Strong mechanical anisotropy and an anisotropic Dirac state in 2D C5N3

Abstract

Two-dimensional (2D) carbon nitride materials have emerged as a versatile platform for the design of high-performance nanoelectronics, but strong anisotropy in 2D carbon nitrides has rarely been reported. In this work, a 2D carbon nitride with strong anisotropy composed of tetra-, penta-, and hexa-rings (named as TPH-C₅N₃) is proposed. This TPH-C₅N₃ exhibits both dynamical and mechanical stability. Furthermore, it also showcases remarkable thermal stability, reaching up to 2300 K, as evidenced by AIMD simulations conducted in an NVT environment utilizing the Nosé–Hoover thermostat. Significantly, TPH-C₅N₃ demonstrates high anisotropic ratios in its mechanical properties, positioning it as the frontrunner in the current carbon nitride systems. In addition, a Dirac cone with an anisotropic ratio of 55.8% and Fermi velocity of 7.26 × 10⁵ m s⁻¹ is revealed in TPH-C₅N₃. The nontrivial topological properties of TPH-C₅N₃ are demonstrated by a non-zero Z₂ invariant and topologically protected edge states. Our study offers theoretical insights into an anisotropic 2D carbon nitride material, laying the groundwork for its design and synthesis.