Nanoconfined Solvothermal Synthesis of Defective 1T‐MoS ₂ Monolayers with High Electrocatalytic Performance

Synthesizing 2D nanosheets in a controlled and scalable manner remains a significant challenge. Here, a nanoconfined solvothermal synthesis is presented of metallic phase MoS₂ (1T-MoS₂) monolayers at kilogram scale. The MoS₂ nanosheets exhibit a remarkably high monolayer ratio of 97%, a 1T content of ≈89%, and a well-defined average lateral size ranging from ≈100 nm to 1.0 µm, with a narrow size distribution. Moreover, these nanosheets possesses abundant surface defects, and the defect density can be regulated in situ through changing the reaction conditions. Intriguingly, the monolayer MoS₂ nanosheets demonstrate good dispersibility and high stability in various solvents, including water, ethylene glycol, dimethyl formamide and others, with a high concentration of up to 1.0 mg mL^-1. They are also proven to be high-performance electrocatalysts for the hydrogen evolution reaction, exhibiting an overpotential of 315 mV at an industrial current density of 1000 mA cm^-2 and maintaining constant current densities of 500 mA cm^-2 for up to 100 h, surpassing the performance of the commercial 20 wt.% Pt/C. Our strategy represents a significant advancement in the controlled synthesis of monolayer MoS₂ at scale, providing a promising avenue for the practical application of 2D materials.