Alkaline Seawater Hydrogen Evolution Boosted by In Situ Electrodeposited Nickel Sulfide Electrocatalyst

The direct electrolysis of alkaline seawater is increasingly recognized as a promising route for sustainable hydrogen production, leveraging the vast abundance of seawater resources. However, the widespread implementation of this technology is hindered by the sluggish kinetics of the hydrogen evolution reaction (HER) and the corrosive nature of seawater electrolytes, which together undermine the long-term catalytic durability and efficiency. In response to these challenges, a series of Ni-S electrocatalyst with different content of S were in situ grown on Ni foam through a one-step electrodeposition process. The optimized catalyst exhibits excellent HER performance in 1.0 M KOH seawater, requiring an overpotential of only 55 mV to achieve 10 mA·cm −2 , while maintaining robust operational stability. Detailed kinetic analysis further reveals a remarkably small apparent activation energy ( E a ) of 19.1 kJ·mol −1 . The superior catalytic behavior is attributed to a synergistic interplay of the reconstructed crystalline Ni 3 S 2 phase, a superhydrophilic surface enhancing mass transport, and a tailored electronic environment arising from controlled Ni/S atomic ratios. This work offers a scalable and industry-compatible fabrication strategy for highly active and stable electrocatalysts, thereby contributing to the progress of commercial-scale hydrogen generation from seawater.