Self-adaptive ZrN coating enables stable acidic oxygen evolution on Co₃O₄ through dynamic surface reconstruction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Proton exchange membrane water electrolyzers (PEMWEs) require acid-stable, non-precious oxygen evolution reaction (OER) catalysts.
• Cobalt oxide (Co3O4) exhibits good OER activity but suffers from dissolution in acidic media.

Purpose of the Study:

• To develop a self-adaptive protection strategy for Co3O4 catalysts to improve stability in acidic environments.
• To investigate the dynamic reconstruction of protective coatings under OER conditions.

Main Methods:

• Magnetron sputtering of ZrN onto Co3O4 precursors.
• Controlled calcination to form a mixed-phase Zr2ON2 and ZrO2 surface layer.
• Electrochemical testing in 0.1 M HClO4 and integration into PEMWEs.

Main Results:

• The ZrN coating transformed into a dual-phase Zr2ON2/ZrO2 layer, providing both conductivity and corrosion resistance.
• The catalyst achieved a low overpotential (362 mV at 10 mA cm-2) and excellent stability (>140 h at 100 mA cm-2).
• Dynamic reconstruction of the coating under OER conditions optimized charge transfer and suppressed cobalt dissolution.

Conclusions:

• Dynamic coating reconstruction is an effective strategy for designing stable acidic OER catalysts.
• The developed catalyst demonstrates practical viability for PEMWE applications, showing sustained performance at high current densities.
• This approach offers a pathway to overcome the stability limitations of non-precious metal catalysts in acidic electrochemical systems.