Two-dimensional (2D) metal borocarbide superconductors represent an emerging category of low-dimensional materials consisting of boron, carbon, and metal atoms, which hold substantial promise for applications in next-generation low-power superconducting electronics and quantum devices. Here, we design a family of 2D metal borocarbide superconductors with the chemical formula $X{\mathrm{B}}_6{\mathrm{C}}_6 (X=\mathrm{Al},\mathrm{Ga},\mathrm{In})$ using a high-throughput structural search combined with first-principles calculations. These compounds crystallize in a graphene-like metal-intercalated structure, belonging to the layer group with $P\overline{6}2m$ symmetry, where metal atoms are intercalated between the honeycomb boron–carbon (B–C) layers. These compounds have an extremely low metal content, with 83% less metal than ${\mathrm{MgB}}_2$ on a per-light-atom basis. The calculated results indicate that superconducting transition temperatures ($T_c$) of 2D ${\mathrm{InB}}_6{\mathrm{C}}_6, {\mathrm{GaB}}_6{\mathrm{C}}_6$, and ${\mathrm{AlB}}_6{\mathrm{C}}_6$ are 43.61 K, 42.20 K, and 39.97 K, respectively, all of which exceed the $T_c$ values of the conventional ${\mathrm{MgB}}_2$ superconductor (39 K). The high-$T_c$ values of these 2D metal borocarbide superconductors are mainly attributed to the strong coupling between the metallized $\sigma /\pi$ orbitals and the in-plane phonon vibrations of the B–C frameworks. These findings confirm that moderate metal doping in 2D light-element frameworks constitutes an effective strategy for achieving high-temperature superconductivity, thereby offering insights for the exploration of further superconductors.

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• Electrical properties
• 2-dimensional systems
• Superconductors
• BCS theory
• Band structure methods
• Density functional theory