Functionalized UIO-66@Ag nanoparticles substrate for rapid and ultrasensitive SERS detection of di-(2-ethylhexyl) phthalate in plastics

Abstract

The rapid and sensitive detection of di-(2-ethylhexyl) phthalate (DEHP) in plastics is of great significance because of its toxicity and persistent contamination. Surface-enhanced Raman scattering (SERS) technology makes the detection of DEHP fast and convenient, but it suffers some disadvantages such as the weak adsorption capacity of target molecules, low efficiency and limited sensitivity. Herein, octahedral UIO-66 of metal-organic frameworks (MOFs) was successfully synthesized, followed by the growth of silver nanoparticles on its surface (UIO-66@Ag NPs) to form a composite SERS substrate to detect DEHP. Taking advantages of large surface area and high porosity of UIO-66, the prepared UIO-66@Ag NPs substrate not only could reduce the aggregation and increase the “hot spots” formed by localized surface plasmon resonance (LSPR) of Ag nanoparticles, but also possess good adsorption capacity for DEHP. The SERS-enhanced mechanism was fundamentally discussed for UIO-66@Ag NPs substrate, and the enhancement factor (EF) of SERS signal for DEHP detection was calculated about 1.1 × 107. The fabricated UIO-66@Ag NPs SERS substrate could realize quantitatively non-destructive determination of DEHP ranging from 10−4 to 10−11 mol/L (R2 = 0.9950) with very low detection limit of 3 × 10−12 mol/L. Meanwhile, the UIO-66@Ag NPs substrate exhibited outstanding reproducibility and stability, and was successfully applied to detect DEHP in real plastic particles with satisfactory recoveries of 81.9–110.1%. These results demonstrated that this method offered a suitable path for the research of advanced SERS sensing materials to achieve monitoring of DEHP in plastics.