Atomic Basal Defect-Rich MoS2 by One-Step Synthesis and Mechanism Exploration

Abstract

Two-dimensional molybdenum disulfide (2D MoS₂) shows great promise as a surface-enhanced Raman scattering (SERS) substrate due to its strong exciton resonance. However, the inert basal plane limits the performance of SERS. In this work, a strategy is proposed for the one-step synthesis of atomically basal defect-rich MoS₂. The study first reveals that NaCl plays a two-stage role in the growth process, where NaCl initially promotes the rapid growth of large MoS₂ as previously reported, and then promotes the formation of atomic basal defects dominated by single sulfur vacancies. Additionally, spectral changes induced by modulation of experimental parameters and density function theory calculation show that defect generation occurs during cooling. Meanwhile, the ratio of $E_{2g}^1$ to A_1g in defect-rich MoS₂ exhibits different variation trends compared with pristine MoS₂ in power-dependent Raman, and the ratio increases with increasing basal defects. In SERS tests, the limit of detection for rhodamine 6G reached 10⁻⁹ m, which is comparable to the performance of conventional noble metal SERS substrate. The activation strategy of the inert basal plane is applicable to other 2D transition metal dichalcogenides, and further has the potential to enhance performance in other domains, such as SERS and hydrogen evolution reactions.