Hybrid photothermal-photocatalyst sheets for solar-driven overall water splitting coupled to clean water production from seawater and waste streams

Photocatalytic water splitting converts sunlight directly into storable hydrogen, but involves commonly pure water, installation on land and production of 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, a UV light absorbing RhCrOx-Al:SrTiO3 photocatalyst 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 0.14±0.02% coupled to 0.95 kg m−2 h−1 of water vapour as a substrate for the PC and collectable purified water. This integrated system maintains operational stability in seawater and other aqueous waste streams for over 154 hours due to the isolation of the PC from the 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.