In situ controlled growth of well-dispersed gold nanoparticles in TiO2 nanotube arrays as recyclable substrates for surface-enhanced Raman scattering

In this paper, well-aligned Au-decorated TiO2 nanotube arrays with high surface-enhanced Raman scattering (SERS) enhancement were prepared using a facile in situ reduction and controlled growth approach. The gold nanoparticles are well-dispersed and assembled on the mouth surface and the inside of the TiO2 nanotubes without clogging. The structure and optical properties of the Au-decorated TiO2 nanotube arrays have been characterized. The Au-decorated TiO2 nanotube arrays were employed as SERS-active substrates, which exhibit good performance due to long-range coupling between Au nanoparticles, and TiO2-assisted enhanced charge-transfer from Au to Rh6G. The SERS activity of the substrates strongly depends on the crystallite size and level of aggregation. The substrates display significant fluorescence quenching ability and uniform SERS responses throughout the whole surface area. Particularly, good recyclability is shown. The photocatalytic property of Au-decorated TiO2 nanotube array was exploited to recycle the substrate through UV light photocatalytic purification. The experimental results showed that the substrate is featured by high reproducibility and can be used as a highly efficient SERS substrate for multiple detection of different chemical and biological molecules.