Department of Engineering Science and Mechanics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States.
Materials Research Institute , Pennsylvania State University , University Park , Pennsylvania 16802 , United States.
ACS Appl Mater Interfaces. 2018 Nov 28;10(47):40773-40780. doi: 10.1021/acsami.8b14585. Epub 2018 Nov 15.
Two-dimensional (2D) transition-metal dichalcogenides (TMDs) are a unique class of 2D materials possessing unique optoelectronic properties when exfoliated into mono- and few-layer sheets. Recently, electroablation (EA) has become of interest as a promising synthesis method for single-layer sheets of TMDs. Here, we introduce spectroelectrochemical micro-extinction spectroscopy (SE-MExS) as a high-throughput technique to study electrochemical thinning of TMDs as it occurs. This approach enables the parallel use of spectroscopy and imaging to nondestructively characterize 2D materials in situ. We unravel optoelectronics of the TMDs by observing changes in optical properties during EA. We find that the EA process for MoS, WS, MoSe, and WSe occurs edge first, generating high density of edge sites. Our results show that stable monolayers of MoS, WS, and MoSe can be synthesized from bulk precursors by the EA process, while conversely, no WSe remains postablation.
二维（2D）过渡金属二卤化物（TMD）是一类独特的 2D 材料，当剥离成单层和少数层薄片时，具有独特的光电特性。最近，电烧蚀（EA）作为一种有前途的 TMD 单层片合成方法引起了人们的兴趣。在这里，我们引入光谱电化学微消光谱（SE-MExS）作为一种高通量技术，以研究 TMD 的电化学变薄过程。这种方法可以并行使用光谱和成像来对原位 2D 材料进行非破坏性表征。我们通过观察 EA 过程中光学性质的变化来揭示 TMD 的光电性质。我们发现 MoS、WS、MoSe 和 WSe 的 EA 过程首先从边缘开始，产生高密度的边缘位。我们的结果表明，MoS、WS 和 MoSe 的稳定单层可以通过 EA 过程从块状前体合成，而相反，WSe 在烧蚀后不存在。
