Highly selective detection of phosphate ion based on a single-layered graphene quantum dots-Al³⁺ strategy

Determination of phosphate ion (PO₄^3-) is important in biomedical and environmental arrays because its controlling concentrations are associated with different pathologies or the quality of water. Herein, we report a new type of photoluminescence (PL) probe for highly selective detection of PO₄^3- based on a single-layered graphene quantum dots chelating with aluminium ions (s-GQDs-Al³⁺) system. The PL of s-GQDs can be enhanced by Al³⁺ through the aggregation-induced emission enhancement (AIEE) effect. With the addition of PO₄^3-, the PL of the s-GQDs-Al³⁺ system is faded away because PO₄^3- has stronger coordination with Al³⁺ which results in the elimination of AIEE effect and the decrease in the PL intensity of the s-GQDs-Al³⁺ system. Therefore, the s-GQDs-Al³⁺ system can behave as an on-off type PL probe for PO₄^3- detection. It is found that the PL intensity ratio (I/I₀) of s-GQDs in the presence of Al³⁺ at 463nm is proportional to the concentration of PO₄^3- in the range of 0.25-7.5μM with the limit of detection as low as 0.1μM. This selective assay has a great application prospect in the complex matrixes owing to its simplicity and specificity for PO₄^3- detection.