Covalently Bonded S‐Scheme Polymer Heterojunction for Highly Efficient Solar Hydrogen Evolution

ABSTRACT The pursuit of efficient solar‐to‐hydrogen conversion is often hindered by sluggish charge carrier dynamics in semiconductor photocatalysts. Although S‐scheme heterojunctions offer an appealing electronic structure for charge separation, their performance in organic systems is typically limited by weak interfacial contacts. Herein, we report a molecularly precise solution: a covalently bonded all‐organic S‐scheme heterojunction (B‐CNx@Py‐CN) constructed via a scalable one‐pot Suzuki–Miyaura coupling strategy. This architecture integrates donor and acceptor (D–A) polymers into a continuous π‐conjugated framework, creating a powerful built‐in electric field and enhanced dipole moment that synergistically drive the directional separation of photogenerated electron–hole pairs. The optimal catalyst, B‐CN2@Py‐CN, achieves a remarkable hydrogen evolution rate of 27.90 mmol g −1 h −1 under visible light and an apparent quantum yield of 14.90% at 420 nm without any co‐catalyst, outperforming its pristine components and physical mixture by factors of up to 1395, 73, and 26, respectively. A combination of spectroscopic analyses and theoretical calculations elucidates that the covalent interfacial bonds serve as atomic‐level charge transport channels, enabling efficient S‐scheme charge transfer. This work establishes covalent interfacial engineering as a powerful strategy for designing high‐performance polymer photocatalysts, providing a new paradigm for sustainable hydrogen production.