The pursuit of room-temperature superconductivity has generated growing interest in hydrogen-rich materials. However, the limited structural and compositional diversity of traditional binary superhydrides hinders further progress in this field. Ternary hydrides, with their enhanced structural flexibility and synergistic intermetallic interactions, provide a promising route to overcome these limitations. In this study, using $\mathrm{Y}{\mathrm{H}}_4$ as the parent material, we successfully synthesized two Y-Sc-H ternary hydrides by controlling laser-heating temperature and scandium doping concentration: the substitutionally doped stoichiometric $P4/mmm-\mathrm{YSc}{\mathrm{H}}_8$ and nonstoichiometric $I4/mmm-\left(\mathrm{Y},\mathrm{Sc}\right){\mathrm{H}}_4$. Electrical transport measurements revealed that $P4/mmm-\mathrm{YSc}{\mathrm{H}}_8$ exhibits a superconducting transition temperature ($T_{\mathrm{c}}$) of 113 K at 191.7 GPa, representing a 41% enhancement over $\mathrm{Y}{\mathrm{H}}_4$ (79 K at 179 GPa), with structural stability retained down to at least 160 GPa. In contrast, $I4/mmm-\left(\mathrm{Y},\mathrm{Sc}\right){\mathrm{H}}_4$ induces only a slight modification of the $T_{\mathrm{c}}$ of the parent $\mathrm{Y}{\mathrm{H}}_4$, which is consistent with the Anderson theorem. Electronic structure calculations reveal that the band structure of $P4/mmm-\mathrm{YSc}{\mathrm{H}}_8$ is substantially reconstructed due to the introduction of Sc $3d$ orbitals. This shifts the van Hove-like features closer to the Fermi level, increases the density of states at the Fermi level, and consequently enhances the electron-phonon coupling, ultimately leading to an elevated superconducting transition temperature $T_{\mathrm{c}}$. These findings demonstrate the effectiveness of elemental synergy strategies in designing high-$T_{\mathrm{c}}$ superhydrides.

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• Superconductivity
• High-temperature superconductors
• Pressure techniques