Cr-Leaching Induced Vacancy Engineering for High-Performance Anion Exchange Membrane Water Electrolysis

Area of Science:

• Electrochemistry
• Materials Science
• Green Energy

Background:

• Anion exchange membrane water electrolysis (AEMWE) is crucial for large-scale green hydrogen production.
• Developing highly active, durable, and scalable catalysts for AEMWE is a significant challenge.

Purpose of the Study:

• To develop and characterize a novel magnetron-sputtered NiFeCr2 thin-film catalyst for AEMWE.
• To evaluate the catalyst's activity, durability, and scalability in membrane electrode assemblies and electrolyzer stacks.

Main Methods:

• Magnetron sputtering for thin-film catalyst fabrication.
• Electrochemical testing (activity, durability) in AEMWE at 60°C.
• In situ spectroscopic characterization and electrochemical mechanistic studies.
• Density functional theory (DFT) calculations.
• Assembly and testing of a large-scale (15 cm × 100 cm²) electrolyzer stack.

Main Results:

• The NiFeCr2 catalyst delivered 3 A cm⁻² at 1.77 V and 8.54 A cm⁻² at 2.10 V.
• Stable operation at 2 A cm⁻² was maintained for 1798 hours.
• A 15 cm × 100 cm² stack achieved a peak power of 12.87 kW, demonstrating scalability.
• Electrochemical reconstruction formed active Ni/FeOOH phases, operating via a lattice-oxygen-mediated mechanism.
• DFT calculations revealed Cr vacancies enhance catalytic activity for the oxygen evolution reaction.

Conclusions:

• The NiFeCr2 thin-film catalyst shows exceptional performance, durability, and scalability for AEMWE.
• Electrochemical reconstruction and Cr vacancies are key to the catalyst's high activity.
• This work validates the practical potential of NiFeCr2 thin films for industrial green hydrogen production.