NiFeS nanosheet array on Ni foam (NiFeS/NF) behaves as a superb bifunctional electrocatalyst for overall seawater splitting, attaining a commercially demanded current density of 500 mA cm ⁻² at a low cell voltage of 1.85 V with robust stability.

In situ Raman spectroscopy studies indicate that the high-valent molybdate ions can promote the generation of disordered NiOOH active species and protect catalysts from Cl⁻ corrosion during seawater oxidation.

Direct seawater electrolysis at ampere-level current densities, powered by coastal/offshore renewables, is an attractive avenue for sustainable hydrogen production but is undermined by chloride-induced anode degradation. Here we demonstrate the use of hexafluorophosphate (PF₆⁻) as an electrolyte additive to overcome this limitation, achieving prolonged operation for over 5,000 hours at 1 A cm⁻² and 2300 hours at 2 A cm⁻² using NiFe layered double hydroxide (LDH) as anode. Together with the experimental findings, PF₆⁻ can intercalate into LDH interlayers and adsorb onto the electrode surface under an applied electric field, blocking Cl⁻ and stabilizing Fe to prevent segregation. The constant-potential molecular dynamics simulations further reveal the accumulation of high surface concentrations of PF₆ ⁻ on the electrode surface that can effectively exclude Cl⁻, mitigating corrosion. Our work showcases synchronous interlayer and surface engineering by single non-oxygen anion species to enable Cl⁻ rejection and marks a crucial step forward in seawater electrolysis.

Seawater electrolysis driven by offshore renewable energy is a promising avenue for large-scale hydrogen production but faces challenges in designing robust anodes that suppress surface chlorine reactions and corrosion at high current densities. Here we report a strategy by selectively docking PW₁₂-polyoxometalate (PW₁₂-POM) onto Fe sites of CoFe hydroxide anode to modulate the electronic structure of adjacent Co active centers and regulate Cl⁻/OH⁻ adsorption for efficient alkaline seawater oxidation. Our CoFe-based anode achieves low overpotentials, high catalytic selectivity, and notable durability, with continuous operation at 1 A cm⁻² for over 1300 hours and at 2 A cm⁻² more than 600 hours. Theoretical calculations and ex situ/in situ analyses reveal that PW₁₂-POM coordination at Fe sites stabilizes Fe, suppresses its leaching, modulates Co acidity, promotes OH⁻ adsorption, and protects metal sites from Cl⁻ corrosion.

RuO ₂ nanoparticles decorated TiO ₂ nanobelt on titanium plate is active for electrocatalytic hydrogen evolution, requiring overpotentials of 130, 143, and 380 mV to drive 100 mA cm ⁻² in 0.5 M H ₂ SO ₄ , 1.0 M KOH, and 1.0 M PBS solution, respectively.