Ab Initio Investigation of Atomistic Insights into the Nanoflake Formation of Transition-Metal Dichalcogenides: The Examples of MoS2, MoSe2, and MoTe2

Author(s)

Caturello, Naidel A. M. S. ^[1] ; Besse, Rafael ^[2] ; Da Silva, Augusto C. H. ^[1] ; Guedes-Sobrinho, Diego ^{[1, 3]} ; Lima, Matheus P. ^[4] ; Da Silva, Juarez L. F. ^[1]

Affiliation

^[1] Univ Sao Paulo, Sao Carlos Inst Chem, POB 780, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, Sao Carlos Inst Phys, POB 369, BR-13560970 Sao Carlos, SP - Brazil

^[3] Technol Inst Aeronaut, Dept Phys, BR-12228900 Sao Jose Dos Campos, SP - Brazil

^[4] Univ Fed Sao Carlos, Dept Phys, BR-13565905 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Journal of Physical Chemistry C; v. 122, n. 47, p. 27059-27069, NOV 29 2018.
• Web of Science Citations: 3

Abstract

An atom-level understanding of the evolution of the physical and chemical properties of transition-metal dichalcogenide (TMD) nanoflakes is a key step to improve our knowledge of two-dimensional (2D) TMD materials, which can help in the designing of new 2D materials. Here, we report a density functional theory (DFT) study of the evolution of the structural, energetic, and electronic properties of (MoQ(2))(n) nanoflakes, where Q = S, Se, and Te and n = 1-16. All optimized DFT configurations for each system (10n) were generated by an in-house implementation of the tree-growth scheme combined with the modified Euclidean similarity distance algorithm, which reduces a large set configurations (10n million) to 10n trial structures. We found that the energetic favored configurations change between two sorts of clusters: frameworks elongated in one dimension with tetrahedral and square pyramidal coordination of Mo atoms, which is followed by 2D nanoflakes with tetrahedral, square pyramidal, and distorted octahedral coordination environments of Mo atoms. Both structure types maintain the same Q-terminated edge configuration, a crucial factor for the increased stability of those nanoflakes in relation to stoichiometric 2H monolayer cuts. The structural properties of the lowest energy configurations evolve smoothly as a function of the nanoflake sizes. We found that more intense effects of charge transfer in the edges are an important factor for the stabilization of the 2D nanoflakes. The smaller charge transfer for larger Q radius leads to the increase of n, which stabilizes the 2D nanoflakes, namely, n = 6, 8, and 9 for MoS2, MoSe2, and MoTe2, respectively. (AU)

• FAPESP's process: 17/11631-2 - CINE: computational materials design based on atomistic simulations, meso-scale, multi-physics, and artificial intelligence for energy applications
• Grantee: Juarez Lopes Ferreira da Silva
• Support Opportunities: Research Grants - Research Centers in Engineering Program
• FAPESP's process: 17/09077-7 - Ab-initio study of the structural, electronic, and optical properties of van der Waals heterostructures
• Grantee: Rafael Besse
• Support Opportunities: Scholarships in Brazil - Doctorate