Low-Loading and Highly Stable Membrane Electrode Based on an Ir@WONR Ordered Array for PEM Water Electrolysis

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy Technologies

Background:

• Proton exchange membrane water electrolysis (PEMWE) is crucial for renewable energy, but requires cost-effective and stable membrane electrode assemblies.
• Iridium is an effective oxygen evolution reaction catalyst for PEMWE, yet its scarcity poses a significant challenge.
• Existing electrode designs face limitations in mass transport and conductivity, impacting overall performance.

Purpose of the Study:

• To design and fabricate a novel electrode structure for PEMWE that reduces iridium loading while maintaining high performance and stability.
• To investigate the impact of ordered array morphology and catalyst dispersion on electrode efficiency and durability.
• To address the cost and durability issues hindering the widespread adoption of PEMWE technology.

Main Methods:

• Fabrication of an ordered array electrode featuring a defective iridium (Ir) film decorated on tungsten oxide nanorods (WONRs) using electrodeposition.
• Characterization of the electrode's morphology, composition, and electrochemical performance, including current-voltage (I-V) measurements and long-term stability tests.
• Comparative analysis with conventional sprayed electrodes to evaluate improvements in mass transport and conductivity.

Main Results:

• The novel Ir@WONRs electrode demonstrated excellent performance, achieving 2.2 A cm^-2 at 2.0 V and maintaining stability for 1030 hours at 0.5 mA cm^-2.
• A significantly reduced iridium loading of 0.14 mg_Ir cm^-2 was achieved, lowering potential costs.
• The ordered structure facilitated enhanced iridium mass activity and improved conductivity, expanding the mass transport polarization region to at least 3.0 A cm^-2.

Conclusions:

• The developed Ir@WONRs electrode offers a promising solution for cost-effective and durable PEMWE by optimizing catalyst utilization and electrode architecture.
• The unique nanostructure enhances water storage and mass transport, overcoming limitations of traditional electrode designs.
• This innovative electrode design has significant potential to accelerate the transition towards a renewable energy future.