Local alkalinity enables high-performance pure water anion exchange membrane electrolysis

Area of Science:

• Electrochemistry
• Materials Science
• Sustainable Energy

Background:

• Anion exchange membrane water electrolysers (AEMWEs) show promise for hydrogen production.
• AEMWE performance is limited by low membrane conductivity in pure water.
• Developing efficient AEMWEs requires strategies to enhance ion transport and durability.

Purpose of the Study:

• To overcome the conductivity limitations of AEMWEs in pure water.
• To develop a local alkalinity engineering strategy for improved AEMWE performance.
• To demonstrate the versatility and scalability of the proposed strategy.

Main Methods:

• Incorporation of TiO2 nanoparticles into catalyst layers of AEMWEs.
• Utilizing scanning electrochemical microscopy with pH microelectrodes to confirm local alkalinity.
• Performance testing of the engineered AEMWE, including current density, voltage, and long-term stability.

Main Results:

• Creation of self-sustaining alkaline microenvironments (pH ~14) at electrode interfaces.
• Achieved a high current density of 3.0 A cm⁻² at 2.08 V, comparable to proton exchange membrane electrolysers.
• Demonstrated long-term stability of ~1400 h at 1.0 A cm⁻², with reduced catalyst and membrane degradation.

Conclusions:

• Local alkalinity engineering is an effective strategy to enhance AEMWE performance.
• The TiO2 nanoparticle approach significantly improves conductivity and durability.
• This universal tactic is applicable to various membranes and scalable for industrial applications.