A ratiometric probe based on Ag₂S quantum dots and graphitic carbon nitride nanosheets for the fluorescent detection of Cerium

Using silver sulfide quantum dots (Ag₂S) and graphitic carbon nitride nanosheets (g-C₃N₄), an effective and facile ratiometric fluorescence sensor for the selective determination of Cerium was developed. The addition of cerium to this probe solution resulted in the fluorescence at 443 nm quenching, while the fluorescence of the Ag₂S QDs at 540 nm recovering. The linear response range of this ratiometric sensor for Cerium was from 0.5 × 10 ^-6 mol L^-1 to 3.2 × 10 ^-5 mol L^-1. In this sensing system, not only was the detection limit as low 6.4 × 10 ^-8 mol L^-1, which was as good or better than similar assays, but the sensing system also demonstrated good selectivity in detecting cerium in the presence of interfering substances. The possible mechanism is discussed. Furthermore, this ratiometric fluorescence probe was successfully employed for the detection of Cerium in real samples with satisfactory results. The results were compared with those obtained using inductively coupled plasma optical emission spectrometry (ICP-OES).