Controlled electrochemical gas bubble release from electrodes entirely and partially covered with hydrophobic materials
Controlled electrochemical gas bubble release from electrodes entirely and partially covered with hydrophobic materials
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DOI：
10.1016/j.electacta.2011.04.104
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发表时间：
2011-08-01
影响因子：
6.6
通讯作者：
Rakib, M.
中科院分区：
文献类型：
--
作者：
Brussieux, C.;Viers, Ph.;Rakib, M.
本文进行了一种毫米级电化学生成氢气气泡的实验研究。本文报道了一种产生气泡的方法，该方法在分离时可控制气泡的数量和大小，并可在平面电极上放置。部分浸湿的复合岛在抛光金属基板上实现。只要岛屿的大小低于取决于其润湿性的限制，只有一个气泡在岛屿上扩散，其分离时的大小由岛屿的周长控制。这种金属-聚四氟乙烯（Ni-PTFE）复合材料是通过电化学共沉积工艺制备的。与现有共沉积模型的预测相反，当电流密度超过Ni2+的极限电流密度时，聚四氟乙烯在沉积物中的质量比显著增加。提出了一种描述氢泡共同演化时共沉积的机制。对完全疏水电极上气体演化的观察表明，在这种电极上气泡的生长速率不同于由溶解气体的质量输运控制的气泡生长速率。气泡通过聚并生长得越多，它的足部在电极上膨胀得越大，分离时的体积也越大。这种三线爬行机制解释了为什么当附着的气泡在分离之前多次合并时，它们在分离时的大小随着电流密度的增加而增加。(C) 2011出版的爱思唯尔有限公司
This paper deals with an experimental study on millimetre-size electrochemically evolved hydrogen bubbles. A method to generate gas bubbles controlled in number, size at detachment and place on a flat electrode is reported. Partially wetted composite islands are implemented on a polished metal substrate. As long as the island size is lower than a limit depending on its wettability, only one bubble spreads on the island and its size at detachment is controlled by the island perimeter. The composite, a metal-polytetrafluoroethylene (Ni-PTFE), is obtained by an electrochemical co-deposition process. On the contrary to predictions of available models for co-deposition, at current densities beyond Ni2+ limiting current density, the mass ratio of PTFE in the deposit strongly increases. A mechanism is proposed to describe co-deposition when hydrogen bubbles are co-evolved. The observation of gas evolution on fully hydrophobic electrodes highlights the fact that bubbles growth rate on such electrodes differs from growth rates when bubble growth is controlled by mass transport of dissolved gas. The more a bubble grows by coalescence the more its foot expands on the electrode the bigger its size at detachment. This triple line creeping mechanism explains why, when attached bubbles coalesce many times before detaching, their size at detachment increases with current density. (C) 2011 Published by Elsevier Ltd.