Two-dimensional van der Waals Heterostructures for Synergistically Improved Surface Enhanced Raman Spectroscopy

TL;DR

This paper introduces van der Waals heterostructures of 2D materials to improve SERS substrates, achieving higher sensitivity, reusability, and reduced fluorescence background through synergistic effects of BN and graphene.

Contribution

It demonstrates a novel 2D heterostructure design that enhances SERS performance and reusability by combining charge transfer, chemical enhancement, and protective layers.

Findings

Enhanced SERS sensitivity via graphene's chemical enhancement.

Reduced fluorescence background through charge transfer in BN-graphene heterostructures.

Reusability of substrates after high-temperature regeneration.

Abstract

Surface enhanced Raman spectroscopy (SERS) is a precise and non-invasive analytical technique that is widely used in chemical analysis, environmental protection, food processing, pharmaceutics, and diagnostic biology. However, it is still a challenge to produce highly sensitive and reusable SERS substrates with minimum fluorescence background. In this work, we propose the use of van der Waals heterostructures of two-dimensional materials (2D materials) to cover plasmonic metal nanoparticles to solve this challenge. The heterostructures of atomically thin boron nitride (BN) and graphene provide synergistic effects: (1) electrons could tunnel through the atomically thin BN, allowing the charge transfer between graphene and probe molecules to suppress fluorescence background; (2) the SERS sensitivity is enhanced by graphene via chemical enhancement mechanism (CM) in addition to electromagnetic field mechanism (EM); (3) the atomically thin BN protects the underlying graphene and Ag nanoparticles from oxidation during heating for regeneration at 360 {\deg}C in the air so that the SERS substrates could be reused. These advances will facilitate wider applications of SERS, especially on the detection of fluorescent molecules with higher sensitivity.