▎ 摘　　要

Graphene quantum dots (GQDs) have been an ideal probe for copper ions detection due to its excellent optical properties, low toxicity and biocompatibility. However, most of GQDs prepared by present methods have low oxidation degree, which could hinder the complexation between copper ions and oxygen functional groups on the surface of GQDs. Therefore, we proposed a universal, mild and in situ post-treated approach for modifying GQDs obtained by any methods, which will increase the oxidation degree of GQDs without any other affect and its influence on the responsivity of copper ions. (C) 2016 Elsevier B.V. All rights reserved.