Leung Chelsea, Briggs Kyle, Laberge Marie-Pier, Peng Smile, Waugh Matthew, Tabard-Cossa Vincent
Department of Physics, University of Ottawa, Ottawa, Canada.
Nanotechnology. 2020 Oct 30;31(44):44LT01. doi: 10.1088/1361-6528/aba86e. Epub 2020 Jul 22.
We present a thorough exploration of nanopore growth under electrical stress in electrolyte solution, and demonstrate that despite their superficial similarities, nanopore formation by controlled breakdown (CBD) and nanopore growth under moderate voltage stress are fundamentally different processes. In particular, we demonstrate that unlike the CBD process, nanopore growth is primarily driven by the level of ionic current passing through the nanopore, rather than the strength of the electric field generating the current, and that enlargement has a much weaker pH dependence than does CBD pore formation. In combination with other works in the field, our results suggest that despite clear current-dependence, Joule heating is unlikely to be the main driver of pore growth during electrical stress, pointing instead toward electrochemical dissolution of membrane material along the pore walls. While the chemistry underlying the growth process remains unclear, the dependence of growth rate on current allows decoupling of the pore enlargement mechanism from the possibility of forming additional nanopores during the growth process, providing a practical method by which to rapidly enlarge a nanopore without risking opening a second nanopore.
我们对电解质溶液中电应力作用下纳米孔的生长进行了全面探究，并证明尽管它们表面相似，但通过可控击穿（CBD）形成纳米孔与在中等电压应力下纳米孔的生长是截然不同的过程。特别是，我们证明与CBD过程不同，纳米孔生长主要由通过纳米孔的离子电流水平驱动，而非产生电流的电场强度，并且其扩大对pH的依赖性比CBD孔形成弱得多。结合该领域的其他研究成果，我们的结果表明，尽管明显依赖电流，但焦耳热不太可能是电应力作用下孔生长的主要驱动力，相反，指向沿着孔壁的膜材料的电化学溶解。虽然生长过程背后的化学原理仍不清楚，但生长速率对电流的依赖性使得孔扩大机制与生长过程中形成额外纳米孔的可能性得以解耦，提供了一种在不冒打开第二个纳米孔风险的情况下快速扩大纳米孔的实用方法。
