Improved Alkaline Seawater Splitting of NiS Nanosheets by Iron Doping

Seawater electrolysis driven by renewable electricity is deemed a promising and sustainable strategy for green hydrogen production, but it is still formidably challenging. Here, we report an iron-doped NiS nanosheet array on Ni foam (Fe- NiS/NF) as a high-performance and stable seawater splitting electrocatalyst. Such Fe-NiS/NF catalyst needs overpotentials of only 420 and 270 mV at 1000 mA cm-2 for the oxygen evolution reaction and hydrogen evolution reaction in alkaline seawater, respectively. Furthermore, its two-electrode electrolyzer needs a cell voltage of 1.88 V for 1000 mA cm-2 with 50 h of long-term electrochemical durability in alkaline seawater. Additionally, in situ electrochemical Raman and infrared spectroscopy were employed to detect the reconstitution process of NiOOH and the generation of oxygen intermediates under reaction conditions.

Automated summary

We report a high-performance and stable seawater splitting electrocatalyst, Fe-NiS/NF, which consists of iron-doped NiS nanosheet array on Ni foam. This catalyst exhibits low overpotentials of 420 and 270 mV for oxygen evolution and hydrogen evolution reactions, respectively, in alkaline seawater. The two-electrode electrolyzer using this catalyst requires a cell voltage of 1.88 V for 1000 mA cm-2 and demonstrates excellent long-term electrochemical durability for 50 hours in alkaline seawater. In situ electrochemical Raman and infrared spectroscopy were employed to study the reconstitution process of NiOOH and the generation of oxygen intermediates under reaction conditions.