Interfacial properties of two-dimensional CdS/GO from DFT

Abstract

CdS/graphene bilayers are nanocomposites that may demonstrate enhanced photocatalytic activity relative to pure CdS. In this study, we examine oxygenating the graphene layer to form graphene oxide (GO) as a means of strengthening interfacial adhesion in the CdS/graphene bilayer and tuning its electronic properties. Specifically, we investigate the effects of oxygen concentration and functional group identity on the interfacial and electronic properties, using density functional theory (DFT) calculations. We find that interfacial adhesion is weakened when the oxygen concentration is increased in epoxy-functionalized GO; however, there is potential for increased adhesion with increasing hydroxyl functional group concentration. The native electronic structure of the CdS monolayer is not significantly affected by the GO layer, preserving its optimal optoelectronic properties for photocatalytic applications. However, the band edge alignment between the layers can be tuned by varying the oxygen composition of GO—increasing the overall oxygen concentration and proportion of epoxy functional groups relative to hydroxyl groups increases the n-type Schottky barrier height, thus enhancing the efficiency of photoexcited charge transfer across the interface.