Ultrasensitive and Visualized Rapid Detection of Organophosphorus Pesticides Using Ultrathin 2D Eu3+@Cd-MOF Fluorescent Nanosheets

Organophosphorus pesticides (OPs) are widely used worldwide. However, OPs residues can cause serious health problems. Traditional analytical approaches for OPs detection fail to offer simple, real-time, and visualization. Herein, Ultrathin Eu³⁺@Cd-MOF nanosheets with a thickness of 6 nm were synthesized via a simple solution route. Due to the antenna effect between 4,4′-dicarboxydiphenyl ether (H₂OBA), 2,2′-bipyridine (BPY), and Eu³⁺, the as-prepared nanosheets displayed characteristic fluorescence emission of Eu³⁺ ions at 616 nm under the excitation of 323 nm. The strong fluorescence was quenched by p-nitrophenyl phosphate (PNPP) without any interference from other pesticide in aqueous systems; Eu³⁺@Cd-MOF nanosheets can serve as a highly sensitive probe for visualizing fluorescence and detecting PNPP in water systems with a low LOD of 65 nM and a rapid response time of 20 s. A systematic investigation of the sensing mechanism indicated that the combination of the photoelectron transfer (PET) and the inner filter effect (IFT) resulted in the selective detection of PNPP. The luminescence detection approach offers a rapid, low-cost, and visualized detection method for PNPP remaining on fruits and vegetables surfaces.