Bubble Formation at a Gas-Evolving Microelectrode

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• 作者：Damaris Fern谩ndez ; Paco Maurer ; Milena Martine ; J. M. D. Coey ; Matthias E. M枚bius
• 刊名：Langmuir
• 出版年：2014
• 出版时间：November 4, 2014
• 年：2014
• 卷：30
• 期：43
• 页码：13065-13074
• 全文大小：562K
• ISSN：1520-5827

文摘

The electrolytic production of gas bubbles involves three steps鈥攏ucleation, growth, and detachment. Here the growth of hydrogen bubbles and their detachment from a platinum microelectrode of diameter 125 渭m are studied using high-speed photography and overpotential frequency spectrum (noise) analysis. The periodic release of large <800 渭m bubbles鈥攇as oscillator behavior鈥攚as often observed, with a corresponding periodic oscillation of the overpotential which is reflected as a main peak and a series of harmonics in the power spectral density. The release frequency is inversely correlated with the bubble size and hydrogen production rate. When the coalescence of bubbles at the electrode surface is inhibited, either chemically with a surfactant or ethylene glycol or hydrodynamically by magnetically induced convection, swarms of small 鈭?0 渭m bubbles are released in an aperiodic stream. The abrupt transition from periodic to aperiodic release occurs when the surface tension falls below 70 mN m^鈥?. Hydrogen bubble growth is also studied on a transparent platinum thin-film electrode, where the bubble coalescence can be observed directly. It leaves sessile droplets of electrolyte within the footprint of the growing bubble, showing that the growth involves scavenging smaller bubbles from solution due to hydrogen generated directly at the electrode. A possible role of nanobubbles in the lift-off process is discussed.