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

Determination of phosphate ion (PO 4 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 PO 4 3- based on a single-layered graphene quantum dots chelating with aluminium ions (s-GQDs-Al 3+ ) system. The PL of s-GQDs can be enhanced by Al 3+ through the aggregation-induced emission enhancement (AIEE) effect. With the addition of PO 4 3- , the PL of the s-GQDs-Al 3+ system is faded away because PO 4 3- has stronger coordination with Al 3+ which results in the elimination of AIEE effect and the decrease in the PL intensity of the s-GQDs-Al 3+ system. Therefore, the s-GQDs-Al 3+ system can behave as an on-off type PL probe for PO 4 3- detection. It is found that the PL intensity ratio ( I / I 0 ) of s-GQDs in the presence of Al 3+ at 463   nm is proportional to the concentration of PO 4 3- in the range of 0.25–7.5   μM with the limit of detection as low as 0.1   μM. This selective assay has a great application prospect in the complex matrixes owing to its simplicity and specificity for PO 4 3- detection.