Symmetry-breaking-induced multifunctionalities of two-dimensional chromium-based materials for nanoelectronics and clean energy conversion

TL;DR

This paper demonstrates that breaking inversion symmetry in 2D chromium-based materials creates multifunctional properties like spin-gapless behavior, low work function, doping, and catalysis, with potential for nanoelectronics and energy conversion.

Contribution

It introduces Janus Cr2NY monolayers as a new class of 2D materials with multiple functionalities derived from symmetry-breaking.

Findings

Cr2NSb is a spin-gapless semiconductor.

Cr2NP and Cr2NHPF induce n- and p-type doping.

Cr2NY shows superior electrocatalytic hydrogen evolution activity.

Abstract

Structural symmetry-breaking that could lead to exotic physical properties plays a crucial role in determining the functions of a system, especially for two-dimensional (2D) materials. Here we demonstrate that multiple functionalities of 2D chromium-based materials could be achieved by breaking inversion symmetry via replacing Y atoms in one face of pristine CrY (Y=P, As, Sb) monolayers with N atoms, i.e., forming Janus Cr2NY monolayers. The functionalities include spin-gapless, very low work function, inducing carrier doping and catalytic activity, which are predominately ascribed to the large intrinsic dipole of Janus Cr2NY monolayers, making them having great potentials in various applications. Specifically, Cr2NSb is found to be a spin-gapless semiconductor, Cr2NP and Cr2NHPF could simultaneously induce n- and p-type carrier doping for two graphene sheets with different concentrations (forming intrinsic p-n vertical junction), and Cr2NY exhibits excellent electrocatalytic hydrogen evolution activity, even superior to benchmark Pt. The results confirm that breaking symmetry is a promising approach for the rational design of multifunctional 2D materials.