An Ionomer-Free Gapless Catalyst-Bridging Membrane Electrode Assembly for High-Performance Pure Water-Fed Anion...

Area of Science:

• Electrochemistry
• Materials Science
• Renewable Energy

Background:

• Anion exchange membrane water electrolyzers (AEMWEs) offer low-cost, high-purity hydrogen production.
• Conventional AEMWEs struggle with pure water due to high ohmic resistance and slow kinetics within the membrane electrode assembly (MEA).

Purpose of the Study:

• To develop an efficient ionomer-free, gapless catalyst-bridging MEA (GCB-MEA) for high-performance AEMWEs using pure water.
• To improve interfacial contact, reduce resistance, and enhance reaction kinetics in AEMWEs.

Main Methods:

• Confined directional deposition of catalyst layers to create an ionomer-free catalyst-bridging MEA (GCB-MEA).
• Fabrication of GCB-MEA by bridging the anion exchange membrane and gas diffusion layer.
• Performance testing of the GCB-MEA-based AEMWE under pure water conditions.

Main Results:

• The GCB-MEA demonstrated more active sites, lower contact resistance, faster mass transfer, and stronger interfacial binding compared to conventional MEAs.
• The GCB-MEA-based AEMWE achieved 85.7% energy conversion efficiency at 1 A cm^-2.
• Exceptional stability was observed with a voltage degradation rate of 65 µV h^-1 at 0.5 A cm^-2 after 1,000 hours, the lowest reported for pure water-fed AEMWEs.
• Stable operation under fluctuating solar energy supply conditions was confirmed.

Conclusions:

• The ionomer-free GCB-MEA is a highly effective strategy for advancing AEMWE performance, particularly for pure water electrolysis.
• This approach significantly overcomes the limitations of conventional MEAs, enabling efficient and stable hydrogen production.
• The developed GCB-MEA technology holds great promise for cost-effective and sustainable green hydrogen generation.