully addressed many fundamental problems and are powerful tools to understand and design new anode materials for Li ion batteries.

  • RESEARCH ARTICLE
    Sa LI, Hong-min ZHAO, Puru JENA

    Clustering of Ti on carbon nanostructures has proved to be an obstacle in their use as hydrogen storagematerials. Using density functional theory we show that Ti atoms will not cluster at moderate concentrations when doped into nanoporous graphene. Since each Ti atom can bind up to three hydrogen molecules with an average binding energy of 0.54 eV/H2, this material can be ideal for storing hydrogen under ambient thermodynamic conditions. In addition, nanoporous graphene is magnetic with or without Ti doping, but when it is fully saturated with hydrogen, the magnetism disappears. This novel feature suggests that nanoporous graphene cannot only be used for storing hydrogen, but also as a hydrogen sensor.

  • RESEARCH ARTICLE
    Jian WANG, Guang-bo CHE, Qing-wei WANG, Wan-xi ZHANG, Li-min WANG

    The Ti0.9Zr0.1V0.2Ni1.5La0.5 alloy samples were synthesized by melt-spinning technique at the different wheel velocity (cooling rate), and the structure and electrochemical hydrogen storage properties were investigated. The result indicated that the structure of the melt-spun ribbons mainly contains C14 Laves phase and V-based solid solution phase. The discharge capacity, cyclic stability, high-rate discharge ability and electrochemical kinetic of the alloy electrodes are correlated with the cooling rate (wheel velocity), and the maximum discharge capacity is over 200 mA·h/g at the wheel velocity of 20 m/s.

  • RESEARCH ARTICLE
    Fen LI, Ji-jun ZHAO, Li-xian SUN

    The hydrogen storage behavior of the TiCr2 and ZrCr2 alloys substituted with the third components (Zr, V, Fe, Ni) have been studied using first-principles calculations. The change of the hydrogen absorption energies caused by metal doping is arising from the charge transfer among the doped alloys interior. Zr and V atoms devoted abundant electrons, leading to a great enhancement of the H absorption energy, while Fe and Ni atoms always accepted electrons, yielding a remarkable decrease of the H absorption energy. The hydrogen diffusion energy barrier is closely correlated with the geometry effect rather than the electronic structure.

  • RESEARCH ARTICLE
    Xiao ZHOU (周啸), Jian ZHOU (周健), Kun Lü (吕坤), Qiang SUN (孙强)

    The key to hydrogen storage is to design new materials with light mass, large surface and rich adsorption sites. Based on the recent experimental success in synthesizing tripyrrylmethane, we have explored Ti-tripyrrylmethane based 2D porous structure for hydrogen storage using density functional theory. We have found that the structure is stable, and the exposed Ti sites can bind three hydrogen molecules with an average binding energy of 0.175 eV/H2, which lies in the energy window for storage and release of hydrogen in room temperature and at the ambient pressure.

  • RESEARCH ARTICLE
    Ming LI (李明), Ya-fei LI (李亚飞), Zhen ZHOU (周震), Pan-wen SHEN (申泮文)

    Density functional theory computations were performed to investigate hydrogen adsorption in metaldecorated defective BN nanosheets. The binding energies of Ca and Sc on pristine BN nanosheets are much lower than the corresponding cohesive energies of the bulk metals; however, B vacancies in BN nanosheets enhance the binding of Ca and Sc atoms dramatically and avoid the clustering of the metal atoms on the surface of BN nanosheets. Ca and Sc strongly bind to defective BN nanosheets due to charge transfer between metal atoms and BN nanosheets. Sc-decorated BN nanosheets with B vacancies demonstrate promising hydrogen adsorption performances with a hydrogen adsorption energy of -0.19~ -0.35 eV/H2.

  • RESEARCH ARTICLE
    Hong ZHANG, Xiao-dong LI, Yong-jian TANG

    The interactions of dihydrogen with lithium containing organic complexes C4H4-mLim and C5H5-mLim (m = 1, 2) were studied by means of density functional theory (DFT) calculation. For all the complexes considered, each bonded lithium atom can adsorb up to five H2 molecules with the mean binding energy of 0.59 eV/H2 molecule. The interactions can be attributed to the charge transfer from the H2 bonding orbitals to the Li 2s orbitals. The kinetic stability of these hydrogen-covered organolithium molecules is discussed in terms of the energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). The results indicate that these organiclithium structures can perhaps be used as building units for potential hydrogen storage materials.