Structural stabilities, electronic structures, photocatalysis and optical properties of γ-GeN and α-SnP monolayers: a first-principles study

• Published in: Materials research express Vol. 8; no. 12; pp. 125010 - 125018
• Main Authors: Liu, Liming, Yan, Cuixia, Gao, Lei, Shangguan, Wei, Dai, Jianqing, Cai, Jinming
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01-12-2021
• Subjects: Absorptivity; Antimony; Bismuth; Electromagnetic absorption; Energy bands; Energy gap; First principles; Free energy; Gamma phase; Germanium; group IV-V monolayers; Lead; Materials selection; Monolayers; Nanoelectronics; Optical properties; Optoelectronics; Photocatalysis; Photocatalysts; Photoelectricity; Silicon; Structural stability; Tin; two dimensional; Two dimensional materials; Water splitting
• ISSN: 2053-1591; 2053-1591
• DOI: 10.1088/2053-1591/ac3fdc

Abstract
Exploring two-dimensional materials with excellent photoelectricity properties is of great theoretical significance and practical value for developing new photocatalysts, electronics and photonic devices. Here, using first-principle calculations, we designed and analyzed systematically a series of
α
,
β
and
γ
phase structures of two-dimensional group IV-V monolayers (IV-V, IV = C, Si, Ge, Sn, Pb; V = N, P, As, Sb, Bi), most of them are semiconductors. Among them,
γ
-GeN and
α
-SnP monolayers with thermodynamic and kinetic stability (at 300 K) have been further studied due to their wide range of energy band gaps (
γ
-GeN: 2.54 eV,
α
-SnP:1.34 eV). The two band gaps are greater than the free energy for water splitting (1.23 eV), which are crucial for photocatalytic decomposition of water. The
γ
-GeN and
α
-SnP monolayers present excellent photocatalystics properties in pH = 0/7 and pH = 10 environments, respectively. Moreover, both of the monolayers show strong light absorption coefficients greater than 10
5
cm
−1
in the visible and ultraviolet regions. In addition, it is found that the band edge positions and band gap sizes of
γ
-GeN and
α
-SnP monolayers can be regulated by biaxial strain. Benefitting from the wide selection of energy band gaps and high absorption coefficients, the
γ
-GeN and
α
-SnP monolayers are the next generation of promising candidate materials for photocatalysts, nanoelectronics and optoelectronics.