A core-shell-satellite structured Fe3O4@MIL-100(Fe)@Ag SERS substrate with adsorption, detection, degradation and recovery functionalities for selective detection of cationic dyes

Recyclable surface-enhanced Raman scattering (SERS) substrates are beneficial to cost reduction and environmental protection and have always been a research topic with great interest. Herein, a core–shell-satellite structured SERS substrate Fe3O4@MIL-100(Fe)@Ag nanoparticles (FMAs) was developed, possessing versatile functionalities of adsorption, detection, degradation and recovery. Results showed that the MIL-100(Fe) with peroxidase-like activity as shell catalyzed H2O2 to generate ·OH degraded pollutants within 5 min to achieve substrate cleaning, making FMAs recyclable for at least 5 times to sequentially detect different cationic dyes with high sensitivity, having low detection limits as low as 15.24 ng/L, 387.87 ng/L and 0.71 ng/g for crystal violet in deionized water, aquaculture water and tilapia, respectively. FMAs also showed good uniformity, reproducibility and stability, with a relative standard deviation value of 5.58 % between substrates and about 78.60 % SERS activity remained after 20 d storage at 4 °C. This FMAs substrate thus has great potential for selective detection of trace cationic dyes in food or other fields.