物理化学学报 >> 2018, Vol. 34 >> Issue (3): 286-295.doi: 10.3866/PKU.WHXB201708172

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嵌入配位不饱和金属位对多孔芳香骨架材料储氢性能的影响

吴选军1,2,*(),李磊1,彭亮1,王叶彤1,蔡卫权1,3,*()   

  1. 1 武汉理工大学化学化工与生命科学学院,武汉 430070
    2 新加坡国立大学化学与生物分子工程系,新加坡 117576
    3 广州大学化学化工学院,广州 510006
  • 收稿日期:2017-07-04 发布日期:2017-12-18
  • 通讯作者: 吴选军,蔡卫权 E-mail:wuxuanjun@whut.edu.cn;caiwq@whut.edu.cn
  • 基金资助:
    国家自然科学基金(51272201, 21476179);国家留学基金委([2016]3099);中央高校基本科研业务费(175220002);2016年武汉市黄鹤英才(科技)计划

Effect of Coordinatively Unsaturated Metal Sites in Porous Aromatic Frameworks on Hydrogen Storage Capacity

Xuanjun WU1,2,*(),Lei LI1,Liang PENG1,Yetong WANG1,Weiquan CAI1,3,*()   

  1. 1 School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, P. R. China
    2 Department of Chemical and Biomolecular Engineering, National University of Singapore 117576, Singapore
    3 School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
  • Received:2017-07-04 Published:2017-12-18
  • Contact: Xuanjun WU,Weiquan CAI E-mail:wuxuanjun@whut.edu.cn;caiwq@whut.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(51272201, 21476179);the China Scholarship Council for the Scholarship Support([2016]3099);the Fundamental Research Funds for the Central Universities(175220002);2016 Wuhan Yellow Crane Talents (Science) Program

摘要:

基于密度泛函理论(DFT)和巨正则蒙特卡洛(GCMC)模拟方法,系统地研究了引入配位不饱和金属位(CUS)对PAF-30n (n = 1–4)材料储氢性能影响的规律。结果表明,77 K下PAF-302MgO2_PBE100的最大过量质量储氢量达到7.97% (w);77 K、10 MPa下100%醇镁功能化改性PAF-302和PAF-303的绝对储氢量分别达到9.9% (w) (65.9 g∙L-1)和15.0% (w) (50.5 g∙L-1),分别超过美国能源部(DOE)标准80% (64.8%)和173% (26.3%),均超过在相同条件下目前储氢性能最佳的NU-1101 (9.1% (w), 46.6 g∙L-1)。即使在243 K、10 MPa下,其绝对质量和绝对体积储氢量也能分别达到5.13% (w)和34.19 g∙L-1,占DOE质量与体积储氢标准的93.3%和85.5%,是目前为止常温储氢性能较为均衡的多孔材料之一。结合等量吸附热(Qst)、径向分布函数(RDF)和质心几率密度分布(MCPD)方法进一步分析,发现有机链长度增加导致孔隙率增加和体积比表面积减小,是引起多孔材料绝对质量和绝对体积储氢量此消彼长的根本原因。另外,引入CUS能提高PAFs材料对H2分子亲和力,显著增强其体积储氢量。

关键词: 多孔芳香骨架材料, 配位不饱和金属位, 储氢, 分子模拟, 巨正则蒙特卡洛模拟

Abstract:

The effect of inserting coordinatively unsaturated metal sites (CUS) into porous aromatic frameworks (PAFs) on their hydrogen storage capacity was investigated systematically by density functional theory and grand canonical Monte Carlo simulations. The results indicate that the maximum excess gravimetric uptake of hydrogen possible with PAF-302MgO2_PBE100 is 7.97% (w) at 77 K. The total uptakes of hydrogen by PAF-302 and PAF-303 functionalized with 100% magnesium alkoxide at 77 K and 10 MPa were determined to be 9.9% (w) (65.9 g∙L-1) and 15.0% (w) (50.5 g∙L-1), respectively. These uptake values are 80% (64.8%) and 173% (26.3%), respectively, more than the gravimetric and volumetric targets set by the Department of Energy (DOE) of USA. They also exceed the targets set by NU-1101, presenting the highest measured performance of 9.9% (w) (46.6 g∙L-1) under the same conditions. Even at 243 K and 10 MPa, the total gravimetric and volumetric uptakes of hydrogen in the former are up to 5.13% (w) and 34.19 g∙L-1, which are about 93.3% and 85.5% of the targets set by DOE, respectively. By analyzing the isosteric heat of adsorption (Qst), radial distribution function, and mass center probability density, it is found that increasing the length of the organic linkers of PAFs incorporated with CUS will result in decreasing volumetric surface areas in spite of the increase in void fractions, which is the root of trade-offs between the total gravimetric and volumetric H2 uptake in porous materials. Additionally, CUS incorporation improves the affinity of PAF materials to H2 molecules, resulting in an enhancement of the volumetric hydrogen storage capacity.

Key words: Porous aromatic framework, CUS, Hydrogen storage, Molecular adsorption, GCMC simulation

MSC2000: 

  • O641