Nanoporous materials have attracted great attention for gas storage, but achieving high volumetric storage capacity remains a challenge. Here, by using neutron powder diffraction, volumetric gas adsorption, inelastic neutron scattering and first-principles calculations, we investigate a magnesium borohydride framework that has small pores and a partially negatively charged non-flat interior for hydrogen and nitrogen uptake. Hydrogen and nitrogen occupy distinctly different adsorption sites in the pores, with very different limiting capacities of 2.33 H₂ and 0.66 N₂ per Mg(BH₄)₂. Molecular hydrogen is packed extremely densely, with about twice the density of liquid hydrogen (144 g H₂ per litre of pore volume). We found a penta-dihydrogen cluster where H₂ molecules in one position have rotational freedom, whereas H₂ molecules in another position have a well-defined orientation and a directional interaction with the framework. This study reveals that densely packed hydrogen can be stabilized in small-pore materials at ambient pressures.

纳米多孔材料在气体储存方面引起了极大的关注，但实现高体积储存容量仍然是一个挑战。在这里，通过使用中子粉末衍射、体积气体吸附、非弹性中子散射和第一原理计算，我们研究了具有小孔和部分带负电的非平坦内部的硼氢化镁框架，用于吸收氢和氮。氢和氮在孔隙中占据明显不同的吸附位点，其极限容量差异很大，为每Mg(BH ₄ ) _{2 2.33 H 2}和0.66 N ₂。氢分子堆积极其致密，密度约为液态氢的两倍（每升孔体积144 g H ₂ ）。我们发现了一个五二氢簇，其中一个位置的 H ₂分子具有旋转自由度，而另一位置的 H ₂分子具有明确的方向以及与框架的定向相互作用。这项研究表明，在环境压力下，密集的氢可以稳定在小孔材料中。