Nanobubble Formation and Coverage during High Current Density Alkaline Water Electrolysis.
Joshua A Hammons1, ShinYoung Kang1, Thomas J Ferron1
1Lawrence Livermore National Laboratory, Materials Science Division, 7000 East Ave., Livermore, California 94550, United States.
Nano Letters
|October 16, 2024
Summary
Gas bubbles from water electrolysis cover electrode surfaces, reducing efficiency. Nanobubbles increase with charge passed, suggesting strategies to reduce dissolved hydrogen can improve water electrolysis performance.
Area of Science:
- Electrochemistry
- Surface Science
- Materials Science
Background:
- Water electrolysis generates hydrogen and oxygen gas bubbles.
- These bubbles reduce the electrode's active surface area, impacting efficiency.
- Understanding the nanobubble life cycle is crucial for optimizing electrolysis.
Purpose of the Study:
- To investigate the evolution of nanobubbles during water electrolysis.
- To correlate nanobubble formation with electrochemical parameters.
- To understand the impact of nanobubbles on electrode performance.
Main Methods:
- Grazing incidence small-angle X-ray scattering (GISAXS) to resolve nanobubble size and coverage.
- Optical microscopy for visual correlation.
- Theoretical calculations to model bubble behavior.
Main Results:
- A significant portion of the electrode surface is covered by nanobubbles.
- Nanobubble size decreases (towards 2 nm) and number increases with charge passed.
- Observed trends align with increased supersaturation, reducing nascent bubble size.
Conclusions:
- Nanobubbles significantly cover electrode surfaces during water electrolysis.
- Reducing dissolved hydrogen is a viable strategy to decrease nanobubble surface coverage.
- Optimizing nanobubble dynamics can enhance water electrolysis efficiency.
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