Tönu Pullerits

Organic pollutants in aquatic environments pose a threat to ecosystems and human health, a challenge that requires urgent resolution. This urgent threat highlights the need for the development of efficient technologies for pollutant detection and degradation in environmental protection. This study presents the successful fabrication of a composite nanomaterial consisting of Ag nanoparticle-decorated NiFe₂O₄ nanoflowers through a combined strategy of chemical reduction, hydrothermal heat followed by calcination, and physical mixing. The resulting Ag@NiFe₂O₄ composite exhibits a large specific surface area, and its unique flower-like hierarchical structure provides abundant adsorption sites, creating favorable conditions for pollutant enrichment detection and catalytic degradation. Notably, this material demonstrates dual functionality. It enables ultrasensitive detection of rhodamine 6G (R6G) at a minimum detectable concentration of 10⁻⁸ mol/L due to its surface-enhanced Raman scattering (SERS) effect. Moreover, it exhibits excellent photo-Fenton degradation performance, achieving 93.4 % degradation efficiency for organic pollutants within 70 min with H₂O₂ assistance. The charge transfer (CT) mechanism and localized surface plasmon resonance (LSPR) between the Ag@NiFe₂O₄ composite SERS substrate and R6G were revealed through synergistic experimental analysis and density functional theory (DFT) and finite difference time domain (FDTD) calculations, with these synergistic effects significantly enhancing SERS signal response. Simultaneously, the photo-Fenton degradation mechanism in the system was systematically elucidated. In this study, a bifunctional nanomaterial that integrates pollutant detection and degradation capabilities was innovatively developed, offering a novel technical strategy to simultaneously address the “detection-degradation” challenge in aquatic environment remediation.