A study on the transfer of photo-excited charge carriers within direct and inverted type-I heterojunctions of CdS and ZnS QDs

Abstract

Herein, the influence of charge transfer behavior with electron-donating and withdrawing moieties in phenols on normal and inverted type-I QD surfaces has been investigated. Steady-state and time-resolved photoluminescence experiments revealed the quenching of both the electron and the hole in ZnS@CdS reverse type-I core/shell in the presence 4-nitrophenol and 4-methoxyphenol, respectively; however, the emission intensities and lifetimes of CdS@ZnS type-I QDs remained nearly unchanged in the presence of both quenchers. The photocatalytic performance of the developed band regimes was also evaluated under solar light irradiation. Compared to ZnS, CdS, and CdS@ZnS, the as-formed ZnS@CdS nanohybrid was found to exhibit highly improved superior performances in the photodegradation of xylenol orange. The roles of reactive oxygen species were revealed by chemiluminescence and terephthalic acid fluorescence probe techniques.