Preparation of Transition Metal Disulfide Nano‐dots via Hydroxyl Radicals‐mediated Cutting Metal‐Sulfur Bonds

The preparation of low‐dimensional transition metal disulfides (MS2, M = Mo, W) via ultrasonication‐assisted liquid‐phase exfoliation from mineral bulk‐MS2 is proven to be advantageous in terms of sulfurizing reagent‐free conditions and operational safety. Nevertheless, mechanical energy input is insufficient to effectively cut metal‐sulfur bonds to form small‐sized MS2 nano‐dots. Herein, we develop an innovative strategy based on hydroxyl radicals‐mediated cutting metal‐sulfur bonds to prepare MS2 nano‐dots with lateral dimension of 10 nm and height of 2 nm, through ultrasonication treatment of bulk‐MS2 in the presence of a mixture of ammonium citrate/N‐Methylpyrrolidone ((NH4)3CA/NMP). A pivotal aspect of this strategy is the in‐situ generation of hydroxyl radicals from citrate ions (CA3‐), which can effectively cut metal‐sulfur bonds of the submicron‐sized sheet that was as‐exfoliated by NMP. Furthermore, the introduced CA3‐ adsorbs onto the surfaces of MS2 nano‐dots, preventing their re‐aggregation in the disperse system. This work provides a facile strategy for the direct preparation of metal disulfide nano‐dots from their bulk‐minerals.