Although predicted in 1935, making metallic hydrogen has proved to be extremely difficult in practice. Researchers have tried to create it in the lab by squeezing tiny samples of hydrogen gas between the tips of two diamonds. These miniature anvils can deliver pressures of hundreds of gigapascals, but the results have often been unclear.
Researchers from the CEA (The French Alternative Energies and Atomic Energy Commission) and the French synchrotron radiation centre, SOLEIL now say have observed a discontinuous change of the direct bandgap of hydrogen, from 0.6 electronvolts to below 0.1 electronvolts near 425 gigapascals. This change is most probably associated with the formation of the metallic state, they write in their paper published in Nature.
To reach this pressure, the team developed new kind of “toroidal” anvil cell in which samples are squeezed between two tiny flat surfaces surrounded by ring-shaped depressions. This, they say, can generate pressures of up to at least 600 GPa. They probed the structural changes and electronic properties of the dense solid hydrogen at 80 K using synchrotron infrared absorption spectroscopy at the SOLEIL synchrotron. The new results also closely match predictions made by theorists in 2015, they add.
Meanwhile, Marc Fontecave together with his colleagues Sarah Lamaison and David Wakerley from the Laboratory of Chemistry of Biological Processes (Collège de France/CNRS) are reporting on the development of new catalysts to reduce CO2 at record speeds for systems based mainly on non-noble metals. Their catalysts, based on highly active Ag-alloyed Zn dendritic electrodes, have a CO2-to-CO selectivity as high as 91% that can be sustained above an average of 90% over 40 hours. Such electrocatalytic conversion of CO2 into valuable chemical feedstocks is a highly sought-after route to recycle CO2 emissions and the new work is an important step forward in this direction.
Finally, we were intrigued by new research published in Translational Psychiatry from the Institut des Neurosciences Paris-Saclay (NeuroPsi) – (CNRS / Université Paris-Saclay) led by Pascale Gisquet-Verrier in which false memories created in traumatized rats can take precedence over an initial, traumatic memory.
The researchers, who created the new memories by injecting the rats with oxytocin (which dampens anxiety and fear before the reactivation of the trauma memory), say that their technique could help reduce traumatic symptoms and their consequences and so be a promising treatment for PTSD.