Flexible π-stacked organic frameworks with dynamic electronic interactions for highly efficient photocatalytic hydrogen evolution

There is growing interest in using light-responsive soft matter with dynamic noncovalent bonding for solar-driven fuel production. Here, we report a supramolecular organic light absorber, the π-stacked organic framework (πOF-1), formed through the self-assembly of π-conjugated photoactive units via dynamic π-π interactions. Its building blocks incorporate flexible and nonfused organic rings with strong visible-light absorption, along with hydrophilic side groups that form high surface-area inner pores and uniformly distributed micropores (~1.8 nm in size). In aqueous surfactant dispersions, πOF-1 forms stable particles that anchor platinum clusters on both internal and external surfaces via photodeposition. Under 1-sun illumination at 70 °C, πOF-1 achieves a record-high hydrogen evolution rate of 618 mmol h-1 g-1, corresponding to an averaged internal quantum efficiency of 17.7% at 450-750 nm range. The performance at elevated temperatures is enabled by dynamic π-stacked networks, which facilitate efficient exciton dissociation and charge transfer via interactions between heterocyclic rings and platinum clusters. For energy conversion and photosynthesis, πOF-1 photocatalysts offer a compelling alternative to traditional soft-matter systems such as covalent organic frameworks, metal-ligand coordination frameworks, or densely packed crystalline semiconductors.