Stainless Steel Activation for Efficient Alkaline Oxygen Evolution in Advanced Electrolyzers

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Developing cost-effective electrocatalysts for the oxygen evolution reaction (OER) is crucial for water electrolysis.
• Stainless steel (SS) is a potential low-cost material, but its intrinsic OER activity needs enhancement.

Purpose of the Study:

• To develop an electrochemical strategy to activate stainless steel electrodes for efficient and stable alkaline OER.
• To investigate the mechanism of activation and the role of leached species in enhancing OER performance.

Main Methods:

• Electrochemical cycling within a specific potential window to activate SS electrodes.
• Electrochemical characterization, Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES), and operando Raman spectroscopy.
• Potential-pulse strategy for OER activity regeneration and stability testing.

Main Results:

• Electrochemical activation significantly decreased the OER overpotential by 40 mV at 100 mA cm⁻².
• Fe leaching accelerated, exposing Cr and Ni species, with Ni accumulating as OER-active Fe-incorporated NiOOH.
• The activated SS electrode demonstrated remarkable stability, showing no performance decay after 300 h and competitive performance in an alkaline water electrolyzer.

Conclusions:

• Electrochemical activation is an effective strategy to enhance the OER performance of stainless steel.
• The mechanism involves controlled leaching and surface reconstruction, leading to the formation of active Ni-based species.
• Activated stainless steel shows promise as a durable and cost-effective alternative to precious metal catalysts in alkaline water electrolysis.