Floating solar hydrogen production

Floatable hydrogel photocatalytic platform at the air–water interface features practical advantages for scale-up of solar H₂ production with light delivery, supply of water, and instantaneous gas separation.

Hydrogen (H₂), as a zero-carbon emission fuel, is forecast to become a major energy source in the future. Among various H₂ production methods, utilizing abundant solar power to produce H₂ from water in the presence of a photocatalytic platform has been an attractive strategy^1,2. To achieve a sizable yield of H₂, large-scale photocatalytic platforms are essential for solar H₂ production³. However, the aggregation of catalysts particles, severe light scattering, and the high cost of continuous agitation in the current mainstream slurry reactors limit the efficiency of scale-up of photocatalysis⁴. Immobilization of powdery photocatalysts with the types of a particulate-sheet-type⁵, film-type⁶, and flat-panel-type³ has been recently proposed to enhance photocatalytic efficiency. All the same, these platforms still have many practical limitations, including the additional requirement of photoelectrodes and forced convection, potential reverse reactions during product separation, continuous leaching of photocatalysts, and poor mass transfer to and from closely-packed photocatalysts.