Quantum dots (QDs) distinctive properties have caused them to be widely used in many fields such as medical diagnostics, drug delivery, and consumer electronics. With the projected market for quantum dot enabled products, QDs entrance to the aquatic environments seems inevitable. Large market for QDs’ unique optical properties has caused more versatile QDs to be introduced to the market. The versatility in QDs composition, structure, and size brings additional difficulty to QD fate studies. In this study, a new kinetic model for QDs photodegradation is proposed, and an effort was made to identify the most important structural properties in QDs photodegradation. A degradation model for core/shell structured QDs is developed based on the assumption that capping ligand, shell, and core dissolution follow a first-order reaction regime. The developed model is then fitted to shell and core metal concentration data from dissolution, and first-order reaction constants for shell and core dissolution are found. First-order reaction constants obtained from photodegradation of several commercially available QDs are correlated with the corresponding QD structural properties. Our observations show that first-order reaction rate constants for both core and shell metals correlate well with the QDs bandgap. The time that is required for complete shell dissolution is in good correlation with QD diameter and shell thickness. The time to reach maximum H2O2 concentration (from the reduction of O2) showed a good correlation with shell thickness. Also, the time required for the core to leach out showed a higher correlation with QD diameter. Our observations show that the bandgap, QD diameter, and shell thickness are the most important structural factors in QDs photodegradation. Results of this study could be used by both modelers to model and predict QDs degradation in aquatic environments and manufacture to produce more stable QDs.

Photodegradation of quantum dots: A new kinetic model and significance of structural parameters

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.