Fabricating AuAg-nanoparticles/ZIF-8 composites for selective detection and efficient extraction of dinitroaniline pesticides

Developing candidate materials that are equipped with the ability of both selective detection and efficient removal of pesticides is greatly desirable for the environment and public health. However, most of reported materials usually possess single function, which considerably limits their applications as sensors or captures. Herein, two fluorescent composites, ZIF-8@AuAg NPs and ZIF-8-AuAg NPs, are prepared by the integration of Au/Ag nanoparticles (M NPs) and a zeolite imidazolate framework (ZIF-8), presenting a more stable fluorescent performance compared with pure AuAg NPs. The characterizations unravel that ZIF-8@AuAg NPs exhibits a core shell type structure, whereas ZIF-8-AuAg NPs are indicative of a dispersed loading type motif. ZIF-8-AuAg NPs features a significant fluorescent quenching effect for three commonly used dinitroaniline pesticides in aqueous matrices. Then, pendimethalin (PDA) is selected as a representative of dinitroaniline pesticides to thoroughly develop the potential applications in the fields of detection and extraction. Impressively, ZIF-8-AuAg NPs made of ZIF-8 shell embedded with AuAg NPs can achieve fluorescence sensing for PDA in a low concentration range with the limit of detection (LOD) of 4.2 nmol/L from aqueous solution and agricultural products, attributed to the combination of competition mechanism and electron transfer. Moreover, ZIF-8-AuAg NPs possesses high adsorption capacity of 125 mg/g for PDA at pH 6, depending on the synergistic effect of unique structural frameworks, coordinative interaction and hydrogen bond. The design for present hybrid composites provides a facile strategy to develop difunctional luminescent adsorbents with the merits of selective detection and effective absorption of dinitroaniline pesticides.