Controllable functionalization of amino-functionalized graphene quantum dots as fluorescent probe for detection of Cu(Ⅱ) ions detection

Abstract

Herein, the amino-functionalized graphene quantum dots (GQDs) can be applied for selective detection of Cu(Ⅱ) ions in solutions via photoluminescence (PL) measurement, the PL emission intensities of the GQDs gradually decreased with the increase of Cu2+ concentration (0–100 μm), the PL intensity (quenching effect) decreases almost linearly with increasing Cu2+ concentration. Its correlation coefficient R2 is 0.9529. Quenching of the PL emission by the presence of copper(Ⅱ) ions is attributed to the surface functional groups attached to the GQDs, which can interact with metal ions so that the electrons in the excited state of the GQDs are transferred into the unoccupied orbits of Cu(Ⅱ) ions. Corresponding physical mechanism is proposed to gain an understanding about how the presence of the Copper(Ⅱ) ions can affect the PL emission from GQDs.