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Nanohybrids of graphene and two-dimensional (2D) layered transition metal dichalcogenides (TMD) nanostructures can provide a promising substrate for extraordinary surface-enhanced Raman spectroscopy (SERS) due to the combined electromagnetic enhancement on TMD nanostructures via localized surface plasmonic resonance (LSPR) and chemical enhancement on graphene. In these nanohybrid SERS substrates, the LSPR on TMD nanostructures is affected by the TMD morphology. Herein, we report the first successful growth of MoS2 nanodonuts (N-donuts) on graphene using a vapor transport process on graphene. Using Rhodamine 6G (R6G) as a probe, SERS spectra were compared on MoS2 N-donuts/graphene nanohybrids substrates. A remarkably high R6G SERS sensitivity up to 2 × 10−12 M has been obtained, which can be attributed to the more robust LSPR effect than in other TMD nanostructures such as nanodiscs as suggested by the finite-difference time-domain simulation. This result demonstrates that non-metallic TMD/graphene nanohybrids substrates can have SERS sensitivity up to one order of magnitude higher than that reported on the plasmonic metal nanostructures/2D materials SERS substrates, providing a promising scheme for high-sensitivity, low-cost applications for biosensing.
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Cation–π Interaction Assisted Molecule Attachment and Photocarrier Transfer in Rhodamine/Graphene Heterostructures
Abstract Cation–π interactions between molecules and graphene are known to have a profound effect on the properties of the molecule/graphene nanohybrids and motivate this study to quantify the attachment of the rhodamine 6G (R6G) dye molecules on graphene and the photocarrier transfer channel formed across the R6G/graphene interface. By increasing the R6G areal density of the R6G on graphene field‐effect transistor (GFET) from 0 up to ≈3.6 × 1013cm−2, a linear shift of the Dirac point of the graphene from originally 1.2 V (p‐doped) to −1 V (n‐doped) is revealed with increasing number of R6G molecules. This indicates that the attachment of the R6G molecules on graphene is determined by the cation–π interaction between the NH+ in R6G and π electrons in graphene. Furthermore, a linear dependence of the photoresponse on the R6G molecule concentration to 550 nm illumination is observed on the R6G/graphene nanohybrid, suggesting that the cation–π interaction controls the R6G attachment configuration to graphene to allow formation of identical photocarrier transfer channels. On R6G/graphene nanohybrid with 7.2 × 107R6G molecules, high responsivity up to 5.15 × 102A W−1is obtained, suggesting molecule/graphene nanohybrids are promising for high‐performance optoelectronics.
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- PAR ID:
- 10451038
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Interfaces
- Volume:
- 7
- Issue:
- 16
- ISSN:
- 2196-7350
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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