Systematic Investigation on the Surfactant‐Assisted Liquid‐Phase Exfoliation of MoS2 and WS2 in Water for Sustainable 2D Material Inks

MoS 2 and WS 2 have gathered significant attention due to their tunable properties and wide range of applications. Liquid‐phase exfoliation (LPE) is a facile method to prepare 2D MoS 2 and WS 2 . Currently, the principally employed solvents for LPE of MoS 2 and WS 2 are expensive and toxic, and have high boiling points. These drawbacks encourage to find more sustainable alternatives to the liquid medium used for the preparation of 2D material inks. Water is the best option, but surfactants are necessary for LPE in water, since MoS 2 and WS 2 are hydrophobic. Organic molecules with amphoteric character such as sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium hexadecyl sulfonate (SHS) are selected as suitable candidates for the role. However, the study of these surfactants used in LPE is barely systematically reported. In this work, a detailed investigation is presented on their impact on the LPE of MoS 2 and WS 2 , which are representatives of transition‐metal dichalcogenides. By characterizing and qualifying the products from average number of layers, it is found that all the surfactants work efficiently to exfoliate MoS 2 and WS 2 into few layers, and SHS stabilizes the 2D layers better than the other two. However, in terms of yield and relative surfactant concentration, a real trade‐off is not identified between maximized quantity of exfoliated materials and minimized surfactant concentration, which prompts to select the colloidal ink based on the specific further needs for processing.