Recent Advances in 2D Inorganic Nanomaterials for SERS Sensing

Research summary

Surface-enhanced Raman spectroscopy (SERS) is an analytical technique capable of detecting chemicals and biomolecules at extremely low concentrations by dramatically amplifying the otherwise weak Raman scattering signal. Since its discovery in the 1970s, most SERS work has relied on noble-metal nanostructures such as gold and silver, which enhance signals mainly through an electromagnetic effect. In recent years, 2D inorganic materials — including graphene, boron nitride, semiconducting metal oxides, and transition metal chalcogenides — have drawn increasing interest as SERS substrates because their properties change with layer thickness and they contribute a complementary “chemical” enhancement mechanism, based on charge transfer between the material and the molecule being detected. This review brings together recent developments in this area, covering the underlying theory, material-specific enhancement mechanisms, and the practical outlook for real-world SERS sensors.

What the study examined

• The fundamental theory of SERS, including the electromagnetic and chemical enhancement mechanisms
• How different classes of 2D inorganic nanomaterials — graphene, hexagonal boron nitride, semiconducting metal oxides, and transition metal chalcogenides such as MoS2, ReS2, and WSe2 — contribute to SERS enhancement
• Material-specific effects such as dipole interactions in boron nitride, charge-transfer processes in transition metal chalcogenides, and functional-group-based enhancement in MXenes
• The practical requirements — material purity, layer control, robustness, and wafer-scale compatibility — for translating these materials into working SERS-based chemical sensors

Main findings

The review shows that 2D inorganic materials enhance Raman signals through mechanisms distinct from, and complementary to, those of traditional metal substrates. Chemical enhancement in these materials is closely tied to charge-transfer interactions between the 2D surface and the probe molecule, and this interaction depends strongly on structural features specific to each material — for example, the number of layers in graphene and transition metal chalcogenides, structural disorder and phase transitions in MoS2, or the in-plane dipole moment of WSe2 monolayers.

Across the surveyed literature, the authors note that most demonstrations of 2D-material SERS sensing remain lab-scale results. Moving toward practical, portable sensors will require materials that can be produced reproducibly, at high purity, and with wafer-level compatibility, alongside properties such as robustness, flexibility, and freedom from interference during quantitative measurements.

Why it matters

By consolidating the mechanisms and material classes behind 2D-material SERS sensing in one place, the review gives researchers a framework for choosing and engineering 2D substrates for specific chemical-detection tasks, and it flags materials synthesis and device integration — rather than sensitivity itself — as the main bottleneck standing between current lab research and deployable SERS sensors for applications such as environmental monitoring and medical diagnostics.