The Design of WTe<sub>2</sub>/Graphene/Ag NPs Heterostructure for the Improvement of the Chemical Enhancement in SERS
Tianyu Sun, Yang Wu, Heqi Ma, Chao Zhang, Chonghui Li, Baoyuan Man, Cheng Yang, Zhen Li
Abstract
Combining the advantages of metal and two-dimensional (2D) nanomaterials, various 2D/metal composite structures are proposed as surface-enhanced Raman spectroscopy (SERS) substrates. However, the chemical enhancement in the composite structure is usually less responsible for the total enhancement. In this work, we proposed a heterostructure including WTe 2 /graphene/Ag nanoparticles (WTe 2 /Gr/Ag) as an effective platform for SERS. The matching of energy levels facilitates charge transfer (CT) within the composite structure, which in turn significantly improves the chemical enhancement of SERS. Compared with WTe 2 /Ag or Gr/Ag substrate, the SERS signals can be amplified up to 18-fold, and the detection limit could further reduce 3 orders of magnitude. Furthermore, the CT process in the SERS test can be further promoted after introducing the pyroelectric field based on the ferro-electricity of WTe 2 . The enhancement factor of the WTe 2 /Gr/Ag substrate finally reached 1.34 × 10 12 . This work proposes a new idea for the design of highly sensitive SERS sensors.