Metallic Cu-incorporated NiFe layered double hydroxide nanosheets enabling energy-saving hydrogen generation from chlorine-free seawater electrolysis coupled with sulfion upcycling

Development of multifunctional non-noble electrocatalysts for seawater electrolysis is imperative but still challenging for scale-up hydrogen production to avoid harmful chlorine chemistry. Herein, the metallic Cu-incorporated NiFe layered double hydroxide (LDH) nanosheets are prepared by a facile consecutive corrosion strategy using iron foam (IF) as a reactive substrate, which enable the corrosion-resistant and chlorine-free seawater electrolysis combined with anodic sulfion oxidation for energy-efficient hydrogen production at ultralow electricity consumption. The NiFe-LDH/Cu-IF exhibits excellent electrocatalytic activities for hydrogen evolution reaction (HER) and sulfion oxidation reaction (SOR), achieving low potentials of 0.203 and 0.310 V (vs RHE) at 100 mA cm−2 in alkaline seawater, respectively. The assembled hybrid HER||SOR seawater electrolyzer realizes the ultra-low cell voltage of 0.619 V and power consumption of 1.48 kWh/m3 H2 at 50 mA cm−2, cutting energy consumption over 67 % compared to conventional seawater electrolysis.