Zhao Panpan, Gong Shuai, Zhang Chaoyang, Chen Siliang, Cheng Ping
School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Paris Elite Institute of Technology, Shanghai Jiao Tong University, Shanghai 200240, China.
ACS Appl Mater Interfaces. 2024 May 29;16(21):27898-27907. doi: 10.1021/acsami.4c02428. Epub 2024 May 15.
Bubble dynamics significantly impact mass transfer and energy conversion in electrochemical gas evolution reactions. Micro-/nanostructured surfaces with extreme wettability have been employed as gas-evolving electrodes to promote bubble departure and decrease the bubble-induced overpotential. However, effects of the electrodes' wickability on the electrochemical reaction performances remain elusive. In this work, hydrogen evolution reaction (HER) performances are experimentally investigated using micropillar array electrodes with varying interpillar spacings, and effects of the electrodes' wettability, wickability as well as bubble adhesion are discussed. A deep learning-based object detection model was used to obtain bubble counts and bubble departure size distributions. We show that microstructures on the electrode have little effect on the total bubble counts and bubble size distribution characteristics at low current densities. At high current densities, however, micropillar array electrodes have much higher total bubble counts and smaller bubble departure sizes compared with the flat electrode. We also demonstrate that surface wettability is a critical factor influencing HER performances under low current densities, where bubbles exist in an isolated regime. Under high current densities, where bubbles are in an interacting regime, the wickability of the micropillar array electrodes emerges as a determining factor. This work elucidates the roles of surface wettability and wickability on enhancing electrochemical performances, providing guidelines for the optimal design of micro-/nanostructured electrodes in various gas evolution reactions.
气泡动力学对电化学析气反应中的传质和能量转换有显著影响。具有极端润湿性的微/纳米结构表面已被用作析气电极，以促进气泡脱离并降低气泡诱导的过电位。然而，电极的芯吸性对电化学反应性能的影响仍不清楚。在这项工作中，使用具有不同柱间距的微柱阵列电极对析氢反应（HER）性能进行了实验研究，并讨论了电极润湿性、芯吸性以及气泡附着力的影响。使用基于深度学习的目标检测模型来获取气泡数量和气泡脱离尺寸分布。我们表明，在低电流密度下，电极上的微观结构对总气泡数量和气泡尺寸分布特征影响很小。然而，在高电流密度下，与平面电极相比，微柱阵列电极具有更高的总气泡数量和更小的气泡脱离尺寸。我们还证明，表面润湿性是影响低电流密度下HER性能的关键因素，此时气泡处于孤立状态。在高电流密度下，气泡处于相互作用状态，微柱阵列电极的芯吸性成为决定性因素。这项工作阐明了表面润湿性和芯吸性在增强电化学性能方面的作用，为各种析气反应中微/纳米结构电极的优化设计提供了指导。
