Bubbles in Porous Electrodes for Alkaline Water Electrolysis

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Porous electrodes are vital for alkaline water electrolysis (AWE).
• Gas bubbles generated during AWE can impede electrode performance by blocking reaction sites and hindering mass transport.
• Observing bubble behavior within opaque porous electrodes is challenging.

Purpose of the Study:

• To investigate the impact of pore structure on bubble dynamics and electrode performance in AWE.
• To elucidate the mechanisms of bubble trapping and release in different porous electrode architectures.

Main Methods:

• Utilized nickel-based porous electrodes with straight and tortuous pore structures.
• Visually captured bubble behavior within the pores of the electrodes.
• Analyzed the relationship between pore geometry, bubble dynamics, and electrode efficiency.

Main Results:

• Tortuous pores led to bubble accumulation and trapping due to collisions with the electrode matrix.
• Straight pores facilitated bubble release, with coalesced bubbles jumping away from surfaces.
• Straight-pore electrodes showed superior performance despite lower specific surface areas compared to tortuous-pore electrodes.

Conclusions:

• Pore structure significantly influences bubble behavior and electrode performance in AWE.
• Straight pore designs are advantageous for minimizing bubble-induced performance degradation.
• Understanding pore structure-bubble dynamics is crucial for designing efficient porous electrodes for electrolysis.