Advances in layered double hydroxides for direct seawater electrolysis: Challenges, strategies, and future perspectives

Direct electrolysis of seawater to produce hydrogen is one of the promising and low-cost ideal hydrogen production technologies. However, being different from freshwater electrolysis, seawater contains lots of ions, microorganisms, and other impurities, which make seawater electrolysis more challenging. In particular, the chloride ion in seawater usually results in a chlorine evolution reaction (CER) and competes with the oxygen evolution reaction (OER) at the anodes, the dominant rate-determining step of overall water electrolysis. In recent years, layered double hydroxides (LDHs) have attracted attention because of their excellent OER activity in alkaline solutions. In this paper, the research progress of LDHs in seawater electrolysis is reviewed, including the structure design and optimization strategies for protecting catalytic sites from Cl− corrosion, and the mechanism study to reveal the inhibition of CER during the OER process. The challenges in improving the corrosion resistance of LDHs in seawater electrolysis are concluded to provide some possible and available ways of seawater electrolysis for generating green hydrogen.