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What compounds or nanostructures contain the most hydrogen atoms per unit of volume in realistic conditions (under 1 GPa). Particularly boron-free compounds because it's to be used in sci-fi nuclear designs.


What I've investigated so far:

  • Zirconium Tetrahydride (0.229 mol/ml, unstable?)
  • Thorium tetrahydride?
  • Ammonium Borohydride (~0.176 mol/ml, unstable?)
  • Aluminum Borohydride (~0.175 mol/ml)
  • Borazane (0.152 mol/ml)
  • Aluminum Hydride (0.148 mol/ml)
  • Tetramethylammonium Borohydride (0.146 mol/ml)
  • Solid Ammonia (0.144 mol/ml)
  • Solid Hydrazine (0.143 mol/ml)
  • Uranium Hydride (0.136 mol/ml)
  • Paraffin Wax (0.131 mol/ml)
  • Liquid Cyclopropane (0.128 mol/ml)
  • Tetramethylammonium Chloride (0.128 mol/ml)
  • Beryllium Borohydride (0.125 mol/ml)
  • Lithium Borohydride (0.122 mol/ml)
  • Liquid Ammonia (0.120 mol/ml)
  • Beryllium hydride (0.118 mol/ml)
  • Sodium Borohydride (0.113 mol/ml)
  • Magnesium hydride (0.112 mol/ml)
  • Water (0.111 mol/ml)
  • Cyclohexane (0.111 mol/ml)
  • Neopentyl alcohol (0.111 mol/ml)
  • liquid ethane (0.109 mol/ml)
  • ammonium fluoride (0.109 mol/ml)
  • Hexane (0.106 mol/ml)
  • Neopentane (0.104 mol/ml)
  • liquid methane (0.105 mol/ml)
  • ethanol (0.103 mol/ml)
  • liquid cubane (0.099 mol/ml)
  • lithium hydride (0.098 mol/ml)
  • lithium aluminum hydride (0.097 mol/ml)
  • liquid propane (0.091 mol/ml)
  • Solid hydrogen (0.087 mol/ml)
  • Liquid hydrogen (0.070 mol/ml)
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  • 2
    $\begingroup$ Just my two cents. I guess you already looked these compounds up, but in "Sustainable Energy Systems and Applications", 2011, is written: "The ammonia-boron compound with chemical formula NH4BH4 appears to be the most “dense” hydrogen storage. " $\endgroup$ – The_Vinz Feb 4 '17 at 11:07
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    $\begingroup$ Zirconium hydride (e.g. $\ce{ZrH}$ or $\ce{ZrH_{1.65}}$, but not $\ce{ZrH4}$) is actually used in some nuclear reactors because of its unusual moderating properties. $\endgroup$ – Faded Giant Feb 4 '17 at 14:57
  • $\begingroup$ As an aside, if you're looking for non-chemisorbed (i.e. the $\ce{H/H2}$ is not bonded to the material), Metal-Organic Frameworks (MOFs) have some of the highest uptakes of the gas -- achieving near-liquid density. NOTT-112 gets ~0.058mol/mL at 77K/60atm if you count the H in the MOF. Obviously not even comparable to bonded H. $\endgroup$ – khaverim Feb 4 '17 at 16:43
  • $\begingroup$ Interesting article about storage in palladium nature.com/nmat/journal/v13/n8/full/… $\endgroup$ – JSCoder says Reinstate Monica Sep 4 '17 at 15:11
  • $\begingroup$ Since it's sf, maybe you can imagine someone figured out a way to keep muons from decaying, in which case muonic H atoms have a radius 200x smaller than regular H atoms, so muonic H2 ought to be about 10^7 times denser than ordinary H2. $\endgroup$ – Christopher Grayce Jun 14 '18 at 5:48