HightemperaturesuperconductorNa2B2Hstabilizedbyhydrogenintercalationunderambientpressure<iclass="icon-zqcb"></i>

Hydrogenated metal borides have attracted much attention due to their potential high-temperature superconductivity. Here, we propose a new strategy for hydrogen intercalation tuning the stability and superconductivity of the boron honeycomb sublattice,and predict an unprecedented layered compound Na2B2H, which hosts excellent superconductivity. Strikingly, the superconducting transition temperature（Tc） of Na2B2H reaches 42 K at ambient pressure. The Tcvalue can be further increase to 63 K under 5% biaxial tensile strain. The excellent superconductivity originates from the strong electron-phonon coupling between theσ-bonding bands near the Fermi level and the B-B stretching optical E modes. The interstitial electron localization and crystal orbitals of the H-intercalated Na ion layer well match the boron honeycomb lattice and act as a chemical template to stabilize the B layer. Furthermore, the introduction of hydrogen tuned the Fermi level, and the coupling vibration of Na and H ions effectively enhanced the dynamic stability of the structure. Na2B2H represents a new family of layered high-temperature superconductors,and the strategy of stabilizing the honeycomb boron sublattice via chemical template hosts great potential for application to more layered compounds.