Hydrogenation induced high-temperature superconductivity in two-dimensional W2C3.

The discovery of highly crystalline two-dimensional (2D) superconductors provides a new alluring branch for exploring the fundamental significances. Based on first-principles calculations, we predict a new kind of 2D stable material W₂C₃, which is a semimetal but not a superconductor because of the weak electron–phonon coupling (EPC) strength. After hydrogenation, W₂C₃H₂ possesses the intrinsic metallic properties with a large density of states (DOS) at the Fermi energy (E_F). More interestingly, the EPC strength is greatly enhanced after hydrogenation and the calculated critical temperature (T_c) is 40.5 K. Furthermore, the compressive strain can obviously soften the low-frequency phonons and enhance the EPC strength. Then, the T_c of W₂C₃H₂ can be increased from 40.5 K to 49.1 K with −4% compressive strain. This work paves the way for providing a new platform for 2D superconductivity. [ABSTRACT FROM AUTHOR]