Hidden Electrides in Alkali Auride Bimetallenes With Programmable Anionic Electron Lattices

Inorganic electrides are conventionally defined by a positive formal oxidation‐state sum, necessitating frameworks with cavities or channels to accommodate charge‐balancing anionic electrons. Here, we identify a distinct class of “hidden electrides”: alkali auride bimetallenes exhibiting a zero formal oxidation‐state sum, yet hosting interstitial anionic electrons (IAE) clearly evidenced by electron localization function and charge density analyses. By manipulating the surface arrangement of alkali metals, we demonstrate a general strategy to program the topology of these anionic‐electron lattices, realizing a family of two‐dimensional bimetallenes with tailored electronic distributions, including Janus‐type monolayer configurations. First‐principles calculations reveal that these hidden electrides possess exotic electronic structures characterized by Dirac‐like crossings, flat bands, and van Hove singularities dominated by IAE. Comprehensive stability screening identifies Li–Au bimetallenes as particularly robust systems that combine low formation energies with ultralow work functions (down to 2.27 eV). Furthermore, in heterostructures with MoS 2 , these bimetallenes form ohmic contacts and achieve electron injection levels up to 3.98 × 10 14 cm − 2 , establishing them as promising candidates for low‐barrier electron injection layers in next‐generation nanodevices.