Dynamically Restructuring Ni_x Cr_y O Electrocatalyst for Stable Oxygen Evolution Reaction in Real Seawater

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Achieving long-term stability for oxygen evolution reaction (OER) electrocatalysts in seawater is crucial but challenging.
• Maintaining intrinsic catalytic activity while preventing degradation in harsh alkaline conditions remains a key obstacle.

Purpose of the Study:

• To develop a robust electrocatalyst for efficient and stable OER in alkaline media and real seawater.
• To investigate the self-restructuring mechanism of the electrocatalyst and its impact on OER activity and stability.

Main Methods:

• Electrochemical measurements (overpotential, current density, long-term stability tests).
• In situ studies to analyze catalyst restructuring (Cr leaching and redistribution).
• Testing in artificial and real Red Sea seawater with added 1 M KOH.

Main Results:

• NiₓCrᵧO exhibited low overpotentials (270 mV at 100 mA/cm², 320 mV at 500 mA/cm²) in 1 M KOH.
• Exceptional stability was observed (>475 h at 100 mA/cm², >280 h at 500 mA/cm²).
• Dynamic Cr redistribution increased electrochemically active surface area and porosity, enhancing OER activity.
• Remarkable stability in real Red Sea seawater (2000 h at 10 mA/cm², 275 h at 100 mA/cm², 100 h at 500 mA/cm²).

Conclusions:

• The NiₓCrᵧO electrocatalyst demonstrates self-restructuring capabilities, leading to improved OER activity and stability.
• The dynamic porosity evolution effectively counteracts seawater impurities, enabling stable operation in real seawater.
• This work presents a promising non-noble metal-based catalyst for direct seawater splitting applications.