Zero-Dimensional Interstitial Electron-Induced Spin-Orbit Coupling Dirac States in Sandwich Electride.

The development of inorganic electrides offers new possibilities for studying topological states due to the nonnuclear-binding properties displayed by interstitial electrons. Herein, a sandwich electride 2[CaCl]+:2e- is designed, featuring a tetragonal lattice structure, including two atomic lattice layers and one interstitial electron layer. The interstitial electrons form nonsymmorphic-symmetry-protected Dirac points (DPs) at the X and M points, which are robust against the spin-orbit coupling effect. DPs exhibit an approximately elliptical shape, characterized by a relatively high anisotropy, resulting from the interplay between the electron and atomic layers. In addition, 2[CaCl]+:2e- possesses a lower work function (WF) (3.43 eV), endowing it with robust electron-supplying characteristics. Due to the low WF and interstitial electrons, 2[CaCl]+:2e- loaded Ru shows outstanding catalytic performance for N2 cleavage. A potential research platform for exploring the formation of topological states and promoting nitrogen cracking in electrides is provided.