Highly specific detection of PET NPs using an amino-functionalized PEC sensor based on a SnS₂@MoS₂ heterojunction

The rapid detection of polyethylene terephthalate (PET) nanoplastics (PET NPs) is hindered by their low concentration, high mobility and lack of a distinguishable interface with other nanoplastics. In this study, we developed an SnS₂@MoS₂/APTES amino-functionalized photoelectrochemical sensor capable of detecting PET NPs with high specificity. The SnS₂@MoS₂ heterojunction synthesized via in situ hydrothermal synthesis and the APTES self-assembled amino-functionalized interface enable PET NPs to interact with amino-functionalized interface at multiple sites through oxygen-containing groups such as ester groups, carbonyl oxygen and ether oxygen. The sensor exhibits a detection range of 0.5-800 μg mL^-1 for PET NPs, with a detection limit of 0.17 μg mL^-1. DFT calculations further indicate that the PET-APTES system exhibits a lower adsorption energy (-1.37 eV) and a more significant interfacial charge rearrangement, demonstrating that the APTES amino siloxane interface exhibits a polymer structural selectivity toward PET. Furthermore, this PEC sensor exhibits good recovery rates (96.04%-102.76%) in practical water samples such as seawater, bottled water and tap water. It provides a new method for interface recognition and signal conversion for the specific PEC detection of PET nanoplastics.