One-Step Synthesis of Transition Metal Dichalcogenide Quantum Dots Using Only Alcohol Solvents for Indoor-Light Photocatalytic Antibacterial Activity.

In this study, we report a one-step direct synthesis of molybdenum disulfide (MoS 2 ) and tungsten disulfide (WS 2 ) quantum dots (QDs) through a solvothermal reaction using only alcohol solvents and efficient Escherichia coli ( E. coli ) decompositions as photocatalytic antibacterial agents under visible light irradiation. The solvothermal reaction gives the scission of molybdenum-sulfur (Mo-S) and tungsten-sulfur (W-S) bonding during the synthesis of MoS 2 and WS 2 QDs. Using only alcohol solvent does not require a residue purification process necessary for metal intercalation. As the number of the CH 3 groups of alcohol solvents among ethyl, isopropyl, and tert ( t )-butyl alcohols increases, the dispersibility of MoS 2 /WS 2 increases. The CH 3 groups of alcohols minimize the surface energy, leading to the effective exfoliation and disintegration of the bulk under heat and pressure. The bulky t -butyl alcohol with the highest number of methyl groups shows the highest exfoliation and yield. MoS 2 QDs with a lateral size of about 2.5 nm and WS 2 QDs of about 10 nm are prepared, exhibiting a strong blue luminescence under 365 nm ultraviolet (UV) light irradiation. Their heights are 0.68-3 and 0.72-5 nm, corresponding to a few layers of MoS 2 and WS 2 , respectively. They offer a highly efficient performance in sterilizing E. coli as the visible-light-driven photocatalyst.