Engineering of CdTe Multicore in ZnO Nanoshell as a New Charge-Transfer Material

Abstract

The synthesis and spectroscopic properties of multicore cadmium telluride (CdTe) quantum dots–zinc oxide (ZnO) shell nanoparticles (mc-CdTe@ZnO) as a new charge transfer material are presented. This colloidal system is easy to process, suitable for large scale production, and adaptable to be used in different solvents. The fabrication process employed a water-in-oil (w/o) reverse microemulsion of Triton X-100/hexanol/cyclohexane. Fluorescence and lifetime measurements for different sizes of CdTe quantum dots and their respective mc-CdTe@ZnO nanoparticles were acquired. Charge injection from CdTe multicores to the ZnO shell was confirmed by pump–probe transient absorption experiments. The presence of multicores increases the net interfacial interaction between CdTe and ZnO when compared to a structure with a single quantum dot core. The mc-CdTe@ZnO particles displayed electron-transfer rates as high as 1012 s–1, a value in the high-end of those reported in the literature for other type II semiconductor composites. Hydrogen production experiments further confirmed the establishment of a type II junction between the CdTe multicore and the ZnO shell.