Nano-arrayed Cu2S@MoS2 heterojunction SERS sensor for highly sensitive and visual detection of polystyrene in environmental matrices

The burgeoning issue of micro/nanoplastics in ecosystems underscores an urgent need for advanced detection techniques. Herein, we introduce a novel SERS-based approach using a noble metal-free CuS@MoS heterojunction sensor, which has been meticulously engineered for enhanced sensitivity and stability in the detection of plastic contaminants. This semiconductor heterostructure harnesses the inherent surface plasmon resonance (SPR) effects of CuS and the efficient charge transfer facilitated by the built-in electric field at the CuS@MoS interface, rivaling the performance of noble-metal-based SERS sensors. The CuS@MoS sensors have demonstrated exceptional sensitivity, achieving a detection limit of 10 M with enhancement factor (EF) of 4.46 × 10 for methylene blue and excellent homogeneity with a relative standard deviation (RSD) of merely 10.3 %. The CuS@MoS sensor was utilized for the detection of micro/nanoplastics, specifically polystyrene (PS) particles, by immobilizing the PS particles on the substrate through a combination of droplet surface tension, liquid adsorption, and the particles' own gravitational force. The sensor demonstrated a high sensitivity with the lowest detectable concentration reaching 50 μg/mL for PS particles. And the sensor exhibited a robust linear correlation with a coefficient of determination (R) value of 0.98, indicating a high degree of accuracy and reliability in the detection process. In addition, this sensor not only provides quantitative analysis but also enables their visual identification of micro/nanoplastics. These capabilities open new avenues for the rapid and accurate detection of environmental contaminants, offering a significant leap forward in environmental monitoring and public health risk assessment methodologies.