NiFe-LDH catalyst for seawater hydrogen production via liquid-phase fluoride ion regulation

Direct seawater electrolysis for hydrogen production is a crucial pathway toward large-scale application of green hydrogen energy. However, the anodic oxygen evolution reaction (OER) faces severe challenges from chloride corrosion and side reactions. This study employs nickel-iron layered double hydroxide (NiFe-LDH) as a catalyst and proposes an interfacial dynamic regulation strategy based on fluoride ion (F⁻) addition of the liquid phase. The influence mechanism of F⁻ concentration on catalytic performance was systematically investigated, and the practical application potential in seawater and high-salinity environments was evaluated. The addition of F⁻ enhances the intrinsic activity of the catalyst. The OER activity exhibits a trend of first increasing and then decreasing with increasing F⁻ concentration, and the optimal F⁻ concentration is 50 mg/L. A low overpotential of 242 mV and a Tafel slope of 15 mV/dec was achieved at a current density of 100 mA/cm². Under the optimal F⁻ concentration, the effect of NaCl concentration (0.5~2.5 mol/L) on catalytic performance was further explored. The overpotential ranges from 244 to 276 mV, and the catalyst shows excellent stability at a current density of 100 mA/cm². This liquid-phase dynamic F⁻ regulation strategy significantly enhances the OER activity and stability of NiFe-LDH in simulated seawater and high-salinity environments without altering the intrinsic structure of the catalyst, providing a simple and efficient new approach to electrolyte engineering for seawater electrolysis hydrogen production.