Solution-Processed MoS 2 Film with Functional Interfaces via Precursor-Assisted Chemical Welding.

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