A split-type structure of Ag nanoparticles and AlO@Ag@Si nanocone arrays: an ingenious strategy for SERS-based detection

• Published in: Nanoscale Vol. 12; no. 7; pp. 4359 - 4365
• Main Authors: Wang, Zhen, Zheng, Chunxue, Zhang, Peng, Huang, Zhulin, Zhu, Chuhong, Wang, Xiujuan, Hu, Xiaoye, Yan, Jian
• Format: Journal Article
• Published: 20.02.2020
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c9nr09238b

Herein, we report a facile strategy of combined SERS measurements based on a split-type SERS substrate, which exhibits excellent SERS activity, detection signal reproducibility and chemical stability. The SERS substrate consists of an ordered Al 2 O 3 @Ag@Si nanocone array and Ag nanoparticles (Ag-NPs), both of which are fabricated individually. The Al 2 O 3 @Ag@Si nanocone array is obtained by ion-sputtering Ag on an Si nanocone array and then coating an ultrathin (∼2 nm) Al 2 O 3 dielectric layer via atomic layer deposition (ALD). Ag-NPs are synthesized via the liquid phase method and then immersed in an organic solvent for liquid seal. For the SERS measurement, Ag-NPs are dispersed in a liquid containing the probe molecules and then, they self-assemble on the surface of the Al 2 O 3 @Ag@Si nanocones. Subsequently, the ultrathin Al 2 O 3 dielectric layer separates Ag-NPs from the Ag@Si nanocones, forming massive gap-introduced hot spots. This substrate is sensitive to 1 pM Rhodamine R6G with an average enhancement factor of up to 10 9 , exhibiting excellent SERS activity. Moreover, due to the protection of the Al 2 O 3 dielectric layer and the organic solvent for the Ag@Si nanocones and Ag-NPs against oxidation, the split-type SERS substrate achieves an SERS signal with almost no attenuation after five months, indicating its good chemical stability. A split-type nanostructure based on an ordered array and Ag nanoparticles was fabricated as an SERS substrate with high-density SERS hot spots, which exhibited excellent detection signal reproducibility and chemical stability.