Aligned TiO2 nanorod arrays decorated with closely interconnected Au/Ag nanoparticles: Near-infrared SERS active sensor for monitoring of antibiotic molecules in water

Near-infrared (NIR) excited surface-enhanced Raman scattering (SERS) spectroscopy is expected to have more appealing multiple-features than that of traditional ultraviolet (UV) or visible light excitation. Herein, we demonstrate an interesting and highly active hybrid semiconductor-based NIR-SERS sensor via well-aligned TiO2 nanorod arrays (NRAs) decorated with bimetallic Au/Ag nanoparticles (NPs). The obtained Au/Ag NPs-TiO2 NRAs with a stronger absorption capacity in 400–1300 nm region exhibit a remarkable higher NIR-SERS activity than that of monometallic Au or Ag loaded on TiO2 NRAs. Then, the established NIR-SERS sensor can provide ultrasensitive 785 nm laser excited-SERS detection of antibiotic ciprofloxacin and chloramphenicol in real-world water samples with detection limits as low as 10–9 M and 10–8 M, respectively. Interestingly, superior to the present bare metallic nanosubstrates, the Au/Ag NPs-TiO2 NRAs with unique heterostructures can also be served as reusable NIR-SERS sensor due to its excellent photocatalytic degradation ability, and ~84.2% residual SERS activity can be maintained after 5 recycling tests. Therefore, it is believed that the established multifunctional NIR-SERS sensor holds greater potential for ultrasensitive monitoring of diverse biomolecules in many specific applications.