Hydrocyclone-enhanced scalable photocatalytic hydrogen generation, from macroscale turbulence to nanoscale reaction dynamics.

Photocatalytic hydrogen production faces barriers to industrialization, including inadequate light absorption and limited mass/momentum transfer at scale. Integrating external hydrocyclones into photoreactors is a promising solution, yet the multiscale complexity of hydrocyclone-driven hydrogen generation impedes mechanistic understanding and rational system design. Herein, we build a scalable hydrocyclone-based photoreactor that achieves 270 mL/h hydrogen yield and 5.26% solar-to-hydrogen efficiency under simulated sunlight, as 4.5 times higher than static conditions. We develop a hierarchical multiscale model combining computational fluid dynamics, solid mechanics and density functional theory, which connects macro-scale hydrocyclone flow strain to atomic-level photocatalytic processes. Here, we show that shear stress-induced nanoscale lattice restructuring of the catalyst modulates photoexcitation pathways, triggers a threshold-activated catalytic amplification effect, and identifies an optimal flow rate of 20-30 L/min. These findings reveal a multiscale force-chemical coupling mechanism linking reactor-scale hydrocyclone flow fields to lattice-scale strain-driven catalytic enhancement, guiding large-scale photocatalytic hydrogen production.