D–A Conjugated Polymer/CdS S‐Scheme Heterojunction with Enhanced Interfacial Charge Transfer for Efficient Photocatalytic Hydrogen Generation

Abstract Owing to the improved charge separation and maximized redox capability of the system, Step‐scheme (S‐scheme) heterojunctions have garnered significant research attention for efficient photocatalysis of H2 evolution. In this work, an innovative linear donor–acceptor (D–A) conjugated polymer fluorene‐alt‐(benzo‐thiophene‐dione) (PFBTD) is coupled with the CdS nanosheets, forming the organic–inorganic S‐scheme heterojunction. The CdS/PFBTD (CP) composite exhibits an impressed hydrogen production rate of 7.62 mmol g−1 h−1 without any co‐catalysts, which is ≈14 times higher than pristine CdS. It is revealed that the outstanding photocatalytic performance is attributed to the formation of rapid electron transfer channels through the interfacial Cd─O bonding as evidenced by the density functional theory (DFT) calculations and in situ X‐ray photoelectron spectroscopy (XPS) analysis. The charge transfer mechanism involved in S‐scheme heterojunctions is further investigated through the photo‐irradiated Kelvin probe force microscopy (KPFM) analysis. This work provides a new point of view on the mechanism of interfacial charge transfer and points out the direction of designing superior organic–inorganic S‐scheme heterojunction photocatalysts.