Solution-Processed MoS Film with Functional Interfaces via Precursor-Assisted Chemical Welding.

Molybdenum disulfide (MoS) presents fascinating properties for next-generation applications in diverse fields. However, fully exploiting the best properties of MoS 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 MoS 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 MoS and subsequent precursor-assisted chemical welding to form defective MoS at the nanosheet interfaces. The formation of defective MoS significantly reduces the electrical contact resistances, and thus the chemically welded MoS film exhibits more than 2 orders of magnitude improved electrical conductivity. Furthermore, the chemical welding provides MoS 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 MoS films with low-quality defective MoS at the interfaces having multifunctionalities in electronics, optoelectronics, and electrocatalysis.