Hybrid photothermal–photocatalyst sheets for solar-driven overall water splitting coupled to water purification

Abstract

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 RhCrOx–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.