Photoassisted decoration of Ag nanoparticles onto TiO2 nanorod arrays for continuously reusable ultrasensitive SERS sensors

Herein, a hybrid nanoarray-based surface-enhanced Raman scattering (SERS) sensor was developed to obtain dual functionalities of SERS signal amplification and photocatalytic reusability for detecting trace organic pollutants and antibiotic residues in environmental water. The plasmonic metal was created by controlling the formation of Ag nanoparticles (NPs), which were uniformly anchored within rutile TiO₂ nanoarrays (r-TNRs) to form the Ag@r-TNRs platform. The SERS performance of the Ag@r-TNRs platform was obtained by optimizing photo-induced reduction strategy. Crystal violet (CV) and chloramphenicol (CAP) were chosen to assess the SERS behavior of the Ag@r-TNRs platform. The high sensitivity for detecting trace amounts of target molecules of Ag@r-TNRs hybrid nanostructure experienced both local electromagnetic mechanism (EM) and efficient charge transfer (CT). The prepared substrates exhibited ultralow detection (10⁻¹² M for CV and 10⁻¹¹ M for CAP) and high enhancement factors (EF) in the order of 4.9 × 10⁹ and 5.6 × 10⁸ for CV and CAP, respectively. Furthermore, duplex detection of dyes (CV and CAP) was successfully accomplished using Ag@r-TNRs to estimate SERS applications. Thanks to the excellent photocatalytic properties of TiO₂, the layered structures possessed steady and effective ultraviolet (UV) cleaning performance. After UV irradiation for 40 min, 99 % of the CV were completely decomposed at a UV illumination. This SERS substrate can be reused for many times with a determined recovery rate of 93 %. Accordingly, the bifunctional Ag@r-TNRs substrate shows great potential for SERS analysis and photocatalytic performance in water environmental remediation.