Nanoconfined MoS2 quantum dots in mesoporous TiO2: a high-performance platform for electrochemical microplastic sensing

The increasing prevalence of microplastic pollution in aquatic environments necessitates the development of sensitive, selective, and rapid detection platforms. Herein, we report the fabrication of a high-performance electrochemical sensor based on nanoconfined MoS₂ quantum dots (QDs) integrated into a mesoporous TiO₂ matrix. The hybrid nanocomposite was synthesized via a template-assisted sol–gel strategy, ensuring uniform dispersion and confinement of MoS₂ QDs (3–6 nm) within TiO₂ mesopores (∼3.5 nm). Structural and morphological analyses confirmed the formation of a highly porous, crystalline framework with preserved mesostructure and enhanced surface area. Electrochemical characterization demonstrated significantly improved redox activity and charge transfer kinetics due to synergistic interactions between the quantum-confined MoS₂ domains and the conductive TiO₂ scaffold. The modified glassy carbon electrodes exhibited excellent sensitivity toward polystyrene (PS) and polypropylene (PP) microplastics across a wide dynamic range (10⁴–10¹⁰ particles per mL), with a limit of detection of 5.0 × 10³ particles per mL. The sensor showed strong selectivity against various ionic and organic interferents, and maintained high analytical performance in complex matrices including seawater, tap water, and simulated environmental samples. Reproducibility and long-term stability were also validated under varying storage conditions. These results highlight the promise of the MoS₂ QD/TiO₂ nanoplatform as a scalable and robust electrochemical system for real-time monitoring of microplastic contaminants in environmental waters.