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Open AccessArticle

Simultaneous Thermal Stability and Ultrahigh Sensitivity of Heterojunction SERS Substrates

1
Institute of Advanced Materials & Technology, University of Science and Technology Beijing, Beijing 100083, China
2
College of Engineering, University of North Texas, Denton, TX 76207, USA
3
Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
4
Jiangsu Key Laboratory for Premium Steel Material, Nanjing Iron and Steel Co., Ltd., Nanjing 210035, China
*
Authors to whom correspondence should be addressed.
Nanomaterials 2019, 9(6), 830; https://doi.org/10.3390/nano9060830
Received: 5 May 2019 / Revised: 19 May 2019 / Accepted: 21 May 2019 / Published: 31 May 2019
This paper reports the design of Ag-Al2O3-Ag heterojunctions based on Ag nanorods (AgNRs) and their applications as thermally stable and ultrasensitive substrates of surface-enhanced Raman scattering (SERS). Specifically, an ultrathin Al2O3 capping layer of 10 nm on top of AgNRs serves to slow down the surface diffusion of Ag at high temperatures. Then, an additional Ag layer on top of the capping layer creates AgNRs-Al2O3-Ag heterojunctions, which lead to giant enhancement of electromagnetic fields within the Al2O3 gap regions that could boost the SERS enhancement. As a result of this design, the SERS substrates are thermally stable up to 200 °C, which has been increased by more than 100 °C compared with bare AgNRs, and their sensitivity is about 400% that of pure AgNRs. This easy yet effective capping approach offers a pathway to fabricate ultrasensitive, thermally stable and easily prepared SERS sensors, and to extend SERS applications for high-temperature detections, such as monitoring in situ the molecule reorientation process upon annealing. Such simultaneous achievement of thermal stability and SERS sensitivity represents a great advance in the design of SERS sensors and will inspire the fabrication of novel hetero-nanostructures. View Full-Text
Keywords: surface-enhanced Raman scattering (SERS); glancing angle deposition (GLAD); heterojunctions; SERS sensitivity; thermal stability surface-enhanced Raman scattering (SERS); glancing angle deposition (GLAD); heterojunctions; SERS sensitivity; thermal stability
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MDPI and ACS Style

Ma, L.; Wang, J.; Huang, H.; Zhang, Z.; Li, X.; Fan, Y. Simultaneous Thermal Stability and Ultrahigh Sensitivity of Heterojunction SERS Substrates. Nanomaterials 2019, 9, 830.

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