Enhancing the selective OH− adsorption for durable alkaline seawater oxidation at industrial current densities

As global freshwater scarcity intensifies, direct seawater electrolysis emerges as a transformative pathway for sustainable hydrogen production. However, chloride-induced corrosion at the anode has long plagued catalyst stability under industrial current densities. Now, researchers from the Chinese Academy of Sciences, University of Macau, and Jiangxi University of Science and Technology, led by Professor Jianmin Yu and Professor Lishan Peng, have developed a breakthrough heterostructured catalyst that achieves record durability in alkaline seawater oxidation.

Why This Catalyst Matters

Conventional NiFe-layered double hydroxides (LDH) suffer from severe corrosion in seawater electrolysis, where high chloride concentrations compete with hydroxide ions for active sites, triggering destructive chlorine oxidation reactions. The team addresses this fundamental challenge through interfacial engineering—integrating Ce(OH)CO₃ with NiFe-LDH to create a Lewis acid-tuned catalytic system that selectively repels chloride while accelerating oxygen evolution.

Innovative Design and Mechanism

Density functional theory and X-ray absorption spectroscopy reveal that Ce(OH)CO₃ incorporation forms a Ce–O–Fe–O–Ni bridging framework, inducing electron transfer from Ni/Fe to Ce. This elevates the oxidation states of Ni and Fe, enhancing their Lewis acidity and shifting d-band centers downward. The result: OH⁻ adsorption energy drops from 1.71 eV to 0.67 eV, while Cl⁻ adsorption becomes thermodynamically unfavorable (2.32 eV). Time-of-flight SIMS confirms the surface is predominantly enriched with OH⁻, with Cl⁻ signals falling below detection limits.

Outstanding Performance

The optimized NiFe-LDH/Ce(OH)CO₃ delivers exceptional catalytic metrics: a low overpotential of 221 mV at 100 mA cm^-2, Tafel slope of 31.37 mV dec^-1, and—most critically—450 hours of continuous operation at 1 A cm^-2 without degradation. When integrated into an anion exchange membrane electrolyzer, the system achieves 68.59% energy efficiency at 500 mA cm^-2, with hydrogen production costs as low as $0.97 per gasoline gallon equivalent—well below the US DOE's 2026 target.

Future Outlook

This work establishes a general strategy for developing corrosion-resistant LDH-based anodes through Lewis acid site engineering, opening viable pathways for large-scale seawater hydrogen production with commercial-grade durability and cost-effectiveness.

Stay tuned for more innovations from this collaborative team!