SERS activity of self-cleaning silver/titania nanoarray

Silver decorated titania nanorod array (Ag/TiO2 NRA) and nanopore array (Ag/TiO2 NPA) had been designed as surface-enhanced Raman scattering (SERS) active substrate for a sensitive detection application. TiO2 NRA grown on glass slide was fabricated through hydrothermal synthesis process. TiO2 NPA grown on the titanium sheet was fabricated by a two-stepped anodization process. Ag/TiO2 NRA and Ag/TiO2 NPA were formed by depositing silver nanoparticles on TiO2 nanoarray through an electroless deposition process. Ag/TiO2 NRA had smaller silver interparticle gaps and more hot-spots than Ag/TiO2 NPA, exhibiting a higher SERS activity. The analytical enhancement factor was accordingly increased from 1.8 × 105 for Ag/TiO2 NPA up to 7.8 × 105 for Ag/TiO2 NRA. Ag/TiO2 NRA substrate achieved a very low detection limit of 5 × 10−12 M 4-mercaptobenzoic acid as a probe molecule, showing a sensitive SERS detection performance. Ag/TiO2 NRA also conducted photocatalysis decomposition of these adsorbed organic molecules to recover a clean surface under UV irradiation, exhibiting a self-cleaning activity. Such an Ag/TiO2 nanoarray with well-controlled size and shape could be suitably applies as a self-cleaning SERS substrate, showing high reproducibility and cycleability in recycling SERS detection application.