Transition metal dichalcogenides, especially in samples with well-characterized and controlled defects, have garnered interest as catalytically active thin films which can be generated in the monolayer limit. Such devices maximize the useful surface area available for catalysis, whilst allowing for tailored surface chemistry depending on choice of transition metal and corresponding chalcogen. In this work, few-layer TaS2 was grown on sulfurized, single-crystal Cu(111) under UHV conditions and transferred into a low-temperature scanning tunneling microscopy (LT-STM) for atomic-scale characterization of topography and local density of states using lock-in scanning tunneling spectroscopy (STS). After the as-grown material was characterized, Ar sputtering at 500 eV was performed in-vacuo in an adjacent sample preparation chamber to controllably induce defects for STM/STS characterization. Such defect sites, in addition to edge sites, can potentially play a crucial role in catalysis by activating molecular species and lowering reaction barriers. We observe a variety of defect structures after Ar sputtering, and the corresponding electronic states near the Fermi energy are probed at individual defect sites. Theoretical calculations and simulations further inform the mechanisms underlying the catalytic nature of TaS2.

Scanning tunneling microscopy and spectroscopy of Ar-sputtered TaS2/Cu(111) at 78K: Investigating catalytic mechanisms

2019 Spring National Meeting

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