Multi-Scale Hierarchical Organic Photocatalytic Platform for Self-Suspending Sacrificial Hydrogen Production from Seawater

The widespread application of photocatalysis for converting solar energy and seawater into hydrogen is generally hindered by limited catalyst activity and the lack of sustainable large-scale platforms. Here, a multi-scale hierarchical organic photocatalytic platform was developed, combining a photosensitive molecular heterojunction with a molecular-scale gradient energy level alignment and micro-nanoscale hierarchical pore structures. The ternary system facilitates efficient charge transfer and enhances photocatalytic activity compared to conventional donor-acceptor pairs. Meanwhile, the super-wetted hierarchical interfaces of the platform endow it with the ability to repeatedly capture light and self-suspend below the water surface, which simultaneously improves the light utilization efficiency, and reduces the adverse effects of salt deposition. Under a Xe lamp illumination, the hydrogen evolution rate of this organic platform utilizing a sacrificial agent can reach 165.8 mmol h⁻¹ m⁻², exceeding that of mostly inorganic systems as reported. And upon constructing a scalable system, the platform produced 80.6 ml m⁻² of hydrogen from seawater within five hours at noon. More importantly, the outcomes suggest an innovative multi-scale approach that bridges disciplines, advancing the frontier of sustainable seawater hydrogen production driven by solar energy.