Density Functional Theory Study on the Interfacial Properties of CuS/Bi2S3 Heterostructure.

Composite heterostructure photocatalysts can effectively improve photocatalytic performance. For narrow‐bandgap semiconductors, such as Bi2S3, constructing heterostructures with other semiconductors can obviously promote the separation of photogenerated electron−hole pairs and improve their photocatalytic performance. However, some basic and important parts of this technology still require further clarification. Herein, the interface properties of CuS/Bi2S3 heterostructure was studied using density functional theory calculations. The results show that the electronic structure of the interface model shows some different characteristics compared with the bulk and surface models due to the different bonding modes and chemical environments at the interface. At the interface of the CuS/Bi2S3 heterostructure, the band edge of CuS is bent downward relative to Bi2S3 to form a type II heterostructure. In addition, in the equilibrium state, the direction of the built‐in electric field of the heterostructure is from Bi2S3 to CuS. Therefore, the photogenerated electron−hole pairs can be separated by the CuS/Bi2S3 interface, which is extremely advantageous for the improvement of photocatalytic performance. The formation of the CuS/Bi2S3 heterostructure not only broadens the light absorption of CuS but also suppresses the recombination of photogenerated electron−hole pairs of the narrow‐bandgap semiconductor Bi2S3. [ABSTRACT FROM AUTHOR]