  Because of their loosely bound electrons, electrides offer physical
properties useful in chemical synthesis and electronics. For these applications
and others, nano-sized electrides offer advantages, but to-date no electride
has been synthesized as a nanomaterial. We demonstrate experimentally that
Ca$_2$N, a layered electride in which layers of atoms are separated by layers
of a 2D electron gas (2DEG), can be exfoliated into two-dimensional (2D)
nanosheets using liquid exfoliation. The 2D flakes are stable in a nitrogen
atmosphere or in select organic solvents for at least one month. Electron
microscopy and elemental analysis reveal that the 2D flakes retain the crystal
structure and stoichiometry of the parent 3D Ca$_2$N. In addition, the 2D
flakes exhibit metallic character and an optical response that agrees with DFT
calculations. Together these findings suggest that the 2DEG is preserved in the
2D material. With this work, we bring electrides into the nano-regime and
experimentally demonstrate a 2D electride, Ca$_2$N.
