Surface-enhanced Raman spectroscopy chips based on two-dimensional materials beyond graphene

Abstract

Surface-enhanced Raman spectroscopy (SERS) based on two-dimensional (2D) materials has attracted great attention over the past decade. Compared with metallic materials, which enhance Raman signals via the surface plasmon effect, 2D materials integrated on silicon substrates are ideal for use in the fabrication of plasmon-free SERS chips, with the advantages of outstanding fluorescence quenching capability, excellent biomolecular compatibility, tunable Fermi levels, and potentially low-cost material preparation. Moreover, recent studies have shown that the limits of detection of 2D-material-based SERS may be comparable with those of metallic substrates, which has aroused significant research interest. In this review, we comprehensively summarize the advances in SERS chips based on 2D materials. As several excellent reviews of graphene-enhanced Raman spectroscopy have been published in the past decade, here, we focus only on 2D materials beyond graphene, i.e., transition metal dichalcogenides, black phosphorus, hexagonal boron nitride, 2D titanium carbide or nitride, and their heterostructures. We hope that this paper can serve as a useful reference for researchers specializing in 2D materials, spectroscopy, and diverse applications related to chemical and biological sensing.

New Trends in Nanoarchitectured SERS Substrates: Nanospaces, 2D Materials, and Organic Heterostructures

“…novel 2D layered materials. [16] Graphene was the first 2D material that demonstrated enhancement of the Raman signal. [76] Since then, several 2D materials have been applied up to date.…”

“…[77][78][79] The ease of preparation by exfoliation or chemical techniques in combination with relatively low cost justifies further SERS studies of 2D layered materials despite their moderate EF (Table 2). [16,77,[80][81][82][83] 2D materials such as transition metal dichalcogenides (TMDs), black phosphorus (BP), hexagonal boron nitride (h-BN), and 2D titanium carbide or nitride (MXenes) have been used as SERS substrates. [78] Because of the low cost, simple preparation, large specific surface area, outstanding optical properties, and good biocompatibility, the application of these materials could bring transformative changes to plasmonic devices.…”

“…[78] Because of the low cost, simple preparation, large specific surface area, outstanding optical properties, and good biocompatibility, the application of these materials could bring transformative changes to plasmonic devices. [16,78] In contrast to common noble-metals plasmonic substrates, where EM enhancement is dominant, [21] in 2D materials, the CM mechanism is more important. [16,78,79] While the mechanism is not clearly understood, three scenarios are possible: 1) CT due to the resonance of the incident beam with excitation from the substrate to analyte molecule; 2) a molecular resonance mechanism, in which the incident beam is resonant with a molecular excitation; and 3) an enhancement due to nonresonant interactions between the surface and the adsorbate.…”

“…[16,78] In contrast to common noble-metals plasmonic substrates, where EM enhancement is dominant, [21] in 2D materials, the CM mechanism is more important. [16,78,79] While the mechanism is not clearly understood, three scenarios are possible: 1) CT due to the resonance of the incident beam with excitation from the substrate to analyte molecule; 2) a molecular resonance mechanism, in which the incident beam is resonant with a molecular excitation; and 3) an enhancement due to nonresonant interactions between the surface and the adsorbate. Therefore, the chemical and electronic structure of both the 2D substrate and the analyte are key factors in achieving high SERS efficacy.…”

“…Other metals including copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), etc., have also been used to obtain higher SERS sensitivity and a lower limit of detection (LoD), reducing the commercialization costs even though most reports have mainly used Au or Ag for SERS substrates. [3,10,11,15] However, the discovery of new 2D nanomaterials from graphene, [16] has revolutionized SERS development, due to the cheaper cost of raw materials, and the simpler, large-scale, and more reproducible preparation methods such as exfoliation or chemical vapor deposition. [17] Transition metal dichalcogenides (TMDs), black phosphorus (BP), hexagonal boron nitride (h-BN), and 2D titanium carbide or nitride (MXenes) have been introduced as promising SERS platforms.…”