Pt@Co(OH)2 nanoarrays supported on nickel foam as an enabling catalytic electrode for efficient and stable seawater electrolysis

Direct seawater electrolysis (DSE) is extremely promising for green hydrogen production as it avoids using scarce freshwater resources, but it faces inherent challenges including slow hydrogen evolution reaction (HER) kinetics at the cathode, active-site blockage by insoluble Mg 2+ /Ca 2+ hydroxides precipitation and chloride corrosion. Herein, we report a high performance HER electrode based on Pt@Co(OH) 2 nanoarrays supported on Nickel foam for DSE, where the dual-catalytic sites on Pt and Co adsorbed ⁎H and ⁎OH, respectively, efficiently promoting water dissociation. The electronic interaction between Pt and Co facilitated the desorption of ⁎H and inhibited the adsorption of Cl - on the electrode. Moreover, positively charged Pt@Co(OH) 2 nanoarrays significantly suppressed Mg 2+ /Ca 2+ migration to the electrode surface, and the ordered pore structure enabled efficient bubble-induced removal of possible precipitation. A pH-asymmetric electrolyzer was assembled with the cathode that achieved a benchmark current density of 100 mA cm -2 with a low voltage of 1.675 V at 80 ℃, and it operated continuously for 1000 hours at 100, 200, 500, 800 and 1000 mA cm -2 without significant degradation. This work provides a synergistic strategy to simultaneously overcome the persistent challenges of reactivity and stability of the cathode in DSE, enabling sustainable industrial-scale green hydrogen production. Pt@Co(OH) 2 nanoarrays supported on nickel foam have been fabricated and comprehensively studied as an enabling electrode for hydrogen evolution reaction in direct seawater electrolysis. The dual-catalytic sites on Pt and Co efficiently promoted water dissociation, and the electronic interaction between Pt and Co inhibited the adsorption of Cl - on the electrode. Positively charged Pt@Co(OH) 2 nanoarrays suppressed Mg 2+ /Ca 2+ migration to the electrode surface, and the ordered pore structure enabled efficient bubble-induced removal of possible precipitation. • Pt@Co(OH) 2 nanoarrays are grown on nickel foam as an enabling cathode for seawater electrolysis. • The positively charged Co(OH) 2 on the cathode repels cations and inhibits hydroxide deposits. • Pt-Co dual catalytic sites cooperatively promote water dissociation and enhance hydrogen production kinetics. • The electronic interaction between Pt and Co weakens Cl - adsorption and boosts corrosion resistance in seawater. • An electrolyzer employed the cathode achieved stable operation at industrial current densities over 1000 h.