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.

Keywords

built-in electric field / charge transfer channel / covalent bond / photocatalytic hydrogen production / S-scheme heterojunction

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