Optically facet-resolved reaction anisotropy in two-dimensional transition metal dichalcogenides. (3rd June 2021)

• Record Type: Journal Article
• Authors: Song, Myeongin; Kang, Haneul; Rhodes, Dan; Kim, Bumho; Hone, James; Ryu, Sunmin
• Is Part Of: 2D materials. Volume 8:Number 3(2021)
• Publication Date: 2021-06-03
• Subjects: anisotropic reactions -- second-harmonic generation -- two-dimensional crystals -- transition metal dichalcogenides -- oxidation; Graphene -- Periodicals; Materials science -- Periodicals; Nanostructured materials -- Periodicals; 620.115
• DOI: 10.1088/2053-1583/ac0297
• Languages: English
• ISSNs: 2053-1583

Abstract

Abstract: Quantifying anisotropy in the chemical reactions of mesoscopic crystals has mostly resorted on the combination of electron microscopy and diffraction. In this work, we established crystal-facet-resolved kinetic measurements of oxidation reactions in two-dimensional (2D) transition metal dichalcogenides (TMDs) using optical second-harmonic generation spectroscopy and scanning probe microscopy. We show the in-plane anisotropy of their bond-breaking reactions is governed by their structure and strongly material-dependent among four TMDs. The facet-resolved analysis directly revealed that the reactions proceed fastest (slowest) for chalcogen (metal)-terminated zigzag edges with armchair edges in the middle. The degree of the anisotropy inducing trigonal oxidation patterns was much higher in MoS2 and MoSe2 than WS2 and WSe2 . Kinetic Wulff construction based on edge-specific reaction rates verified the material-dependent mesoscopic reaction patterns. We also show that the reactions are initiated at substrate-mediated defects located on the bottom and top surfaces of 2D TMDs.