Defect Engineering of Two‐Dimensional Molybdenum Disulfide

Two‐dimensional (2D) molybdenum disulfide (MoS₂) holds great promise in electronic and optoelectronic applications owing to its unique structure and intriguing properties. The intrinsic defects such as sulfur vacancies (SVs) of MoS₂ nanosheets are found to be detrimental to the device efficiency. To mitigate this problem, functionalization of 2D MoS₂ using thiols has emerged as one of the key strategies for engineering defects. Herein, we demonstrate an approach to controllably engineer the SVs of chemically exfoliated MoS₂ nanosheets using a series of substituted thiophenols in solution. The degree of functionalization can be tuned by varying the electron‐withdrawing strength of substituents in thiophenols. We find that the intensity of 2LA(M) peak normalized to A_1g peak strongly correlates to the degree of functionalization. Our results provide a spectroscopic indicator to monitor and quantify the defect engineering process. This method of MoS₂ defect functionalization in solution also benefits the further exploration of defect‐free MoS₂ for a wide range of applications.