Highly sensitive and selective determination of uranyl ions based on Ag/Ag₂O-COF composite SERS substrate

Uranium is an essential nuclear material in civilian and military areas; however, its extensive application raises concerns about the potential safety issues in the fields of environmental protection and nuclear industry. In this study, we developed an Ag/Ag₂O-COF (covalent-organic framework) composite SERS substrate to detect uranyl ions (UO₂²⁺) in environmental aqueous solutions. Herein, the strong SERS effect of uranyl adsorbed in Ag/Ag₂O composite and the high adsorption efficiency of COF TpPa-1 were combined to realize the trace detection of uranyl ions. This method displayed a linear range of 10^-8 mol L^-1 to 10^-6 mol L^-1 with the detection limit of 8.9 × 10^-10 mol L^-1 for uranyl ions. Furthermore, common metal cations and oxo-ions hardly affected the SERS detection of uranyl, which is helpful for the trace analysis of uranyl in natural water samples. Although the proposed strategy is deployed for uranyl detection, the reusable and high-efficiency system may be expanded to trace detection of other substance with Raman activity.