Pickering-enabled ice-templated self-floating photocatalysts for hydrogen evolution

Floating photocatalysts offer a promising route to solar-driven hydrogen production by maximizing light exposure at the air–water interface while preventing catalyst sedimentation. However, organic photocatalysts that simultaneously achieve stable floating operation, interconnected porous architectures, and efficient charge separation within a single monolithic platform remain elusive. Here, we present a Pickering emulsion-enabled ice-templating strategy for fabricating a self-floating porous poly(3-hexylthiophene)/nitrogen-doped graphene quantum dot (P3HT/N-GQDs) sponge. N-GQDs serve as multifunctional interfacial components: stabilizing water-in-chloroform emulsion droplets, preserving the droplet templates during freezing, and forming a charge-separating p-n heterojunction with P3HT. Freeze-drying converts the frozen emulsion into a hierarchically porous sponge with interconnected spherical cavities, enabling enhanced light harvesting through multiple internal scattering and stable partial submersion at the air–water interface. Under simulated solar illumination, the P3HT/N-GQDs sponge achieves a hydrogen evolution rate of 7.16 mmol g −1 h −1 , a 3.14-fold enhancement over the pristine P3HT sponge (2.28 mmol g −1 h −1 ), driven by synergistic structural and electronic contributions of the porous architecture and the p-n heterojunction. This work establishes Pickering-assisted ice templating as a versatile platform for self-floating organic photocatalysts operating at the air–water interface.