Anionic Passivation Enables Reconstruction-Free Seawater Electrolysis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Nonoxide electrocatalysts are promising for seawater oxidation but suffer from instability.
• Surface reconstruction and corrosion limit their practical application under high anodic potentials.

Purpose of the Study:

• To develop a strategy to stabilize nonoxide electrocatalysts against oxidative degradation.
• To enhance the electrocatalytic activity and durability of nonoxide catalysts for seawater oxidation.

Main Methods:

• Anionic ligand passivation strategy using an ultrathin TiOₓ overlayer on FeNiP (FNP) support.
• Growth of atomically ordered Iridium (Ir) arrays on the stabilized scaffold.
• Operando spectroscopy and 18O isotope tracing for mechanistic studies.

Main Results:

• The TiOₓ overlayer stabilizes the phosphide lattice against oxidative leaching by downshifting the P p-band center.
• The stabilized scaffold enables Ir array anchoring, promoting O-O radical coupling via an oxide pathway.
• The TiIr@FNP catalyst exhibits reconstruction-free oxygen evolution reaction (OER) behavior with negligible lattice oxygen participation.
• Achieved ultralow overpotentials (310 mV at 1 A cm⁻²), stable operation (>1200 h) in alkaline seawater, and near-unity Faradaic efficiency.

Conclusions:

• The developed anionic ligand passivation strategy effectively stabilizes nonoxide electrocatalysts.
• This approach enables durable and highly efficient seawater oxidation catalysis under industrially relevant conditions.
• Demonstrates a generalizable method for designing advanced nonoxide anodic electrocatalysts.