Abstract: Photocatalysis, a carbon-neutral catalytic technology, has emerged as a cornerstone in the pursuit of sustainable hydrogen production. A recent breakthrough reports the efficacy of a metal-free 2D/2D S-scheme heterojunction comprising a hydrogen-bonded organic framework (HOF) and a pyrene-based covalent organic framework (COF) for solar-driven hydrogen evolution. Capitalizing on structurally matched pyrene building blocks, the HOF/COF interface achieves atomic-level alignment, amplifying the internal electric field intensity while enhancing π-π conjugation across the heterojunction. These synergistic effects drive directional S-scheme charge transfer and suppress carrier recombination, yielding a high hydrogen production rate with excellent stability. This work establishes a paradigm for designing organic S-scheme photocatalysts through interfacial engineering, advancing the frontier of metal-free photocatalysts for solar-to-fuel conversion.

Key words: S-scheme heterojunction, Photocatalytic hydrogen evolution, Hydrogen-bonded organic framework, Covalent organic framework, Charge transfer mechanism