Ultralow Work Function of the Electride Sr$_3$CrN$_3$

TL;DR

This study uses density functional theory to demonstrate that the electride Sr$_3$CrN$_3$ has an ultralow work function and stable surface properties, making it a promising catalyst with accessible free electrons.

Contribution

We reveal the ultralow work function and stable surface termination of Sr$_3$CrN$_3$, highlighting its potential as a novel electride catalyst.

Findings

Persistent excess electron density on surface terminations

Highly stable crystal termination perpendicular to 1D electron channels

Confirmation of extremely low work function using hybrid functional methods

Abstract

Electrides have valence electrons that occupy free space in the crystal structure, making them easier to extract. This feature can be used in catalysis for important reactions that usually requires a high-temperature and high-pressure environments, such as ammonia synthesis. In this paper, we use density functional theory to investigate the behaviour of interstitial electrons of the 1-dimensional electride Sr$_3$CrN$_3$. We find that the bulk excess electron density persists on introduction of surface terminations, that the crystal termination perpendicular to the 1D free-electron channel is highly stable and we confirm an extremely low work function with hybrid functional methods. Our results indicate that Sr$_3$CrN$_3$ is a potentially important novel catalyst, with accessible, directional and extractable free electron density.