Solution-Processed MoS₂Film with Functional Interfaces via Precursor-Assisted Chemical Welding

Molybdenum disulfide (MoS2) presents fascinating properties for next-generation applications in diverse fields. However, fully exploiting the best properties of MoS2 in largescale practical applications still remains a challenge due to lack of proper processing methods. Solution-based processing can be a promising route for scalable production of MoS2 nanosheets, but the resulting assembled film possesses an enormous number of interfaces that significantly compromise the intrinsic electrical properties. Herein, we demonstrate the solution processing of MoS2 and subsequent precursor-assisted chemical welding to form defective MoS2-x at the nanosheet interfaces. The formation of defective MoS2-x significantly reduces the electrical contact resistances, and thus the chemically welded MoS2 film exhibits more than 2 orders of magnitude improved electrical conductivity. Furthermore, the chemical welding provides MoS2-x interface induced additional defect originated functionalities for diverse applications such as broadband photodetection over the near-infrared range and improved electrocatalytic activity for hydrogen evolution reactions. Overall, this precursor-assisted chemical welding strategy can be a facile route to produce high-quality MoS2 films with low-quality defective MoS2-x at the interfaces having multifunctionalities in electronics, optoelectronics, and electrocatalysis.