Ab initio analysis of some Ge-based 2D nanomaterials

TL;DR

This study uses first-principles calculations to explore the properties of various Ge-based 2D materials, discovering a new stable phase of germanene with potential applications in photocatalysis.

Contribution

It introduces a new phase of germanene called tile germanene, with enhanced stability and distinct electronic properties, expanding the understanding of Ge-based 2D materials.

Findings

Tile germanene is more stable than hexagonal germanene.

GeO and GeC have band gaps exceeding 3 eV.

Tile germanene is a good conductor, unlike hexagonal germanene.

Abstract

The structural, electronic and dynamical properties of a group of 2D germanium-based compounds, including GeC, GeN, GeO, GeSi, GeS, GeSe, and germanene, are investigated by employing first-principles calculations. The most stable structure of each of these systems is identified after considering the most probable configurations and performing accurate phonon calculations. We introduce a new phase of germanene, which we name the tile germanene, which is significantly more stable than the known hexagonal germanene. We apply the modern modified Becke-Johnson (mBJ) and DFT1/2 schemes to obtain an accurate band structure for our selected 2D materials. It is seen that GeO and GeC exhibit the highest band gaps of more than 3 eV in this group of materials. Moreover, we argue that, in contrast to the semi-metallic nature of hexagonal germanene, the tile germanene is a very good conductor. The band edges of our semiconducting 2D materials are accurately aligned to the vacuum level to address the potential photocatalytic application of this system for water splitting and carbon dioxide reduction. The optical properties, including dielectric functions, refractive index, reflectivity, and Loss function of the samples are investigated in the framework of the Bethe-Salpeter approach.