Colloidal Nanostructures of Transition-Metal Dichalcogenides

Abstract

Metrics & MoreArticle Recommendations CONSPECTUS: Layered transition-metal dichalcogenides (TMDs) are intriguing two-dimensional (2D) compounds where metal and chalcogen atoms are covalently bonded in each monolayer, and the monolayers are held together by weak van der Waals forces. Distinct from graphene, which is chemically inert, layered TMDs exhibit a wide range of electronic, optical, catalytic, and magnetic properties dependent upon their compositions, crystal structures, and thicknesses, which make them fundamentally and technologically important. TMD nanostructures are traditionally synthesized using gas-phase chemical deposition methods, which are typically limited to small-scale samples of substrate-bound planar materials. Colloidal synthesis has emerged as an alternative synthesis approach to enable the scalable synthesis of free-standing TMDs. The judicious selection of precursors, solvents, and capping ligands together with the optimization of synthesis parameters such as concentrations and temperatures leads to the fabrication of colloidal TMD nanostructures exhibiting tunable properties. In addition, understanding the formation and transformation of TMD nanostructures in solution contributes to the discovery of important structure−function relationships, which may be extendable to other anisotropic systems.In this Account, we summarize recent progress in the colloidal synthesis, characterization, and applications of TMD nanostructures with tunable compositions, structures, and thicknesses. On the basis of the preparation of Mo-and W-based disulfide, diselenide, and ditelluride nanostructures, we discuss examples of phase engineering where various metastable TMD compounds can be directly accessed at low temperatures in solution. We also analyze the chemistry involved in broadly tuning the composition across the MoSe 2 −WSe 2 , WS 2 −WSe 2 , and MoTe 2 −WTe 2 solid solutions as well as atomic-level microscopic characterization and the resulting composition-tunable properties. We then highlight how the high densities of defects in the colloidally synthesized TMD nanostructures enable unique catalytic properties, including their ability to facilitate the selective hydrogenation of substituted nitroarenes using molecular hydrogen. Finally, using this library of colloidal TMD nanostructures as substrates, we discuss the pathways by which noble metals deposit onto them in solution. We highlight the importance of the relative strengths of the interfacial metal−chalcogen bonds in determining the sizes and morphologies of the deposited noble metal components. These synthesis capabilities for colloidal TMD nanostructures, which have been generalized to a library of composition-tunable phases, enable new systematic studies of structure−property relationships and chemical reactivity in this important class of 2D materials.

Intercalation‐Driven Defect‐Engineering of MoS2for Catalytic Transfer Hydrogenation

“…Typically, electronwithdrawing by halogen substituents can activate nitro-group due to the weakened π coupling with the benzene ring, leading to the high efficiency of hydrogenation. By contrast, the electrondonation by substituents, e.g., CH 3 , CH 2 CH 3 , OH, OCH 3 , and OCH 2 CH 3 , resulted in the relatively lower activity as compared with halogen-substituted nitroarenes (Table 1, entries [10][11][12][13][14]. The conversion of p-nitroanisole and p-nitrophenyl ethyl ether was only 41% and 59% respectively (Table 1, entries 13 and 14).…”

“…

anion vacancies in TMDs are capable of dissociating substrates and stabilizing surface-bound intermediates to enable efficient catalytic (de)hydrogenation. [11][12] Introducing defect-rich TMDs as the costefficient and noble-metal-free catalysts has made witnessed progresses in the hydrogenation of nitroarenes toward valueadded aniline derivatives, [13][14][15] which is industrially significant for manufacturing dyes, pigments, pharmaceuticals, and agrochemicals. [16][17][18] However, challenge is still remained in safety and eco-friendliness due to the use of high-pressure hazardous H 2 .

…”

Two-dimensional copper based colloidal nanocrystals: synthesis and applications

“…The advances in colloidal synthesis approaches over the past decade have resulted in unprecedented synthesis control over several solution-processed two-dimensional (2D) nanocrystals (NCs), with layered and non-layered structures, that display extraordinary physical and optoelectronic properties. [1][2][3][4][5][6][7][8] In the layered structures, each monolayer with a covalently bonded atomic arrangement is vertically stacked together via the weak van der Waals (vdW) force. Using colloidal approaches, a range of layered transition metal chalcogenides of ME 2 (M = Mo, W, Zr, Hf ), SnS, GeS, InS, and GaS have been successfully synthesised.…”

Structural control in the nanoassembly of the tungsten and molybdenum dithiolene complex analog

“…Currently, nanostructures of molybdenum and tungsten-based complexes have attracted special attention from chemists because of their potential applications in catalysis, energy storage and harvesting, magnetism, optics, and biomedicine. [22][23][24][25] Furthermore, water soluble molybdenum and tungsten dithiolene complexes are useful as pharmaceutical or radiopharmaceutical agents. Although several water-soluble transition metal dithiolenes have been reported, only a few molybdenum and tungsten dithiolene complexes are known.…”