Theoretical exploration of electronic, optical, and photocatalytic properties of CdS(Se)/graphene oxide heterostructures.

CdS(Se)/graphene oxide (GO) heterostructures have received significant attention due to their potential application in optoelectronic devices with tunable bandgap, efficient charge transfer, and enhanced photocatalytic and photovoltaic activity. In this work, Density Functional Theory (DFT) calculations of the photocatalytic properties of CdS(Se)/GO heterostructures were performed. The results of work function, band gap, optical absorption, and band edges of CdS and CdSe in the (001) and (110) directions on graphene oxide are presented. Various approaches to simulate graphene oxide with a different concentration of oxygen, and their subsequent integration into CdS (Se)-GO heterostructures are discussed. DFT calculations were employed to determine the equilibrium value and adhesion energy for various compositions of layers at the interface, as well as different stacking arrangements between graphene oxide and CdS slabs. The results revealed that some oxygen atoms migrate to the CdS matrix and form bonds with Cd atoms. It was observed that the semiconductor band gap can be controlled by the oxidation degree in graphene oxide, and the electronic properties of CdS(Se) depend on the semiconductor orientation and slab number. Notably, surface states are found to be responsible for the negative part of the dielectric function at low frequencies, significantly influencing the electronic properties and charge transfer dynamics. The results show that both structures form type II heterostructures, which is promising for photocatalytic hydrogen generation.