[and all we’ve been worried about is nanotech, DNA labs, and AI]
SKOLKOVO INSTITUTE OF SCIENCE AND TECHNOLOGY (SKOLTECH)
Research news
PICTURE: A NOVEL HYDROGEN CLATHRATE HYDRATE show more CREDIT: PAVEL ODINEV / SKOLTECH
Scientists from the USA, China and Russia have described the structure and properties of a novel hydrogen clathrate hydrate that forms at room temperature and relatively low pressure. Hydrogen hydrates are one possible solution for storing and transporting hydrogen, the most environmentally friendly fuel. The research was published in the journal Physical Review Letters.
Ice is a highly complex substance with several polymorphic modifications, the number of which increases as scientists make discoveries. The physical properties of ice also vary widely: for example, hydrogen bonds become symmetrical at high pressures, making it impossible to distinguish a single water molecule, while low pressures cause proton perturbation and bring water molecules into many possible spatial orientations within the crystal structure. The ice around us, including the snowflakes, is always proton disrupted. Ice can contain xenon, chlorine, carbon dioxide or methane molecules and form gas hydrates, which often have a different structure than pure ice. Most of the earth’s natural gas is in the form of gas hydrates.
In their new study, chemists from the United States, China, and Russia focused on hydrogen hydrates. Gas hydrates are of great interest both for theoretical research and for practical applications such as the storage of hydrogen. When hydrogen is stored in its natural form, there is a risk of explosion, while the density is far too low even in compressed hydrogen. That is why scientists are looking for cost-effective hydrogen storage solutions.
“This isn’t the first time we’ve turned to hydrogen hydrates. In our previous research, we predicted a new hydrogen hydrate with 2 hydrogen molecules per water molecule. Unfortunately, this extraordinary hydrate can only exist at pressures above 380,000 atmospheres, which is easy to achieve in the laboratory, but is hardly usable in practical applications. Our new paper describes hydrates that contain less hydrogen but can exist at much lower pressures, ”says Skoltech professor Artem R. Oganov.
The crystal structure of hydrogen hydrates strongly depends on the pressure. At low pressures, it has large cavities, which Oganov says resemble Chinese lanterns, each of which holds hydrogen molecules. As the pressure increases, the structure becomes denser, with more hydrogen molecules being packed into the crystal structure, although their degrees of freedom become significantly less.
In their research published in the Physical Review Letters, scientists from the Carnegie Institution of Washington (USA) and the Institute of Solid State Physics in Hefei (China), led by Alexander F. Goncharov, professor at these two institutions, conducted experiments to investigate the properties various hydrogen hydrates and discovered an unusual hydrate with 3 water molecules per hydrogen molecule. The team led by Professor Oganov used the USPEX evolution algorithm developed by Oganov and his students to figure out the structure of the compound responsible for their peculiar behavior. The researchers simulated the experimental conditions and found a new structure that is very similar to the well-known proton-ordered C1 hydrate, but differs from C1 in the orientation of the water molecules. The team showed that proton perturbation should occur at room temperature, which explains the X-ray diffraction and Raman spectrum data obtained in the experiment.
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From EurekAlert!
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