Enhancement effect of silver nanoparticles decorated titania nanotube array acting as active SERS substrate

Abstract

Silver nanoparticles decorated titania nanotube array (Ag-TiO2 NTA) had been designed as active SERS substrate for a sensitive molecule detection. The Ag nanoparticles are deposited on the gaps and nanotube walls of the tubewall-separated TiO2 NTA to form the independent Ag-TiO2 NTA, alternatively on the nanotube wall surface of the tubewall-connected TiO2 NTA to form the interconnected Ag-TiO2 NTA. The microstructure of TiO2 NTA is more critical to affect the SERS performance rather than the deposition cycles. The analytical enhancement factor was accordingly enhanced from 1.67 × 105 for the interconnected Ag-TiO2 NTA up to 9.44 × 105 for the independent Ag-TiO2 NTA. The microstructure-tailored and Ag deposition level-promoted Ag-TiO2 NTA substrate achieved sensitive detection of 4-mercaptobenzoic acid. The superior SERS performance is caused by synergizing the localized electromagnetic field enhancement of Ag nanoparticles and the charge transfer chemical enhancement of TiO2 NTA along with the light scattering enhancement of vertically aligned nanoarray architecture.