Dynamic Dissolution-Replenishment Equilibrium Enables Efficient and Durable Oxygen Evolution on Self-Reconstructing...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Industrial water electrolysis requires efficient and stable electrocatalysts for the oxygen evolution reaction (OER).
• Non-noble electrocatalysts often suffer from irreversible surface degradation under harsh oxidative conditions, limiting their industrial applicability.
• Developing robust electrocatalysts that maintain performance at high current densities is a critical challenge.

Purpose of the Study:

• To develop a non-noble electrocatalyst with high activity and durability for industrial OER.
• To investigate the in situ surface reconstruction mechanism of a high-entropy alloy during OER.
• To demonstrate the catalyst's performance in anion-exchange membrane electrolyzers for alkaline and seawater electrolysis.

Main Methods:

• Synthesis of a FeCoNiCrW0.6 dual-phase high-entropy alloy.
• In situ electrochemical characterization during high-current-density OER.
• Analysis of the reconstructed surface architecture and composition.
• Performance testing in a three-electrode system and an anion-exchange membrane electrolyzer.

Main Results:

• The FeCoNiCrW0.6 catalyst undergoes controllable in situ surface reconstruction, forming a porous architecture with an amorphous oxide layer.
• This reconstruction facilitates a transition to the lattice oxygen mechanism, enhancing intrinsic activity.
• A dynamic dissolution-replenishment equilibrium involving W and Cr leaching ensures long-term stability.
• The reconstructed catalyst achieved a low overpotential (223 mV at 10 mA cm-2) and operated stably for over 700 hours at high current densities.
• In an electrolyzer, it enabled efficient alkaline and seawater electrolysis at 1 A cm-2 with a cell voltage of 1.79 V.

Conclusions:

• The FeCoNiCrW0.6 high-entropy alloy exhibits a dynamic self-reconstruction paradigm for stable and active OER.
• This approach overcomes the limitations of surface degradation in non-noble electrocatalysts.
• The findings pave the way for designing advanced electrocatalysts for industrial water electrolysis applications.