Two-Dimensional GaTe/Bi₂Se₃ Heterostructure: a Promising Direct Z-scheme Water Splitting Photocatalyst

Among various photocatalytic materials, Z-scheme photocatalysts have drawn tremendous research interest due to high photocatalytic performance in solar water splitting. Here, we perform extensive hybrid density functional theory calculations to explore electronic structures, interfacial charge transfer, electrostatic potential profile, optical absorption properties, and photocatalytic properties of a proposed two-dimensional (2D) small-lattice-mismatched GaTe/Bi _2 Se _3 heterostructure. Theoretical results clearly reveal that the examined heterostructure with a small direct band gap can effectively harvest the broad spectrum of the incoming sunlight. Due to the relative strong interfacial built-in electric field in the heterostructure and the small band gap between the valence band maximum of GaTe monolayer and the conduction band minimum of Bi _2 Se _3 nanosheet with slight band edge bending, these photogenerated carriers transfer via Z-scheme pathway, which results in the photogenerated electrons and holes effectively separating into the GaTe monolayer and the Bi _2 Se _3 nanosheet for the hydrogen and oxygen evolution reactions, respectively. Our results imply that the artificial 2D GaTe/Bi _2 Se _3 is a promising Z-scheme photocatalyst for overall solar water splitting.