Rational Synthesis of Core-Shell-Structured Nickel Sulfide-Based Nanostructures for Efficient Seawater Electrolysis

Versatile electrocatalysis at higher current densities  for natural seawater splitting to produce hydrogen demands active and  robust catalysts to overcome the severe chloride corrosion, competing  chlorine evolution, and catalyst poisoning. Hereto, the  core-shell-structured heterostructures composed of amorphous NiFe  hydroxide layer capped Ni₃S₂ nanopyramids which are directly grown on nickel foam skeleton (NiS@LDH/NF)  are rationally prepared to regulate cooperatively electronic structure  and mass transport for boosting oxygen evolution reaction (OER)  performance at larger current densities. The prepared NiS@LDH/NF delivers the anodic current density of 1000 mA cm⁻² at the overpotential of 341 mV in 1.0 m KOH seawater. The feasible surface reconstruction of Ni₃S₂-FeNi  LDH interfaces improves the chemical stability and corrosion  resistance, ensuring the robust electrocatalytic activity in seawater  electrolytes for continuous and stable oxygen evolution without any  hypochlorite production. Meanwhile, the designed Ni₃S₂ nanopyramids coated with FeNi₂P layer (NiS@FeNiP/NF) still exhibit the improved hydrogen evolution reaction (HER) activity in 1.0 m KOH seawater. Furthermore, the NiS@FeNiP/NF||NiS@LDH/NF pair requires cell voltage of 1.636 V to attain 100 mA cm⁻² with a 100% Faradaic efficiency, exhibiting tremendous potential for hydrogen production from seawater.