Enthralling Anodic Protection by Molybdate on High-Entropy Alloy-Based Electrocatalyst for Sustainable Seawater...

Area of Science:

• Electrochemistry
• Materials Science
• Corrosion Science

Background:

• Seawater electrolysis is crucial for sustainable hydrogen production but is hindered by anode corrosion from chloride ions.
• Developing robust electrocatalysts and protective strategies is essential for efficient and long-lasting seawater oxidation.

Purpose of the Study:

• To design a high-entropy alloy electrocatalyst with high oxygen evolution reaction (OER) activity.
• To develop a method for protecting the anode surface from chloride corrosion under high current densities or potentials.
• To investigate the role of molybdate as an inhibitor in seawater electrolysis.

Main Methods:

• Synthesis and characterization of a high-entropy alloy-based electrocatalyst.
• Electrochemical testing including OER performance and stability measurements in simulated seawater.
• In-situ/ex-situ analysis to understand the protective mechanism of molybdate ions.

Main Results:

• The high-entropy alloy electrocatalyst achieved an overpotential of 230 mV at 20 mA cm⁻² for OER.
• The addition of molybdate (MoO₄²⁻) as an inhibitor protected the anode, allowing stable operation for over 500 hours at 1 A cm⁻² or 2.0 V vs RHE.
• Molybdate ions formed a protective layer on the anode surface via electrostatic accumulation, preventing chloride corrosion without hindering OER.

Conclusions:

• A novel high-entropy alloy electrocatalyst demonstrates excellent OER activity for seawater electrolysis.
• Molybdate effectively inhibits anode corrosion, ensuring catalyst stability under demanding conditions.
• This combined approach offers a promising solution for efficient and sustainable seawater electrolysis.