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. 2017 Jun 28;7(7):159.
doi: 10.3390/nano7070159.

Controllable Charge Transfer in Ag-TiO₂ Composite Structure for SERS Application

Yaxin Wang  1 , Chao Yan  2 , Lei Chen  3 , Yongjun Zhang  4 , Jinghai Yang  5   6
Affiliations

Controllable Charge Transfer in Ag-TiO₂ Composite Structure for SERS Application

Yaxin Wang et al. Nanomaterials (Basel). .

Abstract

The nanocaps array of TiO₂/Ag bilayer with different Ag thicknesses and co-sputtering TiO₂-Ag monolayer with different TiO₂ contents were fabricated on a two-dimensional colloidal array substrate for the investigation of Surface enhanced Raman scattering (SERS) properties. For the TiO₂/Ag bilayer, when the Ag thickness increased, SERS intensity decreased. Meanwhile, a significant enhancement was observed when the sublayer Ag was 10 nm compared to the pure Ag monolayer, which was ascribed to the metal-semiconductor synergistic effect that electromagnetic mechanism (EM) provided by roughness surface and charge-transfer (CT) enhancement mechanism from TiO₂-Ag composite components. In comparison to the TiO₂/Ag bilayer, the co-sputtered TiO₂-Ag monolayer decreased the aggregation of Ag particles and led to the formation of small Ag particles, which showed that TiO₂ could effectively inhibit the aggregation and growth of Ag nanoparticles.

Keywords: SERS; TiO2-Ag nanocap array; magnetron sputtering; metal-semiconductor composite.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic diagram of the preparation process for the nanocap arrays of the TiO2/Ag bilayer and the TiO2-Ag monolayer.
Figure 2
Figure 2
SEM images of bilayer TiO2 (10 nm)/Ag t nm (from (a) to (d), t = 10 nm, 20 nm, 30 nm, 40 nm) on the PS template for different thicknesses of the Ag layer. The illustration is the cross-section of the sample.
Figure 3
Figure 3
SERS spectra of (a) PS/TiO2 (10 nm) /Ag (10–40 nm) bilayer; (b) PS/Ag (10–40 nm) monolayer resembled on 200 nm PS template; (c) UV-Vis absorption spectra of PS/TiO2 (10 nm)/Ag (10–40 nm) bilayer; (d) UV-Vis absorption spectra of PS/Ag (10–40 nm).
Figure 4
Figure 4
Column statistics of relative peak intensity and charge transfer for (a) I1391/I1072 of the PS/TiO2 (10 nm)/Ag (10–40 nm) bilayer and (b) I1389/I1071 of the pure PS/Ag (10–40 nm) monolayer.
Figure 5
Figure 5
(a–c) SEM images and (d) SERS spectra of TiO2-Ag (20 nm) with different TiO2 atomic percent contents: (a) 10%; (b) 15%; (c) 25%.
Figure 6
Figure 6
TEM and HRTEM images of (a,c) the TiO2 (10 nm)/Ag (10 nm) bilayer, and (b,d) the co-sputtered TiO2-Ag (20 nm) monolayer.
Figure 7
Figure 7
Reproducibility test for SERS spectra of the TiO2 (10 nm)/Ag (10 nm) bilayer.
See this image and copyright information in PMC

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