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Compact Shielding of Graphene Monolayer Leads to Extraordinary SERS-Active Substrate with Large-Area Uniformity and Long-Term Stability.

Liu X, Wang J, Wu Y, Fan T, Xu Y, Tang L, Ying Y - Sci Rep (2015)

Bottom Line: Surface-enhanced Raman scattering (SERS) can significantly boost the inherently weak Raman scattering signal and provide detailed structural information and binding nature of the molecules on the surface.Besides, our fabrication strategy were also capable of fabricating the reproducible SERS sensing spots array, which may serve as a promising high-throughput or multi-analyte sensing platform.Taken together, the graphene-shielded SERS substrate holds great promise both in fundamental studies of the SERS effect and many practical fields.

View Article: PubMed Central - PubMed

Affiliation: College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.

ABSTRACT
Surface-enhanced Raman scattering (SERS) can significantly boost the inherently weak Raman scattering signal and provide detailed structural information and binding nature of the molecules on the surface. Despite the long history of this technology, SERS has yet to become a sophisticated analytical tool in practical applications. A major obstacle is the absence of high-quality and stable SERS-active substrate. In this work, we report a monolayer graphene-shielded periodic metallic nanostructure as large-area uniform and long-term stable SERS substrate. The monolayer graphene acting as a corrosion barrier, not only greatly enhanced stability, but also endowed many new features to the substrate, such as alleviating the photo-induced damages and improving the detection sensitivity for certain analytes that are weakly adsorbed on the conventional metallic substrates. Besides, our fabrication strategy were also capable of fabricating the reproducible SERS sensing spots array, which may serve as a promising high-throughput or multi-analyte sensing platform. Taken together, the graphene-shielded SERS substrate holds great promise both in fundamental studies of the SERS effect and many practical fields.

No MeSH data available.


Related in: MedlinePlus

SERS spectra of CV from the SERS substrate with (a) and without (b) graphene protection at different time points. For the substrate without graphene protection, the weakening of SERS intensities were observed with increasing aerobic exposure duration; (c) The variation of the SERS intensities at 1167 cm−1 cm−1 versus the time of aerobic exposure (normalized the SERS intensities before the exposure).
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f4: SERS spectra of CV from the SERS substrate with (a) and without (b) graphene protection at different time points. For the substrate without graphene protection, the weakening of SERS intensities were observed with increasing aerobic exposure duration; (c) The variation of the SERS intensities at 1167 cm−1 cm−1 versus the time of aerobic exposure (normalized the SERS intensities before the exposure).

Mentions: Besides SERS activity and signal reproducibility, the long-term stability is of most concern in practical applications. Despite its effectiveness in generating SERS, the poor stability of Ag nanostructure (against oxidation in particular) undermines its potential in this aspect. To evaluate the stability of our graphene-shielded SERS substrate against oxidation, the substrate was exposed to air at room temperature after soaking in CV solution and dried. The Raman spectra were collected at different time intervals (Fig. 4a). For comparison, the SERS substrate without graphene coating were tested under same conditions (Fig. 4b). For the uncovered substrate, we noticed the degradation of the signal began after very short exposure. Quantitatively, as indicated in Fig. 4c, the signal dropped to ~60% of its initial value after 2 h and dropped to ~30% after 18 h, indicating severe oxidation occurred on uncovered substrate. In contrast, the CV signal from the graphene-shielded SERS substrate maintained their intensities and fine features. It did not suffer any obvious degradation even after 7 days of exposure. The variation of the intensities were less than 10% in this period. It has been reported that graphene- passivated surface can suppress the oxidation and reserve the plasmonic activity of the metallic nanostructures232436, since the seamless graphene is impenetrable to most of the gases, including O2. An extreme case is shown in Figure S9, in which displays a graphene-shielded SERS substrate stored in ambient conditions for 8 months. The heavy oxidation caused the uncovered silver film turning dark brown, while in the graphene-covered area, it still shined brightly. This may serve as a vivid example of the excellent anti-oxidation ability of the graphene-coating.


Compact Shielding of Graphene Monolayer Leads to Extraordinary SERS-Active Substrate with Large-Area Uniformity and Long-Term Stability.

Liu X, Wang J, Wu Y, Fan T, Xu Y, Tang L, Ying Y - Sci Rep (2015)

SERS spectra of CV from the SERS substrate with (a) and without (b) graphene protection at different time points. For the substrate without graphene protection, the weakening of SERS intensities were observed with increasing aerobic exposure duration; (c) The variation of the SERS intensities at 1167 cm−1 cm−1 versus the time of aerobic exposure (normalized the SERS intensities before the exposure).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663485&req=5

f4: SERS spectra of CV from the SERS substrate with (a) and without (b) graphene protection at different time points. For the substrate without graphene protection, the weakening of SERS intensities were observed with increasing aerobic exposure duration; (c) The variation of the SERS intensities at 1167 cm−1 cm−1 versus the time of aerobic exposure (normalized the SERS intensities before the exposure).
Mentions: Besides SERS activity and signal reproducibility, the long-term stability is of most concern in practical applications. Despite its effectiveness in generating SERS, the poor stability of Ag nanostructure (against oxidation in particular) undermines its potential in this aspect. To evaluate the stability of our graphene-shielded SERS substrate against oxidation, the substrate was exposed to air at room temperature after soaking in CV solution and dried. The Raman spectra were collected at different time intervals (Fig. 4a). For comparison, the SERS substrate without graphene coating were tested under same conditions (Fig. 4b). For the uncovered substrate, we noticed the degradation of the signal began after very short exposure. Quantitatively, as indicated in Fig. 4c, the signal dropped to ~60% of its initial value after 2 h and dropped to ~30% after 18 h, indicating severe oxidation occurred on uncovered substrate. In contrast, the CV signal from the graphene-shielded SERS substrate maintained their intensities and fine features. It did not suffer any obvious degradation even after 7 days of exposure. The variation of the intensities were less than 10% in this period. It has been reported that graphene- passivated surface can suppress the oxidation and reserve the plasmonic activity of the metallic nanostructures232436, since the seamless graphene is impenetrable to most of the gases, including O2. An extreme case is shown in Figure S9, in which displays a graphene-shielded SERS substrate stored in ambient conditions for 8 months. The heavy oxidation caused the uncovered silver film turning dark brown, while in the graphene-covered area, it still shined brightly. This may serve as a vivid example of the excellent anti-oxidation ability of the graphene-coating.

Bottom Line: Surface-enhanced Raman scattering (SERS) can significantly boost the inherently weak Raman scattering signal and provide detailed structural information and binding nature of the molecules on the surface.Besides, our fabrication strategy were also capable of fabricating the reproducible SERS sensing spots array, which may serve as a promising high-throughput or multi-analyte sensing platform.Taken together, the graphene-shielded SERS substrate holds great promise both in fundamental studies of the SERS effect and many practical fields.

View Article: PubMed Central - PubMed

Affiliation: College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.

ABSTRACT
Surface-enhanced Raman scattering (SERS) can significantly boost the inherently weak Raman scattering signal and provide detailed structural information and binding nature of the molecules on the surface. Despite the long history of this technology, SERS has yet to become a sophisticated analytical tool in practical applications. A major obstacle is the absence of high-quality and stable SERS-active substrate. In this work, we report a monolayer graphene-shielded periodic metallic nanostructure as large-area uniform and long-term stable SERS substrate. The monolayer graphene acting as a corrosion barrier, not only greatly enhanced stability, but also endowed many new features to the substrate, such as alleviating the photo-induced damages and improving the detection sensitivity for certain analytes that are weakly adsorbed on the conventional metallic substrates. Besides, our fabrication strategy were also capable of fabricating the reproducible SERS sensing spots array, which may serve as a promising high-throughput or multi-analyte sensing platform. Taken together, the graphene-shielded SERS substrate holds great promise both in fundamental studies of the SERS effect and many practical fields.

No MeSH data available.


Related in: MedlinePlus