Nitrogen-Doped Graphene Quantum Dots as a New Catalyst Accelerating the Coordination Reaction between Cadmium(II) and 5,10,15,20-Tetrakis(1-methyl-4-pyridinio)porphyrin for Cadmium(II) Sensing.

Small molecules or metal ions can be employed as catalysts to accelerate metalloporphyrin formation. Herein, we for the first time report the coordination reaction between cadmium(II) and 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin can be accelerated by nitrogen-doped graphene quantum dots (NGQDs). This catalytic reaction results in the change of the absorption of porphyrins and the fluorescence of NGQDs as a result of the inner filter effect (IFE) of the porphyrins on the assembled NGQDs. Both signals can be used for rapid and sensitive determination of metal ions. The present work promises a novel strategy for constructing sensors for metal ions.