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arXiv · 2401.00742

Raisins in a Hydrogen Pie: Ultrastable Cesium and Rubidium Polyhydrides

Di Zhou·Dmitrii V. Semenok·Michele Galasso·Frederico Gil Alabarse·Denis A. Sannikov·Ivan A. Troyan·Yuki Nakamoto·Katsuya Shimizu·Artem R. Oganov
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Abstract

We proposed a new method for synthesis of metal polyhydrides via high-pressure thermal decomposition of corresponding amidoboranes in diamond anvil cells. Within this approach, we synthesized molecular semiconducting cesium ($\textit P4/nmm$-CsH$_7$, $\textit P$1-CsH$_{15+x}$) and rubidium (RbH$_{9-x}$) polyhydrides with a very high hydrogen content reaching 93 at%. Preservation of CsH$_7$ at near ambient conditions, confirmed both experimentally and theoretically, represents a significant advance in the stabilization of hydrogen-rich compounds. In addition, we synthesized two crystal modifications of RbH$_{9-x}$ with pseudo hexagonal and pseudo tetragonal structures identified by synchrotron X-ray diffraction and Raman measurements. Both phases are stable at 8-10 GPa. This is an unprecedented low stabilization pressure for polyhydrides. These discoveries open up possibilities for modifying existing hydrogen storage materials to increase their efficiency.

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Di Zhou, Dmitrii V. Semenok, Michele Galasso, Frederico Gil Alabarse, Denis A. Sannikov, Ivan A. Troyan, Yuki Nakamoto, Katsuya Shimizu, Artem R. Oganov. 2024-01-01. Raisins in a Hydrogen Pie: Ultrastable Cesium and Rubidium Polyhydrides. https://doi.org/10.1002/aenm.202400077

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