Dy(III)-induced aggregation emission quenching effect of single-layered graphene quantum dots for selective detection of phosphate in the artificial wetlands.

Carbon quantum dots (CQDs), prepared by one-step hydrothermal treatment of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and triethylamine (TEA), could be exfoliated or delaminated into single-layered graphene quantum dots (s-GQDs) with methanol for the first time, with fluorescence (FL) emission at 500 nm when excited at 417 nm. The s-GQDs, with more sufficient carboxyl groups on the surface than CQDs, could be induced to be aggregated by metal ion dysprosium (Dy3+), resulting in aggregation-induced emission quenching effect subsequently. However, the presence of phosphate (PO43-) destroys the Dy3+-induced aggregates of s-GQDs owing to the strong coordination between Dy3+ and PO43-, inducing the FL emission recovery of the s-GQDs and providing selective detection method of PO43- in the artificial wetlands with the linear range of 0.2-30 µM and determination limit of 0.1 µM (3σ).