Detection of Heavy Metals in Water Using Graphene Oxide Quantum Dots: An Experimental and Theoretical Study

In this work, we investigate by ab initio calculations and optical experiments the sensitivity of graphene quantum dots in their use as devices to measure the presence, and concentration, of heavy metals in water. We demonstrate that the quenching or enhancement in the optical response (absorption, emission) depends on the metallic ion considered. In particular, two cases of opposite behaviour are considered in detail: Cd2+, where we observe an increase in the emission optical response for increasing concentration, and Pb2+ whose emission spectra, vice versa, are quenched along the concentration rise. The experimental trends reported comply nicely with the different hydration patterns suggested by the models that are also capable of reproducing the minor quenching/enhancing effects observed in other ions. We envisage that quantum dots of graphene may be routinely used as cheap detectors to measure the degree of poisoning ions in water.

Automated summary

The work investigates the sensitivity of graphene quantum dots in detecting heavy metals in water through ab initio calculations and optical experiments. Different behaviors in the optical response of Cd2+ and Pb2+ are observed, with Cd2+ showing increased emission optical response with concentration while Pb2+ shows quenching. It is suggested that graphene quantum dots could be used as cheap detectors for measuring poisoning ions in water.