Interfacial properties of pure and doped CdS/graphene composites: CdS (0001)/graphene and a CdS/graphene bilayer

The photocatalytic performance of CdS can be improved by pairing it with graphene, and new CdS/graphene nanoarchitectures offer the potential to optimize this enhancement. In this work, we explore the interfacial properties of CdS(0001)/graphene and a novel CdS/graphene bilayer using density functional theory (DFT), and examine whether doping with B and N can strengthen interfacial adhesion. We first determine an appropriate DFT method for bulk CdS and graphene, and study the properties of the isolated components. The CdS/graphene bilayer is then optimized and found to exhibit high interplanar distances and low adhesion energies, which are indicative of interfacial adhesion via dispersion. Doping the graphene layer with B and N does not significantly modify the strength of adhesion, but doping does enable modulation of the band edge and Fermi level alignments, which affect the driving force for photoexcited charge transfer. The CdS(0001)/graphene interface is also optimized and found to be similarly adhered via dispersion interactions. Here, doping with B considerably strengthens adhesion in the interface, due to chemical interactions between B and a surface Cd atom, while doping with N had no effect.