▎ 摘　　要

The paper reports a facile synthesis of histidine-functionalized graphene quantum dots (His-GQDs) via a thermal pyrolysis of citric acid and histidine. The resulting His-GQDs are composed of the graphene sheets with the average size of 3.2 nm and shows high water-solubility. Zn2+ reacted with the His-GQD to produce Zn-His-GQD framework nanoparticles by coordination bonds, which exhibit a better amphiphilicity with pristine His-GQDs. The styrene-in-water emulsion stabilized by the framework nanoparticles offer an excellent stability and pH-switching behaviour, and was successfully applied in the emulsion polymerization of styrene. The as-prepared polystyrene microspheres coated with His-GQD were used for the adsorption of Cu2+ from water. The adsorption capacity of Cu2+ reaches to 61 mg g(-1) with high reusability. This study also provides a prominent approach for fabrication of GQD-based functional materials, which could have a wide range of potential applications such as in emulsion polymerization, sensor, catalysts and energy storage.