Storing solar energy in chemical bonds aided by heterogeneous photocatalysis is desirable for sustainable energy conversion. Despite recent progress in designing highly active photocatalysts, inefficient solar energy and mass transfer, the instability of catalysts and reverse reactions impede their practical large-scale applications. Here we tackle these challenges by designing a floatable photocatalytic platform constructed from porous elastomer–hydrogel nanocomposites. The nanocomposites at the air–water interface feature efficient light delivery, facile supply of water and instantaneous gas separation. Consequently, a high hydrogen evolution rate of 163 mmol h^–1 m^–2 can be achieved using Pt/TiO₂ cryoaerogel, even without forced convection. When fabricated in an area of 1 m² and incorporated with economically feasible single-atom Cu/TiO₂ photocatalysts, the nanocomposites produce 79.2 ml of hydrogen per day under natural sunlight. Furthermore, long-term stable hydrogen production in seawater and highly turbid water and photoreforming of polyethylene terephthalate demonstrate the potential of the nanocomposites as a commercially viable photocatalytic system.

在异质光催化的辅助下，将太阳能储存在化学键中对于可持续的能源转换是可取的。尽管最近在设计高活性光催化剂、低效太阳能和传质方面取得了进展，但催化剂的不稳定性和逆反应阻碍了它们的实际大规模应用。在这里，我们通过设计由多孔弹性体-水凝胶纳米复合材料构建的可浮动光催化平台来应对这些挑战。空气-水界面处的纳米复合材料具有高效的光传输、方便的水供给和瞬时气体分离等特点。因此，即使没有强制对流，使用 Pt/TiO ₂冷冻气凝胶也可以实现163 mmol h ^–1  m ^–2的高析氢速率。^{当在 1 m 2}的面积上制造并与经济上可行的单原子 Cu/TiO ₂光催化剂结合时，纳米复合材料在自然阳光下每天产生 79.2 毫升的氢气。此外，在海水和高浊度水中的长期稳定制氢以及聚对苯二甲酸乙二醇酯的光重整证明了纳米复合材料作为商业上可行的光催化系统的潜力。