Design monolayer iodinenes based on halogen bond and tiling theory

TL;DR

This paper introduces a novel class of 2D iodine monolayers called iodinenes, stabilized by halogen bonds, constructed using tiling theory and ab initio methods, revealing unique properties like flat bands and nontrivial topology.

Contribution

It uncovers the role of halogen bonds in 2D group-VIIA monolayers and proposes a bottom-up design of stable iodinenes with diverse tiling patterns, a novel approach in 2D material design.

Findings

Successful design of stable iodinenes with various tiling patterns

Revealed properties include flat bands and nontrivial topology

Halogen bonds play a key role in 2D material stability

Abstract

Xenes, two-dimensional (2D) monolayers composed of a single element, with graphene as a typical representative, have attracted widespread attention. Most of the previous Xenes, X from group-IIIA to group-VIA elements have bonding characteristics of covalent bonds. In this work, we for the first time unveil the pivotal role of a halogen bond, which is a distinctive type of bonding with interaction strength between that of a covalent bond and a van der Waals interaction, in 2D group-VIIA monolayers. Combing the ingenious non-edge-to-edge tiling theory and state-of-art ab initio method with refined local density functional M06-L, we provide a precise and effective bottom-up construction of 2D iodine monolayer sheets, iodinenes, primarily governed by halogen bonds, and successfully design a category of stable iodinenes, encompassing herringbone, Pythagorean, gyrated truncated hexagonal, i.e. diatomic-kagome, and gyrated hexagonal tiling pattern. These iodinene structures exhibit a wealth of properties, such as flat bands, nontrivial topology, and fascinating optical characteristics, offering valuable insights and guidance for future experimental investigations. Our work not only unveils the unexplored halogen bonding mechanism in 2D materials but also opens a new avenue for designing other non-covalent bonding 2D materials.