Facile synthesis of soluble graphene quantum dots and its improved property in detecting heavy metal ions

• An effective green approach to produce GQDs has been developed.
• PSS was used to improve the solubility and increase the negative charge of GQDs.
• The obtained GQDs were applied to modify glassy carbon electrode.
• A remarkably low detection limit of 7 × 10−9 M for Pb2+ was achieved.
• A schematic diagram was proposed for synthesis of GQDs for electrochemical detection.

An effective approach to produce graphene quantum dots (GQDs) has been developed, which based on the cutting of graphene oxide (GO) powder into smaller pieces and being reduced by a green approach, using sodium polystyrene sulfonate (PSS) as a dispersant and l-ascorbic acid (l-AA) as the reducing agent, which is environmentally friendly. Then the as-prepared GQDs were further used for the detection of heavy metal ions Pb2+. This kind of GQDs has greater solubility in water and is more biocompatible than GO that has been reduced by hydrazine hydrate. The few-layers of GQDs with defects and residual OH groups were shown to be particularly well suited for the determination of metal ions in the liquid phase using an electrochemical method, in which a remarkably low detection limit of 7 × 10−9 M for Pb2+ was achieved.

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