A Self-Limiting Electro-Ablation Technique for the Top-Down Synthesis of Large-Area Monolayer Flakes of 2D Materials.
We report the discovery of an electrochemical process that converts two dimensional layered materials of arbitrary thicknesses into monolayers. The lateral dimensions of the monolayers obtained by the process within a few seconds time at room temperature were as large as 0.5 mm. The temporal and spatial dynamics of this physical phenomenon, studied on MoS2 flakes using ex-situ AFM imaging, Raman mapping, and photoluminescence measurements trace the origin of monolayer formation to a substrate-assisted self-limiting electrochemical ablation process. Electronic structure and atomistic calculations point to the interplay between three essential factors in the process: (1) strong covalent interaction of monolayer MoS2 with the substrate; (2) electric-field induced differences in Gibbs free energy of exfoliation; (3) dispersion of MoS2 in aqueous solution of hydrogen peroxide. This process was successful in obtaining monolayers of other 2D transition metal dichalcogenides, like WS2 and MoTe2 as well.
Department of Engineering Science and Mechanics &Material Research Institute, Pennsylvania State University, State College, 16803, USA.
Saptarshi
S
Das
DUBBLE-CRG, European Synchrotron Radiation Facility, CS40220, 38043 Grenoble Cedex 9, France.
Mrinal K
MK
Bera
Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois, 60439, USA.
Sheng
S
Tong
Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois, 60439, USA.
Badri
B
Narayanan
Department of Chemistry, University of Missouri, Columbia, Missouri, 65211, USA.
Ganesh
G
Kamath
Energy Science Division, Argonne National Laboratory, Argonne, Illinois, 60439, USA.
Anil
A
Mane
Material Science Division, Argonne National Laboratory, Argonne, Illinois, 60439, USA.
Arvydas P
AP
Paulikas
Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois, USA.
Mark R
MR
Antonio
Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois, 60439, USA.
Subramanian K R S
SK
Sankaranarayanan
Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois, 60439, USA.
Andreas K
AK
Roelofs