Amidoxime-grafted fluorinated graphene nanosheets as a trace electrochemical sensing platform of uranyl ion

Current electrode recognition materials have limited the realization of rapid real-time monitoring of trace uranyl ion (UO22+) in real-world waters. Herein, amidoxime-grafted fluorinated graphene (AO-FG) is synthesized via the addition and subsequent amidoximation reactions of FG for the electrochemical determination of trace UO22+. Spectroscopies and microscopies reveal the synthetic and morphological characteristics of AO-FG. Electrochemical measurement indicates a significant improvement in the UO22+ redox activity of FG after amidoximation, which is attributed to the introduction of more UO22+ binding sites on the electrode surface and the restoration of charge transfer of graphene. By optimizing the modifier concentration, pH, temperature, and enrichment time, the linear range of the AO-FG-based electrochemical UO22+ sensor is determined to be 0.015-0.1 ppm (R2 = 0.9945), and the detection limit reaches 9.97 x 10-10 M. Furthermore, it exhibited excellent repeatability, air stability, and reliability in the detection of UO22+ in water samples. This study constitutes a novel pathway of constructing high-efficiency, low-cost, and portable UO22+ sensors via grafting of specific groups on FG substrates.