Three‐Dimensional TiO₂−Ag Nanopore Arrays for Powerful Photoinduced Enhanced Raman Spectroscopy (PIERS) and Versatile Detection of Toxic Organics

Abstract It is highly desirable to readily detect the residues of toxic organics in the field with a portable device. Herein, we report a photo‐induced enhanced Raman spectroscopy (PIERS) technique combined with a portable Raman approach to detect toxic analytes at trace levels. A new type of TiO₂−Ag nanopore array as a powerful PIERS substrate was fabricated by depositing Ag nanoparticles on TiO₂ nanopores. This semiconductor‐metal three‐dimensional hybrid nanostructure achieved an 8‐fold PIERS enhancement over normal SERS due to the light‐induced charge transfer from TiO₂ to the Ag nanoparticles upon UV irradiation. In particular, this PIERS substrate exhibited excellent detection of a variety of toxic substances. A low concentration of 10⁻⁹ M for antiseptics (Crystal violet) and 10⁻⁵ M for pesticides (carbaryl, phoxim and thiram) could be readily detected by a portable Raman device. Meanwhile, the successful incorporation of plasmonic Ag nanoparticles in TiO₂ nanopores further enhanced the photocatalytic ability and the structure is robust enough for multiple reuse cycles. The demonstrated PIERS technique may become an effective way for enhancing Raman scattering, which has great potential for portable Raman detections.