CdSe/CdS/ZnS core/multi-shell QDs: new microwave synthesis and applications for dye photodegradations
Farzad Farahmandzadeh, Mehdi Molaei
Abstract
CdS and ZnS shells were grown around CdSe quantum dots (QDs) by a new, simple and ultrafast microwave synthesis. XRD result confirmed formation of CdSe/CdS/ZnS core/multi-shell structures and synthesized QDs had zinc blend structure. PL (photoluminescence) results showed that formation of CdS and ZnS shells enhanced PL intensity of CdSe QDs. TEM results showed that synthesized QDs were spherical. These QDs were characterized by using absorption, EDX, Raman, and FT-IR spectrums. Photocatalyst performance of CdSe/CdS/ZnS QDs was investigated for methylene blue, methylene orange and Rhodamine B as pollutants under both sun and UV illuminations. The obtained results showed that the best photodegradation among all samples belonged to the CdSe/CdS/ZnS QDs with MB under UV irradiation. Its dye degradation percentage and the linear kinetic rate constant (k) were 88.9% and 24.9 × 10−3 min−1. Radical scavengers were used to discover the main reactive species in the degradation of methylene blue with CdSe/CdS/ZnS QDs under UV irradiation; electrons play the key role in the degradation process.