Interfacial Electrostatic Engineering for Chlorine Ions Blocking Toward Long-Lasting Alkaline Seawater Oxidation

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Seawater electrolysis faces challenges with chloride ions (Cl-) causing reduced selectivity and material degradation.
• Existing catalysts struggle with chlorine evolution reaction (CER) interference and chlorine pitting.
• Anion layers show promise in repelling Cl- while allowing oxygen-containing anion diffusion.

Purpose of the Study:

• To develop a hierarchical catalyst for enhanced seawater electrolysis.
• To improve oxygen evolution reaction (OER) selectivity and material stability.
• To mitigate the negative effects of chloride ions in electrochemical systems.

Main Methods:

• Fabrication of a hierarchical catalyst: NiFe-LDH active layer on a MnO2 layer, supported by Ni foam (NiFe-LDH@MnO2/NF).
• Utilized interfacial electrostatic engineering for catalyst design.
• In situ generation of OH- groups on the MnO2 surface for Cl- repulsion.

Main Results:

• The NiFe-LDH@MnO2/NF anode demonstrated stable operation at 100 mA cm-2 for 100 hours at 70°C.
• Achieved 97.9% OER selectivity, significantly reducing CER interference.
• Reduced OER overpotential by 136 mV compared to commercial Ni mesh.
• The catalyst effectively repelled Cl- via electrostatic repulsion through in situ generated OH- groups.

Conclusions:

• The developed hierarchical catalyst offers a robust and efficient solution for seawater electrolysis.
• The strategy of in situ OH- generation and electrostatic repulsion effectively suppresses Cl- interference.
• This work presents a promising, cost-effective, and stable anode for industrial seawater electrolysis, potentially powered by renewable energy sources.