Hierarchical Fe-based electrocatalyst for lattice oxygen mediated water oxidation with Industrial-Level activity

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Industrial alkaline water electrolysis demands efficient electrocatalysts for the oxygen evolution reaction (OER) at high current densities.
• Transition metal-based catalysts are crucial for improving energy conversion efficiency.

Purpose of the Study:

• To rationally design and synthesize a novel 3D hierarchical heterostructure electrocatalyst for enhanced OER performance.
• To investigate the catalytic mechanism and understand the factors contributing to superior activity and durability.

Main Methods:

• Fabrication of a Fe2O3 nanoparticle-decorated FeMoO4 nanorod catalyst supported on Ni foam.
• Electrochemical characterization including OER activity, overpotential measurements, and long-term durability tests.
• In-situ FTIR spectroscopy and theoretical calculations to elucidate the OER mechanism.
• Operando electrochemical impedance spectroscopy to assess charge transport properties.

Main Results:

• The Fe2O3/FeMoO4/NF electrodes demonstrated excellent OER activity, with low overpotentials of 315 mV at 1000 mA cm⁻² and 352 mV at 2000 mA cm⁻².
• Exceptional long-term durability was observed, maintaining performance for over 900 hours at 500 mA cm⁻².
• In-situ FTIR and theoretical studies confirmed a lattice-oxygen-mediated mechanism (LOM) involving direct OO radical coupling, which accelerates kinetics.
• Operando EIS indicated rapid charge transport within the catalyst structure.

Conclusions:

• The hierarchical Fe2O3/FeMoO4/NF electrocatalyst exhibits industrial-level OER activity and stability.
• The enhanced performance is attributed to abundant heterointerfaces and the LOM-dominated mechanism, which overcomes scaling limitations.
• This work offers a promising strategy for developing advanced electrocatalysts for practical alkaline water electrolysis applications.