Two-Dimensional Dirac Nodal Line Carbon Nitride to Anchor Single-Atom Catalyst for Oxygen Reduction Reaction

Two-dimensional carbon nitride (2DCN) materials have emerged as an important class of 2D materials beyond graphene. However, 2DCN materials with nodal-line semimetal characteristic are rarely reported. In this work, a new nodal-line semimetal 2DCN with the stoichiometry C4N4 is designed by using density functional theory (DFT) calculations and its application to anchor single-atom catalysts (SACs) for the oxygen reduction reaction (ORR) is investigated. C4N4 is a planar covalent network (sp(2) hybridization) with regular holes formed by the four N atoms, which is dynamically, thermodynamically, and mechanically stable. The nodal line is contributed by the p(z) orbitals of C and p(x/y) orbitals of N atoms. C4N4 shows an anisotropic Fermi velocity and high electron mobility. Because of its porous structure, C4N4 can anchor heteroatoms as SACs for electrocatalysis. C4N4 anchored with Fe or Co is shown to be highly active for the ORR with a rather high half-wave potential of around 0.90 V, which is higher than those of SACs on other carbon nitrides. These findings may provide a new strategy to design novel substrates for SACs.

Automated summary

In this study, a new 2D carbon nitride material, C4N4, with nodal-line semimetal characteristic was designed and its application as an anchor for single-atom catalysts for the oxygen reduction reaction (ORR) was investigated. The results showed that C4N4 exhibited high activity as an electrocatalyst and provided a new strategy for the design of novel catalysts.