Ultra‐Durable Solar‐Driven Seawater Electrolysis for Sustainable Hydrogen Production

Abstract Ions in seawater hinder direct sewage electrolysis due to the extreme corrosion of Cl − to the anode and reaction of Mg 2+ and Ca 2+ on the cathode producing solid substances, which reduce the electrolytic efficiency. However, traditional desalination consuming fossil fuel with massive CO 2 emissions threatens human survival. Therefore, zero‐carbon emission, ultra‐durable, large‐scale production of freshwater from seawater for water electrolysis is urgently needed. Herein, a multifunctional system for seawater is demonstrated electrolysis based on ultra‐durable solar desalination outdoors. The solar evaporators reach an evaporation flux of 1.88 kg m −2 h −1 with a photothermal conversion efficiency of solar energy as high as 91.3% with excellent ultra‐durable salt resistance even for saturated saltwater due to the Marangoni effects. Moreover, the condensation of pure water from solar desalination based on the evaporation system reaches 0.54 L m −2 h −1 outdoors, which is suitable for a 20 cm × 20 cm engineered electrode equipped with a Janus membrane powered by a solar panel to produce H 2 outdoors. The ultrafast unidirectional transport of H 2 bubbles enabled by Janus membranes can greatly improve the H 2 production efficiency at a rate approaching 85 mL h −1 for continuous 24 h outdoors.