Electrocatalytic seawater splitting: Nice designs, advanced strategies, challenges and perspectives

H2 has a sufficiently high energy density and a combustion process that emits no carbon, therefore being an appealing storable alternative to fossil fuels. With evident advantages of seawater resources available worldwide, electrochemically making H2 from seawater holds a great development prospect towards the global deployment of H2-based energy plants. However, with current water splitting technologies, this is not an easy task, and the primary obstacle is impurities in natural seawater including halide salts, magnesium salts, organic matter, etc., which readily cause the electrocatalysis systems to shut down. We herein present a timely review of seawater electrolysis systems at both lab-scale fundamental research and pilot-scale reactor level on the basis of most representative studies. We analyze some of the crucial experimental details that are frequently ignored, such as seawater treatments, product detection, electrode assembly, reactors, electrolyte feeding modes, etc. We then systematically emphasize the latest and representative strategies and catalytic materials designs as well as whether corresponding electrodes are genuinely stable as two key quests to find out truly reliable and exploitable electrode engineering. Gas release behaviors/kinetics at high reaction rates are highlighted as well. In addition, we introduce valuable contents like how to learn from ocean life for electrocatalytic system design. We conclude by taking a look at the future research directions and opportunities for encouraging more practical applications of seawater electrolysis systems/technologies.