title: Functionalization of Two-Dimensional MoS2 : On the Reaction Between MoS2 and Organic Thiols.
abstract: Two-dimensional layered transition metal dichalcogenides (TMDs) have attracted great interest owing to their unique properties and a wide array of potential applications. However, due to their inert nature, pristine TMDs are very challenging to functionalize. We demonstrate a general route to functionalize exfoliated 2H-MoS2 with cysteine. Critically, MoS2 was found to be facilitating the oxidation of the thiol cysteine to the disulfide cystine during functionalization. The resulting cystine was physisorbed on MoS2 rather than coordinated as a thiol (cysteine) filling S-vacancies in the 2H-MoS2 surface, as originally conceived. These observations were found to be true for other organic thiols and indeed other TMDs. Our findings suggest that functionalization of two-dimensional MoS2 using organic thiols may not yield covalently or datively tethered functionalities, rather, in this instance, they yield physisorbed disulfides that are easily removed.
authors.affiliation: CRANN/AMBER Nanoscience Institute, Trinity College Dublin, The University of Dublin, College Green, Dublin, 2, Ireland.|School of Chemistry, Trinity College Dublin.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.affiliation: CRANN/AMBER Nanoscience Institute, Trinity College Dublin, The University of Dublin, College Green, Dublin, 2, Ireland.|School of Chemistry, Trinity College Dublin.
authors.forename: Nina C
authors.initials: NC
authors.lastname: Berner
authors.affiliation: CRANN/AMBER Nanoscience Institute, Trinity College Dublin, The University of Dublin, College Green, Dublin, 2, Ireland.|School of Physics, Trinity College Dublin.
authors.forename: Claudia
authors.initials: C
authors.lastname: Backes
authors.affiliation: CRANN/AMBER Nanoscience Institute, Trinity College Dublin, The University of Dublin, College Green, Dublin, 2, Ireland.|School of Chemistry, Trinity College Dublin.
authors.forename: Georg S
authors.initials: GS
authors.lastname: Duesberg
authors.affiliation: CRANN/AMBER Nanoscience Institute, Trinity College Dublin, The University of Dublin, College Green, Dublin, 2, Ireland. aidan.mcdonald@tcd.ie.|School of Chemistry, Trinity College Dublin. aidan.mcdonald@tcd.ie.
authors.forename: Aidan R
authors.initials: AR
authors.lastname: McDonald
keywords: 2D materials; liquid exfoliation; organic thiol; surface functionalization; transition metal dichalcogenides