The recent discovery of high-temperature superconductivity in hydrogen-based compounds under pressure has fueled the hope for the exploration of hydrides with high critical temperatures ($T_c$). In this work, we systematically investigated pressure-stabilized ternary C-Se-H and C-Te-H compounds using the state-of-the-art structure prediction approach in combination with first-principles calculations. As a result, our simulations identified two cubic phases ($\mathrm{CSe}{\mathrm{H}}_6$ and ${\mathrm{C}}_2\mathrm{Te}{\mathrm{H}}_8$) with a metastable stability feature. $Fd\text{−}3m$-structured $\mathrm{CSe}{\mathrm{H}}_6$ adopted a diamond-type host Se framework with an embedded guest $\mathrm{C}{\mathrm{H}}_6$ covalent octahedron, and ${\mathrm{C}}_2\mathrm{Te}{\mathrm{H}}_8$ with $Fm\text{−}3m$ symmetry adopted a face-centered cubic arrangement of ${\mathrm{H}}_8$ cubes, which are interlinked by a molecular unit $\mathrm{C}{\mathrm{H}}_4$ tetrahedron. Electron-phonon coupling simulations reveal that $\mathrm{CSe}{\mathrm{H}}_6$ has high-temperature superconductivity with a $T_c$ of 80.6 K at 250 GPa. This high superconductivity could be attributed to the fact that the C $2p$, Se $4p$, and H $1s$ electron states near the Fermi energy couple with high-frequency H-associated phonons. Furthermore, ${\mathrm{C}}_2\mathrm{Te}{\mathrm{H}}_8$ was estimated to have an even higher $T_c$ of 151.4 K at 300 GPa due to the large average phonon frequency and the strong coupling between C- and H-derived optical phonons and electrons (C $2p$, Te $5p$, and H $1s$) near the Fermi level. The present results shed light on the future exploration of high-temperature superconductivity among multinary hydrides.

• Received 25 January 2024
• Accepted 10 April 2024

DOI:https://doi.org/10.1103/PhysRevB.109.174507