TiO₂ Thickness-Dependent Charge Transfer in an Ordered Ag/TiO₂/Ni Nanopillar Arrays Based on Surface-Enhanced Raman Scattering

Abstract

In this study, an ordered Ag/TiO2/Ni nanopillar arrays hybrid substrate was designed, and the charge transfer (CT) process at the metal–semiconductor and substrate–molecule interface was investigated based on the surface-enhanced Raman scattering (SERS) spectra of 4-Aminothiophenol (PATP) absorbed on the composite system. The surface plasmon resonance (SPR) absorption of Ag changes due to the regulation of TiO2 thickness, which leads to different degrees of CT enhancement in the system. The CT degree of SERS spectra obtained at different excitation wavelengths was calculated to study the contribution of CT enhancement to SERS, and a TiO2 thickness-dependent CT enhancement mechanism was proposed. Furthermore, Ag/TiO2/Ni nanopillar arrays possessed favorable detection ability and uniformity, which has potential as a SERS-active substrate.

Keywords

• TiO₂-thickness dependence
• charge transfer
• SPR
• interface
• SERS