![]() ![]() 7Ĭatalysts that facilitate selective hydrogenation reactions using H 2 are desirable based on atom economy considerations and the formation of water as the only reduction byproduct. For example, the selective hydrogenation of substituted nitroarenes is important for accessing aniline compounds that are useful intermediates in pharmaceutical and agrochemical production. 6 Hydrogenation catalysts that can target one reducible group on a molecule when others are present and accessible are especially important. #TERMINATIONS IN CRYSTALMAKER FREE#3– 5 The near-zero free energy of adsorption of molecular hydrogen on edge and defect sites makes TMDs ideal candidates as active hydrogenation catalysts. Two-dimensional transition metal dichalcogenide (TMD) materials are active catalysts for a broad range of chemical transformations, including the hydrogen evolution reaction, 1 the electrochemical reduction of CO 2, 2 and various hydrotreating and hydrogenation reactions. These mechanistic insights reveal how the various defect structures and configurations on 2-D TMD nanostructures facilitate functional group selectivity through distinct mechanisms that depend upon the adsorption geometry, which may have important implications for the design of new and enhanced 2-D catalytic materials across a potentially broad scope of reactions. At lower sulfur vacancy concentrations on the basal planes, parallel adsorption of the nitroarene is favored, and the nitro group is selectively hydrogenated due to a lower kinetic barrier. At tungsten-terminated edges and on regions of the basal planes having high concentrations of sulfur vacancies, vertical adsorption of the nitroarene is favored, thus facilitating hydrogen transfer exclusively to the nitro group due to geometric effects. Microscopic and computational studies reveal the important roles of sulfur vacancy-rich basal planes and tungsten-terminated edges, which are more abundant in nanostructured 2-D materials than in their bulk counterparts, in enabling the functional group selectivity. Free-standing, colloidal 2H-WS 2 nanostructures containing few-layer nanosheets are shown to catalyze the selective hydrogenation of a broad scope of substituted nitroarenes to their corresponding aniline derivatives in the presence of other reducible functional groups. Here, colloidal 2H-WS 2 nanostructures are used as a model 2-D TMD system to understand how high catalytic activity and selectivity can be achieved for useful organic transformations. Two-dimensional (2-D) TMDs, which contain single- and few-layer nanosheets, are increasingly studied as catalytic materials because of their unique thickness-dependent properties and high surface areas. Transition metal dichalcogenides (TMDs) are well known catalysts as both bulk and nanoscale materials. Free-standing, colloidal 2H-WS2 nanostructures containing few-layer nanosheets are shown to catalyze the selective hydrogenation of a broad scope of substituted nitroarenes to their corresponding aniline derivatives in the presence of other reducible functional groups. Here, colloidal 2H-WS2 nanostructures are used as a model 2-D TMD system to understand how high catalytic activity and selectivity can be achieved for useful organic transformations. ![]() ![]()
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