Nanobubble Formation and Coverage during High Current Density Alkaline Water Electrolysis

• Published in: Nano letters 2024-10, Vol.24 (43), p.13695-13701
• Main Authors: Hammons, Joshua A., Kang, ShinYoung, Ferron, Thomas J., Aydin, Fikret, Lin, Tiras Y., Seung, Kansas, Chow, Paul, Xiao, Yuming, Davis, Jonathan T.
• Format: Article
• Language: English
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/acs.nanolett.4c03657

Gas bubbles are a necessary byproduct of water electrolysis whereby hydrogen and oxygen are produced from water. These attached gases reduce the electrode’s active area, which necessitates a deep understanding of the bubble life cycle starting from nanobubbles. Synchronized with the electrochemistry, the time evolution of the surface nanobubble size and coverage is resolved using grazing incidence small-angle X-ray scattering (GISAXS) and correlated with optical microscopy and theoretical calculations to show that a significant portion of the surface is covered in nanobubbles after larger micron-sized bubbles are observed. These nanobubbles increase in number and decrease in size, toward 2 nm diameter, with the charge passed. The trend in size and number is consistent with an increase in supersaturation, which reduces the nascent bubble size. Altogether, this study suggests a significant portion of the surface contains nanobubbles and that strategies to reduce the dissolved hydrogen would be effective at reducing the nanobubble surface coverage.