Organic Solvent Based Synthesis of Gold Nanoparticle - Semiconducting 2H-MoS2 Hybrid Nanosheets

The development of simple, versatile strategies for the synthesis of gold nanoparticles (AuNPs) on semiconducting transition-metal dichalcogenide (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-MoS ₂ NSs) via an N,N-dimethylformamide (DMF)-based hot-injection synthesis route. This organic solvent-based synthesis route eliminates problems of poor dispersion of AuNPs@2H-MoS ₂ NS hybrids and at the same time maintains the semiconducting crystalline quality of the pristine 2H-MoS ₂ NSs. In addition, the study establishes the important role of trisodium citrate in enhancing the nucleation and improving the hybridization of AuNPs on 2H-MoS ₂ 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.