Se-doped MoS₂ with aggregation-induced emission effect for the detection of Hg²

In this work, MoS₂ was structurally modified through a combination of Se doping and tetraphenylethylene (TPE) with aggregation-induced emission (AIE) effect to obtain the TPE@Se-MoS₂ composite. Se doping induces lattice strain and sulfur vacancies, which can increase active site density and accelerate electron transfer kinetics. TPE incorporation introduces fluorescence property, as well as modifying the surface charge and dispersion state through its aggregation in aqueous media, further facilitating substrate-catalyst interactions. The combination of these effects results in a marked enhancement of the peroxidase-like activity of TPE@Se-MoS₂. Furthermore, according to the hard-soft-acid-base (HSAB) theory, Hg²⁺ can form strong covalent bonds with the S and Se species in the material, thereby triggering and enhancing the oxidase-like activity of TPE@Se-MoS₂. Meanwhile, due to the inner filter effect (IFE), the addition of Hg²⁺ also quenched the intrinsic fluorescence of TPE@Se-MoS₂ at 445 nm. Consequently, the dual-wavelength fluorometric detection of Hg²⁺ was achieved with a linear range of 0.1-7 μM and a detection limit of 0.018 μM. Finally, the developed method was successfully applied to the determination of Hg²⁺ in environmental water and soil samples, with recoveries ranging from 88.4% to 118.2% and relative standard deviations below 5%. This work provides a potential platform for Hg²⁺ detection in environmental samples.