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Published February 23, 2022 | Supplemental Material
Journal Article Open

Experimental and Theoretical Comparison of Potential-dependent Methylation on Chemically Exfoliated WS₂ and MoS₂

Abstract

Reductant-activated functionalization is shown to enhance the methylation of chemically exfoliated MoS₂ (ceMoS₂) and ceWS₂ by introducing excess negative charge to facilitate a nucleophilic attack reaction. Relative to methylation in the absence of a reductant, the reaction produces a twofold increase in coverage of ceWS₂, from 25 to 52% coverage per WS₂. However, at every potential, the methyl coverage on ceWS₂ was ∼20% lower than that on ceMoS₂. We applied grand canonical density functional theory to show that at constant potential, more negative charge is present on 1T′-MoS₂ than on 1T′-WS₂, making methylation both thermodynamically and kinetically more favorable for 1T′-MoS₂ than 1T′-WS₂. This effect was moderated when the reactions were compared at constant charge, emphasizing the importance of comparing the reactivity of materials at nominally identical electrode potentials.

Additional Information

© 2022 American Chemical Society. Received: October 29, 2021; Accepted: January 19, 2022; Published: February 11, 2022. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under award DE-FG02-03ER15483. E.X.Y. would also like to thank Bill Ling for assistance with DLS measurements. R.B. is an Awardee of the Weizmann Institute of Science─National Postdoctoral Award Program for Advancing Women in Science and the Zuckerman STEM Leadership Program. Research was possible only with the use of instrumentation maintained in the Molecular Materials Resource Center of the Beckman Institute of the California Institute of Technology. The computations presented here were conducted on a Caltech high-performance cluster, partially supported by a grant from the Gordon and Betty Moore Foundation. S.K., C.B.M., W.A.G., and the H.P.C. calculations were supported by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub, under award number DE-SC0021266. The authors declare no competing financial interest.

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Additional details

Created:
August 22, 2023
Modified:
October 23, 2023