@article{d71bb4d55fff4b769a95bee3b799b9c8,
title = "Potential response of single successive constant-current-driven electrolytic hydrogen bubbles spatially separated from the electrode",
abstract = "The presence of bubbles in gas-evolving electrolytic processes can heavily alter the mass transport of gaseous products and can induce severe overpotential penalties at the electrode through the action of bubble coverage (hyperpolarization) and electrolyte constriction (Ohmic shielding). However, bubble formation can also alleviate the overpotential by lowering the concentration of dissolved gas in the vicinity of the electrode. In this study, we investigate the latter by considering the growth of successive hydrogen bubbles driven by a constant current in alkaline-water electrolysis and their impact on the half-cell potential in the absence of hyperpolarization. The bubbles nucleate on a hydrophobic cavity surrounded by a ring microelectrode which remains free of bubble coverage. The dynamics of bubble growth does not adhere to one particular scaling law in time, but undergoes a smooth transition from pressure-driven towards supply-limited growth. The contributions of the different bubble-induced phenomena leading to the rich behaviour of the periodic fluctuations of the overpotential are identified throughout the different stages of the bubble lifetime, and the influence of bubble size and applied current on the concentration and Ohmic overpotential components is quantified. We find that the efficiency of gas absorption, and hence the concentration-lowering effect, increases with increasing bubble size and also with increasing current. However, the concentration-lowering effect is always eventually countered and overcome by the effect of Ohmic shielding as the bubble size outgrows and eclipses the electrode ring beneath.",
keywords = "Bubbles, Electrochemistry, Electrode, Hydrogen, UT-Hybrid-D",
author = "Akash Raman and Pablo Pe{\~n}as and {van der Meer}, Devaraj and Detlef Lohse and Han Gardeniers and {Fern{\'a}ndez Rivas}, David",
note = "Funding Information: We would like to thank S. Schlautmann for the fabrication of the experimental substrates in the cleanroom and SEM imaging, R. P. G. Sanders and G.-W. Bruggert for the discussions on the experimental set-up, and the MESA+ Nanolab for the use of their facilities. This work was supported by the Netherlands Center for Multiscale Catalytic Energy Conversion (MCEC), an NWO Gravitation program funded by the Ministry of Education , Culture and Science of the government of the Netherlands. This project has received funding from the European Union{\textquoteright}s Horizon 2020 research and innovation programme under the Marie Sk{\l}odowska-Curie grant agreement No. 801359 . Funding Information: We would like to thank S. Schlautmann for the fabrication of the experimental substrates in the cleanroom and SEM imaging, R. P. G. Sanders and G.-W. Bruggert for the discussions on the experimental set-up, and the MESA+ Nanolab for the use of their facilities. This work was supported by the Netherlands Center for Multiscale Catalytic Energy Conversion (MCEC), an NWO Gravitation program funded by the Ministry of Education, Culture and Science of the government of the Netherlands. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk{\l}odowska-Curie grant agreement No. 801359. Publisher Copyright: {\textcopyright} 2022 The Author(s)",
year = "2022",
month = sep,
day = "1",
doi = "10.1016/j.electacta.2022.140691",
language = "English",
volume = "425",
journal = "Electrochimica acta",
issn = "0013-4686",
publisher = "Elsevier Ltd",
}