Harnessing Anion Intercalation to Activate Layered Double Hydroxides for Efficient and Stable Seawater Splitting
Direct seawater electrolysis offers a sustainable route to green hydrogen, yet is hindered by the competing chlorine evolution reaction and severe catalyst corrosion. Layered double hydroxides (LDHs), with tunable host layers and exchangeable interlayer galleries, are promising for the oxygen evolution reaction (OER) in seawater, but their intrinsic activity and chloride tolerance need enhancement. Anion intercalation engineering has emerged as a powerful strategy to address these challenges. By inserting functional anions—from simple inorganic ions and polyoxometalates to organic molecules—into LDH interlayers, it is possible to expand interlayer spacing for improved mass transport, modulate the electronic structure of metal centers to boost intrinsic OER activity, and create a negatively charged interfacial microenvironment that selectively enriches OH−. This review comprehensively examines design principles, mechanistic insights, and catalytic performance of various anion-intercalated LDHs for seawater splitting. It highlights representative breakthroughs in material design, discusses integration strategies in practical electrolyzer devices, and evaluates long-term stability under industrial operating conditions. Finally, it outlines key challenges and future directions for rational design and scalable deployment of high-performance, durable LDH-based catalysts for sustainable hydrogen production from seawater.