  The development of simple, versatile strategies for the synthesis of gold
nanoparticles (AuNPs) on semiconducting transition metal dichalcogenides (TMDC)
layers is of increasing scientific and technological interest in
photocatalysis, optical sensing, and optoelectronics sectors, but challenges
exist on the nucleation and hybridization of AuNPs with the TMDC basal plane.
At present, the widely used aqueous solution approaches suffer from poor
dispersion of produced hybrids as well as from limited growth and coverage of
the AuNPs on the TMDC semiconducting plane, since Au nanoclusters nucleate
preferentially at the electron rich defect edges, which act as reducing agents
and not on the defect free basal plane. Here, we report for the first time, the
controlled synthesis of AuNPs on the basal plane of semiconducting molybdenum
disulfide nanosheets (2H-MoS2 NSs) via a N,N-dimethylformamide (DMF)-based
hot-injection synthesis route. This organic solvent-based synthesis route
eliminates problems of poor dispersion of AuNPs@2H-MoS2 NS hybrids, whereas at
the same time maintains the semiconducting crystalline quality of the pristine
2H-MoS2 NSs. In addition, the study establishes the important role of trisodium
citrate, on enhancing the nucleation and improving the hybridization of AuNPs
on 2H-MoS2 NSs as evidenced by the induced p-type doping. This organic solvent
synthesis approach can be adopted for other hybrid systems opening the way for
controlled hybridization of semiconducting layers with metal nanoparticles.
