Accelerating Oxygen Evolution Activity via Premagnetization-Induced Active Sites in Ferromagnetic Nickel-Iron...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• External magnetic fields can potentially enhance catalytic performance for the oxygen evolution reaction (OER).
• The precise mechanisms, including effects on surface adsorbates, intermediates, and catalyst structure, are not fully understood.

Purpose of the Study:

• To investigate the adsorbate evolution mechanism during OER catalyzed by NiFe-hydroxide (LDH-FeOOH) after magnetic field exposure (premagnetization, PM).
• To elucidate how PM treatment impacts catalyst electronic structure, surface reconstruction, and spin-related processes for improved OER kinetics.

Main Methods:

• Utilized ferromagnetic NiFe-hydroxide (LDH-FeOOH) catalysts subjected to premagnetization (PM) treatment.
• Analyzed changes in electronic structure, Ni-O bonding, surface reconstruction, and adsorbate adsorption energies.
• Validated performance enhancements in laboratory-scale anion-exchange membrane (AME) and industrial-scale alkaline water electrolyzers.

Main Results:

• PM treatment significantly reduced the Tafel slope of LDH-FeOOH from 111.7 to 44.6 mV/dec, indicating enhanced catalytic activity.
• PM induced surface reconstruction, forming highly active high-valenced nickel (oxy)-hydroxide species.
• Established a spin conduction channel optimizing intermediate adsorption and spin-oriented electron transfer.

Conclusions:

• PM treatment enhances OER kinetics through interfacial electronic modulation, surface reconstruction, and optimized spin-dependent electron transfer.
• The study provides critical mechanistic insights into magnetic field effects on catalysis.
• Demonstrated the significant potential of PM for improving industrial hydrogen production via water electrolysis.