Dual-anion regulation engineering enhances the chloridion corrosion resistance for long-lasting industrial-scale seawater splitting

Developing non-precious metal electrocatalysts with high activity and high chlorine (Cl^–) corrosion resistance under industrial-scale current density remains challenging for large-scale seawater splitting. Targeting at this problem, we rationally design an amorphous cobalt-iron layered double hydroxides with the intercalation of borate anions (B₄O₅(OH)₄^2--CoFe-LDH) grown over the crystalline sulfurized cobalt molybdate with sulfate-rich surface (SO₄^2--CoMoO₄) nanohybrid (B₄O₅(OH)₄^2--CoFe-LDH/SO₄^2--CoMoO₄). Through sulfidation and amorphous/crystalline interface construction, multiple synergistic effects are induced, effectively modulating the electronic structure, enhancing accessible active site, and promoting electron transfer. The density functional theory calculations and in-situ spectroscopy measurements demonstrate that the integration of B₄O₅(OH)₄^2--CoFe-LDH and SO₄^2--CoMoO₄ synergistically optimize the adsorption energy of intermediates, lower the reaction energy barrier, and facilitate the formation of CoOOH active species, enhancing the catalytic activity for oxygen evolution reaction. The unique B₄O₅(OH)₄^2-/SO₄^2- dual-anion layers block unfavorable adsorption of Cl^– and contribute to increased resistance to Cl^–, enabling long-term corrosion protection for stable seawater splitting. Inspiringly, the B₄O₅(OH)₄^2--CoFe-LDH/SO₄^2--CoMoO₄ nanohybrid stably sustains the industrial current density (1 A cm^-2) in alkaline simulated seawater for 720 hours, with only a minimal concentration of hypochlorite (ClO^–, 0.0003%) in the electrolyte.