Plasmon Coupling and Efficient Charge Transfer in Rough-Surfaced Au Nanotriangles/MXene Hybrids as an Ultrasensitive Surface-Enhanced Raman Scattering Platform

Abstract

The rational design of Raman substrate materials with prominent electromagnetic enhancement and charge transfer is quite important for surface-enhanced Raman scattering (SERS). Herein, an efficient SERS substrate based on two-dimensional ultrathin Ti3C2T x MXene and rough-surfaced Au nanotriangles (NTs) was successfully prepared for efficient detection of organic molecules due to the synthetic effect of an optimized electromagnetic field and charge transfer. Uniform Au NTs with tunable surface roughness were controllably prepared by selectively depositing of Au on the smooth Au NTs. Due to the large surface area, tunable plasmon resonance, and abundant hotspots on the planar surface, the modified Au NTs showed much better SERS performance than initial Au NTs. By combination of the rough-surfaced Au NTs with MXene, the Ti3C2T x /Au NT hybrids exhibited much better SERS performance than initial Au NTs and Au NTs with a rough surface. The detection limit is down to 10–12 M, and the analytical enhancement factors reach 3.6 × 109 (at 1174 cm–1) on detecting crystal violet excited at 785 nm. This is because the strong plasmon coupling between the in-plane resonance of Au NTs and transversal plasmon resonance of Ti3C2T x MXene around 785 nm can generate an intense interfacial electromagnetic field for amplifying SERS signals. Additionally, the efficient charge transfer between Au NTs, MXene, and molecules also plays an important role in enhancing the SERS performance. This work presents a new insight to develop high-performance SERS substrates based on plasmon.

Plasmon mediated SERS and photocatalysis enhancement in Au nanoparticle decorated 2D-TiSe2

“…The energy difference between the E f of Au and the LUMO level of R6G is 1.7 eV, which is less than the incident photon energy (2.33 eV). Thus the plasmon-induced hot electron can be efficiently transferred from the E f of Au NPs to the LUMO of the R6G molecule [46]. In addition, the energy difference between the E f of TiSe 2 and the LUMO level of R6G is 2 eV, which is less than the incident energy (2.33 eV).…”

Ultrasensitive Trace Detection of Dye Molecules Based on Scanning Microsphere-Coupled Surface-Enhanced Raman Spectroscopy

“…In the listed SERS work, the largest enhancement factor recorded was achieved by a SERS substrate based on two-dimensional ultrathin Ti 3 C 2 T x MXene and rough-surfaced Au nanotriangles at 3.6 × 10 9 (the detection limit of CV molecules is down to 10 −12 M). 38 The highest Raman efficiency reported to date for the microsphere-coupled SERS system, on the other hand, is an enhancement factor ∼10 11 , achieved by combining the refractive optics of silica nanospheres with the plasmonic optics of plasmonic nanostructures. 18 Based on the survey of relevant literature (refer to Section 9 in the Supporting Information for further details), it is evident that our approach holds a clear advantage in terms of the achieved Raman enhancement efficiency.…”

“…A majority of research endeavors have focused on designing and producing SERS substrates with diverse nanostructures to optimize the near-field electromagnetic field strength for high performance. In the listed SERS work, the largest enhancement factor recorded was achieved by a SERS substrate based on two-dimensional ultrathin Ti 3 C 2 T x MXene and rough-surfaced Au nanotriangles at 3.6 × 10 9 (the detection limit of CV molecules is down to 10 –12 M) . The highest Raman efficiency reported to date for the microsphere-coupled SERS system, on the other hand, is an enhancement factor ∼10 11 , achieved by combining the refractive optics of silica nanospheres with the plasmonic optics of plasmonic nanostructures …”

Micromolding-Assisted Production of SERS-Active Microcylinders for Size- and Charge-Selective Molecular Detection

“…Even though the Raman signal is typically weak, 1 metal nanostructures can remarkably enhance it by localizing electromagnetic fields near the metal surfaces, a phenomenon known as surface-enhanced Raman scattering (SERS). 2−4 For SERS optimization, metal nanostructures are meticulously designed to include sharp tips, 5−7 rough surfaces, 8,9 or nanoscale gaps. 10−14 It has been reported that two-dimensional inorganic materials show chemical enhancement of Raman signals despite relatively low degree, which improves chemical stability and biocompatibility in comparison with conventional metallic SERS substrates.…”

“…Raman analysis, a nondestructive and label-free method, is highly effective for molecular identification. Even though the Raman signal is typically weak, metal nanostructures can remarkably enhance it by localizing electromagnetic fields near the metal surfaces, a phenomenon known as surface-enhanced Raman scattering (SERS). − For SERS optimization, metal nanostructures are meticulously designed to include sharp tips, − rough surfaces, , or nanoscale gaps. − It has been reported that two-dimensional inorganic materials show chemical enhancement of Raman signals despite relatively low degree, which improves chemical stability and biocompatibility in comparison with conventional metallic SERS substrates. − As such, SERS serves as a potent tool for label-free molecular detection of even minuscule amounts of molecules, making it widely studied in fields such as environmental monitoring − and food safety. − However, the application of SERS does face some challenges, particularly in relation to potential surface contamination. The metal surfaces often undergo surface passivation due to the irreversible adsorption of unwanted adhesive molecules present in real samples. − This issue severely restricts the access of target molecules and, consequently, leads to a substantial decrease in SERS performance.…”