Photocatalytic water splitting converts sunlight directly into storable hydrogen, but commonly involves the use of pure water and land for plant installation while generating unusable waste heat. Here we report a hybrid device consisting of a photocatalyst (PC) and a solar vapour generator (SVG) for simultaneous overall water splitting and water purification from open water sources. Specifically, an ultraviolet light-absorbing RhCrO_x–Al:SrTiO₃ PC is deposited on top of a floating, visible and infrared light-absorbing porous carbon SVG, which produces green fuel with a solar-to-hydrogen efficiency of 0.13 ± 0.03% and 0.95 kg m⁻² h⁻¹ of water vapour as the feed for the PC and collectable purified water. This integrated system maintains operational stability in seawater and other aqueous waste streams for over 154 h due to the isolation of the PC from contaminants in the liquid feedstock. This work provides a new concept for developing an off-grid energy production/storage solution and is a first step towards alleviating both energy and water supply challenges.

光催化水分解将阳光直接转化为可储存的氢气，但通常需要使用纯净水和土地来安装工厂，同时产生无法利用的废热。在这里，我们报告了一种由光催化剂（PC）和太阳能蒸汽发生器（SVG）组成的混合装置，用于同时从开放水源进行整体水分解和水净化。具体来说，将吸收紫外线的RhCrO _x –Al:SrTiO ₃ PC沉积在漂浮的、吸收可见光和红外光的多孔碳SVG的顶部，产生太阳能制氢效率为0.13 ± 0.03%的绿色燃料0.95 kg m ^-2  h ^-1水蒸气作为PC的进料和可收集的纯化水。由于 PC 与液体原料中的污染物隔离，该集成系统可在海水和其他含水废物流中保持运行稳定性超过 154 小时。这项工作为开发离网能源生产/存储解决方案提供了新概念，也是缓解能源和供水挑战的第一步。