Dynamic chloride ion adsorption on single iridium atom boosts seawater oxidation catalysis

Area of Science:

• Electrochemistry
• Materials Science
• Green Chemistry

Background:

• Seawater electrolysis is a promising route for green hydrogen production.
• Chloride (Cl-) corrosion of anodes hinders commercialization of seawater electrolysis.

Purpose of the Study:

• To develop a novel catalyst for alkaline seawater electrolysis that addresses anode corrosion.
• To tailor chloride adsorption and modulate the electronic structure of the active site.

Main Methods:

• Synthesis of an atomic iridium catalyst on cobalt iron layered double hydroxide (Ir/CoFe-LDH).
• Utilized operando characterizations and theoretical calculations.
• Tested catalyst performance in alkaline seawater and chloride-free electrolytes.

Main Results:

• Established a unique Ir-OH/Cl coordination state that lowers oxygen evolution reaction (OER) activation energy by 1.93 times.
• Ir/CoFe-LDH demonstrated superior OER activity (202 mV overpotential) in 6 M NaOH + 2.8 M NaCl compared to chloride-free conditions (236 mV overpotential).
• Achieved 100% catalytic selectivity and stability at high current densities (>1,000 hours).

Conclusions:

• The developed Ir/CoFe-LDH catalyst effectively mitigates anode corrosion in seawater electrolysis.
• The unique Ir-OH/Cl coordination is key to enhanced catalytic performance and stability.
• This advancement paves the way for cost-effective green hydrogen production from seawater.