Ultra-dense packing of hydrogen molecules on the surface

nature chemistry (2022). DOI: 10.1038 / s41557-022-01019-7″ width=”685″ height=”335″/>

attributed to him: nature chemistry (2022). DOI: 10.1038 / s41557-022-01019-7

Hydrogen (H2) currently as an ideal energy carrier for renewable energies. Hydrogen has the highest gravitational energy density of all chemical fuels (141 MJ / kg), which is three times higher than that of gasoline (46 MJ / kg). However, its low volumetric density restricts its wide use in transportation applications – where current storage options require a significant amount of space.

in ambient temperatureHydrogen is a gas, and one kilogram of hydrogen occupies a volume of 12,000 liters (12 cubic metres). In fuel cell vehicles, hydrogen is stored under very high pressures of up to 700 times Atmospheric pressurereducing the volume to 25 liters per kilogram of H2. Liquid hydrogen exhibits a higher density resulting in 14 liters per kilogram, but requires very low temperatures since boiling point of hydrogen at minus 253 degrees Celsius.

Now, a team of scientists from the Max Planck Institute for Intelligent Systems, Technical University of Dresden, Friedrich Alexander, University of Erlangen-Nuremberg, and Oak Ridge National Laboratory has shown that hydrogen condenses on a surface at a very low temperature near H2 Boiling point, the formation of a super-dense monolayer exceeding the density liquid hydrogen almost tripled, reducing the volume to just 5 liters per kilogram of hydrogen2.

The surprising result was that twice the number of H2 Molecules of the noble gas argon atoms covered the surface, although they are both about the same size. To double the number of molecules in each region, H2 The particles are tightly compressed together, forming a super-dense layer.

The study by R. Balderas-Xicohténcatl et al. High-resolution cryo-adsorption experiments included highly ordered medium pore silica which exhibits well-defined porosity and surface properties to determine the number of condensed particles on the surface of the material.

Inelastic neutron scattering is an ideal tool for following the formation of a two-dimensional hydrogen layer. For the first time, the presence of this super-dense hydrogen has been confirmed at the site. this is direct observation It was only possible with VISION’s High Resolution Vibrational Neutron Spectrometer, which has an inelastic counting rate over 100 times that of any similar available spectrophotometer.

Theoretical studies confirm experimental observations of the unusually high hydrogen density in the absorbing layer. The attractive forces at the surface were stronger than the intermolecular repulsion of hydrogen which resulted in the packing of ultra-dense hydrogen on the surface of the mesoporous silica. The super density is a result of the high compressibility of hydrogen, which has no core electrons.

The formation of the super-dense hydrogen layer at lower temperatures near the boiling point is of fundamental importance. It should be considered for quantitative analysis from H.2 Isoporous at 20 K. It may also open up new possibilities to enhance the volumetric capacity of cryogenic hydrogen storage systems for many applications in the upcoming hydrogen economy.

The search was published in nature chemistry.

Paving the way for more efficient hydrogen cars

more information:
Rafael Balderas-Xicohténcatl et al, Formation of a super-dense hydrogen monolayer on mesoporous silica, nature chemistry (2022). DOI: 10.1038 / s41557-022-01019-7

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