Interface-Engineered NiSe₂/Ni-Fe₂P Nanocubes for Efficient and Durable Seawater Electrolysis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Seawater electrolysis offers a sustainable route for hydrogen production but faces challenges from impurities and chlorine evolution.
• Existing catalysts are often hindered by seawater's complex composition and side reactions during the oxygen evolution reaction (OER).

Purpose of the Study:

• To develop a robust catalyst for efficient seawater electrolysis by addressing impurity interference and chlorine evolution.
• To synthesize and characterize a novel NiSe₂/Ni-Fe₂P catalyst using a self-sacrificial template strategy.

Main Methods:

• A self-sacrificial template strategy using NiSe₂/NF was employed.
• K₃[Fe(CN)₆] etching induced in situ synthesis of NiSe₂@NiFe-PBA nanoboxes, transformed into NiSe₂/Ni-Fe₂P nanocubes via phosphidation.
• Electrochemical performance for OER and hydrogen evolution reaction (HER) was evaluated in alkaline seawater and KOH electrolyte.
• Density Functional Theory (DFT) calculations were performed to understand the catalytic mechanism.

Main Results:

• The NiSe₂/Ni-Fe₂P catalyst exhibited an ultralow OER overpotential of 281 mV at 100 mA cm⁻² in alkaline seawater with >100 h stability.
• The full water-splitting electrolyzer achieved 100 mA cm⁻² at 1.854 V with >200 h stability.
• The NiSe₂@NiFe-PBA/NF catalyst demonstrated excellent HER activity, reaching -10 mA cm⁻² at 168 mV overpotential in 1.0 M KOH.
• DFT calculations confirmed that the NiSe₂@NiFe-PBA heterostructure enhances HER activity by optimizing hydrogen adsorption and reducing reaction barriers.

Conclusions:

• The developed NiSe₂/Ni-Fe₂P catalyst effectively addresses challenges in seawater electrolysis, showing superior OER and HER performance.
• The self-sacrificial template strategy and phosphidation process are crucial for creating highly active and stable electrocatalysts.
• This work provides a promising pathway for efficient hydrogen production from seawater resources.