Assembled Quantum Dot Porous Clusters for Enhanced Photocatalytic Reduction of Quinone to Hydroquinone
Yufeng Qin, Xiang Chen, Zhuo Zhao, Chaodan Pu
Abstract
Colloidal quantum dots (CQDs) have been extensively studied as promising photocatalysts in various fields. The presence of long ligands can cause serious spatial hindrance, impeding charge transfer and mass transportation during photocatalysis. However, removing ligands would introduce surface traps and lead to uncontrolled aggregation, which also impairs the photocatalytic activity. Here, we demonstrate that this contradiction can be resolved by assembling CQDs into porous clusters. The assembled CQDs exhibited a 13-fold higher photocatalytic activity compared to that of isolated CQDs for reducing quinone to hydroquinone. Quantitative analysis of the steady and transient photoluminescence spectra showed that compared with isolated CQDs, except for a longer decay lifetime, a higher accessibility of charge to the reactants resulting from charge delocalization also contributed to improving the charge transfer efficiency. In conjunction with a reaction kinetics study, a higher radical reaction rate constant was further confirmed for the assembled porous photocatalysts.