posted on 2021-11-11, 21:29authored byChangjiang Nie, Mingming Yin, Ye Zhao, Chuanwen Zhao, Butian Zhang, Xinxin Song, Xin Yi, Youwei Zhang, Liang Luo, Shun Wang
Two-dimensional
layered MoS2 has attracted tremendous
attention because of its unique physical and chemical properties and
promising application prospects. To further expand its applications
to areas such as gas sensing, biosensing, drug delivery, and photothermal
therapy, surface functionalization has been employed to engineer its
properties according to multiple perspectives. Herein, we demonstrate
a scalable surface modification method to generate functionalized
MoS2 flakes by the step-by-step covalent assembly of lipoic
acid (LA) and fluorescein isothiocyanate (FITC) molecules. In our
approach, reactive disulfide-containing LA molecules were first chemically
bonded to the sulfur vacancies (SVs) of MoS2 surfaces.
FITC was then linked to MoS2 through LA by a condensation
reaction between the amino group of FITC and the carboxyl group of
LA. It was demonstrated that the initial LA functionalization enhanced
the electronic mobility via the filling of SVs, and
the second-step functionalization with FITC induced electron doping
of MoS2. Moreover, the covalent attachment of FITC decorated
the PL spectrum of MoS2 with an additional green fluorescence
at ∼530 nm. This strategy is a universal route to construct
a versatile platform for chemical modification of functional groups
and provides new opportunities of controlling the electronic and optical
properties of transition-metal dichalcogenides.