Sulfur Vacancy-Rich MoS2 Flower-Like Microsphere with Synchronously Tunable Electromagnetic and Chemical Effects for Boosting Semiconductor SERS

Abstract

Combined contribution of electromagnetic and chemical effects and their synchronous tuning are an effective strategy for constructing semiconductor surface-enhanced Raman scattering (SERS) substrates with ultra-high sensitivity. In this work, a sulfur vacancy-rich MoS₂ flower-like microsphere is successfully prepared for the first time through the combination of morphology regulation and defect engineering strategies, achieving a synchronous contribution of electromagnetic and chemical effects to SERS enhancement. SERS enhancement factor is as high as 2.54 × 10⁸, which represents the highest sensitivity among the currently reported semiconductor SERS-active substrates. The theoretical calculations and experiments elucidate the observed enhancement activity and the synchronous enhancement mechanism of electromagnetic and chemical effects. The unique flower-like structures of MoS₂ can induce Mie resonance by multiple reflection and scattering of incident light in the cavity structure, which realizes a strong electromagnetic enhancement effect. Meanwhile, a high-efficient carrier separation in substrate and a multiple-channel charge transfer mode between substrate and analyte can be achieved by means of abundant surface sulfur-vacancy defects, which provide a strong chemical enhancement effect for target analyte. This work opens up a new idea and perspective for constructing supersensitive semiconductor SERS sensors, ultimately advancing practical application of semiconductor SERS technology.