Enhancing Photocatalytic Efficiency for Water Splitting: Advances in Semiconductor. Heterostructure Designs

Lecturer — prof. Ramin Yousefi (State Key Laboratory of Biobased Material and Green Papermaking, College of Food Science and Engineering, Qilu University of Technology, Shandong Academy of Science, Jinan, Shandong, China).

An effective way to improve the efficiency of nanostructure photocatalysts, particularly semiconductor-based ones, is by creating heterostructures. These combine at least two semiconductors with different conduction and valence band positions. Optimally selecting these bands ensures that electrons with the highest reduction potential and holes with the highest oxidation potential are generated, while those with lower potentials recombine. This enhances photocatalytic efficiency and minimizes the recombination of charge carriers, a major issue in redox reactions. Three types of heterostructures are widely studied: Type-II, Z-Scheme, and S-Scheme. While Z-Scheme and S-Scheme are subsets of Type-II, they differ in functionality. Both Type-II and Z-Scheme structures face thermodynamic challenges, raising doubts about their reliability. In contrast, the S-Scheme heterostructure is based on robust physical principles. It relies on the bending of energy bands at the semiconductors interface in the heterostructure, which creates an internal electric field. This field enables efficient electron and hole transfer, enhancing photocatalytic activity. As a result, S-Scheme heterostructures provide a more reliable solution for improving processes like water splitting and are a key focus of research.

Participants: students, postgraduates and scientific-pedagogical workers of the faculty of Sciences of RUDN and other Universities.