10,000-h-stable intermittent alkaline seawater electrolysis

Area of Science:

• Electrochemistry
• Materials Science
• Renewable Energy

Background:

• Seawater electrolysis is a promising route for green hydrogen production.
• Direct seawater electrolysis faces anode corrosion and competing reactions due to halide ions.
• Previous research focused on anode stability, overlooking cathode degradation under intermittent operation.

Purpose of the Study:

• To investigate cathode degradation during intermittent seawater electrolysis.
• To develop a strategy for enhancing cathode stability and performance in fluctuating conditions.
• To enable practical seawater splitting technologies powered by renewable electricity.

Main Methods:

• Investigated dynamic evolution and degradation of seawater splitting cathodes.
• Proposed and implemented a catalyst passivation layer strategy.
• Utilized in situ-formed phosphate passivation on NiCoP-Cr2O3 cathodes.

Main Results:

• Identified cathode degradation mechanisms under intermittent electrolysis.
• Demonstrated that a phosphate passivation layer protects active sites from oxidation and repels halide ions.
• Achieved stable operation at 0.5 A cm⁻² for 10,000 hours in alkaline seawater with a low voltage increase rate (0.5% khr⁻¹).

Conclusions:

• Cathode passivation is crucial for stable seawater electrolysis with intermittent renewable energy.
• The phosphate passivation layer effectively enhances cathode durability and performance.
• This strategy advances the development of practical seawater splitting technologies.