These observations collectively provide clear evidence that the SSCP protocol developed in this study effectively passivates (removes) the sulfur vacancy trap states in 2D WS2, thereby extending the excited state lifetime and slowing the decay dynamics. This explains the observed increase in PL photon intensity and charge carrier mobility. To determine the stoichiometry of untreated and treated WS2 monolayers, we employed the XPS and HAXPES. The W4f and S2p core level photoelectron spectra were analyzed and the ratio of the two core level areas was compared before and after surface treatment (Fig. ). The area of the respective peak was obtained from the fit after background subtraction, using curve fitting. The Scofield ionization cross-section values for the respective core levels were taken into account (1.68 for S2p and 9.80 for W4f). The S/W ratio was found to be 1.81 for the untreated WS2 sample and 2.43 for the sample treated with FSH. The increase in the relative amount of sulfur suggests that the sulfur from the FSH surface treatment fills some of the SVs in the WS2 monolayer. The sulfur 2p core level spectra, as depicted in Fig. , reveal a WS2 binding energy of 162.0 eV (2p3/2 component) for both untreated WS2 and the FSH-treated sample. In the case of treated sample and sample treated with Li-TFSI only, sulfur peaks originating from Li-TFSI are observed. These peaks exhibit similar binding energies, with a minor shift of 0.1 eV between the two samples (2p3/2 component at 168.4 eV and 168.3 eV, respectively), indicating that there is no chemical reaction with Li-TFSI treatment. This is further supported by the HAXPES measurement showing that The S1s peak originating from the WS2 layer (2470.1 eV) is consistent across the untreated WS2, the FSH treated, and the Li-TFSI-only treated sample (Fig. ). The overall XPS spectra of WS2 before and after varied treatments with detailed discussion can be found in Supplementary Note 7, Fig. and the core-level binding energies are summarized in Table . Overall, these XPS and HAXPES data indicate the effective passivation of the new chemical protocol without necessitating the chemical modification of the WS2 monolayer. Specifically, FSH molecules are found to be chemically adsorbed in the presence of two neighboring SVs, and Li+ ions show enhanced stability on the 2D WS2 surface when coordinated by the FSH molecules, under both neutral and charged SV conditions. Our work sets a new benchmark by simultaneously enhancing the optical and electronic properties of 2D WS2. Moreover, our SSCP protocol is sustainable and suitable for integration into device fabrication. This research provides a robust framework for binding chemistry engineering, enabling precise manipulation of the optical and electronic properties of 2D WS2 and paving the way for advanced applications in electronics and optoelectronics.