A topological quantum catalyst: the case of two-dimensional traversing nodal line states associated with high catalytic performance for the hydrogen evolution reaction

Abstract

Topological quantum catalysts (TQCs), where metallic surface states from the nontrivial band topology serve as the mechanism to favor heterogeneous catalysis processes, have been well demonstrated in three dimensional (3D) examples but have been rarely discussed on the 2D scale. Here, we develop a design scheme to realize 2D TQCs showing a traversing nodal line at the Brillouin zone boundary, large Fermi arc on the edge, and nearly zero Gibbs free energy (ΔG_H*) for the hydrogen evolution reaction (HER). We demonstrate that the 2D Cu₂C₂N₄ sheet is such an example. The material manifests an open nodal line traversing the whole k-path S–Y. It shows a long Fermi arc that spans the entire edge boundary, which is robust against spin–orbit coupling and H adsorption. As a result, the edge of the Cu₂C₂N₄ sheet is relatively active for HER catalysis with a ΔG_H* as low as 0.10 eV, which is comparable with that of Pt and superior to that of other traditional catalysts and 3D TQCs as well. Our work offers an effective route to high performance HER catalysts without noble metals by utilizing 2D TQCs with a traversing nodal line.