Single-Layer Clathrane: A Potential Superconducting Two-Dimensional Hydrogenated Metal Borocarbide

We propose a new family of two-dimensional (2D) metal borocarbide clathrane superconductors derived from three-dimensional (3D) MM′B₆C₆ clathrates. First-principles calculations reveal that hydrogen passivation and surface metal decoration stabilize the M₂M′B₈C₈H₈ monolayers. These 2D systems exhibit tunable superconductivity governed by hole concentration, structural anisotropy, and electron–phonon coupling. We find that in-plane anisotropy competes with superconductivity, reducing T_c despite favorable doping. Biaxial strain mitigates this anisotropy, enhances Fermi surface nesting, and increases T_c by an average of 15.5 K. For example, the T_c of Sr₃B₈C₈H₈ is predicted to increase from 11.3 to 22.2 K with strain engineering. These findings identify 2D clathranes as promising, strain-tunable superconductors and highlight design principles for optimizing low-dimensional superconducting materials.