Engineering cadmium-doped NiFe-LDH nanosheet arrays via low-temperature etching for robust high-current-density seawater electrolysis

Abstract

Seawater electrolysis offers a sustainable pathway for hydrogen production by utilizing abundant seawater resources, yet the severe chloride-induced corrosion and competitive chlorine evolution reaction (ClER) remain critical challenges. Herein, we propose a facile low-temperature etching strategy to construct cadmium-doped NiFe-layered double hydroxide (NiFeCd-LDH) nanosheet arrays on nickel foam (NF) as a highly efficient and corrosion-resistant anode. The optimized NiFeCd-LDH/NF demonstrates exceptional oxygen evolution reaction (OER) activity in alkaline simulated seawater, achieving an ultralow overpotential of 337 mV at 1000 mA cm⁻², while maintaining robust stability under saline conditions (0.5 M NaCl). When integrated into an anion exchange membrane (AEM) electrolyzer with a Pt/C/NF cathode, the full cell requires only 1.84 V to deliver 500 mA cm⁻² in a 6 M KOH and 0.5 M NaCl solution at 80 °C, with negligible performance decay over 50 h. Systematic investigations reveal that the enhanced chloride tolerance originates from the cadmium-induced electronic modulation, which suppresses ClER kinetics and stabilizes the active metal sites. Furthermore, dynamic parameter optimization (temperature, electrolyte concentration, and current response) significantly reduces cell voltage and improves energy conversion efficiency. This work not only provides a scalable synthesis route for anti-corrosive LDH-based catalysts but also advances the practical deployment of seawater electrolysis systems.