Constructing recyclable SERS platform based on peroxidase-like Cu2O/g-C3N4/Ag composites for sensitive sensing of fungicides

In this work, we proposed a straightforward self-assembly and in-situ deposition protocol to construct Cu 2 O/g-C 3 N 4 /Ag composites, which demonstrated peroxidase-like attribute and exceptional SERS activity. These composites proved to be an effective SERS analysis tool for detecting organic fungicides like malachite green (MG) and crystal violet (CV). Remarkably, they achieved detection limits as low as 10 −9  M in DI water as well as fish pond water, and exhibited a strong linear correlation between logarithmic concentrations and SERS intensities (R 2  ≥ 0.97). Beyond that, with the aid of hydrogen peroxide (H 2 O 2 ), the peroxidase-like Cu 2 O/g-C 3 N 4 /Ag composites rapidly degraded MG and CV molecules within just 5 min. Furthermore, their practical reusability based on the peroxidase-like reaction was proved by high SERS performance across 5 detection cycles. These results emphasize the immense potential of Cu 2 O/g-C 3 N 4 /Ag in SERS-based trace fungicide detection and suggest future applications in ecological restoration through peroxidase-like reactions.