The tailored fabrication and advanced characterization of two-dimensional nanostructures of transition-metal dichalcogenides (2D-TMCs), such as MoS₂, WS₂, MoSe₂, and WSe₂ made of a single to few stacked atomic layers, represent hot research topics of extreme significance to the broad (nano)materials science community as these nanomaterials stand out as the inorganic analogues of graphene. 2D-TMCs exhibit unique thickness-dependent properties that make them considerably attractive for several applications, such as photovoltaic devices, lithium-ion batteries, hydrogen-evolving photocatalysts, transistors, and memory devices. However, the production of individually addressable, easily-processable 2D-TMCs with controllable and uniform thickness and lateral dimensions is very challenging. The currently available repertory of 2D-TMCs mostly comprises sheet-like nanostructures with irregular micrometer-scale extended edges derived by liquid-phase exfoliation of corresponding bulk materials or by vapour-phase deposition on solid substrates, which inherently suffer from low chemical and mechanical stability against folding, wrinkling and uncontrolled aggregation when post-synthesis manipulated for device integration. Recently, wet-chemical synthetic approaches have emerged a powerful alternative routes to achieve morphologically and structurally controlled 2D-TMDs in the form of robust freestanding nanostructures with finely adjusted geometric parameters, stabilized by organic ligands bound to their surface and, hence, sufficiently stable in the liquid phase to be safely manipulated and transferred to applications.

In this contribution, we describe an effective liquid-phase synthetic protocol for the synthesis of colloidal 2D-WS₂ and 2D-WSe₂ nanocrystals with tunable platelet- or sheet-like habits via a direct surfactant-assisted pyrolytic route. By adjusting synthetic parameters, the lateral edge sizes and morphology of the nanocrystals can be varied within the sub-50 nm regime. We have monitored the reaction progress by the combination of different techniques of structural-morphological investigation (XRD, SEM, TEM) and spectroscopic measurements. We demonstrate that the developed an easy-handling soft organic-template approach leads to soluble and stable 2D-WS₂ and 2D-WSe₂ nanostructures with high structural and optical quality.