Defect-Rich Monolayer MoS2 as a Universally Enhanced Substrate for Surface-Enhanced Raman Scattering.

Ruihao Sun,Dongwei Li,Shiyu Sun,Guanchen Xu,Hongyu Gong,Xiu Liang,Jingying Zheng,Guanliang Sun,Dan Wang,Xingshuang Zhang,Yong Li,Meng Gao

doi:10.3390/nano12060896

Abstract

Monolayer 2H-MoS2 has been widely noticed as a typical transition metal dichalcogenides (TMDC) for surface-enhanced Raman scattering (SERS). However, monolayer MoS2 is limited to a narrow range of applications due to poor detection sensitivity caused by the combination of a lower density of states (DOS) near the Fermi energy level as well as a rich fluorescence background. Here, surfaced S and Mo atomic defects are fabricated on a monolayer MoS2 with a perfect lattice. Defects exhibit metallic properties. The presence of defects enhances the interaction between MoS2 and the detection molecule, and it increases the probability of photoinduced charge transfer (PICT), resulting in a significant improvement of Raman enhancement. Defect-containing monolayer MoS2 enables the fluorescence signal of many dyes to be effectively burst, making the SERS spectrum clearer and making the limits of detection (LODs) below 10−8 M. In conclusion, metallic defect-containing monolayer MoS2 becomes a promising and versatile substrate capable of detecting a wide range of dye molecules due to its abundant DOS and effective PICT resonance. In addition, the synergistic effect of surface defects and of the MoS2 main body presents a new perspective for plasma-free SERS based on the chemical mechanism (CM), which provides promising theoretical support for other TMDC studies.

Highlights

IntroductionTwo-dimensional transition metal dichalcogenides (TMDCs) have been very popular semiconductor materials with potential applications in many fields due to their unique structural and physicochemical properties [1–5]
Publisher’s Note: MDPI stays neutralTwo-dimensional transition metal dichalcogenides (TMDCs) have been very popular semiconductor materials with potential applications in many fields due to their unique structural and physicochemical properties [1–5]
Sublimable sulfur powder and molybdenum foil were used to prepare monolayer MoS2 in a chemical vapor deposition (CVD) system, which was an improvement demonstrated in previous works [40,41]

Summary

Introduction

Two-dimensional transition metal dichalcogenides (TMDCs) have been very popular semiconductor materials with potential applications in many fields due to their unique structural and physicochemical properties [1–5]. Semiconductor monolayers of MoS2 are of great interest for applications in electronic sensor devices, energy storage applications, catalytic fields, and composite materials. MoS2 monolayers are substrates for potential applications of surface-enhanced Raman scattering (SERS) based on molecular detection, which strongly depends on the electronic and optoelectronic properties of monolayer MoS2 [6]. The core of SERS research is the preparation of substrates [10,13–16], which requires a perfect balance between enhancement capability, homogeneity, stability, and economy. SERS substrate materials are enhanced by different mechanisms, which are the electromagnetic mechanism (EM) and the chemical mechanism (CM) [17–19]. The EM originates from localized surface plasmon resonance generated by with regard to jurisdictional claims in published maps and institutional affiliations

Methods

Results

Conclusion