Intercalation‐Driven Defect‐Engineering of MoS₂for Catalytic Transfer Hydrogenation

Abstract

Crystal defects are pivotal to boosting catalytic performance and an in‐depth understanding of the working mechanism of transition‐metal chalcogenides (TMDs), but their facile and controllable engineering are yet challenging. Herein, a new route is introduced to engineer defects on MoS2 via in situ intercalation during its hydrothermal preparation, accomplishing the efficient catalytic transfer hydrogenation (CTH) of nitroarenes. The combination of multiple structural characterizations demonstrates that the density of S defects can be tuned by the intercalation of ammonium and dimethylamine cations due to lattice strain/distortion and ligand substitution. As a proof of concept, the defect‐dependent catalytic performance is evidenced in the CTH of nitrobenzene with isopropanol, highlighting the significance of coordinatively unsaturated Mo sites in generating reactive chemisorbed H for subsequent hydrogenation. The good efficiency of defective MoS2 within a broad substrate scope further verifies the promise of the intercalation‐driven defect‐engineering strategy for designing TMDs‐based catalysts.

Selective Electrocatalytic Hydrogenation of Nitroarenes on Interlayer-Expanded MoS2

“…As summarized in Figure c, CN Mo–S dropped from 6.0 in MoS 2 to 4.8 in MoS 2 -DMA, consistent with the change in molar S/Mo ratios ( n S / n Mo ) determined by ICP-OES and EDS. Abundant V S are thereby identified after the intercalation of DMA cations into MoS 2 , probably due to the lattice strain/distortion and ligand substitution . Typically, V S can be formed to relieve the lattice strain in the expanded lattice of MoS 2 ; meanwhile, some Mo–S bonds are destroyed due to the strong coordination between Mo centers and N-containing intercalants.…”

“…38 The corresponding Fourier transform results in R space were further analyzed for the extended X-ray probably due to the lattice strain/distortion and ligand substitution. 41 Typically, V S can be formed to relieve the lattice strain in the expanded lattice of MoS 2 ; 42 meanwhile, some Mo− S bonds are destroyed due to the strong coordination between Mo centers and N-containing intercalants. Accordingly, the EPR profile of MoS 2 -DMA demonstrated a stronger signal (g = 2.02) than MoS 2 (Figure 2d), associated with the enriched V S .…”

“…Moreover, abundant V S favors the chemisorption and activation of nitro groups on the surrounding Mo sites with unsaturated coordination, which has been well-identified in previous reports. 41,45 Therefore, we propose a working mechanism for the ECH (Figure 4c). At first, H 2 O discharges on the V S -rich edge sites of MoS 2 -DMA through a Volmer step to form H ads , and the nitro group of p-NSE is simultaneously activated on the coordinatively unsaturated Mo sites due to the strengthened chemisorption.…”

Alloying promotion of Pd-based metallenes in electrocatalytic hydrogenation of functionalized nitroarenes

“…[1][2][3][4] For example, the hydrogenation of nitroarenes to aniline derivatives, a key process for manufacturing medicine, dyes, spices, and other chemicals, [5][6][7] is challenged by the trade-off between activity and selectivity in thermo-catalysis owing to the difficult control over pathways under heated and pressurized conditions. 8,9 ECH enables a more controllable alternative to accommodate such multi-electron transfer processes via the convenient and accurate modulation of potential or current on working electrodes. 8,10,11 Thereinto, electrocatalysts with elaborately designed surface congurations usually play a paramount role in promoting an efficient transformation via target routes.…”

Carrier and Phonon Dynamics in Multilayer WSe2 Captured by Extreme Ultraviolet Transient Absorption Spectroscopy

“…Semiconducting transition metal dichalcogenides (TMDs) have attracted much scientific interest in recent years as an active material of photocatalytic systems, photovoltaics, optoelectronics, and photodetectors based on their unique optical, spin, and electronic properties. − TMDs, generally expressed as MX 2 (M = transition metal, such as Mo and W, and X = chalcogen, such as S, Se, and Te), are two-dimensional nanomaterials composed of covalently bonded X–M–X sheets that are stacked together through van der Waals interactions. Each layer may harbor defects, which can serve as a tool for modifying electronic properties, optical responses, and catalytic activities. − Moreover, due to the layered structure, they show important layer-dependent properties, e.g., the crossover from an indirect band gap in multiple-layered TMDs to a direct band gap in a monolayer with spin–valley coupling …”