Carbonate-retaining multilayer Co(OH)2@FeOOH electrodes enable superior stability in seawater oxygen evolution: Sustaining 5000 h at 1 A cm−2

Direct seawater electrolysis for hydrogen production faces significant challenges, particularly regarding stability due to chlorine corrosion and oxidation. Herein, we present an earth-abundant alkaline seawater oxidation electrocatalyst (CO 3 2− -Co(OH) 2 @FeOOH) capable of sustained electrolysis for 5000 h without a significant attenuation at 1 A cm −2 , achieving 100% oxygen Faradaic efficiency. This multilayer electrode, featuring an amorphous FeOOH coating on crystalline cobalt carbonate hydroxide, not only generates a CoFe (oxy)hydroxide active layer but also effectively inhibits the release of CO 3 2− into the electrolyte during the reconstruction process. The synergistic effect of CO 3 2− and the distinct structure contributes to the catalyst's high activity, selectivity, and corrosion resistance. The constructed Pt/C/NF||CO 3 2− -Co(OH) 2 @FeOOH electrochemical cell achieves seawater electrolysis of 500 mA cm −2 at 1.80  V cell voltage, resulting in a power consumption of only 4.30 (kWh m −3 H 2 ). The voltage of the anion exchange membrane electrolyzer remains stable after 600 h of continuous operation at 500 mA cm −2 . The calculated gasoline-equivalent (GGE) per gallon of H 2 is as low as $0.96. This work emphasizes the synergistic effect of multilayer electrodes and anions. and provides a potential catalyst for commercialization.