Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (11): 2043-2054.doi: 10.3866/PKU.WHXB201409222

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

Simulation on the Hydrogen Storage Properties of New Doping Porous Aromatic Frameworks

WU Xuan-Jun1, ZHAO Peng1, FANG Ji-Min2, WANG Jie2, LIU Bao-Shun3, CAI Wei-Quan1,3   

  1. 1. School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, P. R. China;
    2. College of Natural Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, P. R. China;
    3. State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, P. R. China
  • Received:2014-07-31 Revised:2014-09-22 Published:2014-10-30
  • Contact: WU Xuan-Jun, CAI Wei-Quan E-mail:wuxuanjun@whut.edu.cn;caiwq@whut.edu.cn
  • Supported by:

    The project was supported by the Natural Science Foundation of Hubei Province, China (2013CFB344), National Natural Science Foundation of China (51272201), Program for New Century Excellent Talents in University of the Ministry of Education, China (NCET-13-0942), and Fundamental Research Funds for the Central Universities ofWuhan University of Technology, China (2013-II-014, 201410497039).

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Abstract:

Several new porous aromatic frameworks (PAFs) were designed by Li doping or B substitution based on the PAF-301 molecular model. The hydrogen storage capacities of these materials were investigated using quantum mechanics and molecular mechanics methods. First, the binding energies between H2 and the different molecular fragments were calculated using quantum mechanics, and the atomic charge distributions of the molecular fragments were calculated by the density-derived electrostatic and chemical charge (DDEC) method. Then, the adsorption equilibrium properties of H2 on the different PAFs were calculated at 77 and 298 K using grand canonical Monte Carlo (GCMC) simulations. The results indicate that the binding energy between H2 and benzene without Li doping is poor, while the binding energies between H2 and Li-doped six-member rings are improved. Li atoms doped into the benzene ring result in higher positive charges, and the electronegativity of the original carbon atoms in the benzene ring increase after its two carbon atoms are replaced with two boron atoms. Among these new materials, PAF-301Li has the highest hydrogen storage capacity at 77 K, while PAF-C4B2H4-Li2-Si and PAF-C4B2H4-Li2-Ge have better hydrogen storage capacities at room temperature than at 77 K. However, the hydrogen storage capacities of these various materials at room temperature are far below the capacities at cryogenic temperature. The preferential adsorption sites for H2 on the PAFs at 77 K were analyzed through the potential energy surfaces and mass center density distribution of the adsorption equilibrium. It was found that there are four obvious high-density adsorption regions in the frameworks of PAF-301 and PAF-301Li because of their wide low-energy regions in the crystal center, while there are only two distinct high-density adsorption regions in the other three PAFs because of their narrow low-energy regions in the unit cell center.

Key words: Porous aromatic framework, Doping, Hydrogen storage, Atomic charge, Molecular simulation

MSC2000: 

  • O641