Plasma-Engineered Monolayer MoS₂ Films for Ultra-Sensitive Molecular Detection

Recent surface-enhanced Raman spectroscopy (SERS) developments involve using nonmetallic materials as substrates. Molybdenum disulfide (MoS2) is a notable nonmetal semiconductor surface-enhanced Raman scattering (SERS) substrate because of its low cost, abundance, remarkable stability, and considerable chemical activity. However, its limited SERS activity has significantly impeded its advancement in SERS research. Herein, we report a facile and efficient approach for rapidly producing monolayer MoS2 films with adjustable sulfur vacancies via nitrogen plasma treatment. Monolayer MoS2 films exhibit exceptional sensitivity for SERS detection by manipulating the vacancy density. The optimized MoS2 substrate achieved a detection limit of roughly 10–10 M and an enhancement factor of 2.29 × 105 for rhodamine 6G (R6G) probe molecules. We further illustrated that introducing sulfur vacancies can alter the bandgap structure of MoS2, thereby facilitating the separation of internal charge carriers and intensifying interactions with the target components. The vacancy-assisted technique paves the path for the widespread use of semiconductor-based ultrasensitive molecular detection.