Graphene Quantum Dots-based Fluorescence "Turn-On" Probe for Selective Detection of Fe(II)

A "turn-on" fluorescence probe was developed based on terephthalic acid functionalized graphene quantum dots (TPA@GQDs) for highly selective detection of Fe2+. The TPA@GQDs were prepared by a one-step hydrothermal method using GO as carbon source and terephthalic acid as modifying group, where potassium hydroxide served as the cutting agent and hydrogen peroxide as the auxiliary cutting agent. The structure and component of TPA@GQDs were studied by a variety of characterization methods, and the optical properties and feasibility of TPA@GQDs as a fluorescent probe were further explored. Based on the electron-donating function of Fe2+ to induce the fluorescence enhancement of TPA@GQDs, a "turn-on" fluorescent probe was constructed for sensitive detection of Fe2+. The linear ranges were from 0.33 to 20 mu mol/L and 20 to 60 mu mol/L, with the limit of detection (3 sigma) of 0.33 mu mol/L, and the corresponding linear equations were F/F-0 = 0.0638C + 1.1385 (R-2 = 0.9974) and F/F-0 = 0.0244C + 1.9215 (R-2 = 0.9989), respectively. Moreover, this system demonstrated good selectivity toward Fe2+, and Fe3+ had no effect on the detection of Fe2+. Finally, the proposed probe was applied to accurate determination of Fe2+ in underground water with recoveries of 98.5%-102.0 %, showing broad application prospects in water quality monitoring.