Topological electride Hf₂Se: Enhanced hydrogen evolution reaction activity from nontrivial topological Fermi arc

Abstract Recently, the emergence of topological electride catalysts has attracted significant attention in the fields of condensed matter physics, chemistry, and materials science. In this study, we found that electride Hf 2 Se exhibits various types of topological quantum states under the constraint of symmetric operations, particularly the Weyl point (WP) located at the K valley. The WP is closely aligned with the Fermi level and generates an extensive Fermi arc surface state on the (001) surface. In addition, electride Hf 2 Se exhibits a lower work function on the (001) surface. Remarkably, electride Hf 2 Se exhibits extremely high stability in both air and water environments. The catalytic activity of electride Hf 2 Se for hydrogen evolution reaction (HER) was significantly improved by utilizing its robust surface state and low work function. Therefore, we provide a new insight into the application of electrides in HER.