Porous rod-shaped Fe₂O₃/Ag/BP: a novel substrate for highly sensitive SERS detection of persistent organic pollutants

A surface enhanced Raman scattering (SERS) substrate of porous rod-shaped ferric oxide (Fe₂O₃) combined with silver nanoparticles (Ag NPs) and black phosphorus (Fe₂O₃/Ag/BP) was fabricated to detect the persistent organic pollutants (POPs) at low concentration. The organic pollutant Rhodamine 6G (R6G) was used as the probe molecule to study the performances of Fe₂O₃/Ag/BP, and 4-chlorobiphenyl (PCB-3) was the target of detection. The limit of detection (LOD) of R6G based on this novel SERS substrate Fe₂O₃/Ag/BP was as low as 1.0 × 10^-15M, which was five orders of magnitude lower than that of Fe₂O₃/Ag (10^-10M). The enhancement factor (EF) of Fe₂O₃/Ag/BP was 6.44 × 10⁸, which was 3.1 times higher than that of porous rod-shaped Fe₂O₃/Ag (2.08 × 10⁸). The Raman signal of R6G based on Fe₂O₃/Ag/BP had a good homogeneity, and the relative standard deviation (RSD) of Raman signal intensities of R6G at 1643 cm^-1was only 5.97%. Furthermore, the Fe₂O₃/Ag/BP substrate exhibited a recyclability through the photocatalytic degradation of R6G. The LOD of PCB-3 based on Fe₂O₃/Ag/BP was 10^-9M. Besides, Fe₂O₃/Ag/BP had a high SERS activity even it was kept in a centrifuge tube without requiring complicated treatment. These results highlight the potential application of Fe₂O₃/Ag/BP for ultra-trace detection of POPs in the environment.